Based on the diffusion mechanism of water molecules in the polymer membrane, defects on the surface of polymer encapsulation will be filled and decomposed into smaller areas by Al2O3 nanoparticles to delay or hinder the penetration of water molecules. Accordingly, the dense Al2O3 nanoparticles are utilized to fill and repair the surface of the organic polymer by low-rate atomic layer deposition. This paper takes the pressure sensor as an example to carry out the corresponding research. Experimental results show that the proposed method is very effective and the encapsulated sensors work properly in a saline solution after a period of time equivalent to 153.9 days in body temperature, maintaining their accuracy and precision of 2 mmHg. Moreover, the sensors could improve accuracy by about 43% after the proposed encapsulation. Therefore, the water molecule anti-permeability encapsulation would have broad application prospects in micro/nano-device protection.The demand for waterproofing of polymer (parylene) coating encapsulation has increased in a wide variety of applications, especially in the waterproof protection of electronic devices. However, parylene coatings often produce pinholes and cracks, which will reduce the waterproof effect as a protective barrier. This characteristic has a more significant influence on sensors and actuators with movable parts. Thus, a defect filling method of micro-nano composite structure is proposed to improve the waterproof ability of parylene coatings. The defect filling method is composed of a nano layer of Al Micro/nano film coating has many important applications in device encapsulation and protection ,2,3,4,5.At present, micro/nano film coatings are generally made of micron-level thickness polymer materials ,14,15. PHowever, Parylene C film coatings need to be improved in terms of duration and effectiveness of long-term waterproofing mainly because Parylene C is a kind of polymer material, and its arrangement of molecular chains is not as dense as the atoms of metal and ceramic materials, and material preparation defects are unavoidable in production. Thus, Parylene C film coatings still possess certain water permeability, which is very unfavorable for long-term waterproof protection devices .2/Al2O3/HfO2)(ALD-3)/PI structure packaging material. Al2O3 and HfO2 layers were deposited by an atomic layer deposition (ALD) process at 250 °C, in the form of an ALD-3 stack. The copper protected by ALD Al2O3 and ALD-3 is effective at temperatures below 70 °C, and a life span of 37 °C can be estimated. After soaking in Phosphate Buffered Saline (PBS) at 60 °C for more than 1215 days, the PI/ALD-3/PI barrier did not degrade. Xie and Rieth et al. evaluated the long-term reliability of a dual-layer coating package with 52 nm ALD Al2O3 and 6 μm Parylene C deposited sequentially for the neural interface of the Utah electrode array (UEA), and compared it with the use of only parylene coating. The packaged devices were compared. The accelerated life test was carried out in PBS at 57 °C. The equivalent immersion time of double-layer coated devices at 37 °C was as long as 1044 days, while the package using only Parylene C had only about 100 days of life. Moisture diffusion and interface pollution are important reasons for Parylene C packaging failure [A study in 2020 by Li and Cauwe et al.  prepared failure ,23. HoweIn the actual working process, liquid gradually reaches the surface of devices through permeation in Parylene C thin film, causing device failure. Thus, analyzing the penetration mechanism of liquid in the Parylene C coating is important, and allows us to improve the effectiveness of water molecule anti-penetration. In simple terms, water molecules in polymer materials can pass through the instantaneous molecular chain gap caused by the thermal movement of the molecular chain, diffusing in the free volume of the chain and slowly accumulating on the surface of the devices after a long infiltration time. For devices with waterproof requirements, oxidation and corrosion of several materials in the devices will occur when the moisture content on the surface of the devices exceeds a certain value, eventually leading to the destruction and failure of the device. Encapsulation coating materials may also cause interface stratification, aging cracking, and other problems with the penetration of water molecules, thereby accelerating water penetration. Avoiding the surface and internal defects of the materials prepared is also difficult, and the high surface energy at the defects accelerates the diffusion of water molecules along with the defects ,25.2O3 layer, the micron polymer Parylene C layer, and the defect filling method of the micro-nano composite structure layer, were compared. The experimental results show that the waterproof performance of the device was improved substantially by using the micro-nano composite structure layer. Furthermore, the influence of the packed micro–nano composite encapsulation layer on the error and sensitivity were studied, as well as the variation of the error in the simulated body fluid. The results provide a reference for the current encapsulation protection and improvement of medical devices [According to this problem, this paper studies and analyzes the water penetration mechanism of Parylene C coatings. On this basis, we put forward a kind of defect filling method of micro-nano composite structure and encapsulation method for the water permeability of Parylene C. Surface defects of Parylene C coating are covered and filled by depositing nanoscale oxide coating on Parylene C thin film to improve the waterproof permeability of the encapsulation coating effectively . A contr devices .Parylene C is a linear, unbranched, and highly crystalline polymer material with good water vapor barrier properties. It has become a commonly used moisture-proof protective coating in implantable device encapsulation. The permeation mechanism of Parylene C coating was analyzed by using the diffusion principle and free volume theory .From a microscopic point of view, the permeation of water molecules in Parylene C is essentially a diffusion movement of molecules. Diffusion is a migration caused by the irregular thermal motion of molecules. In a humid environment, the diffusion of water molecules in polymer Parylene C is driven by the concentration gradient of water molecules as diffusion agents; thus, this diffusion belongs to transfer diffusion under a non-equilibrium system .Researchers have proposed various models such as the free volume model, barrier model, and concentration-dependent model to study this diffusion behavior better . The perThe free volume model identifies that the interior of polymer materials can be considered to consist of three parts: the volume occupied by polymer chains, the free volume existing between polymer chains, and the gap volume generated by the chain movement. Free volume is defined as the ratio of blank volume in the membrane to total volume and is related to external parameters such as temperature and pressure. According to relevant research, the diffusion of water molecules in polymer films is not continuous motion but continuous reciprocating motion over a small distance and jumping motion over a large distance, which conforms to the hole jump-diffusion theory; that is, diffusion is not continuous. In this process, the size and distribution of free volume inside the polymer film greatly influence the diffusion rate of small molecules in the film. The mechanism of jump diffusion involves the polymer segments around the permeated molecules. Although simulation calculation generally considers that a “pore” structure will be formed between two consecutive penetration positions in the polymer, the “pore” structure may not be strictly formed, but the permeated molecules and their surrounding polymer segments share a certain volume before and after the diffusion jump. The diffusion behavior of small molecules in the film has two forms: the tiny movement of small molecules in the free volume voids between polymer chains most of the time and the jump diffusion of small molecules between the free volume voids in the polymer. First, small molecules vibrate in the free volume voids. When the thermal motion of the flexible polymer chain forms a temporary channel connecting the two free volume voids, the water molecules that have gained energy may jump to another small space to complete the jump diffusion ,32,33,342O molecules is around 3 Å. Parylene C is relatively dense in polymer materials and the composition of molecular chains does not contain hydrophilic groups, which makes the material itself highly hydrophobic. Therefore, the entire Parylene C film ideally reflects excellent water vapor barrier performance.The results of simulation calculations show that free volume voids with a radius greater than 1 Å in Parylene C are less than 10% of the total volume, while the voids with a radius greater than 2 Å account for only about 1.5% of the total volume . TheoretHowever, the Parylene C film material actually fabricated cannot be equivalent to the ideal model, and the permeation of water molecules in Parylene C encapsulation coating is influenced by other factors. For example, in actual production and use, surface defects such as microcracks and pinholes usually occur on the surface of materials due to preparation, environmental conditions, structural composition, preparation thickness, and other reasons. Parylene C has good insulation properties ,37, whicIn summary, if the free volume of the material can be artificially reduced, the effective area where small molecules can jump and diffuse can be reduced, the number of defects on the surface and inside can be reduced, the crystallinity of the polymer material can be improved, and water molecules will have greater difficulty diffusing between polymer chains. This method can improve the impermeability of the prepared Parylene C material. However, considering that adjusting the free volume of the prepared Parylene C is not easy, we propose a defect filling method of micro-nano composite structure to solve surface defects and improve the waterproof ability of the encapsulation.Analysis based on the permeation mechanism of Parylene C coating shows that the permeation rate of water molecules in the polymer film is affected by the size of the free volume inside, and the number of surfaces and internal defects. We propose a double-layer encapsulation method with a filling mechanism for Parylene C defects because the deposited Parylene C has preparation defects such as pinholes and micro-cracks on the surface of the material. The deposition schematic diagram of the encapsulation method is shown in From the perspective of the anti-permeability mechanism of the method, on the one hand, the overall waterproof ability of the encapsulation increases due to the addition of the dense nano-scale inorganic oxide layer. On the other hand, the surface defects of Parylene C polymer film will be filled by nano-scale inorganic oxide particles at a low deposition rate. This makes the microscopic defects fill with nanoparticles and decompose into many smaller voids, which make the permeation space smaller, thus effectively hindering the rapid permeation of water molecules through the defects.After a nano-scale inorganic oxide layer is applied to the surface of Parylene C, according to the proposed mechanism, we found that most defects such as pinholes and microcracks on and near the surface of Parylene C were filled with inorganic oxide nanoparticles, thus repairing Parylene C to a certain extent. Moreover, the interfacial gaps between the two films were reduced due to the filling of the defects to reduce the probability of water molecules nucleating and accelerating condensation in the interfacial gaps. The interface had less room for water molecules; thus, it can effectively delay the permeation of water molecules and further affect the rate of the entire permeation.We obtained the encapsulation method based on the penetration mechanism of the Parylene C encapsulation method and the defect filling method of micro-nano composite structure, then we designed a series of verification tests. The reliability of the implantable medical devices must be considered to avoid the danger of working in the human environment. Therefore, in this experiment, we used such devices as an example to verify the proposed method. Among medical implantable devices, a large class of implantable devices has a movable structure, such as a mechanical quantity sensor and actuator. This large class of implantable devices has higher requirements for encapsulation technology due to the movable structure. Compared with ordinary devices, the waterproof encapsulation of implanted devices usually needs to meet three basic conditions: (1) implantation safety, (2) waterproof ability, and (3) work performance after encapsulation. Especially, higher requirements are proposed for the waterproof ability of the encapsulation layer of the implanted devices with movable parts, where the encapsulation cannot have a great influence on the motion of the movable structure in the device to ensure the working performance, that is, the encapsulation layer cannot be very thick. The encapsulation material must be flexible to ensure that the sensitivity and accuracy of the sensor will not be excessively lost.A kind of implantable pressure sensor with movable parts was selected as the experimental device.This kind of implantable pressure sensor can be implanted into the body to continuously monitor the body’s pressure for a long time. In actual clinical use, the service life of the device in the human body needs to reach months or even years. Therefore, compliant encapsulation is essential for the long-term stable operation of implantable pressure sensors in vivo.Parylene is a commonly used polymer encapsulation material. As mentioned above, the waterproof encapsulation of the implantable pressure sensor also needs to meet at least three conditions: (1) implantation safety, (2) waterproof ability, and (3) work performance, and the two latter requirements need a higher guarantee than in ordinary devices. Parylene is a type of semi-crystalline hydrophobic polymer and often used for encapsulation and protection due to its properties . Referring to Parylene can deposit conformal films using chemical vapor deposition (CVD). Commonly used types of parylene include Parylene C, Parylene D, Parylene N, and Parylene HT. Parylene C has a chlorine atom on the benzene ring, which is chemically inert and has low moisture permeability. Although its temperature resistance is lower in several parylenes, Parylene C is a Class VI material in the United States Pharmacopoeia and has the highest biocompatibility certification of plastic materials. Parylene C also has good micromachining compatibility and is commonly used in Micro-electromechanical Systems (MEMS) devices. As a flexible polymer material, it also exhibits mechanical flexibility and low intrinsic stress, coupled with the use of vacuum vapor deposition to prepare higher-quality Parylene C film. In general, Parylene C film can protect the movable structure of the sensor, and it ensures that the sensitivity and accuracy of the sensor will not be excessively lost. In summary, the selection of Parylene C is more consistent with the encapsulation requirements for implantable pressure sensors in this experiment.2O3) material with good waterproof ability as the nano-scale inorganic oxide layer in the defect filling method. For the low-rate deposition method indicated in the structure, we selected the atomic layer deposition (ALD) technique. The nano-scale Al2O3 film prepared by atomic layer deposition technology not only has a dense structure, few defects, and excellent waterproof penetration performance but also can cover irregular surfaces highly conformably with high film quality. The dense Al2O3 film has low mechanical flexibility, which may cause adverse effects on the sensitivity and accuracy of pressure sensors with movable parts. However, in the above defect filling method, Parylene C flexible material is used as the bottom buffer layer to separate Al2O3 from the sensitive element, which can also reduce the loss of pressure sensor sensitivity and accuracy. Next, we verified it through experiments.We selected dense alumina  group of defect filling method of micro-nano composite structure encapsulation: 1 um Parylene + 50 nm Al2O3. The fabricated device was placed in the physiological saline solution, and working life time and change of error were recorded regularly.To verify the proposed method and achieve new encapsulation methods, we designed a comparative experiment and fabricated three groups of devices in this paper: (1) group of only Parylene C encapsulation: 1 um Parylene C; (2) group of only alumina encapsulation: 50 nm Al2O3, and Epoxy AB adhesive (the main component is the epoxy resin). The specific process was as follows:All reagents and solvents are commonly available materials and can be used without further purification. The SM5420 sensor of SMI Company was used as an example in the experiment. The encapsulation material was Parylene C, Al(1) Parylene C encapsulation. The special coating system  PDS2010 was selected to form Parylene C coating film with strong adhesion on the surface of SM5420 pressure sensor using the following steps: First, the SM5420 pressure sensor was placed in the vacuum deposition chamber of the Parylene special coating system to form a nano-level A-174 coupling agent molecular layer on the surface of the device. Next, the Parylene C raw material was placed in the evaporation chamber of the Parylene special coating system. When the vacuum degree in the vacuum deposition chamber of the Parylene special coating system reached 10 mTor, the raw Parylene C material in the evaporation chamber was heated. When the temperature reached to 175 °C, Parylene C raw material was sublimated. The gaseous Parylene C obtained by sublimation entered the cracking chamber of the Parylene special coating system. When the temperature of the cracking chamber reached 690 °C, the gaseous Parylene C were cracked into gaseous monomers. The gaseous monomer entered the vacuum deposition chamber, deposited, and polymerized on the surface of the pressure sensor to form a Parylene C polymer coating.2O3 encapsulation. The device was placed in an atomic layer deposition chamber, and the deposition material was deposited layer-by-layer in the form of a monoatomic film on the periphery of the device at a deposition temperature of 200 °C. We used ALD deposition equipment (Sentech SI-ALD) for the plasma deposition process, the environment temperature was 200 °C, and the deposition time was 1.5 h. After completing the process, we achieved the deposition of 50 ± 1.5 nm Al2O3. The coating thickness was measured using an in-situ ellipsometer.(2) Al2O3 atomic layer deposition was applied to the device after coating with Parylene C.(3) Defect filling method of micro-nano composite structure encapsulation. Al2O3. Because the ellipsometer was not in contact with the sample during the measurement, there was no damage to the sample. Thus, this method is widely used in the thickness measurement of nano-scale materials. After the measurement, the average thickness of the Al2O3 coating was 50 nm.In the experiment, the thickness of Parylene C coating was measured by a Dektak XT step instrument, its working principle is to use a probe to measure the thickness of the film. When measuring, the Parylene C film was placed on the step instrument to make the probe pass near the edge of the step. The probe fluctuated when passed through the junction. The circuit was used by converting the fluctuations into electrical signals and the thickness of Parylene C film could be measured. After setting the chamber pressure and power, several points were randomly selected, and the average value of the coating thickness was 1 μm. At the same time, the experiment used an ellipsometer to measure the thickness of nano-scale AlTo improve the experimental efficiency, this paper adopted accelerated waterproof test experiments by higher temperatures. In the experiment, 67 °C was selected as the accelerated aging temperature, and its aging rate was eight times that of 37 °C body temperature. The sensor encapsulated with Parylene C was soaked in normal saline and device error was tested regularly. Moreover, we defined the sensor error as being beyond 2 mmHg as the pressure sensor damage standard.A pressure sensor measurement system was designed to test the error of the pressure sensor, as shown in NL), hysteresis (H), and repeatability (R). Total error value (TE) is obtained by the sum of the squares of the three types of error sources [The error testing method is as follows: in a room temperature environment, the sensors which need to be measured were placed in the pressurized cabin. No fewer than three circulation preloads were applied to the sensors, then six measurement points were selected at equal intervals within the full range including the upper and lower process of the sensor measurement, and the output corresponding to the input pressure point was recorded. The pressure measurement range was 0 to 75 mmHg and the pressure interval was 15 mmHg. The sensor output corresponding to the input pressure point was recorded, and the cycle was repeated more than four times. The least-square method was used to obtain the relationship curve between the sensor output voltage and the pressure, where the slope is the sensitivity. The error value is related to three error sources derived from non-linear error ( sources :(1)ET=NLAfter processing the test results, the errors of the pressure sensor before and after encapsulation were obtained.2O3 was 1.01 days, that of the device encapsulated with Parylene C was 89.5 days, and that of the device encapsulated with the defect filling method of micro-nano composite structure was 153.9 days. After analyzing the waterproof time data obtained by testing the sensors with three different encapsulation structures, we can conclude that the average waterproof days of the device after the micro-nano composite structure encapsulation was greater than the only Al2O3 or the only Parylene C encapsulation. The sum of the waterproof time of the Parylene C coated device and the Al2O3 coated device was close to 1.70 times than micro-nano composite coating devices. The phenomenon that the waterproof time is greatly improved shows that the waterproof effect of the double-layer micro-nano composite structure encapsulation is not a simple superposition of the waterproof effects of the two materials, and further mechanism explanations will be given in the discussion section. The simulated body fluid in the experiment was 0.9% normal saline.We conducted performance durability tests in the simulated human body fluid environment on the devices using three encapsulation methods and regularly measured the error of the device. The test results of the waterproof time are shown in 2O3 failed after working in simulated body fluid for less than 1 day, as shown in We separately analyzed the relationship between the error of the device and waterproof time, and characterized the relationship curve in 2O3 is too dense and rigid to coat directly onto the sensitive area of the pressure sensor because it may weaken the elastic deformation of the sensitive element and affect the performances of the sensor , which will reduce the sensitivity of sensor sensitive components and increase the error. Among them, it had the most significant effect on the error. For example, after the device was coated with a single layer of Al2O3, its error was increased. After the experiment, we found that the error value of the device before encapsulation was 0.2436 mmHg, while it was 0.5003 mmHg after encapsulation; the error change rate reached −105.39%. In terms of device error, the experimental results show that the defect filling method of micro-nano composite structure improved the error to a certain extent, as illustrated in 2O3 material in the micro-nano composite structure encapsulation was not directly in contact with the device and it did not negatively affect the error by the Al2O3 layer.During the experiment, we found that Al2O3 dropped substantially: the change rate of repeatability was more than 200%, but the two indicators were improved for the devices over Parylene C encapsulation. Similarly, the device with double-layer micro-nano composite structure encapsulation improved the adverse effects of Al2O3 encapsulation on devices in nonlinearity and repeatability. The performance change of the device is shown in 2O3. The superiority of this encapsulation method in device encapsulation and the defect filling method of micro-nano composite structure can achieve a better waterproof effect.According to the error theory, we selected several key indicators as examples for analysis. For example, the non-linearity and repeatability of the device after the atomic layer deposition of Al2O3 from the sensitive components, preventing Al2O3 from directly contacting the sensor sensitive components, and reducing the effect of the dense and large elastic Al2O3 encapsulation on the movable parts, which was verified from the experimental results. In general, the double-layer micro-nano composite structure encapsulation can reduce the effect of the encapsulation material on the movable parts, which is longer than the sum of the waterproof time of the two single-layer micro-nano encapsulation methods. Moreover, the thickness of this encapsulation method is extremely thin. After encapsulation, the sensitivity of the sensor only decreased by about 1.3%. Therefore, the defect filling method of micro-nano composite structure based on Parylene coating proposed in this paper can achieve the double guarantee of waterproof time and sensor performance.The double-layer micro-nano encapsulation structure proposed in this paper can use Parylene C film with good flexibility as a base buffer material between the nanomaterial and the sensor, separating Al2O3 double-layer encapsulation had a relatively long waterproof time. The waterproof time of the double-layer encapsulation made of two materials was longer than the sum of the waterproof time of the individual encapsulation of each material, and the same material kept the same thickness in the comparative experiment. This finding means that the waterproof effect of micro–nano double-layer encapsulation made of two kinds of materials is not simply the superposition of single-layer effects but also the other increase of waterproof effect. The composite of micro-nano double-layer materials promotes the overall waterproof ability on the original basis.The experimental results in 2O3 film will be deposited on Parylene C by atomic layer deposition technology, covering the lower layer compactly, uniformly, and conformally. Under the atomic layer deposition with low-rate deposition conditions, Al2O3 nanoparticles had sufficient time and space to fill the surface defects of Parylene C material and continue multi-cycle deposition, thus forming a compact 50 nm Al2O3 layer. From the perspective of the anti-permeability, on the one hand, the overall waterproof ability of the encapsulation increased, which is a simple addition of the waterproof effect of the original Parylene C single layer. On the other hand, the surface defects of Parylene C polymer will be filled with Al2O3 nanoparticles, and these defects will be filled and separated into many smaller voids on the micro-level. Therefore, the permeation path of water molecules in the Parylene C encapsulation layer was prolonged, and the permeation space was reduced. Thus, the rapid permeation of water molecules through defects is effectively hindered, and the waterproof ability can be additionally improved with Parylene C and ALD Al2O3 micro-nano composite structure encapsulation. In the experiment, the life days of the double-layer coated device group was not the simple sum of the life days of the single-layer control group. The results of control experiments show that the micro-nano composite coating proposed in this paper achieved good results for the encapsulation of implantable devices.The proposed defect filling method of micro-nano composite structure can explain and prove this phenomenon well. Pinholes, microcracks, and other defects were observed on the surface of Parylene C, which were directly exposed to water in the case of a single layer. Using the defect filling method, a thin Al2O3 is better than that of polymer Parylene C. However, if ALD Al2O3 is used alone for encapsulation, the coating thickness and deposit ALD Al2O3 on the device surface must be increased, which will lead to several serious problems. The Al2O3 encapsulation layer is dense and has a large elastic modulus. In the experiment of the only ALD Al2O3 encapsulation, we found that although the Al2O3 encapsulation layer has only nanometer thickness, if it is directly covered in the sensitive area of the pressure sensor, the elastic deformation of the sensitive element will be weakened, which will lead to the decrease of sensitivity and the increase of error of the sensor sensitive element. However, in the defect filling method of micro-nano composite structure proposed in this paper, Parylene C, a polymer material with good flexibility and low elastic modulus, was used as the inner anti-permeability coating, which has minimal effect on the elastic deformation of sensitive elements. Then, the surface of Parylene C was filled with nano-scale ultra-thin ALD Al2O3, which compensated for the permeation defects of Parylene C. However, Parylene C flexible material was used as the internal buffer layer of the encapsulation, which avoided the direct contact between Al2O3 and sensor sensitive elements and reduced the loss of device sensitivity. These two layers were thin. Thus, after double-layer encapsulation, the experiment shows that the sensitivity of the sensor only decreased by about 2%. The experimental results in The defect filling method of micro-nano composite structure proposed in this paper has other advantages for implantable pressure sensors. Theoretically, the waterproof ability of dense ALD Al2O3 particles in the micro-nano composite structure were like “rivets”. The overall mechanical properties of the sensor are improved such that the combination between the Parylene C coating and the movable parts was more stable. Fourth, the light and thin micro-nano-composite-coating will not affect the flexibility of the movable structure in the pressure sensor and the output of the sensor signal. Therefore, the encapsulation method of the defect filling method of micro-nano composite coating can reduce nonlinear error and repeatability error of the sensor and make the output of the pressure sensor more accurate.Why is the measurement error of the pressure sensor reduced after the defect filling method of micro-nano composite structure encapsulation? Our analysis shows that the micro-nano composite action of the defect filling method reduced the error of the pressure sensor. First, the micro-nano composite structure coating had good barrier protection ability, which can isolate the medium effect on the performance of the pressure sensor in the external environment such as the corrosion of water molecules and oxygen. Second, the Parylene C coating in the micro-nano composite structure had low thermal conductivity, which reduced the interference of the temperature change of the external environment on the pressure sensor. Third, the gap between the Parylene C coating and the movable parts in the sensor was effectively filled because the nano-scale Al2O3 deposited by the atomic layer showed a 105% sharp fall in errors and the average waterproof time of the devices was only 1.01 days. The average waterproof time of the devices coated with only Parylene C deposited by the chemical vapor was 112 days. Therefore, the results show that the proposed method is plausible and practicable. The new encapsulation method has the advantages of ultra-thin thickness, high adhesion, strong robustness, and good protection for body fluids, minimal impact on device performance and size, and good biocompatibility. It has a promising application prospects in the field of the industrial devices working in harsh environments and implantable devices such as implantable sensors.In this paper, aimed at solving the water penetration problem caused by the surface and internal defects with parylene fabrication, a defect filling method is proposed based on the diffusion mechanism of water molecules in the polymer membrane. According to the proposed method, a feasible method to prepare such a micro-nano composite coating with parylene is also proposed. This method and its waterproofing effects are studied and verified through its encapsulation on pressure sensors. The experimental results show that the encapsulated sensor has superior long-term stability in vivo, while maintaining high sensitivity and accuracy. The sensitivity of the pressure sensor decreased by only 1.3% after using the proposed micro-nano composite coating encapsulation even though the coated material was attached to the sensitive area of the sensor. The error was reduced by 43% and the devices remained in a good performance after working in the simulated body fluid for 180 days. By contrast, the devices coated with only Al


These prediction models are expected to be utilized in whole-building simulation programs for estimating the energy consumption of TERPs in the heating mode.The purpose of this study is to investigate the suitable operation and performance of a thermoelectric radiant panel (TERP) in the heating operation. First, the hypothesis was suggested that the heating operation of TERP can operate without a heat source at the cold side according to theoretical considerations. To prove this hypothesis, the thermal behavior of the TERP was investigated during the heating operation using a numerical simulation based on the finite difference method. The results indicated that it is possible to heat the radiant panel using a thermoelectric module without fan operation via the Joule effect. A mockup model of the TERP was constructed, and the numerical model and hypothesis were validated in experiment 1. Moreover, experiment 2 was performed to evaluate the necessity of fan operation in the heating operation of TERP regarding energy consumption. The results revealed that the TERP without fan operation showed the higher coefficient of performance (COP) in the heating season. After determining the suitable heating operation of the TERP, prediction models for the heating capacity and power consumption of the TERP were developed using the response surface methodology. Both models exhibited good R Thermoelectric modules (TEMs) are attracting increasing attention as a non-vapor compression based technology ,2,3,4,5 2 in Hong Kong in a simulation. Shen et al. [2 for TERP. Lim et al. [Lim and Jeong  proposedn et al.  developem et al.  developem et al. .On the other hand, the heating operation of the TERP was still not established in the previous studies, even though the same TERP can be easily operated for heating purpose. The heating and cooling sides of the TEM can be simply switched by changing the direction of a direct current based on the Peltier effect . AdditioT between the hot and cold sides was <20 °C [T between the cold and hot sides of the TEM was ranged from 12 to 38 °C. However, the previous studies were conducted under the low supply air and a low radiant surface temperature. Additionally, few radiant-heating approaches have been investigated using TEM. Therefore, it is necessary to investigate the characteristics of the TERP in the heating mode and evaluate its performance under various operation conditions.In previous studies, TEMs have been employed for heating applications. The performance of a thermoelectric air heater for building was theoretically investigated using dynamic analysis . The ress <20 °C . Sun et s <20 °C  proposedIn this study, the performance of the TERP for heating operation was analyzed via numerical and experimental investigations. First, the hypothesis was proposed that it is unnecessary to supply air  to the cold side for the heating operation of TERP during the heating season, according to the theoretical background. Then, a thermal behavior of the TERP was numerically simulated using the finite difference method in the heating mode. In experiment 1, the numerical model and hypothesis were validated. Experiment 2 was conducted to estimate the necessity of fan operation in the heating mode of the TERP. Finally, empirical models were developed to predict the energy consumption and heating capacity of the TERP in the heating mode.A TERP consists of an aluminum panel, insulation, heat sinks, and TEMs, as shown in SITc and SITh), Joule effect (0.5I2R), and heat conduction (KΔT). The driving force of the Peltier effect is an electromotive force, and heat conduction from the cold to the hot side of TEM. Simultaneously, heat is transferred from the hot side to the cold side of the TEM by the driving force of the temperature difference. Additionally, the TEM has its own electrical resistance; thus, heat is generated by the Joule effect.The amount of heat absorption and rejection at TEM are calculated using theoretical equations (Equations (1) and (2)) . TEM worThe cooling operation of TERP employs outdoor air to remove the rejected heat for maintaining the cooling performance. In a previous study , a lowerIn the heating mode, heat is absorbed from the outdoor air and transferred to the aluminum panel, similar with the air source heat pump a. The COBetween the surface of heating panel and air in the room, the heat is transferred through radiation and convection . HoweverA numerical model for the TERP was established to investigate the thermal behavior of the TERP in the heating mode without fan operation . The principle of the heating mode without fan operation in the TERP can be confirmed by validating the results of the numerical model and in situ experiments.A two-dimensional (2D) numerical simulation was conducted using the finite difference method. The main purpose of numerical simulation was to confirm the working process of TERP for the vertical heat transfer through TEM, therefore the 2D analysis was suitable for this study. The thermal behavior of the base plate, insulation, aluminum panel, and TEM was analyzed. The air temperature in the duct was assumed to be constant, i.e., equal to the ambient temperature, which was assumed to be 26 °C. In the initial condition, all the nodes were set to the ambient temperature. For the boundary contacts with insulation, the Neumann boundary condition (BC) was used. The symmetric BC was applied at the center of the TEM to reduce the calculation time. Additionally, for the boundary contacts with the air side, a constant BC was used, according to the assumptions that the air temperatures of the room air and duct were constant. Binary control in an open-loop system was used to achieve the target surface temperature of TERP . In each time step of the simulation, the mean surface temperature was calculated to investigate the operation of the TEM. Power was supplied, unless the mean surface temperature was higher than the target value with a 1 °C deadband.K), electrical resistivity (R), and Seebeck coefficient (S) of the TEM are given by Equations (3)–(5), respectively. When the input current is determined, the cooling and heating capacities can be derived using Equations (1) and (2) with the calculated thermophysical properties of the TEM. Additionally, the input voltage and power consumption can be derived using Equations (6) and (7).The thermophysical properties of the TEM were simulated according to the properties of the TEM in In Re) and Nusselt (Nu) number of the room air at the panel surface were calculated using Equations (8) and (9), respectively [cL) was 0.4 m, which is equal to the length of the panel (panelL) because the room air on the surface of the panel is an external fluid [Gr) was derived using Equation (10), and if convh) could be directly determined using Equation (13). Unless it is <1.1, the convection should be treated as natural convection, and the correction equations for the Nusselt number (Nu) should be used in Equations (11) and (12) [The heat convection and radiation at the surface of the TERP can be determined using Equations (8)–(16). The Reynolds  ,44. ConsTMRT) was considered being equal to the room air temperature (Troom) [εpanel) was 0.95. Finally, the amount of heat radiation from the panel to the room can be calculated using Equation (16).The heat-radiation coefficient was determined using Equation (15) . The mea (Troom) . This as (Troom) . The surQcond,1 and Qcond,3) was calculated according to the simple heat conduction equations of Equations (17) and (18), independently. Additionally, the rejected and absorbed heat of TEM were derived using Equations (1) and (2), respectively.The amount of heat conduction at the hot side and cold side of TEM to the panel and base plate (Cp), and heat conductivity (κ). Equations (20)–(23) are the governing equations for the top surface of the base plate, cold side of the TEM, hot side of the TEM, and bottom surface of the aluminum panel, respectively.The governing equations were established (Equations (19)–(23)) using the finite difference method. Equation (19) is a governing equation for non-boundary nodes. The properties were applied according to the location of the node, such as the density (t) must be higher than the minimum time step in Equation (31). The minimum time interval purposes to avoid the denominator becoming zero in the equations from the finite difference method (FDM). An algorithm of the whole simulation process is shown in For computational calculation, the governing equations were discretized using Equations (24)–(26), and the results are given by Equations (27)–(30), which correspond to Equations (20)–(23). For the stable analysis condition, the time interval  and combined heat transfer coefficient (hcomb) in Equation (33). Additionally, its effect can be replaced with the heat conduction through insulation [The heating capacity of the TERP is derived using Equation (32) and is based on the convection and radiation, as indicated by Equations (14) and (16). Therefore, the thermal resistance between the room and the panel surface  were 8 and 36 °C, respectively, i.e., the greatest difference possible according to the capacity of the environment chamber. The minimum and maximum surface temperatures (Tsurf) were set as 45 and 60 °C, respectively [3/h, in accordance with a previous study [2K by using 5-mm-thick expanded polystyrene (EPS) insulation between the plate and the TERP and the room temperature was set as 24 °C using the Peltier plate.The objective of experiment 2 was to investigate the necessity of the fan operation from the viewpoint of the energy performance of heating operation of TERP. The energy consumption was measured according to three variables: the surface temperature, volume air flow rate, and air temperature in the duct. Using the 2 the fan . The minectively ,50,51. Tus study . The floIn OAT for achieving energy saving by operating the fan were estimated through linear regression between two points. The simple linear regression method could be used based on the linearity between the energy consumption of TEM and ΔT between the hot and cold side of TEM [The criteria of e of TEM ,28, sincTOA was <32.4 °C regardless with 3/h had energy benefits when OAT was higher than 28.4 and 36.8 °C, respectively. These criteria for TOA based on Tsurf was 45 °C. They differed when Tsurf was 60 °C because using increased Tsurf was 45 °C, the energy saving for the TEM achieved by increasing Tsurf was 60 °C. As there is no heating season when TOA is >28 °C, it can be concluded that fan operation is unnecessary in the heating operation of the TERP.It was unnecessary to operate the fan for TERP heating when k factorial design method was employed to develop a regression model using the response surface methodology (RSM) [It was revealed in the previous section that the TEM is only activated for heating in the TERP. As described in this section, empirical models were developed to predict the energy consumption and heating capacity of the TERP in the heating operation. For the experiment design, the 2gy (RSM) .Tsurf), room temperature (TRA), and combined heat-transfer coefficient (hcomb). In Tsurf), room temperatures (TRA), and the combined heat transfer coefficient (hcomb) had as wide a range as possible, for maximizing the utilization of the empirical models. The minimum and maximum combined heat-transfer coefficients (hcomb) were derived according to the combination of natural and forced convection, for a mean radiant temperature (TMRT) between 20 and 28 °C.Three model parameters were defined as the following independent variables: the target surface temperature  and the heating capacity (Qpanel). The heating capacity of the TERP (Qpanel) was not affected by the properties of TEM; however, the required power (P) depended on the TEM. Therefore, the normalized power ) was used for dimensionless modeling. The maximum power (Pmax) can be easily calculated using the properties of the TEM. Therefore, the actual required power (P) can be derived with the normalized power (P*). This method can be applied when it was postulated that the performance curves of commercial TEMs showed an alike value [2Te3) for the thermocouples. Additionally, they have similar fractions of the total TEM area covered by thermocouples, despite the different numbers of thermocouples. The heating COP of TEM should be higher than 1.0, which is higher than that of an electric heater owing to the heat from the cold side by the Peltier effect when the normalized power (P*) is higher than 0.05.The dependent variables were the required power  of the TERP in the experiments was calculated using Equation (35). The room temperature (TRA) and combined heat-transfer coefficient (hcomb) were fixed independent variables, and the actual surface temperature  was the average value for seven thermocouple sensors on the surface of the TERP. It is also specified that the unit of heating capacity of TERP (Qpanel) is watt per square meter (W/m2).The heating capacity (Qpanel) and normalized power (P*) showed mostly a steady value or fixed value, therefore it was not suitable using all raw data for statistical analysis.The operation data was collected from the eight experiment cases in Qpanel) and normalized power (P*) are summarized in hcomb) showed a higher system COP of TERP, which means the conditions in forced convection. The lower room temperature (TRA) also presented the higher system COP of TERP because of the higher temperature difference between the room and panel surface.The measured heating capacity of TERP (py) and the propagation error (by)—as described by Equation (36). The random error (py) was calculated using Equation (37) with the mean value (M) and standard deviation (Sr) of the measured surface temperature. The propagation error (by) occurred from a propagation in data reduction. However, there was no data reduction because there was only one parameter  to measure. Hence, a fixed error (by) equal to the multiplication of the standard deviation of the measured surface temperature  was used instead of the actual surface temperature . Due to the uneven surface temperature distribution of TERP, the actual surface temperature could not be higher than the target surface temperature in the heating operation. It is natural that the radiant panel had a surface-temperature difference in the heating mode, as ASHRAE recommended that the surface temperature should not exceed 10 °C [The prediction models for the heating capacity and energy consumption are given by Equations (39) and (40). The residuals followed a normal distribution well in the normal probability for both developed models without distortion. In ed 10 °C . This isk factorial design, the axial point, and the center point. The 2k factorial design matrix was previously used for statistical modeling; therefore, the axial (Case 1–6) and center point (Case 7) matrices were selected for validation experiments, as shown in Using the center composite design (CCD) method , the addA total of 2726 data samples were acquired from seven experiment sets for validation. Using the proposed prediction models (Equations (39) and (40)), the predicted energy consumption and heating capacity of the TERP were compared with the measured values, as shown in The empirical models for predicting the heating capacity and energy consumption of the TERP agreed well (within 10% error bounds) with the values from the measurements. Additionally, the theoretical heating capacity of the TERP is compared in In the present study, the suitable operation of the TERP for space heating was investigated using a numerical simulation and experiments. Additionally, empirical models were developed for predicting the energy consumption and heating capacity of the TERP in the heating mode.The results indicated that TERP showed better performance when it was operated without a fan, which supplies the heat source to the cold side of TEM. It means the low temperature air source in the heating season hinders the heating operation of TERP, and it is better to operate the TERP autonomously. This operation strategy can also avoid the frosting problem without the defrosting process. From the experiment, the system COP of TERP for space heating was ranged from 0.4 to 1.2. The system COP of TERP was similar or slightly higher than that of electric radiator, while it has the advantage that the TERP can be used for heating and cooling both, different with the electric radiator.The developed prediction models exhibited good agreement (with 10% error bounds) with actual values in validation experiments. The two developed models are dimensionless, and their independent variables can be easily defined; therefore, these prediction models can be used for the design stage and building energy simulation programs. In addition, the prediction model for the energy consumption can be applied on the control logic to determine the input power according to the target surface temperature and room condition. In the future study, the extended study will be conducted to reclaim the waste heat from the exhaust air for heating operation of TERP integrated with a ventilation system.


To quantify the age-dependent changes in the relative volume of elastic fibers, collagen fibers and the proportion of collagen types I/III in the corpus spongiosum of rats.Forty-eight rats, raised under similar conditions, were divided into four groups (G1 to G4) and underwent penectomy at the ages of 6, 9, 12 and 24 months, respectively. Histological sections from the middle segment of the penis were stained with Weigert’s resorcin-fuchsin, Masson’s trichrome and Picrosirius red, the volumetric density of elastic fibers, collagen fibers and the proportion of collagen types I and III in the corpus spongiosum were determined by stereological analysis.A reduction in the proportion of collagen I/III between the groups G3 and G4 (p < 0.048) was observed. In the volumetric analysis of elastic fiber, we observed a significant rise between the groups G2 and G3 (p < 0.03) and a reduction of the volume between the groups G3 and G4 (p < 0.01). However, there was no difference in the quantity of total collagen between the groups (p > 0.54).Aging in rats did not change the quantity of total collagen but reduced the proportion of collagen types I/III and the volume of elastic fibers. The process of aging impacts the urinary system and affects the functioning of essentially all urinary organs. A number of these changes have a direct impact on genitourinary health, urologic function and clinical decision-making related to urologic care.,The changes associated with aging can particularly affect the functioning of the lower urinary tract and cause urinary incontinence and urinary irritative symptoms,With aging, the need for auxiliary procedures that tend to be frequently performed via endoluminal therapy also increases. However, these procedures often result in scarring of the CS that may be worsened with aging. Therefore, there is a need to understand the tissue composition and the natural physiology of the CS with aging in order to avoid surgical complicationsIt should also be noted that several changes in the female urethra associated with age have been well described; however, no such studies on the male urethra existThis study followed the ethical principles of animal experimentation established by the Brazilian College of Animal Experimentation (COBEA) and the norms of the Canadian Council on Animal Care (1993). It was approved by the Ethics Committee on Animal Experimentation (CEEA), Department of Biological Sciences of the Universidade Federal do Paraná, as part of the project “Anatomical and physiological evaluation of male urogenital aging” process No. 23075.032620/2010-10.Rattus norvegicus var. albinus), maintained under a light-dark cycle of 12 h and controlled temperature (22 °C) and receiving water and food  ad libitum, until they were sacrificed. Rats were divided in four even groups, kept in even conditions until the age each group was ascribed for the time of the sacrifice for the study. The rats were randomly divided into four groups of 12 rats each . The rats underwent sacrifice and resection of the penis and other organs for research at the ages of 6 (G1), 9 (G2), 12 (G3) and 24 (G4) months of age. For the sacrifice procedures, the rats were anesthetized intraperitoneally with a solution of ketamine hydrochloride (57.67 mg/mL) and 2% xylazine hydrochloride at a dose of 1 mL/kg body weight. A one-punch cardiac puncture was performed and cardiac arrest was induced by exsanguination. This procedure was followed by resection of the penis and kidneys, bladder, liver, brain, heart and aorta for use in multiple other researches of the aging process in a multidisciplinary.Forty-eight male Wistar rats  were prepared. Ten consecutive sections were mounted on slides and stained using Picrosirius red for distinguishing collagen type I and III, Masson’s trichrome for total collagen and Weigert’s resorcin-fuchsin method for visualizing elastic fibers. The images of the slides were captured using a video camera coupled with an optical microscope at 400 × magnification for the sections stained with Masson’s trichrome and Weigert’s resorcin-fuchsin methods. To capture the images of Picrosirius red staining, we used an optical microscope at 400 × magnification under polarized light to differentiate collagen type I (red fibers) from Type III (green fibers). We used the Zen 2.3 software (blue edition) from Carl Zeiss Microscopy GmbH, 2011 for scanning and editing the images .In order to perform the stereological analysis, we used the Image Pro Plus software, from Media Cybernetics, to calculate the total area of CS and the percentage of elastic fibers, total collagen fibers and collagen types I and III. This method was used to determine the area occupied by the spectrum of colors that represent a particular fiber in the CS. Such color area quantification was performed using HSI histogram-based color segmentation, after color equalization by the same software. The color area was divided by the complete area of CS to determine the percentage of CS occupied by that specific fiber. The areas of collagen types I and III were calculated in a separate manner and the area of collagen type I was divided by the total area of collagen type III to determine their ratios.A Pearson correlation statistical test was used to evaluate the association between the ages of rats and the relative areas of collagen and elastic fibers in the CS. Tukey’s multiple comparison test was used to assess the statistical significance of the differences in relative areas observed between the groups. A significance level of 95% was considered (p < 0.05) as statistically significant.The analysis of variance indicated significant difference between the proportions of collagen in at least one pair of groups. Tukey’s multiple comparison test identified significant differences between G3 and G4 with the p-value adjusted to 0.048. However, the other contrasts were not significant. The Pearson’s correlation coefficient estimated between the ages and the proportion of collagen types I/III was 0.4, with the p-value of 0.004, indicating that an increase in the age is associated with diminution in the proportion of collagen types I/III . No signThe analysis showed a significant difference between at least one pair of ages. Tukey’s multiple comparison test revealed a significant difference between G1 and G3, with the adjusted p-value of 0.03, and between G3 and G4, with the adjusted p-value of 0.01. However, the other contrasts were not significant. In this case, we observed an increase in the volume of elastic fibers until 12 months and then a significant decrease within 24 months, which is possible.We observed the impact of the aging process in the extracellular matrix of the CS based on our results. These changes encompassed an initial increase followed by a decrease in the amount of elastic fibers and proportion of collagen type I/III.et al.In this study, we found an initial increase followed by a reduction in the quantity of elastic fibers with age. These changes, marked by a decrease in the volume of elastic fibers at the later stage, could be attributed to the late-onset of hypogonadism related to aging, as explained by Pradidarcheepet al.et al.et al.et al.et al.da Silva et al.et al.et al.The elastic fibers in the extracellular matrix is known to affect the elasticity of the tissue and, therefore, may enhance obstructive symptoms, as demonstrated by Idzenga et al.By analyzing the decrease in the ratio of collagen type I/III, we found a similar result to Rodrigues et al.et al.Our study did not find any significant change in the quantity of total collagen with the increase in age. This finding contradicted from the aforementioned study by da Silva Additionally, our findings provide a better understanding of the age-related changes in the CS and thereby creates a base for developing new strategies to treat urinary system-related diseases and prevent the disease pathology. However, the greatest limitation of our study is that we cannot infer whether the exact same process occurs in humans as well and therefore more studies on human CS should be done. Further studies are also needed to correlate these histologic alterations with the direct impact on LUTS and the healing process in humans.Aging has a considerable impact on the composition of the extracellular matrix. These changes occur for elastic fibers as well as for collagen fibers.


Intravenous delivery is the fastest conventional method of delivering drugs to their targets in seconds, whereas intramuscular and subcutaneous injections provide a slower continuous delivery of drugs. In recent years, nanoparticle-based drug-delivery systems have gained considerable attention. During the progression of nanoparticles into the blood, the sound waves generated by the particles create acoustic pressure that affects the movement of nanoparticles. To overcome this issue, the impact of sound pressure levels on the development of nanoparticles was studied herein. In addition, a composite nanostructure was developed using different types of nanoscale substances to overcome the effect of sound pressure levels in the drug-delivery process. The results demonstrate the efficacy of the proposed nanostructure based on a group of different nanoparticles. This study suggests five materials, namely, polyimide, acrylic plastic, Aluminum 3003-H18, Magnesium AZ31B, and polysilicon for the design of the proposed structure. The best results were obtained in the case of the movement of these molecules at lower frequencies. The performance of acrylic plastic is better than other materials; the sound pressure levels reached minimum values at frequencies of 1, 10, 20, and 60 nHz. Furthermore, an experimental setup was designed to validate the proposed idea using advanced biomedical imaging technologies. The experimental results demonstrate the possibilities of detecting, tracking, and evaluating the movement behaviors of nanoparticles. The experimental results also demonstrate that the lowest sound pressure levels were observed at lower frequency levels, thus proving the validity of the proposed computational model assumptions. The outcome of this study will pave the way to understand the interaction behaviors of nanoparticles with the surrounding biological environments, including the sound pressure effect, which could lead to the useof such an effect in facilitating directional and tactic movements of the micro- and nano-motors. In recent years, nanoparticles have attracted considerable interest for various restorative applications. Under a rotating attractive field (AMF), certain magnetic nanoparticles (MNPs) can create heat through hysteresis that can be exploited to treat malignant growth. Furthermore, MNP heating has been presented as a strategy for remote neuromodulation . The desAn acoustic field was incorporated into a projection-based stereolithography (PSL) framework to design diverse microparticles into thick parallel bends or systems in the fluid tar. The impact of acoustic field settings and assembling process parameters on the design was described . MoreoveIn recent years, Polymer nanocomposites have attracted considerable attention from scientists, and they have been extensively utilized for various biomedical methods, including drug-delivery . PolymerThe purpose of this research is to conceptualize the structure of these nanoparticles. Through this synthesis, the molecules can overcome the effect of sound pressure levels resulting from their movement as they flow into the blood to reach the target cells. Moreover, an experimental method is proposed, and the results are discussed.The proposed structure of the nanoparticle drug and the related computational model are described in detail. The experimental validation of the proposed nanotechnology-based drug-delivery system is presented using various medical ultrasound (US) machines. The US images are evaluated on physically simulated models by injecting Aluminum 3003-H18 particles.x1, x2, x3) in each structure. Furthermore, i is the position of the nanoparticle in the proposed architecture. Moreover, Green’s function is used to solve the differential equations of the proposed system. Since the proposed structure is acceptable, some of its parts separate from the other parts because of heterogeneity using the following equation:i. Then, the solution to the proposed arbitrary linear differential is presented by the following equation:u is given by Poisson’s formula that achieves the prescribed boundary values and x and z dimensions is represented by Equations (3) and (4). For a small The proposed drug composition consists of a group of asymmetric nanoparticles that are intertwined in a circular form. The structure of pharmaceutical nanoparticles depends on the formation of molecules in multiple structures of similar composition, as shown in It follows x, z and y satisfy If To study the effect of the serum protein on the movement of the proposed structure, we use the equation that represents the relationship between the molecules and the serum protein :(7)N=4π,Equation (10) represents the effect of the serum protein on the velocity of the proposed structure in terms of the radii of protein particles.x or y, it is concluded thatIn the two-dimensional case with v =  is the speed vector. x = ; p is the pressure, where p = ; ma is the total mass of the composite nanoparticles and d is the diameter of the circular architecture of the composite nanoparticles. From Equations (12) and (13), the Euler equation to measure the effect of the pressure is represented in terms of the angular velocity of the composite nanoparticles:Consider the following Euler equation to measure the effect of the pressure due to the flow of the composite nanoparticles in the blood:By considering the conservation mass, the following equation is considered in terms of angular velocity:Assume that the blood is compressible and the following state function is applied 2O3 and a cosmetic powder) to mimic the texture and color of human soft tissues. The ratios for mixing these prototype phantom components were 97.52% of silicone rubber, 0.26% of face cosmetic powder, and 2.22% of Al2O3 [The experimental validation of the proposed nanotechnology-based drug-delivery system was performed using various medical ultrasound (US) machines. The US images produced were evaluated on physically simulated models by injecting Aluminum 3003-H18 particles  intravenously. The experimental preparation included the development of a prototype US medical phantom with comparable characteristics of human soft tissues in terms of the interaction of US waves with tissue . The US of Al2O3 . The mixof Al2O3 .This section presents the validation results of the novel sound pressure computational model using acoustic-structure interaction COMSOL application. Then, the experimental validation results of the proposed nanotechnology-based drug-delivery system are presented. The results of the computational model and the experimental results are discussed.−9 dB at 1 nHz, as shown in case (A), which did not have a strong effect on the movement of the nanoparticle due to the SPL effect on one end. The value of SPL of the nanoparticle of polyimide increased to 1 × 10−8 dB at 10 nHz, as shown in case (B), at both ends of the nanoparticle, which showed that SPL did not have a strong effect on its improvement. The value of SPL of the nanoparticle decreased to 6 × 10−9 dB at 20 nHz, which did not affect the motion of the nanoparticle, as shown in case (C). The value of SPL reached a maximum of 6 × 10−9 dB at 60 nHz as shown in case (D). It can be noted that at different frequencies of the nanoparticle of polyimide, the maximum value of SPL was noted at 10 nHz and the lowest value was noted at 20 nHz. −8 dB at a repeat frequency of 1 nHz, as shown in case (A); in this case, the presence of the SPL impact was toward one side. The SPL of the nanoparticle of acrylic plastic increased to 1.6 × 10−8 dB at a repeat frequency of 10 nHz, as shown in case (B).The proposed structure was simulated using acoustic–structure interaction COMSOL application . Differe−9 dB, which did not influence the movement of the nanoparticle. Case (D) demonstrates the estimation of SPL at a repeat frequency of 60 nHz, where it reached the extreme value of 4 × 10−9 dB. At various frequencies of the nanoparticle of acrylic plastic, the most extreme estimation of SPL was noted at 10 nHz. −10 dB at 1 nHz, as shown in case (A), which did not have a strong effect on the movement of the nanoparticle due to the SPL effect on both the ends. At a frequency of 10 nHz, the SPL of nanoparticle of Aluminum 3003-H18 increased to 3.6 × 10−10 dB, as shown in case (B). This effect was at only one end of the nanoparticle, which shows that SPL did not have a strong effect on its improvement. In case (D), the SPL of the nanoparticle decreased to 4 × 10−10 dB at 20 nHz, which did not affect the motion of the nanoparticle. Case (D) shows the value of SPL reached the maximum value of 3.8 × 10−9 dB at 60 nHz. At different frequencies of the nanoparticle of Aluminum 3003-H18, the maximum value of SPL was observed at 60 nHz. −10 dB at a repeat frequency of 1 nHz, as shown in case (A), which did not have a strong effect on the motion of the nanoparticle in view of the closeness of SPL sway along the nanoparticle. At a repeat frequency of 10 nHz, the value of SPL of nanoparticle of Magnesium AZ31B increased to 1.1 × 10−9 dB, as shown in case (B). This was along both the ends, which shows that SPL did not have a strong effect on its improvement. Owing to the nanoparticle improvement at 20 nHz, the SPL value reached 2.4 × 10−9 dB, which did not impact the development of the nanoparticle, as shown in case (C).Owing to the nanoparticle development at 20 nHz, the value of SPL was 4 × 10−10dB. At different frequencies of the nanoparticle of Magnesium AZ31B, the most outrageous estimation of SPL was noted at 20 nHz. −10 dB at 1 nHz as shown in case (A). This value did not have a strong effect on the movement of the nanoparticle due to the appearance of the SPL effect on both the ends. Case (B) shows that at a frequency of 10 nHz, the value of SPL of the nanoparticle of polysilicon increased to 3 × 10−10dB. This was at only one end of the nanoparticle, which showed that SPL did not have a strong effect on its improvement. In case (C), SPL reached 8 × 10−9 dB at 20 nHz. Case (D) shows the value of SPL reached the maximum value of 2.2 × 10−9 dB at 60 nHz. That is, at different frequencies of the nanoparticle of polysilicon, the maximum value of SPL was observed at 20 nHz. In some cases, the value of SPL was noted at its lowest level around the body of the nanoparticles such as in the following cases: using polyimide nanoparticles in the blood flow at 1, 20, and 60 nHz.Case (D) shows the estimation of SPL at a repeat frequency of 60 nHz where SPL was the most outrageous at 10 × 10Using acrylic plastic nanoparticles at 60 nHz; using Aluminum 3003-H18 nanoparticles at 1 nHz; using Magnesium AZ31B nanoparticles in the blood flow at 20 nHz; and using polysilicon nanoparticles in the blood flow at 10 nHz. The lowest level of sound pressure interaction on the nanoparticle terminals was achieved at lower levels of frequencies. Three phases of ultrasound scanning were conducted; in each phase, one of the simulated blood vessels was scanned and evaluated five times at different places through the length of the tube . Each scan was composed of two scanning orientations, at all selected scanning areas, which show the simulated vessels along the longitudinal and transverse planes. This medical imaging experiment produced 30 sonographic images, and the peak systolic velocity (PSV) was recorded as an indication for the angular speed inside the simulated vessels, as the blood circulation in this experimental setup was isolated from the effect of irregular blood flow rate  through the use of a mono-type fluid pump. The PSV was recorded 10 times for each scanned simulated vessel and the recorded values were averaged. Furthermore, the presented sonographic images were qualitatively evaluated.As seen in The deep main vessels inside the human body are wider , and the vessels become narrower close to the superficial layer of the skin. Therefore, the aliasing effect could be a potential marker that can be used to trace nanoparticles for drug-delivery purposes, as the experimental results are in agreement with the computational models’ outcome.Ultrasound technologies are challenged, as they have minimal clinical impact in quantifying the blood flow in small blood vessels; however, the recent advances in ultrasound technologies have paved the way to detect the blood microcirculation inside the human body. Furthermore, they could facilitate the possibility of tracing nanoparticles inside convoluted blood vessel networks . MoreoveThe use of nanotechnology in medicine is increasing rapidly. Nanoparticles encounter a number of sequential obstacles as they travel through the bloodstream to reach the affected cell, thus gradually reducing their movement. As a result, the drug transmission process is slow. One of the obstacles is the acoustic pressure levels created by the sound waves associated with the molecules as they circulate in the blood. This study aimed to achieve nanoparticle synthesis of drug molecules that act as catalysts for drug nanoparticles in overcoming acoustic pressure levels. The results demonstrate the potential of the proposed design. A weak effect of pressure levels was observed on both ends and around the body of nanoparticles. The research suggests the use of five material molecules, namely polyimide, acrylic plastic, Aluminum 3003-H18, Magnesium AZ31B, and polysilicon, owing to their lower cost and availability. The experimental validation method was proposed and conducted. The experimental results proved the possibility of evaluating the effect of sound pressure on the movement of nanoparticles. In addition, the results are in good agreement with those of the proposed computational model in that the lowest levels of sound pressure were noted at lower frequencies of the nanoparticles. Moreover, potential technologies for detecting and tracing nanoparticles for drug-delivery purposes were discussed. It is worth mentioning that employing advanced medical imaging technologies in nanoparticle detection and evaluation can positively contribute to various computational nanoparticle models in terms of proofing the concepts and validating the proposed models. Furthermore, the produced results could facilitate further evaluation of the sound pressure effect in terms of advancing the methods used for directional and tactic motions of micro- and nano-motors.


The guanine nucleotide exchange factor GBF1 is a well-known factor that can activate different ADP-ribosylation factor (Arf) proteins during the regulation of different cellular vesicular transport processes. In the last decade, it has become increasingly evident that GBF1 can also regulate different steps of the replication cycle of RNA viruses belonging to different virus families. GBF1 has been shown not only to facilitate the intracellular traffic of different viral and cellular elements during infection, but also to modulate the replication of viral RNA, the formation and maturation of viral replication complexes, and the processing of viral proteins through mechanisms that do not depend on its canonical role in intracellular transport. Here, we review the various roles that GBF1 plays during the replication of different RNA viruses. Eukaryotic cells contain a collection of diverse organelles that perform specialized functions depending on the enzymatic activities of their components. Although these organelles are spatially separated, there is a dynamic interaction between them by different trafficking events, some of which are mediated by vesicle transport . This trBased on the protein elements that form the coat, three important transport vesicles have been extensively described in which the function depends on either the coatomer protein I (COPI), COPII, or clathrin ,12. ThesThe mechanism of COPI vesicle formation is a complex process regulated by the activation of the small GTPase Arf1 (ADP-ribosylation factor 1) . This prIn addition to Arf proteins, the participation of specific Arf GEFs has also been shown to play an essential role in the regulation of the vesicle transport. For instance, the activation of Arf1 can be driven either by GBF1 to promote COPI transport, or by the Brefeldin A-inhibited GEFs 1 and 2 (BIG1 and BIG2) to initiate clathrin transport; thus, it is thought that Arf1 is committed to each transport pathway depending on the interaction with a specific GEF. In order to achieve this regulation, the different GEFs have been shown to be restrained to particular sites where a specific transport is needed; for example, GBF1 is located at sites where COPI exerts its functions, either in the cis-Golgi cisternae, the ERGIC or the LDs ,35, wherGBF1 is the GEF that specifically regulates the COPI vesicle transport. Based on its size, GBF1 belongs to the group of large Arf GEFs, which also contains BIG1 and BIG2. This group of GEFs shares a catalytic Sec7 domain that regulates the activation of Arf proteins through binding to the Arf-GDP form, inducing its conformational change, and promoting the exchange of GDP for GTP that leads to the dissociation of the protein from GBF1 ,37. ThroThe multidomain structure of GBF1 allows this protein to engage in numerous interactions with other proteins, leading GBF1 to participate in many different cellular processes and even in the process of infection of some bacteria ,46. In aDENV, dengue virus; TBEV, thick-borne encephalitis virus; YFV, yellow fever virus; KUN, Kunjin virus; CSFV, classic swine fever virus; HCV, hepatitis C virus; CVA21, coxsackievirus A21; CVB3, coxsackievirus B3; CVB4, coxsackievirus B4; EV71, enterovirus 71; HRV2, human rhinovirus 2; HRV14, human rhinovirus 14; CHIKV, chikungunya virus; SINV, Sindbis virus; HEV, hepatitis E virus; MHV, mouse hepatitis coronavirus; SARS-CoV, severe acute respiratory syndrome coronavirus; HCoV-229E, human coronavirus 229E; VSV, vesicular stomatitis virus; HPIV3, human parainfluenza virus 3; IAV, influenza virus; LCMV, lymphocytic choriomeningitis virus.Flaviviruses are enveloped, positive-sense, single-stranded RNA viruses with a genome of approximately 9.4–13 kb in length. The genome is organized as a long open reading frame (ORF) encoding a polyprotein that is cleaved into three structural  and seven nonstructural  proteins. During infection, flaviviruses induce a profound rearrangement of cellular membranes to provide platforms for viral replication. It has been observed that RNA replication occurs in vesicular structures called vesicle packets derived from membranes of the ER . AlthougIn recent years, increasing evidences have shown that GBF1 is an important cellular factor involved in the replication of several flaviviruses, including dengue virus (DENV) ,78,79,80In addition to the role of GBF1 in RNA replication, it has been reported that depletion of this factor or its pharmacological inhibition with BFA could also affect the DENV assembly by blocking the accumulation of the C protein into the LDs, which depends on the catalytic activity of GBF1 . MoreoveOf interest, the increment of the C protein transport and the inhibition of viral progeny production has also been recapitulated by treating TBEV-infected cells with interferon 1 (INF1), through the induction of the expression of the viperin  protein ; viperinOn the other hand, it has been shown that the simultaneous depletion of Arf4 and Arf5 decreases the secretion of DENV and YFV particles, without affecting the constitutive secretory pathway . The facPestivirus genus, was also demonstrated to be strongly inhibited in the presence of BFA [Although many aspects of the pestiviruses replication cycle remain unknown, a recent study described that replication of the classical swine fever virus (CSFV) depends on the activity of GBF1. It was described that both BFA or GCA are able to reduce the viral titers and the viral RNA level, and depletion of GBF1 is sufficient to cause this effect . It seeme of BFA , suggestHepacivirus genus, induces an extensive remodeling of intracellular membranes to produce a membranous web composed of ER membranes, LDs, and double-membrane vesicles containing HCV nonstructural proteins  as well as the HCV RNA [Infection by hepatitis C virus (HCV), the only member of the  HCV RNA ,86. Alth HCV RNA ,88. Once HCV RNA ,86,89. I HCV RNA ,55. A de HCV RNA . GBF1 in HCV RNA ,55. In t HCV RNA , suggest HCV RNA ,91; this HCV RNA .Arf1 activation has also been shown to be related with the viral assembly of HCV through modulation of the recruitment of the adipose differentiation-related protein (ADRP) to LDs. ADRP, a member of the perilipin family, is a major protein associated with LDs in various cell types. This protein has been proposed to play a positive role for HCV RNA replication while performing a negative function for HCV assembly . AlthougSimilar to Arf1, the simultaneous depletion of Arf4 and Arf5, in which the activation also depends on GBF1, has been reported to reduce the RNA replication of HCV probably through affecting the morphology of LD but not the secretion pathway ,91. AltoIn addition to the role of GBF1 in the transport of cellular and viral proteins relevant for RNA replication and viral assembly, it has also been observed that this factor can regulate the lipid composition of the membranous web induced by HCV. Inhibition of GBF1 activity and Arf1 activation abolishes the accumulation of phosphatidylinositol 4-phosphate (PI4P) in the membranes of the HCV replication complexes , a proceIn a mechanism apparently different from the regulation of protein traffic, it has been found that GBF1 might also modulate the processing of the HCV polyprotein by regulating the protease activity of the NS3-NS4A complex; this regulation process requires the interaction between the Sec7 domain of GBF1 and the protease domain of NS3. Moreover, the protease activity of the NS3-NS4A complex has been shown to depend on the catalytic activity of GBF1 .Enterovirus (EV) includes a collection of small non-enveloped viruses with a small positive-sense single-stranded RNA genome. These viruses have been classified into 15 serologically distinct groups, comprising 12 groups of enterovirus (EV-A to L), and three groups of rhinovirus (RV) (RV-A to C). The replication cycle of EV starts with the attachment of the virus to specific cell host receptors. After virus internalization, the viral genome is released into the cytoplasm to direct the synthesis of a single polyprotein, which is auto-processed by viral proteases 2A and 3C to produce three structural proteins  and seven nonstructural proteins (2A–2C and 3A–3D), as well as some stable protein precursors  that can also participate in the replication cycle. As the infection progresses, EV promotes the creation of viral cytoplasmic replication complexes formed by clusters of tightly associated vesicles of heterogeneous size, where the viral RdRp 3D protein directs the replication of the genomic RNA. The novel genomic RNA then is either translated or packaged into preassembled procapsids . Finally, the newly EV procapsids are secreted into the extracellular medium through a process in which VP0 is cleaved into VP2 and VP4, to form the mature, infectious virus particles.The genus Although many of the details of the EV replication cycle have been described, the role of host factors in the replication complexes of EV are less characterized. One of the most intriguing features of EV replication is the participation of the cellular secretory pathway in the infectious process. The inhibition of this pathway by BFA and GCA revealed that the RNA replication of many members of EV genus, such as poliovirus, CVB3, coxsackievirus B4 , coxsackievirus A21 , enterovirus 71 , echovirus 11 , and bovine enterovirus type 2  are sensitive to these drugs ,102,103.Although it is generally accepted that GBF1 interacts with the 3A protein, the importance of this interaction for the replication of the EV RNA remains to be elucidated. The use of different GBF1 mutants revealed that mutations in this protein that abolish the interaction with 3A reduce the ability of this cellular factor to support EV RNA replication ,59. HoweThe relevance of the Arf activation in the replication cycle of EV is also unclear. The depletion of Arf proteins has been shown to reduce the replication of EV71, CVB4, and CVB3 ,62,64, iPicornaviridae family. Encephalomyocarditis virus , the foot-and-mouth disease virus , as well as the Aichi virus  have been shown to be resistant to the effects of BFA, indicating that GBF1 is not involved in their replication cycle [Parechovirus genus) is partially sensitive to BFA [In contrast to the strong evidence regarding the relevance of GBF1 for the replication of several enteroviruses, this dependency is not a common feature shared by all members of the on cycle ,114,115.e to BFA .This genus includes a large number of mosquito-borne viruses that can infect mammals, birds, fish, reptiles, and amphibians. Alphaviruses consist of enveloped viral particles that contain a single-stranded positive-sense RNA genome that encodes two ORFs. The first ORF directs the synthesis of four non-structural proteins (nsP1-4), whereas the second ORF codes for the structural capsid protein (CP) and two surface envelope glycoproteins (E1 and E2) . Once inGiven the involvement of the secretory pathway in the proper processing and transport of E1/E2 to the plasma membrane, this transport has been thought to be important only for virus particle maturation. However, in recent years it was found that the inhibition of protein transport by BFA or GCA could disturb the RNA replication and protein synthesis of Sindbis virus (SINV) ,67, the Aedes aegypti females [On the other hand, taking into account that Arf4 and Arf5 participate in maintaining the LD morphology, but are not important for protein transport , the inv females  seems toHepeviridae englobes a group of hepatitis E viruses (HEV) that are non-enveloped and contain a positive-sense single-stranded RNA genome that contains two ORFs. The first ORF encodes a non-structural polyprotein (ORF1 protein) that exhibits several functions, such as methyltransferase, protease, RNA helicase, and RdRp, while the second ORF codes for the capsid protein (CP). Due to the low efficiency of these viruses to grow in cell culture, their replication process is poorly understood, although it has been proposed that it might be similar to that of togaviruses [Togaviridae family, the RNA replication of HEV was sensitive to treatments with BFA and GCA, and that GBF1 plays an essential role in this process although, unlike togaviruses, the inhibition of GBF1 activity by BFA does not affect the formation of the HEV replication complexes.The family aviruses . In factThe members of this genus are enveloped viruses that contain a large positive-sense, single-stranded RNA genome with several ORFs that direct the synthesis of 16 nonstructural proteins (nsp1 to nsp16), four structural proteins  and, in some viruses, a group of up to eight accessory proteins that are key for the efficient replication of the virus in natural conditions . Once reRecent evidence has indicated that the secretory pathway participates in the formation and function of both RTC and RVN. It has been reported that the inhibition of the secretory pathway by BFA or GCA strongly reduces the RNA replication of different coronavirus strains such as the human coronavirus 229E , the mouse hepatitis coronavirus , and the severe acute respiratory syndrome coronavirus  ,69,70. TOn the other hand, the finding that overexpression of the dominant-negative mutant Arf1-T31N strongly inhibits MHV replication , togetheVesiculovirus genus comprises a distinct monophyletic group of enveloped bullet-shaped viruses that contain a negative-sense, single-stranded RNA genome that codes for five structural proteins: the nucleocapsid protein (N), the phosphoprotein (P), the matrix protein (M), the glycoprotein (G), and the RdRp (L). After virus entry into the cell, the viral nucleocapsid is released into the cytoplasm. Once free, the virion polymerase complex, composed by the N, P, and L proteins drives the transcription of the viral mRNAs, which then direct the synthesis of the different viral proteins. Once sufficient quantities of the N and P protein have been produced, the virion polymerase complex starts the synthesis of a full-length complementary antigenome RNA of positive sense. The antigenome then serves as a template to synthetize new viral negative-sense genome molecules, which can be used for a second round of transcription or can be assembled into new viral particles. The union of the N protein to the newly genomic RNA compromises these molecules to the formation of helical nucleocapsids that interact with the M protein and are transported to cell membrane sites enriched by the spike G glycoprotein. Budding of the nucleocapsid through these sites leads to the formation of the final enveloped virus [The ed virus .Given that the transport of the G protein to the cell membrane depends on a functional secretory pathway, the vesicular transport was thought to only play a role in the final steps of vesiculovirus replication. However, studies with the vesicular stomatitis virus (VSV), the prototypic member of this genus, revealed that this transport was also important for the synthesis of the viral RNA. It was observed that BFA or GCA treatments induce a substantial reduction in the levels of viral mRNA, and the antigenome RNA of VSV ,125,126.Vesiculovirus genus, which has emerged as a pediatric encephalitic virus in India [On the other hand, a structure-based computational analysis of possible protein–protein interactions between human proteins and the proteins of Chandipura virus (CHPV), another member of the in India ,128, revin India . AlthougOn the other hand, considering that the microtubule-dependent transport of viral mRNAs from the VSV inclusions to the cytoplasm has been proved to be essential for their efficient translation , it mighInfluenza viruses are enveloped viruses that contain a segmented negative-sense, single-stranded RNA genome that can be formed by seven or eight RNA segments, depending on the virus strain. The genome of these viruses codes for three proteins that form the viral RdRp , a nucleoprotein (NP) that is associated with each genome segment, a hemagglutinin (HA) protein that facilitates virus attachment, and the matrix protein 1 (M1) that acts as an adaptor protein between the viral ribonucleoproteins (RNPs) and the membrane envelope. Moreover, some members also code for a neuraminidase (NA) that contains sialidase activity essential for the releasing of the mature viral particles, and a small integral membrane matrix protein 2 (M2), a proton selective ion channel. In addition to structural proteins, these viruses may also code for two nonstructural proteins . After cell entry, the RNPs are released into the cytoplasm; once free, the RNPs are then imported to the cell nucleus, where the viral RdRp synthesizes the mRNAs that direct the synthesis of the viral proteins in the cytoplasm of the cell. During their synthesis, the proteins HA, NA, and M2 are inserted into the ER membrane, and are transported to the sites of viral assembly in the plasma membrane. Concomitant with this process, the NP, PA, PB1, and PB2 proteins are imported into the nucleus and bind the newly synthesized RNA genome segments to form the novel RNPs that are then exported to the cytoplasm and subsequently transported to the sites of viral assembly in the plasma membrane. Finally, the budding of RNPs in the enriched HA, NA, and M2 membrane sites produces the new influenza virus infectious particles ,133.Two models have been proposed to explain the RNP traffic to the plasma membrane, and in both cases the interaction of the RNPs with Rab11 is involved ,135,136.Besides its role in regulating the transport of viral proteins to the plasma membrane, it has been shown that GBF1 interacts specifically with the protein M2 . AlthougParamyxoviridae family), as well as that of the lymphocytic choriomeningitis virus  have also shown to be dependent on the GBF1 activity. Depletion of this factor by RNAi or its pharmacological inhibition by BFA or GCA, has shown to significantly reduce the protein synthesis of these viruses [The participation of GBF1 in the replication of negative-sense RNA viruses is not restricted to IAV. The replication of human parainfluenza virus type 3  that code for six nonstructural (NSP1-6) and six structural  proteins. The inner core of rotavirus is composed by the protein VP2, which encloses the replication machinery formed by the dsRNA segments, the RdRp VP1, and the protein VP3. The intermediate layer, formed by VP6, surrounds the viral cores to form double-layered particles (DLPs). Finally, the addition of the glycoprotein VP7 and the spike protein VP4 onto the DLPs forms the infectious triple-layered particles (TLPs). The replication of rotavirus occurs in cytoplasmic non-membranous electron-dense inclusions termed viroplasms. Replication and packaging of the viral genome into newly synthesized DLPs take place in these inclusions. The novel DLPs then bud into the lumen of ER through membrane sites modified by the presence of NSP4 and VP7, acquiring a transitory lipid envelope bearing the NSP4, VP7, and VP4 proteins. As the new DLPs move into the lumen of the ER, the transient lipid envelope is removed by an unknown process in which NSP4 is eliminated while VP4 and VP7 are assembled to produce the final infectious TLPs .Although many of the steps of rotavirus replication have been elucidated in recent years, the precise mechanism of the final events of rotavirus assembly is not well understood. It is known that NSP4 (a transmembrane ER glycoprotein) plays a crucial role in the last steps of rotavirus assembly. The interaction of NSP4 with VP4 and VP7 , togetheIn recent years, the use of genome-wide RNAi screens has shown that the vesicle transport mediated by the COPI/Arf1 machinery is relevant for virus replication, since knocking down the expression of some of the proteins that integrate such machinery significantly impairs the yield of rotavirus progeny ,142; simIt has been shown that the inhibition of GBF1 by either BFA or GCA, or the depletion of this factor by RNAi, alters the electrophoretic mobility of the viral glycoproteins VP7 and NSP4 ,143. AltGiven that GBF1 functions at the ER-Golgi interface, mediating the retrograde vesicular transport, and that rotaviruses mature in the ER, it seems likely that Golgi-ER transport is the relevant process required for the correct maturation of rotavirus. However, considering that LDs have been proposed to play a significant role in the replication cycle of these viruses, it remains possible that the protein transport between the ER and LDs is also relevant, although, a so far uncharacterized function of GBF1 cannot be discarded.On the other hand, in support of the requirement of an active GBF1 transport during rotavirus infection, it was found that catalytically inactive mutants of GBF1 failed to support replication of the virus in the presence of BFA, suggesting that GBF1 activity is essential for rotavirus progeny production. However, given that knocking down the expression of Arf1 was found not to affect the production of infectious virus, it is likely that rotavirus replication does not depend on the GBF1/Arf1 transport but might require the activation of other GBF1 substrates, such as Arf4 or Arf5, that could compensate for the reduced level of Arf1. Moreover, it was also found that while the C-terminal domain of GBF1 is dispensable for the viral replication, the first N-terminal amino acids of this factor are essential to support replication of the virus . The reqAs intracellular pathogens, the infection of viruses depends on their capacity to replicate successfully within the host cell. The restricted coding potential imposed by the small size of viral genomes had led the viruses to hijack essential systems of cellular functions to facilitate their replication. In this regard, emerging data have shown that many cellular factors are susceptible to be reprogrammed during viral infections to perform novel functions that benefit these pathogens. One of these cellular elements is the guanine nucleotide exchange factor GBF1, which has proved to be essential for the efficient replication of many RNA viruses. It has been shown to be required for different stages of the virus lifecycles, including the formation and maturation of viral replication complexes as well as the coordination of RNA genome replication, virus assembly, and release. The role of GBF1 has been found, principally, to depend on its ability to activate distinct Arf proteins, to regulate different transport pathways that permit the communication between the viral replication organelles and cellular organelles (ER and LDs) involved in virus infection. However, for many viruses, the role of GBF1 in virus replication has also been shown not to depend on the catalytic activity of the protein. Although it is not well understood how GBF1 could exert this non-catalytic activity, the multidomain structure of the protein seems to play an essential role by permitting GBF1 to engage in the interaction with many cellular and viral proteins that seems to regulate, directly or indirectly, viral replication. The relevance of GBF1 for the replication of several RNA viruses identifies this factor as a potential candidate for antiviral therapies to control a broad-spectrum of viral infections. However, given the essential role of GBF1 in the secretory pathway, and in other so far ill-characterized functions of the cell, the development of safe and effective antiviral therapies that could help to deal with viral infections, without harming the host cells, represents a challenging mission.In conclusion, the data discussed in this review bring to light a new diverse range of functions of GBF1 that might explain how this factor serves for so many processes in different compartments of the cell. Future studies aimed to clarify the mechanisms underlying the multiple functions associated with this interesting molecule would help to advance our understanding of virus and cell biology.