In recent years, CO2 separation technology, such as membrane technology, has become highly desirable. Fabricated mixed matrix membranes (MMMs) have the most desirable gas separation performances, as these membranes have the ability to overcome the trade-off limitations. In this paper, blended MMMs are reviewed along with two polymers, namely polyether sulfone (PES) and polyethylene glycol (PEG). Both polymers can efficiently separate CO2 because of their chemical properties. In addition, blended N-methyl-2-pyrrolidone (NMP) and dimethylformamide (DMF) solvents were also reviewed to understand the impact of blended MMMs’ morphology on separation of CO2. However, the fabricated MMMs had challenges, such as filler agglomeration and void formation. To combat this, functionalised multi-walled carbon nanotube (MWCNTs-F) fillers were utilised to aid gas separation performance and polymer compatibility issues. Additionally, a summary of the different fabrication techniques was identified to further optimise the fabrication methodology. Thus, a blended MMM fabricated using PES, PEG, NMP, DMF and MWCNTs-F is believed to improve CO2/nitrogen separation.With an ever-increasing global population, the combustion of fossil fuels has risen immensely to meet the demand for electricity, resulting in significant increase in carbon dioxide (CO As a comissions . These rmissions . This stmissions . Thus, t as well . Accordi of 2 °C .Currently, there is a need to implement and retrofit carbon capture systems to new and existing plant designs that assist to capture 90% of emissions and limit the energy costs by 35% ,8. As a 2 and H2O, which is created by using pure oxygen rather than ambient air [2 is captured and stored. Furthermore, the NOx emissions are lower because they are carried out in a nitrogen-depleted environment. As such, this process allows the CO2 concentration to be higher at the output stream, thereby creating easier separation of exhaust gases due to the high flame temperature [Oxy-fuel combustion uses a flue gas primarily of COient air . After uperature . The maiperature . Howeverperature .2 is the undesired product generated and captured [2 [2 are observed, which allow better absorption efficiency [In a pre-combustion system, a conversion process occurs where COcaptured . Both catured [2 . This sytured [2 . A chemitured [2 . Therefoficiency .2 by 5–15% when it is captured from the waste gas stream after conversion from the carbon source [2 pressure and are is achieved during capture, requiring more energy and cost [2 emissions [2 concentration in the feed stream [A post-combustion capture system has the ability to reduce the concentration of COn source . Additioand cost . This syand cost . By usinand cost . As suchand cost . Thus, tmissions . Howeverd stream .2 emissions. Nonetheless, post-combustion capture is more advantageous than the other two systems because it can be retrofitted into existing plants, hence lowering the initial capital costs of this mitigation source [The three systems are potentially helpful in mitigating the global COn source .2 from the flue gas creates a challenge, as the latter consists of other gas components [2’s selectivity among the other gas particles. The lower the CO2 selectivity, the higher the cost of using this system [2 through physical and chemical processes, such as absorption, adsorption, cryogenic distillation and membrane separation technologies [Currently, the post-combustion carbon capture technology is widely applied, as it is the most promising and can be retrofitted into existing power plants . Howevermponents . Furthers system . Moreovenologies .2 [2 occurs at high pressure and low temperature [2 being dependent and limited by the solvent; (ii) the solvents promoting corrosion in the equipment; (iii) the regeneration of solvent requiring high energy, leading to this not being economically viable; (iv) evaporation causing a significant loss of solvent and (v) the oxygen-rich environment degrading the solvent [Absorption is commonly used in industries that have acid-like gases in their stream and, being a mature technology, uses chemical solvents to capture CO2 . It is d2 . The phyperature ,30. Acidperature ,32. Examperature ,34,35. W solvent .2 particle size during the CO2 capture process, the particles can be adsorbed using the appropriate adsorbents, such as zeolites, metal oxides, porous silicates and metal organic frameworks [This is a selective process that allows the molecules in the gaseous mixture to adhere to a solid surface known as an adsorbent. The quality of the adsorption is determined by the properties of the adsorbed particles and the adsorbent . Regardlameworks . The proameworks . Furtherameworks .Additionally, the adsorption technology is attractive to use due to its low energy requirements, flexibility, simplicity to operate and ease of maintenance . On the 2, as it applies the concepts of condensation and cooling [2, it is not be ideal to use this process, as the low temperatures will compromise equipment safety [This process requires a stream with a high concentration of CO cooling ,40. Cryo cooling ,42. This cooling ,43. Howe cooling . Furthert safety ,45. As st safety .2 separation is dependent on the type of materials utilised in fabrication, and CO2 permeability (AP) and selectivity (αAB) [2 is crucial, as the partial pressure can be affected [2 capture with membrane technology depends on the following criteria: high CO2/N2 selectivity, high CO2 permeance, chemical and thermal robustness, good resistance to aging and plasticisation, and cost-effective with low manufacturing costs [This pressure-driven technique allows the difference in partial pressure between the feed and the permeate sides to create a driving force for separation to occur . Membranty (αAB) . Other faffected . Hence, affected . Overallng costs .To conclude, the advantages and disadvantages of these techniques have been summarized in 2 separation, membrane technology has lower overall costs [4) in an ammonia (NH3) plant [2 from the flue gas without needing a high concentration of CO2 in the inlet [Over the years, chemical separation using membrane technology has attracted enormous interest in fields such as gas separation, water purification, food processing, pervaporation, membrane contactors and reactors, and so on ,54. Membll costs . The 1983) plant ,59. Furthe inlet . Additiohe inlet ,60,61. Lhe inlet ,63. Figuhe inlet ,65.In membrane separation, the internal structure or morphology is a significant criterion of how the membrane can be used and how effective it is. As shown in The first type (isotropic) is a dense microporous (non-porous) membrane, which has a low flux due to its thickness and small pore size. This type of membrane is used in labs rather than in industrial processes ,68. The 2 capture and separation [The membrane-based separation method has slowly gained recognition, as it is a promising option because it is economical, efficient and environmental friendly for COparation . There aparation .There are two different polymeric membranes, which are glassy and rubbery. These membranes are also known to exhibit an inverse proportionality of permeability and selectivity. This means that when selectivity increases, the gas permeability tends to decrease ,72. This2 separation possess properties that increase their thermal and chemical stability and reduce their selectivity and permeability when compared with other membranes [2 from flue gas. In addition, zeolite membranes may be used for CO2 capture, but this approach is not as advanced as the polymeric CO2 capture techniques [In the fabrication process of inorganic membranes, materials such as carbon, metals and ceramics are embedded . Ceramicembranes ,75. Furtembranes . A typicchniques . The effchniques .2 increased the separation performance when 5A zeolites were added to a rubbery polymer membrane known as polydimethylsiloxane (PDMS). In light of these results, further research focused on composite membrane structures with the incorporation of various fillers to aid in the separation performance of MMMs [It can be concluded that between polymeric and inorganic membranes, polymeric membranes have higher economic benefits due to their flexible physical structure and solution processability . However of MMMs ,82MMMs are an up-and-coming category of membranes, which allow higher selectivity and permeability, and are much more advantageous than polymeric membranes. The MMMs are fabricated from organic polymer layers and inorganic filler particles. These two heterogeneous membranes can only coexist through synergistic interactions between them . The inoMMMs allow the trade-off between selectivity and permeability in pure polymer membranes to be broken . This isIn summary, the advantages and disadvantages of these membranes have been tabulated in 2/N2 separation [There are several challenges faced during the fabrication of MMMs, such as the desired morphology, gas separation properties and mechanical/chemical stability . Some ofparation .2 molecules. However, in many common cases, this is not always true. It has been recognised that both these conditions—permeability and selectivity—are inversely related [Choosing an ideal membrane would require: (i) high selectivity and (ii) high permeability of CO related . The upp related . In poly related . The adv related .2 [2/N2 upper bound limits [The MMMs are considered as upcoming membranes for gas purification . There h2 ,94. The 2 . A drawbd limits . Thus, ad limits .2/N2 separation [2 and selectivity for N2 because of its rubbery material [2 from natural gas has been the only membrane-based separation being carried out on a large scale [2 and N2 permeability, both polymers are used for CO2/N2 separation [Both polyether sulfone (PES) and polyethylene glycol (PEG) are different types of polymer material. Each of these polymers has its own set of characteristics, making them unique in the process of COparation . PES is paration ,98. Eachparation . PES is material . Since 2ge scale . PEG actparation .2 as well as reduce the non-selective voids and increase the gas selectivity [2 and N2 [The morphology of membranes is strongly affected by the solvents used during fabrication . Membranectivity . This soectivity ,107. Fur2 and N2 ,105.2/CH4 selectivity of 2.56 compared with the PES-DMAc (2.13) and PES-NMP (2.4) membranes [2 solubility [2/N2 separation due to the different phase inversion processes [In a comparative study, Ahmad and coworkers studied the gas permeation and morphology of dense PES membranes using three solvents, namely DMAc, DMF and NMP. Their study concluded that the morphology of the three membranes produced dense structures and were able to diffuse the permeation through pressure, concentration or the potential gradient . This shembranes . The DMFlubility . Hence, rocesses ,108,109.The morphology and performance of membranes are significantly affected by parameters such as the type of polymer matrix and the inorganic fillers interacting between the two phases . By usin2 and N2 permeation. However, due to surface chemistry and the distribution of pore sizes, porous inorganic filler materials are more compatible with a polymer matrix. This results in higher efficiency in gas separation compared with using non-porous inorganic fillers [Non-porous organic fillers increase the matrix pattern and decrease the diffusion layer, thus increasing the separation performance of the MMM . A commo fillers . In term fillers . This, i fillers . Therefo fillers .2 separation is created. A prime example of these are carbon nanotubes (CNTs) [Other commonly used inorganic fillers include metal oxide, silica and carbon molecular sieves (CMS) . Howevers (CNTs) .Carbon nanotubes (CNTs) in MMMs show a robust and promising possibility of overcoming the trade-off of selectivity and permeability, which is the primary issue experienced in MMMs ,115,116.To summarized, the up to date blend membrane works have been tabulated in The fabrication method of membrane is dependent on the type of desired membrane (isotropic or anisotropic) and the materials used for synthesizing . Once thThe first fabrication method is called stretching, which is a technique that is applied to semi-crystalline polymer materials. The semi-crystalline polymer materials go through the process of extruding and stretching . The pro10 cm−2, respectively [The next technique is track etching, where a non-porous polymer film is irradiated with energetic heavy ions, leading to linear impaired tracks in the irradiated polymer film . This faectively . Chemicaectively . An examectively .Phase inversion is a demixing process, which transforms liquids to solids in a controlled manner from a homogeneous polymer solution . The polIn membrane technology, a common gas separation transport mechanism used is diffusion. This is the movement of gaseous components from a higher concentration to a lower concentration until equilibrium is reached ,130. HowThe Hagen–Poiseuille mechanism is used if the pore sizes are from 200 nm to 3000 nm and bigger compared with the transporting molecules’ free path. This mechanism is driven by the pressure gradient between the two sides . Additior) are smaller than the gas molecules in the free path (λ), which is shown in Equation (1) [Knudsen diffusion occurs when the pore sizes are smaller than the free path of the transporting molecules ,132,135.tion (1) .(1)λ=3ηR is the universal gas constant, T is the absolute temperature, P is the pressure and M is the molar mass. This equation further illustrates that when the membrane pore size is smaller than λ , more wall collisions occur compared with collisions among the molecules. This means that the molecules are moving independently. Based on this concept, gas separation is carried out through the velocity differences of the different component molecules, where the lighter ones go through the membrane. As such, the molar flux is calculated as shown in Equation (2) [Knudsen is the molecular flow of the gas, r is the pore radius, P1 is the partial pressure on the feed side gas, P2 is the partial pressure of the permeate side gas, L is the pore length, M is the molar mass, R is a gas constant and T is the absolute pressure.In Equation (3), tion (2) , where GFurthermore, the Knudsen mechanism’s selectivity of separation is predicted from the ratio of the molecular weights and its square root, which is shown in Equation (3) .(3)αKn=The last method of transportation is molecular sieving, where the sizes of both the transported molecules and pores are very similar. This means that molecules of a larger size would not be able to transport through the membrane .2, which, in turn, increases the selectivity of CO2. In addition, together with PES, the mechanical and chemical stability of the membrane is improved. Further, PES is in the ether-oxygen group, which binds CO2, thus increasing the selectivity again. On the other hand, blended NMP and DMF reduce non-selective void formation in the membrane and cause low density, respectively, which cause an improvement in CO2 permeability and solubility. Finally, by utilising MWCNTs-F, the permeability and selectivity of the membrane can be enhanced, thereby allowing faster gas transportation across the membrane. Hence, a blended MMM fabricated using PES, PEG, NMP, DMP and MWCNTs-F is believed to have a desirable effect on CO2/N2 separation. Lastly, the challenges of developing this new blended MMM such as cost and compatibilities should be further considered.As PEG has a polar ether group presence, it can be concluded that this polymer has a strong affinity towards COThe following conceptual prospect shows that blending different polymers and solvents to fabricate MMMs would overcome the trade-off limitations between selectivity and permeability. This is due to the combination of the benefits of polymeric and inorganic membranes, and the morphology created by the solvents. Moreover, with the introduction of inorganic fillers, the gas separation properties can be improved. However, an abundance of different combinations of possible polymers, solvents and fillers remains to be discovered and researched. Thus, future research should be focused on studying different combinations of polymers, solvents and inorganic fillers by utilising the concept of blending and MMM fabrication to synthesise a membrane capable of breaking the trade-off limitations. Additionally, a future prospect for a proposed blended MMM concept would be to conduct a gas separation study along with a kinetic study to better understand the effects of the chosen polymers and inorganic fillers, and the resulting selectivity and permeation. These outcomes will expand growth in the membrane technology field and allow researchers to further advance in this field.


As to the individual food components of the Medi-Lite score, 84% of students reported non-optimal consumption  of meat and meat products, and over 50% reported non-optimal consumption of vegetables, legumes, dairy products, and fish. Significant differences between girls and boys were observed for fruit (p = 0.003), cereals (p < 0.001), meat and meat products (p < 0.001), and dairy products (p = 0.003). By conducting a principal component analysis, we observed that Medi-Lite items on the consumption of some animal products (meat and meat products and dairy products) and some plant products  generated contrasting patterns of responses, denoting excessive consumption in the first case and underconsumption in the second. This result suggests the need for effective actions to promote healthy eating habits in young people.Our aim was to assess adherence to the Mediterranean diet in a group of 726 secondary school students  who completed the web-based Medi-Lite questionnaire simultaneously, during school hours, at the “Istituto Professionale per l’Enogastronomia e l’Ospitalità Alberghiera Marco Polo” in Genoa, Italy. The mean adherence score was 9.28 ± 2.29, with significantly ( The Mediterranean diet is one of the most studied and appreciated dietary patterns in the scientific community . It is cDespite the health benefits of the Mediterranean diet, widely documented in both epidemiological and clinical studies , currentA Flash Mob on the Mediterranean diet was held at the “Istituto Professionale per l’Enogastronomia e l’Ospitalità Alberghiera Marco Polo” in Genoa, Italy, on 3–4 March 2021. The Flash Mob was carried out by the 5th classes at the end of an educational and nutritional program that saw as protagonists the teachers of the classes and the students themselves (the “#facciamoComunicAzione” project). The teachers, together with the principal, presented the project to the students and their families and, after obtaining the approval of the school board, sent a letter to the families explaining the project and obtaining their consent to have their children participate in the initiative. No inclusion and/or exclusion criteria were established. http://www.medi-lite.com (accessed on 30 June 2021) after applying the copyright of the University of Florence, Italy. Compared to the paper version, published in its original version in 2014 [The web-based version of the Medi-Lite score was developed in 2018 by NUME PLUS srl  and published online as a free version at  in 2014 , and val in 2014 , the webIn this study, due to the age of the students, the question on alcohol consumption was not administered. Therefore, the final score ranged from 0 to 16 points and indicated low or high adherence to the Mediterranean diet. Suboptimal consumption for each food group composing the Medi-Lite score was defined as the choice that produced ≤ 1 point and corresponded to the following consumption levels: fruit < 2 portions/day, vegetables < 2.5 portions/day, legumes < 2 portions/week, cereals < 1.5 portions/day, meat and meat products > 1 portion/day, fish < 2.5 portions/week, dairy products > 1 portion/day, and non-regular use of olive oil. Both portion sizes, which differed across food categories, and consumption frequencies were defined based on data obtained in the analysis of cohort studies that estimated an association between the Mediterranean diet and overall mortality, as previously described .http://www.medi-lite.com (accessed on 30 June 2021), ensuring that participants’ responses were protected. The IP address of the client computer was used to identify potential duplicate responses from the same user. In the event of duplicate responses, the most recent response was kept for analysis. Because all responses were anonymous and voluntary, ethics committee approval was not required.All students were allowed to self-administer the questionnaire at the same time, during school hours, without any parent or teacher supervision. Before measuring adherence to the Mediterranean diet, they were asked to provide their gender. The response format was closed and structured. To preserve student privacy, responses were collected at the website p-value < 0.05 was considered statistically significant.Statistical analysis was performed using the statistical package PASW 27.0 for Macintosh . Descriptive statistics were used to analyze and report data. Histograms and boxplots were used to assess the distributional assumptions and to check for possible outliers. The results were expressed as mean ± standard deviation (SD), median and min–max range, or number and percentage (%), as appropriate. Differences between groups were estimated using the unpaired t-Student test. The Pearson’s chi-square was used to test for proportions. To understand whether the Medi-Lite items generated similar patterns of responses, a principal components analysis (PCA) with varimax rotation was performed. For all tests, a p = 0.017) higher values in girls (9.50 ± 2.19) than boys (9.09 ± 2.35). Categorizing the Medi-Lite score into tertiles, we obtained three adherence groups: low , moderate , and high . The prevalence rate of low adherents was significantly (p = 0.012) higher in boys  than girls . A total of 726 students aged 17–19 years participated in the Flash Mob and completed the web-based Medi-Lite questionnaire. Of these, 336 were girls (46.3%) and 390 were boys (53.7%). The scores obtained from the Medi-Lite questionnaire ranged from 2 to 15, with a median of 10. The mean adherence score was 9.28 ± 2.29, with significantly  reporting suboptimal consumption . In addition, 319 (42%) students reported suboptimal consumption of fruit (<2 portions/day), 385 (53%) reported suboptimal consumption of vegetables (<2.5 portions/day), 474 (65%) reported suboptimal consumption of legumes (<2 portions/week), and 433 (61%) reported suboptimal consumption of fish (<2.5 portions/week). Surprisingly, 391 students (56%) reported not using extra virgin olive oil regularly. Cereal consumption, on the other hand, was in line with the principles of the Mediterranean diet in most of the sample . Regarding the individual food components of the Medi-Lite score, the meat and meat products group showed the highest number of students (p = 0.003), cereals (p < 0.001), meat and meat products (p < 0.001), and dairy products (p = 0.003). As shown in Significant differences between girls and boys, in terms of suboptimal consumption of individual food components of the Medi-Lite score, were observed for fruit (To understand the different patterns of consumption among the adolescents investigated, we conducted a PCA analysis of the Medi-Lite scores regarding the individual food components. As shown in A cluster of overconsumptions was identified for animal-based food products such as meat and meat products as well as dairy products. Another cluster was composed of fruit, vegetables, legumes, fish, and olive oil, which showed the same pattern of suboptimal consumption. In the present study, we assessed adherence to the Mediterranean diet through the web-based Medi-Lite questionnaire in a group of secondary school students during a Flash Mob on the Mediterranean diet. The data obtained showed a moderate adherence to the Mediterranean diet, with high consumption of animal-based food products and low consumption of vegetables, legumes, fish, and olive oil. Nutrition is crucial for the development and long-term health of adolescents. Adopting good eating habits at a young age can protect against numerous health problems, such as obesity and cardiovascular disease . In thisIn our study, the median value of adherence was 10 points on a scale of 0 to 16, denoting a moderate level of adherence to the Mediterranean diet in the population examined. These results are in line with previous studies reporting a low-to-moderate level of adherence to the Mediterranean diet among young populations living in the Mediterranean area. In a representative sample of Greek adolescents, only 8.3% of adolescents reported eating habits that followed the principles of the Mediterranean diet , and lesOur data also showed that boys were more likely than girls to show low adherence to the Mediterranean diet, which is consistent with previous studies conducted in Greek and Balearic Islands adolescents ,26. HoweFinally, the consumption of the individual food components of the Medi-Lite score reported by our group of students was similar to that reported by previous studies examining the dietary habits of adolescents living in countries bordering the Mediterranean Sea ,27,28. IThe study has some limitations that should be discussed. First, the information collected was self-reported. This may have led to recall bias and misreporting due to the nature of the study and the young age of the participants. Second, the study sample was from a single institution and was not representative of the population of students attending secondary schools. In addition, adherence to the Mediterranean diet was assessed by considering the daily and weekly intake of eight food groups composing the Medi-Lite score: fruit, vegetables, cereals, legumes, meat and meat products, fish, dairy products, and olive oil. As previously described , both poIn conclusion, the data obtained in a group of secondary school students aged 17–19 years showed a moderate adherence to the Mediterranean diet, emphasizing the need to plan educational interventions aimed at improving the behaviors of adolescents. In particular, the consumption of fruit, vegetables, legumes, and fish should be encouraged, as well as the reduced consumption of meat and meat products.


Silver and gold nanoparticles can be found in a range of household products related to almost every area of life, including patches, bandages, paints, sportswear, personal care products, food storage equipment, cosmetics, disinfectants, etc. Their confirmed ability to enter the organism through respiratory and digestive systems, skin, and crossing the blood–brain barrier raises questions of their potential effect on cell function. Therefore, this manuscript aimed to summarize recent reports concerning the influence of variables such as size, shape, concentration, type of coating, or incubation time, on effects of gold and silver nanoparticles on cultured cell lines. Due to the increasingly common use of AgNP and AuNP in multiple branches of the industry, further studies on the effects of nanoparticles on different types of cells and the general natural environment are needed to enable their long-term use. However, some environmentally friendly solutions to chemically synthesized nanoparticles are also investigated, such as plant-based synthesis methods. Nanoparticles are defined as structures with at least one of the dimensions in the 1 to 100 nm range ,3,4.From the clinical standpoint, the use of nanoparticles (NPs) is mainly motivated by their relatively large surface-to-volume area during interaction with cells. Further advantages include their specific physicochemical characteristics, such as catalytic properties and relatively low melting point . Moreover, to ensure the safety of their use and appropriate dosage, correlations between these characteristics and the potential toxicity of nanoparticles can be determined using nanotoxicology techniques ,6,7.NPs can be characterized according to their shapes. These include simple spherical, triangular, rod, triangle, and round, and more complex octagonal or polyhedral ,8,9. GolIt has been proven that silver nanoparticles (AgNP) have the ability to penetrate the cellular walls of bacteria, altering their cell membranes and even potentially causing cell death. Moreover, through the release of silver ions, it is possible to increase cell membrane permeability, produce reactive oxygen species, and disturb DNA replication ,14,15,16Gold nanoparticles (AuNP) exhibit significant biocompatibility, promote corrosion, and possess optical and electronic properties depending on their shape and size ,17,18. AThe rapid development of nanotechnology is constantly affecting the methods of diagnosis, prevention, and treatment of various diseases, enabling novel therapeutic approaches. NPs currently have a range of applications, including, e.g., antibacterial agents, and components of drug delivery systems and diagnostic tools. It is worth noting that they are also commonly used as components of skincare products and cosmetics ,27.Staphylococcus aureus, Pseudomonas aeruginosa, Xanthomonas axonopodis pv. Citri), fungicidal , and antiviral properties, also affecting the SARS-CoV-2 virus [+) is also known to be toxic to aquatic organisms even at g/L concentrations by inhibiting the effects of ATPase Na+/K+ and causing ionic imbalance. These effects of AgNPs were similar in different marine animals, such as fish, daphnia, and crayfish [AgNPs are among the most commonly used substances in consumer products, such as laundry machines, dusting cloths, and personal hygiene products. Hence, NPs contained in everyday household items are often discarded directly in sewage and can potentially be transported into waterways. They are mainly described to exhibit antibacterial properties ,29,30,31-2 virus ,36,37. I-2 virus ,39. Silvcrayfish ,41.AgNPs are easily assimilated by cells. Therefore, they are mainly applied in the biomedical industry due to their unique surface, electronic, and optical properties. They are also used as innovative tools in diagnostic research, e.g., the detection of heart disease or cancer biomarkers, and in drug delivery systems ,45,46,47In contrast, other teams of scientists have found no cytotoxic effects in cancerous cell lines treated with gold nanoparticles ,50,51. SSilver nanoparticles can be absorbed through the respiratory and digestive systems, and through the skin ,57.3 doses [3 [In Sprague–Dawley rats subject to inhalation exposure, silver nanoparticles were detected in the blood and lungs. In smaller amounts, they were also seen in other internal organs such as the liver, kidneys, spleen, heart, and brain. These experiments did not describe changes in body weight gain, internal organ weight, or biochemical parameters. However, there were some differences in respiratory parameters in rats, e.g., decreased respiratory volume and minute ventilation, and histopathological changes in the lungs at 90-day exposure to 20 nm silver nanoparticles at 49, 133, and 515 µg/m3 doses . In Spradoses [3 .Spherical AgNP (20 nm) at doses of 50, 150, 300 mg/kg can be ingested orally, absorbed through the intestines into the bloodstream, and then accumulate in other organs such as the duodenum, liver, kidneys, and spleen. While this has been confirmed in mice, the authors of the study did not report any associated pathological changes . Moreovew/w), 8 h at night for five consecutive days. While the study confirmed the presence of AgNP aggregates in the skin, deeper layers there were less affected than those closer to the surface [In addition, Guinea pigs were found to accumulate free aggregate AgNP in the epidermis layers after 24 h of exposure at the highest dose used . However, microscopic evaluation did not reveal any abnormalities in the epidermis and skin layers in exposed areas of groups treated with colloidal AgNPs  compared to controls . The per surface .Previously, George et al. (2014) demonstrated the presence of clusters of silver in the stratum corneum and deeper layers of the epidermis after five days of skin exposure of healthy individuals to nanocrystal silver dressing . Thus, they confirmed the possibility of AgNP penetration through intact skin. However, despite the deposition of silver in the dermis, silver nanoparticles did not reach systemic circulation and should therefore not have systemic consequences .Studies in rats show that gold nanoparticles can be absorbed through the respiratory and digestive systems ,64.3) [In Sprague–Dawley rats subjected to spheroid AuNP (diameter under 6 nm) inhalation for 90 days, a decrease in respiratory parameters, i.e., lung function, respiratory volume, and minute volume, was observed compared to the control. Furthermore, histopathological examination demonstrated minimal alveoli, inflammatory infiltration of mixed cell type (lymphocytes/neutrophils/macrophages), and increased macrophage counts in rats receiving high doses of AuNP (20 μg/m3) .3) by inhalation in rats. About 30% of AuNP accumulated in the epithelium of the respiratory tract, causing rapid mucociliary removal and swallowing into the gastrointestinal system. Long-term removal (after 28 days) of AuNP was dominated by macrophage-mediated transport through interstitial tissue to the larynx and gastrointestinal tract. Furthermore, AuNP retention has also been observed in the liver, spleen, kidneys, uterus, and brain [Moreover, studies by Kreyling et al. (2018) also confirmed the absorption of “potato-shaped” gold nanoparticles , more than 50% of AuNP accumulated in the liver with smaller amounts in the lungs and spleen. This occurrence was associated with the collection of AuNPs from the circulation by the mononuclear phagocyte system. The total AuNP content of all organs represented 60% of the initial dose. In contrast, oral administration showed almost 50 times lower AuNP levels at the same amount . Most AuNP was excreted in feces within four days after exposure. In turn, alterations in biochemical parameters were observed 72 h after intravenous AuNP administration. An increase in AST (aspartate aminotransferase) was observed, with a decrease in ALT , which affects the physiology of the liver. Furthermore, an increase in blood glucose has also been noted; thus, the effect of AuNP on pancreatic functions cannot be excluded .v/v) [The penetration of gold nanoparticles through the skin of the hind paw and the anterior abdominal wall of Sprague–Dawley rats was also confirmed by Raju et al. (2018), with smaller AuNPs (22 nm) showing higher penetration compared to larger nanoparticles (105 and 186 nm). The effect of 3-hour AuNP incubation on a fibroblast cell line (L929 mouse fibroblast cells) was also investigated, with no observed effect of AuNP on cell viability at any of the concentrations used  .In mice, the kidneys were the primary site of AuNP accumulation after oral administration for 8 days at 25, 22, 20, 18, and 15 μg gold/kg bodyweight concentrations, and subsequent intestinal absorption. AuNP can induce anti-inflammatory effects in macrophage RAW264.7 cells pretreated with 1/1000 OD of the AuNP for 5 h before stimulation with lipopolysaccharides (LPS) and incubation for another 20 h. AuNP reduce by reducing the lipopolysaccharide receptor expression on the cell surface, as well as catalytic detoxification of nitrite peroxide and hydrogen peroxide. The highest accumulation of gold nanoparticles was shown by those that were 5 nm in size and coated with PVP, compared to 5 nm AuNPs coated with citrate or tannic acid (TA) .In other studies conducted in men subjected to nanoparticle inhalation for 2 h during intermittent exercise, AuNP was also confirmed to enter the lungs. Gold was detected in the urine after exposure to 4 nm AuNPs, but not in the urine of volunteers exposed to larger particles (34 nm). In mice, gold nanoparticles were also detected in urine only after exposure to particles ≤5 nm. AuNP found in human blood was usually at low levels after inhalation of AuNP, although the concentration of smaller particles was notably higher. This effect was also confirmed in mice, in which the incidence of detected gold and blood gold levels were significantly higher after exposure to smaller particles .The possibility of absorption through human skin has been studied using surgically resected dermal fragments incubated for 24 h with AuNP. The permeability of spherical nanoparticles (15 and 100 nm) was confirmed by using a TEM (transmission electron microscope), with nanoparticles observed in the deeper stratum corneum, epidermis, and dermis .Excessive ROS production can cause DNA damage and activate several signaling pathways, i.e., p53 suppressor protein, AKT (serine/threonine protein kinase B), and MAPK (mitogen-activated protein kinases) . FurtherIn various physiological states, ROS are produced as intermediate products. Their concentrations in cellular organelles are strongly regulated by various detoxifying enzymes, such as superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT), or by different antioxidants including flavonoids, ascorbic acids, vitamin E, and glutathione (GSH). The production of free radicals induced by nanoparticles leads to a reduction of GSH to oxidized form, followed by induction of oxidative stress ,73,74,75Based on the data shown in A more significant impact of smaller nanoparticles on increased apoptosis induction, and an increase in dye fluorescence intensity resulting from increased production of reactive oxygen species compared to larger nanoparticles, were also observed ,86,87,89A link between the phenomenon of apoptosis and incubation of silver nanoparticles in different sizes has been proposed by researchers:Carlson et al. —Based onLiu et al. —The studSriram —AnalysisSmaller nanoparticles cause structural modifications, e.g., changes in lymphocyte cell membrane morphology with nanoparticles ≤ 20 nm, with no similar effects observed for particles ≥ 200 nm in size . Cell shWith a low concentration of nanoparticles, cells are capable of defending against oxidative stress through antioxidant action, restoring redox balance. However, this mode of action is not possible at higher concentrations, causing toxicity of cells and inflammation ,83,84,85+ ions that impair mitochondrial function. ROS, accumulating as byproducts of the electron transport chain, cause mitochondrial damage and impairment of function, depolarization of the mitochondrial membrane, damage to mtDNA , and peroxidation of lipids and protein elements, eventually leading to apoptosis  treatment of human Chang liver cells , human lThe use of instrumental neutron activation analysis (INAA) by Antsiferova et al. (2015) allowed for studying biokinetics of silver nanoparticles in biological tissues. The results confirm the highest uptake of nanoparticles through the liver and blood by mice, with a single exposure to 34 nm AgNP, compared to the brain. The animals were incubated with AuNP at a concentration of 100 μg/mL for one day. Furthermore, with an increase in incubation time of up to two months and the same dose, a higher accumulation of nanoparticles was observed in the liver than in the blood. The effectiveness of a month-long distilled water feeding on the level of silver nanoparticle removal from the organism after two months of exposure was also investigated, with the fastest reduction in AuNP observed in the liver. The study confirmed the ability of the liver and blood to quickly dispose of silver nanoparticles. It also ruled out the possibility of dangerous effects of AgNP on these organs .3), medium (81.8 ± 11.4 μg/m3), and high (115.6 ± 30.5 μg/m3), confirmed the presence of AgNPs in bronchoalveolar lavage (BAL). Furthermore, similar to previously mentioned studies, no effect of nanoparticles on body weight was noted. In turn, there was a statistically significant change in the weight of the right lung after a 7-day post-exposure observation based on average concentration. Biochemical changes, such as hemoglobin concentrations in erythrocytes, lymphocyte percentage, asparagine transaminase (AST), and lactate dehydrogenase (LDH) levels, were also observed at each of the concentrations used. Based on the number of neutrophils, indicating inflammation, significant increases were observed in high concentration groups [The research Jo et al. (2020), conducted on Sprague–Dawley rats exposed for 28 days to silver nanoparticle aerosols of variable size (18.1–19.6 nm) and three concentration groups: small  investigated the effects of spherical gold nanoparticle toxicity on the in vitro rat model of embryonic fibroblast cells (REF), and in vivo—male mice weighing 25 to 30 g. REF cells were incubated for 48 h with AuNP concentrations of 1, 5, and 10 μg/mL. In turn, gold nanoparticles were intraperitoneally administered in mice, at a dose of 100 μg/Kg, for 28 days. Toxicity in REF cells was investigated using an MTT test. Furthermore, histopathological analysis of preparations from the liver, lungs, and spleen of mice was carried out using a fluorescent microscope. REF cells showed toxicity only at 10% at the highest AuNP dose. For concentrations of 1 and 5 μg/mL, this parameter was even lower. The analyzed cells showed no change in nuclear morphology, and no changes in histopathological slices. Moreover, nanoparticles did not affect the bodyweight of mice. The results of these in vitro and in vivo tests therefore confirmed the safety of gold nanoparticle use at low concentrations .The effects of spherical AuPEG toxicity in mice were also studied by Chinese researchers in 2011. The study focused mainly on the size of nanoparticles, with four different sizes used: 5, 10, 30, and 60 nm. Mice were treated with gold nanoparticles at a concentration of 4000 μg/kg bodyweight for 28 days. A particle analyzer was used to assess the concentration of nanoparticles in the heart, lungs, spleen, and kidneys. Using a transmission electron microscope, preparations of bone marrow and blood were also characterized. Furthermore, biochemical blood tests were performed to evaluate the numbers of morphotic elements and enzyme levels.Both the heart and kidneys exhibited the highest concentration of 5 nm nanoparticles. In turn, 10 nm nanoparticles were most commonly detected in the liver, while those 30 nm mainly aggregated in the spleen. Five nanometer nanoparticles were also observed in the bone marrow without any significant reduction in their size, indicating that they did not undergo disintegration. Furthermore, other nanoparticle sizes were also localized in both intracellular and extracellular compartments of bone marrow, indicating longer NP retention in this tissue.In blood, nanoparticles of 5 nm were aggregated and could form 10–20 nm long structures. A similar situation was observed at 10 and 60 nm but not at 30 nm. Moreover, the presence of gold nanoparticles after 28 days of incubation indicated their long retention time in blood.Due to the lack of immune response caused by gold nanoparticles of different sizes, no statistically significant differences of the mg/g index were detected between the study and control groups in either the thymus or the spleen.Hematology results after 28 days of intraperitoneal injection at the dose of 4000 μg/kg gold nanoparticles are shown in An increase in the number of white blood cells observed in mice treated with 10 nm particles indicates an inflammatory reaction. In contrast, a decrease in the number of white blood cells observed in mice treated with 5 and 30 nm particles may be associated with infection. Furthermore, the increase in the number of red blood cells found in mice treated with 10 and 60 nm nanoparticles indicates that particles of this size affect the hematopoietic system.The level of biochemical enzymes in the blood of mice was also investigated .Biochemical changes suggest that 10 nm particles may be highly toxic to the liver, and 60 nm particles could present toxicity to both the kidneys and liver. However, no liver and kidney damage was observed for 5 and 30 nm AuPEGs.The study results suggest that 10 nm gold nanoparticles coated with PEG are not sufficiently safe to be administered at a concentration of 4000 μg/kg. The results of the studies presented above contradict previous assumptions linking in vitro cell incubations with smaller nanoparticles with higher toxicity .Lasagna-Reeves et al. (2010) investigated the possibility of toxicity induction in 12-week-old mice through the administration of 12.5 nm colloidal AuNPs with regular shape for eight days, in doses of 40, 200, and 400 µg/kg/day. The evaluation of this parameter aimed to clarify the possibility of AuNP use in, e.g., drug delivery or disease diagnostics. Hematological analysis evaluating white and red blood cells, platelets, hemoglobin, and hematocrit was performed using a hematological analyzer (Coulter T540 hematology system). Histopathological evaluation was performed based on H&E (hematoxylin-eosin) staining. The distribution of gold nanoparticles was characterized using GF–AAS (graphite furnace atomic absorption spectrophotometry) and ICP–MS (inductively coupled plasma mass spectrometry). The concentration of gold nanoparticles in the liver, kidneys, spleen, and lungs increased with dosage. Considering different sizes of organs, the total percent of the applied dose detected was highest in the liver, followed by kidneys and the spleen. In turn, the level of AuNP in the blood was independent of the administered doses, which indicates that uptake and absorption of gold nanoparticles mainly occur in tissues. In addition, the percentage of accumulated gold decreases with the increase in AuNP dose, which suggests efficient removal of nanoparticles from the body.Concentrations of urea nitrogen, uric acid, and creatinine were examined to evaluate AuNP nephrotoxicity. Moreover, total bilirubin and alkaline phosphatase levels in the blood were used for functional evaluation of the liver and bile ducts. The biochemical analysis of these parameters did not show statistically significant differences in any metabolites, regardless of the dose used. Furthermore, the hematological analysis did not show statistically significant differences between gold nanoparticle incubated mice and control samples. This confirms the conclusion that gold nanoparticles do not cause extensive inflammation in mice. In addition, for observation of possible toxic effects, macroscopic morphological analysis of tissues was carried out. Tissue damage was not shown in any of the sections taken from the kidneys, liver, spleen, brain, or lungs. Gold nanoparticles also did not affect the weight of mice regardless of the dose of nanoparticles used .The effect of the surface functionalization of gold nanoparticles was studied by Zhang et al. (2020); AuNPs stabilized by PEG (polyethylene glycol) are commonly used as nanodrug carriers due to their biocompatibility, obtained through nanoparticle stabilization. The study compared surface functionalization of nanoparticles using PEG (AuPEG) and Trolox (AuTrolox). The second substance is a Vitamin E derivative, with its administration leading to inhibition of oxidative stress through the removal of ROS and nitrogen oxides.The studies were conducted in vitro on the SH-SY5Y neuroblastoma cell line. The cells were incubated with gold nanoparticles of 4.5, 13, and 30 nm and 25 μg/mL for 24 h. An MTT test was used to investigate the toxicity of SH-SY5Y cells. Using a laser confocal microscope, the level of reactive oxygen species was measured. Furthermore, malondialdehyde  levels were assessed as a marker of oxidative stress. Subsequently, mitochondrial membrane potential was also investigated using JC-1 dye and confocal microscopy techniques. In turn, the effect of gold nanoparticles on apoptosis values was measured using a flow cytometer and a commercial reagent kit. To determine which apoptotic proteins are involved in signaling pathway induction, Bcl-2, caspase-3, and PARP (poly (ADP-ribose) polymerase) proteins were investigated. Finally, using the ICP–MS (inductively coupled plasma mass spectrometer) method, the distribution of AuPEG and AuTrolox in individual mouse organs was investigated.AuPEG nanoparticles of 4.5 nm were shown to have higher toxicity than particles of other sizes. Therefore, they were selected for further studies evaluating the effects of antioxidants on nanoparticle-induced oxidative stress.For AuPEG, six times higher levels of ROS and two times higher MDA values were demonstrated compared to control. However, a significant reduction in MDA and ROS occurred after the surface of nanoparticles was functionalized with Trolox. Furthermore, through increased green fluorescence signal and reduced red signal of JC-1 dye, mitochondrial damage in cells incubated with AuPEG was confirmed. A decrease in green fluorescence levels was also observed when AuTrolox was used.AuPEG and AuTrolox nanoparticles (4.5 nm) were used to evaluate apoptosis, at concentrations of 2.5, 5, 10, 25, 50, 75, and 100 μg/mL, during 24-hour incubation. AuPEG was shown to significantly affect cell viability, with a decrease of almost 40% confirmed for concentrations of 50, 75, and 100 μg/mL. However, AuTrolox mediated inhibition of apoptosis was also detected. After 48-hour incubation of SH-SY5Y cells, at 25 μg/mL concentration, the apoptosis level in AuPEG treated cells was 40%, while it was 20% for AuTrolox. Flow cytometry results also confirmed differences in apoptosis induction. Furthermore, Western-blot analysis showed a decrease in Bcl-2 protein expression, and activation of caspase-3 and PARP.The study confirmed that the use of Trolox on the surface of gold nanoparticles significantly reduces the adverse effects of ROS and MDA and improves antioxidant enzyme activities compared to AuPEG. According to the researchers, Trolox is an antioxidant with proven effects in the reduction of oxidative stress. The authors also state that combining antioxidants with gold nanoparticles can increase their activity.The possibility of AuPEG induction of apoptosis via the mitochondrial apoptosis signaling due to ROS presence was also confirmed. However, this process was reversed after the application of AuTrolox.An in vivo model of male mice weighing approximately 20 g was used to further assess the neurotoxicity of nanoparticles, with the animals receiving ranging NP doses (12.5 and 25 mg/Kg).Using ICP–MS, the greatest accumulation of gold nanoparticles was detected in the liver and then in the spleen, especially compared to the heart, kidneys, and lungs. This occurrence was associated with increased phagocytic activity in the cells of the mononuclear phagocyte system. Furthermore, higher concentrations of nanoparticles translated into their higher accumulation in the test organs. No difference in body weight was observed between mice treated with AuPEG and AuTrolox.In samples taken from the mouse hippocampus, the levels of antioxidant enzymes such as SOD (superoxide dismutase), CAT , and GSH-Px (glutathione peroxidase) were evaluated. The principle of antioxidant action is presented in Application of AuPEG at 25 mg/kg for three months caused a decrease in MDA and antioxidant enzyme levels  in the hippocampus, compared to AuTrolox .Through induction of oxidative stress in cells, gold nanoparticles lead to the accumulation of free radicals and thus reduce the activity of liver antioxidant enzymes  and GSH levels .Overall, the publication of Zhang et al. (2020) demonstrates the possibility of inducing oxidative stress and apoptosis by 4.5 nm PEG-stabilized AuNPs. Inhibition of this process through the use of an antioxidant—Trolox—was also noted. This research provides a reasonable basis for the potential development of a nanoparticle drug delivery system .A mouse fibroblast cell line  was the subject of research by Coradeghini et al. (2013). Gold nanoparticles of 5 and 15 nm in size and concentrations of 10, 50, 100, 200, and 300 μM were used. Incubation with AuNP was conducted for 2, 24, and 72 h. Culture performance tests assessing colony-forming efficiency (CFE) and Trypan blue were used to determine the toxicity of nanoparticles. A transmission electron microscope was also used to evaluate NP location qualitatively. In turn, the quantitative uptake of nanoparticles by Balb/3T3 cells was characterized using ICP–MS.In the CFE test, smaller nanoparticles showed higher toxicity at 72 h of incubation, especially at concentrations above 50 μM. For 15 nm NPs, no statistically significant differences were observed for any concentration and incubation time. Based on the Trypan blue dye test, 5 and 15 nm nanoparticles were not toxic to mouse fibroblasts, regardless of the concentration and exposure period used.Furthermore, the cells were incubated with 10 and 30 μM gold nanoparticles for 2 and 24 h. Using a transmission electron microscope, cellular internalization was determined to occur in both AuNP sizes used. Moreover, enclosure of nanoparticles inside vesicles was observed. However, AuNPs did migrate to other organelles, such as the nucleus, mitochondria, or Golgi apparatus. The number of nanoparticles collected in endocytotic vesicles increased with concentration. Moreover, autophagosome formation was also shown to be possible. Furthermore, it was noted that even after 2 h of incubation, the nanoparticles already reached the the end of the endo/lysosomal pathway.The uptake of nanoparticles after 2 h was confirmed using ICP–MS (plasma mass spectrometry). The number of nanoparticles increased with incubation time and was higher in those 15 nm in size.Summarizing, the study confirmed 5 nm AuNP toxicity at incubation time 72 h and concentrations above 50 μM. Therefore, the importance of the nanoparticle size used should be taken into account in studies determining their effects on cell biology .Scientists in Gdansk 2019 investigated the effect of the shape of gold nanoparticles on toxicity in cancer cells. They used four cell lines: human fetal osteoblast (hFOB 1.19), human bone osteosarcoma (143B), human osteosarcoma cell line (MG-63), and pancreatic duct (hTERT-HPNE). The gold nanoparticle shapes investigated were nanosphere, nanostar, and nanorod. Nanoparticle morphology was characterized using SEM and TEM microscopes. The average length of nanoparticles of a nanosphere shape was 14 nm, while the size of the nanostars was about 200 nm. Nanorods had an average length of 45 nm and a diameter of 16 nm. The cell lines investigated were incubated with different AuNP shapes for 24 h.Cell viability was tested using the MTT test to measure the cellular activity of NADPH-dependent oxidoreductase, as reduced cell life span may be associated with the process of apoptosis. In order to assess the ability of live undamaged cells to collect dye in lysosomes, neutral red (NR) assay was used, as this test also allows for measuring the integrity of the cell membrane. Concentrations of nanoparticles of 0.3, 0.6, 1.2, 2.5, and 5 μg/mL were used for both tests.A comparison of tests determining cell viability showed that nanostars had the most significant impact on reducing cell lifespan. In this shape, the survival rate of the cell lines investigated decreased as the concentration increased. The highest susceptibility to toxicity caused by nanostars was attributed to the 143B cell line cells. However, the NR test did not show similar activity for nanostars at 0.3 μg/mL concentration. Nanorods showed significant toxicity at higher concentrations (2.5 and 5 μg/mL), especially with MG63 and 143B cell lines. However, the NR test results showed a lower effect on cell survival at the same concentrations of these nanoparticles. Nanospheres exerted the smallest impact on cell line survival. Despite that, a slight reduction in cell life of 143B cells was shown in the MTT test. Moreover, the results of both tests point to toxicity mediated by AuNPs via alterations in mitochondrial activity (MTT) and integrity of the cellular membrane (NR).Owing to these toxicity results, nanostars and nanorods were further analyzed in relation to their effect on the levels of apoptotic proteins. The NR test showed that hFOB1.19 cells were the most resistant to nanoparticles, prompting the use of 2 remaining cell lines (MG63 and 143B) for further study. The concentrations of a proapoptotic protein (Bax) and antiapoptotic protein (Bcl-2) were determined using the Western blot method. The concentrations used were 1 and 2 μg/mL for nanorods and 0.1, 0.3, 0.6, and 1 μg/mL for nanostars. Both 143B and MG63 cell lines showed an increase in proapoptotic protein levels in the presence of nanorods. Concerning the antiapoptotic protein, a decrease in Bcl-2 levels was observed only in MG63 cells. For the 143B cell line, an increase in Bcl-2 at 1 μg/mL and a decrease at 2 μg/mL was demonstrated.In turn, nanostars increased Bax levels as their concentrations increased for both cell lines. They also caused a decrease in Bcl-2 expression in both 143B and MG63 cells. The most significant changes in Bax and Bcl-2 protein levels were observed at AuNP concentration of 1 μg/mL.The morphology of the hTERT-HPNE cell line was analyzed in a TEM. Nanostars and nanorods were shown to penetrate cells and cause changes in their ultrastructure. Nanostars were used at a concentration of 10 μg/mL, resulting in intensive vacuolization of the cytoplasm, with an especially prominent appearance of autophagic vacuoles. At a concentration of 50 μg/mL, cell damage occurred, consisting of cell membrane rupture, cytoplasmatic vacuolization, and cell degeneration.In turn, nanorods at a concentration of 10 μg/mL localized outside the cell, along the cell membrane. As a result of endocytosis, they were also observed in endosomes. At this concentration, the cell showed an unchanged structure of the rough endoplasmic reticulum, and the presence of numerous autophagosomes. At a higher concentration (50 μg/mL), cell degradation occurred, including cell membrane damage,.Given the demonstrated relationship between the shape of the nanoparticles used and the resulting toxicity, this parameter should be considered when designing biomedical applications .Summarizing, the size of the gold nanoparticles used is essential for their biokinetics. Smaller nanoparticles (approximately 10 nm) accumulate in many organs, e.g., liver, spleen, kidneys, testicles, and lungs, and blood . SmallerSeveral research groups evaluated silver (dispersion NP) and gold nanoparticle  toxicity in comparative experiments. Results of one of such study conducted on a mouse model were published by Shrivastwa et al. in 2015. The study was based on male Swiss albino mice, 25–30 g in weight. Blood and tissues from the brain, liver, kidneys, and spleen were used for the experiment. The nanoparticles analyzed were silver and gold, with a size of 20 nm, at concentrations of 1 and 2 μM/kg. AgNP and AuNP were administered to mice interally for 14 days.The amount of reactive oxygen species in treated mice was examined through the analysis of the fluorescence level of the DCFH-DA dye in blood and mouse tissues. GPx (glutathione peroxidase) and GST (glutathione-S-transferase) were used to assess the level of antioxidant enzymes in the blood and tissues. Within the tissues, the ratio of GSH: GSSG was evaluated (reduced glutathione: oxidized glutathione), while total glutathione levels were analyzed in blood. Furthermore, the level of inflammation was marked in soft tissues using IL-6 (interleukin-6).Concerning the results of the analysis, significant weight loss was observed in mice exposed to nanoparticles, especially at a higher dose (2 μM). Moreover, AgNP seemed to cause more substantial weight loss than AuNP. The intensity of fluorescence increased after incubation of blood with nanoparticles in both doses compared to control, with the largest difference noted for AgNP at 2 μM dose. Concerning blood analysis, AgNPs at a dose of 2 μM were found to be the most stimulating, as AgNPs inhibited analyzed enzymes to a greater extent than AuNPs.The effect of gold and silver nanoparticles on soft tissues is presented in GPx (glutathione peroxidase) activity decreased in the brain, especially at a concentration of 2 μM AgNP. In contrast, its level increased significantly in the kidneys at the same dose. An increase in value was also observed at a concentration of 1 μM for both types of NP. In the liver, gold had a stimulating effect on GPx levels, especially at a dose of 1 μM, while silver inhibited this enzyme at the same amount.Concerning GST levels in the brain, one µM AgNP resulted in the most significant increase of this protein. In the liver and kidneys, all NPs acted inhibitory, with the most considerable effect attributed to AgNPs at 2 µM. In turn, in the spleen, the largest inhibitory potential was presented by 2 µM AgNPs.An increase in the fluorescence intensity of the DCFH-DA dye was noted in blood and all soft tissues incubated with AgNPs and AuNPs. In the brain, liver, kidneys, and spleen, 2 μM levels had the most promoting effects, especially concerning silver nanoparticles. Furthermore, a significant increase in IL-6 levels was observed in both types of nanoparticles, especially at a dose of 2 μM, compared to the control sample.The application of nanoparticles also significantly affected toxicity. This process manifested through inflammation and increased ROS release resulting from oxidative stress. More pronounced adverse effects were attributed to silver nanoparticles, especially at higher analyzed doses .In another study, Barkur et al. (2020) studied oxidative stress caused by silver and gold nanoparticles on human red blood cells (RBC) using Raman spectroscopy. The cells were incubated for 24 and 48 h with 50 nm silver and gold nanoparticles. Moreover, thiol levels were studied through absorbance measurements.Raman spectroscopy showed an adverse effect of increasing concentrations of nanoparticles on the binding of oxygen to hemoglobin. After 24 h of incubation, minimal spectral changes were observed. RBC treated with 100 μL of silver nanoparticles ruptured after 48 h of incubation, making it impossible to perform spectroscopy. Using 50 μL of NPs, more significant spectral fluctuations were shown in cells incubated with silver than gold nanoparticles. The Raman spectra showed more variability with AgNPs of 30 nm, compared to larger sizes . In addition, for AuNPs, the highest and lowest spectral variability levels appeared at 30 and 10 nm sizes, respectively. This indicates a more harmful effect of AgNPs on the affinity of hemoglobin in erythrocytes for binding oxygen. Due to their antioxidant properties, examination of thiol levels in cells allowed for evaluation of oxidative stress in the presence of nanoparticles. Significant changes in thiol values indicate that such a state can result from NP administration, with more reduced thiol content observed for silver nanoparticles, indicating greater levels of oxidative stress.In addition, changes in hemoglobin structure resulting from incubation with NPs were demonstrated. This occurrence was related to the possibility of nanoparticle adherence to the cell membrane of erythrocytes, causing oxidative stress. Adverse effects of nanoparticles on hemoglobin oxygen-binding ability were also observed. Such processes could potentially cause negative side effects of metal nanoparticle penetration into the human body .The main properties and applications of silver and gold nanoparticles are shown in The antimicrobial activity of nanoparticles is related to their electrostatic interaction with negatively charged cell surfaces, which improves their ability to penetrate cellular membranes. This process leads to the damage of biological membranes, coagulation of proteins, stimulation of ROS production, and ultimately to the reduction of microbial viability ,102,103.Candida albicans, Trichophyton rubrum, Stachybotrys chartarum, and Mortierella alpina. AgNPs induce the formation of perforations on the cell membrane surface, leading to osmotic shock and ultimately fungal death [The antimicrobial activity of silver nanoparticles occurs through their attachment to the cell wall and penetration to the cytoplasm. There, the released silver ions interact with proteins at the amino acid level, disrupt electron transport in the respiratory chain and inhibit DNA replication. Due to the release of silver ions and alteration in the cell surface structure, cellular enzymes are deactivated, resulting in ROS production. These changes induce toxicity and ultimately lead to microbial death ,101,102.Candida albicans [The antimicrobial effect of gold nanoparticles is related to their attachment to the bacterial cell wall, resulting in the creation of pores and penetration into the intracellular space. There, they disrupt the metabolic processes, bind to DNA and inhibit the transcription process, and distort the ribosome units for tRNA binding. These effects ultimately result in a breakdown in the biotic mechanism of the bacteria ,101,102.albicans . FurtherAntimicrobial activity also depends on the nanoparticle size, shape, concentration, and surface modification ,102,103.The large surface-to-volume ratio of silver and gold nanoparticles enables high absorption of various molecules, e.g., polymers and therapeutic agents, facilitating their common use in biomedical fields ,102. FurThe unique optical properties of gold and silver nanoparticles occur due to the excitation of localized resonance of surface plasmons, with greater excitation occurring on silver NPs, compared to their gold counterparts ,102,104.Due to the increasing use of nanoparticles, the possibility of them crossing the blood–brain barrier (BBB) remains a significant concern. This process was confirmed, e.g., by Tang et al., in an experiment based on rat brain microvessel vascular endothelial cells (BMVEC) and astrocytes (AC) incubated with spherical AgNP (100 µg/mL). Under culture conditions, nanoparticles were observed to localize inside endothelial cells. NPs were described to enter the cells to transcytosis, a process that also allows them to infiltrate other tissues of the organism. Further in vitro studies have also confirmed the possibility of AgNPs crossing the blood–brain barrier and have identified potentially harmful effects of AgNP on brain tissue and their interaction with cellular organelles such as mitochondria and the rough endoplasmic reticulum ,105.3, which are associated with increased rBMEC  monolayer permeability and may cause BBB dysfunction. The permeability of primary rBMEC monolayers was evaluated as the percentage of fluorescein flow across the rBMEC monolayers. AgNP was used at a concentration of 15 µg/cm3. Furthermore, systemic exposure to AgNPs, depending on their size, can result in microvascular damage to the brain. It has been reported that smaller (25 nm) AgNPs produce a more robust inflammatory response, correlated with increased brain microvascular permeability and cell monolayer perforation compared to larger AgNPs (40 and 80 nm) [Hence, due to their ability to cross the BBB, spherical AgNPs are considered as a potential neurotoxin. The increased transport of fluorescein by BBB indicates an NP size-dependent increase in BBB permeability, correlated with the severity of immunotoxicity. AgNPs have been shown to induce an increased release of pro-inflammable mediators, i.e., tumor necrosis factor (TNF-α), interleukins , and prostaglandin E2 (PGE2) in concentration of AgNP 50 µg/cmd 80 nm) .Feeding mice with 34 nm silver nanoparticles for two months significantly increased the concentration of AgNP in the brain compared to one-day incubation. The effect of month-long distilled water administration on the AgNP concentration was also investigated, proving that the level of nanoparticles remained at about 6%. This may be related to the mechanism of endocytosis and exocytosis across the blood–brain barrier and confirm the accumulation of silver nanoparticles in the brain. Therefore, low levels of AgNP removal from the brain may be a risk to patients treated with products containing NPs, potentially resulting in an opposite rather than expected effect during long-term use ,106.Moreover, an experiment studying the effects of long-term oral administration of AgNPs confirmed continuous accumulation of silver nanoparticles in the mouse brain due to exposures lasting up to 4 months. The accumulation of 34 ± 1.4 nm AgNPs at a concentration of 25 μg/mL in the brains of experimental animals was significantly higher after 4-month vs. 2-month administration. Slow removal of AgNP from the brain was also observed after discontinuation of NP intake. After specific administration periods, the amount of silver accumulated in brain tissues was determined by neutron activation analysis (NAA) and compared with Morris water maze (MWM) behavioral test results. The presence or absence of AgNP in the body did not have an apparent effect on memory: differences in dynamics and ranges of parameters described above were found in both the experimental and control subgroups. However, there is a possibility of the results being affected by the memory effect, as the animals, after testing in MWM, could have retained information about the research area, such as the structure of its internal space and the location of external clues .Furthermore, Lasagna-Reeves et al. (2010) confirmed the ability of 12.5 nm colloidal AgNPs with regular shape for crossing the blood–brain barrier in mice. Given the relatively constant level of gold in the blood after AgNP administration at different doses, increased accumulation of gold in the brain suggests their uptake from the blood to the brain. An increase of AuNP accumulation with dosage confirms the possibility of nanoparticle use for targeted therapy in the brain without production of detectable toxicity. These properties emphasize the potential application of gold nanoparticles to treat and diagnose neurodegenerative disorders .Nanoparticles in the brain were also observed in mice administered 4.5 nm gold nanoparticles intravenously for three months. Nonetheless, AuPEG accumulation in the brain was much higher than with AuTrolox. Furthermore, morphological changes have been studied through HE staining. In the AuPEG group, some hippocampus neurons were condensed and darkly stained in the CA1, CA3, and Hilar regions, indicating their damage and loss. However, cells incubated with AuTrolox were rarely stained and had visible nuclei, implying a Trolox mediated decrease in AgNP toxicity.Next, immunohistochemical staining was performed using a primary antibody against NeuN. This protein is localized in nuclei and nuclear cytoplasm of most central nervous system neurons in mammals and is considered a reliable indicator of post-mitotic neurons. The intensity of hematoxyline staining was studied using a tissue cytometer (TissueFAXS-plus), showing decreased CA1, CA3, and Hilus regions at both 12.5 and 25 mg/kg AuNPs. With the addition of Trolox, an increase in NeuN antibody expression and inhibition of apoptosis were observed when compared to the AuPEG group.After isolating and homogenizing the hippocampus, LDH (lactate dehydrogenase) levels were investigated. After treatment of cells with AuPEG at a 25 mg/kg concentration, a two-fold increase in LDH levels was observed, indicating that AuPEG may cause cell death .The history of the use of silver and gold nanoparticles began in antiquity. Ancient Greeks used silver-coated dishes to store wine for longer times ; this meDue to the development of nanotechnology and the use of nanoparticles, it is necessary to study their effects on cells. Many parameters of NPs influence toxicity, including size, shape, concentration, type of coating, and incubation time ,106. It The effect of an increase in the concentration of silver nanoparticles leading to apoptosis is shown in AgNPs have a higher potential for toxicity compared to AuNPs. Therefore, an increase in the share of the use of AuNP was observed, especially in functionalized, therapeutic, and diagnostic methods . Given tGold nanoparticles, characterized by increased biocompatibility, stability, and low toxicity, are considered one of the most suitable carrier systems for medicines. AuNPs functionalized by PEG, due to their ability to bind to cell membranes, have an increased ability to penetrate target cells. Furthermore, fluorescent dye coating allows for monitoring of their movement .Increased use of hazardous chemicals used in the production of nanoparticles could become a serious cause of environmental degradation. Hence, the use of nanoparticles of plant origin could aid in the reduction of harmful chemicals in NP synthesis, as research indicates the possibility of their therapeutic use. They were described to manifest anticancer potential in the treatment of lung, liver, and cervical cancer, and were proposed for use in antidiabetic drugs, acting as an inhibitor of α-amylase. The green synthesized nanoparticles were proven to prevent the development of microbes and have therefore been used in disinfectants and as an antimicrobial coating on medical devices such as catheters. However, the mechanisms of action of these nanoparticles are not yet fully understood. While additional research is needed, the results of past experiments provide an optimistic perspective of a potential increase in the use of plant-based nanoparticles in industry and medicine ,114.The emerging discrepancies between literature data on the correlation between the physicochemical properties of nanoparticles such as size, shape, type of functionalized surface, and induced toxicity are the inspiration for further scientific research . It is a


Direct Contact Membrane Distillation (DCMD) is a promising and feasible technology for water desalination. Most of the models used to simulate DCMD are one-dimensional and/or use a linear function of vapour pressure which relies on experimentally determined parameters. In this study, the model of DCMD using Nusselt correlations was improved by coupling the continuity, momentum, and energy equations to better capture the downstream alteration of flow field properties. A logarithmic function of vapour pressure, which is independent from experiments, was used. This allowed us to analyse DCMD with different membrane properties. The results of our developed model were in good agreement with the DCMD experimental results, with less than 7% deviation. System performance metrics, including water flux, temperature, and concentration polarisation coefficient and thermal efficiency, were analysed by varying inlet feed and permeate temperature, inlet velocity, inlet feed concentration, channel length. In addition, twenty-two commercial membranes were analysed to obtain a real vision on the influence of membrane characteristics on system performance metrics. The results showed that the feed temperature had the most significant effect on water flux and thermal efficiency. The increased feed temperature enhanced the water flux and thermal efficiency; however, it caused more concentration and temperature polarisation. On the other hand, the increased inlet velocity was found to provide increased water flux and reduced temperature and concertation polarisation as well. It was also found that the membrane properties, especially thickness and porosity, can affect the DCMD performance significantly. A two-fold increase of feed temperature increased the water flux and thermal efficiency, 10-fold and 27%, respectively; however, it caused an increase in temperature and concertation polarisation, at 48% and 34%, respectively. By increasing Reynolds number from 80 to 1600, the water flux, CPC, and TPC enhanced by 2.3-fold, 2%, and 21%, respectively. The increased feed concentration from 0 to 250 [g/L] caused a 26% reduction in water flux. To capture the downstream alteration of flow properties, it was shown that the ratio of inlet value to outlet value of system performance metrics decreased significantly throughout the module. Therefore, improvement over the conventional model is undeniable, as the new model can assist in achieving optimal operation conditions. Water scarcity is increasing globally due to population growth, climate change, and expanded industrial activities, leading to a severe global challenge ,2,3. To  sources ,8. Secon sources ,10.Not being cost effective in terms of energy efficiency is one of the main MD challenges that should be addressed. One of the main reasons for the low energy efficiency is the heat loss along the module. Meticulously understanding the flow properties alterations along the module is necessary to find a solution for this issue. Several studies have employed semi-empirical Nusselt and Sherwood correlations to investigate DCMD system performance ,12. WithTemperature polarisation and concentration polarisation are two main phenomena that cause a reduction in temperature difference, and consequently in transmembrane vapour flux ,24,25,26Although water vapour transmembrane mass flux is the most important parameter in MD system modelling, studies have applied constant fitting parameter, single-gas mass transfer equation, and/or only considered the transition region in their modelling approaches ,21,35,36Membrane characteristics are also critical in MD simulation and MD performance analysis ,42,43,44To develop and validate a semi-empirical model that is able to capture downstream variables, including transmembrane water flux, Temperature Polarisation Coefficient (TPC), Concentration Polarisation Coefficient (CPC), and thermal efficiency on a DCMD module;To model DCMD with a self-sustained water flux equation which allows to systematically investigate different membranes with few assumptions;To conduct a sensitivity analysis to understand which parameters have more significant effects on DCMD performance;To analyse 22 commercially available membranes in terms of performance metric evaluation to assess the suitability of these membranes for DCMD application.Within the above context, the following specific objectives were set for this study:n elements on the basis that transmembrane mass and heat transfer, and flow through the channels, were directly dependent on temperature alterations along the membrane and channel. Employing continuity, Navier-Stokes, and energy equations, n feed, and permeate bulk temperatures along the channel were calculated. Based on the feed and permeate bulk temperatures, and Nusselt correlation, the temperature on both sides of the membrane, permeate flux, and all system performance metrics, including TPC and CPC, and thermal efficiency were derived.The methodology involved the use of computational modelling wherein the channel and membrane were sub-divided into In general, MD can be conveniently defined into three stages: feed-side, membrane, and permeate-side. The process happening in each stage leads to a resistance to heat and mass transfer. As in MD, isothermal conditions are assumed. Based on the dusty gas model , the watTwo main mass transport assumptions were made to study gas transport through the membrane as a porous media: single gas and binary gas mixture through porous media. Two main gases are involved in the membrane: air and water vapour. The binary gas mixture is considered to have more exact mass transport model through membrane. The value of Knudsen number needs to be calculated to select the mechanism applicable to model the mass transport through the membrane (The water mass flux (tion (4) :(1)J={JKTwo contributions to the heat transfer in the membrane exist. First, the heat conduction transfer through the membrane and, second, the latent heat transfer owing to the flux of water vapour. As illustrated in In the literature, mainly two models have been employed to predict the effective thermal conductivity of membrane—the parallel model and series model. As the membrane is comprised of polymer, water vapour, and air, to predict the thermal conductivity of membrane, all components must be considered. The thermal conductivity of trapped air and water vapour is similar, and both can be estimated by Equations (A9) and (A10) .The semi-empirical approximation using Nusselt correlation and numerical simulation are two approaches which are used to calculate the temperature along the membrane.The feed and permeate heat transfer coefficients can be calculated using dimensionless Nusselt number, which can be obtained using semi-empirical correlations (Equations (A13)–(A20)) .To calculate the feed and permeate temperatures at the membrane surface and, accordingly, calculate temperature polarisation as one of the main causes of the loss of driving force in MD, heat transfer balance must be applied by Equation (8).As for Equation (8), in MD, the heat flux in the membrane, feed, and permeate must be equal. We estimate the feed and permeate heat transfer with the Nusselt empirical Equations (A21) and (A22).The governing equations for the laminar flow in the feed and permeate channel are the continuity, Navier-Stokes, and energy equations, as follows:n elements, and the Navier-Stokes, continuity, and heat transfer equations are solved by employing Fluent ANSYS. As the heat along the feed channel transfers to the permeate side, the bulk feed temperature along the membrane decreases, whereas the permeate temperature increases. The obtained bulk temperatures enable us to calculate downstream flow properties and membrane temperatures on both sides. Since the equations to compute membrane temperature on both sides in the semi-empirical model are dependent on water flux, and to include the effects of water flux on the temperature results on the numerical model, the algorithm illustrated in As shown in The pressure-based method, the SIMPLE algorithm, and a second-order accuracy for the spatial discretization scheme were employed to solve the steady state governing equations. The convergence criterion was defined to ectively ,52.L and height of h as a baseline system, consisting of a PTFE membrane, was considered. The porosity, tortuosity, pore diameter, and thickness of the membrane are 0.62, 2.34, 0.36 µm, and 84 µm, respectively [To validate our model with experiment data , as illuectively . HoweverA comprehensive parametric study on DCMD system was undertaken. As presented in Some metrics evaluations were used to assess the performance of MD, including TPC, CPC, water flux, and thermal efficiency. To assess the convective heat flux in the flow channels and the effect of temperature boundary layer and temperature polarisation, the TPC was calculated. The TPC is defined as the ratio of the temperature difference across the membrane surfaces to the temperature difference between the bulk feed and the bulk permeate, as follows:To characterise concentration polarisation and measure lateral mass concentration in the feed-side channel, CPC is calculated, as follows:Thermal efficiency defines the ratio of latent heat of evaporation to the total heat transfer across the membrane, as follows:Downstream alterations of the water flux, membrane temperatures, and membrane vapour pressures along the module were compared with the results of reference  for valiFour level of meshes have been generated to assess the independency of discretized mesh on the solution. The As illustrated in To study the influence of inlet feed and permeate temperature, a counter-current arrangement of a DCMD system was modelled for the inlet feed and permeate temperatures ondition .To examine the effects of the inlet velocity, a counter-current arrangement of a DCMD system was modelled for 0.01To examine the influence of inlet feed concentration, a counter-current arrangement of a DCMD system was modelled for the inlet feed concentration To study the influence of channel length, we modelled a counter-current arrangement of a DCMD system for As shown, with the increase of channel length, water flux increases 2.7-fold from 1.82 for 100 To analyse the effect of membrane characteristics, 22 different commercially available membranes were explored .A comparison of the 3M 0.2 µm membrane with 3M 0.45 µm  showed that different nominal pore size led to a minor change in membrane temperature and vapour pressure difference. It was shown that, with the increase of nominal pore size, from 0.59 µm for 3M 0.2 µm membrane, to 0.79 µm for 3M 0.45 µm, the water flux, CPC, and thermal efficiency increases by 3%, 1.5%, and 1%, respectively A, howeveA comparison of Milipore Porosity 0.4 with Milipore Porosity 0.7 membranes, which have different membrane porosity, 0.4 and 0.7, respectively, showed that, as porosity increases, the water production rate, CPC, and thermal efficiency increases; however, TPC decreases. This is due to the increase in water flux, which occurs due to the increase in the void of membrane. Membrana PP Accurel 2E and Membrana M1 were compared to analyze the effect of membrane thickness. As the membrane thickness increases, from 91 µm to 163 µm, TPC increases by 25% D, the waIn summary, as can be seen from By improving the conventional model that uses one-dimensional and considering downstream alterations, this study performed an extensive and comprehensive analysis of DCMD system performance. Most of the modelling studies that explored DCMD process have limited their investigations to simple correlations to model water flux, minimal discussion on concentration polarisation, broad analysis of different effective parameters, and to few commercially available membranes. Applications of the model showed advantages over the conventional modelling approach, such as capturing downstream alterations along the module, extensive discussion on concentration polarisation effects on different effective parameters of DCMD process, and more accurate water flux values. The improved model was in a good agreement with the experimental results. With the increase of feed temperature from Analysing different aspects of membrane characteristics, it was shown that by increasing the thickness from 91 µm to 163 µm, water flux and CPC decreased by 22% and 3%, and TPC and thermal efficiency increased by 25% and 4%, respectively. By increasing pore size from 0.59 µm to 0.79 µm, the water flux, CPC, and thermal efficiency increased by 3%, 1.5%, and 1%; however, TPC decreased by 1.5%. By increasing porosity from 0.4 to 0.7, the water flux, CPC, and thermal efficiency increased by 73%, 3%, and 23%, respectively; however, it caused a 17% reduction in the TPC.Our results suggest that increasing velocity and Re number is more valuable than increasing temperature difference in terms of temperature and concentration polarisation phenomena and, therefore, extending our study on turbulence promoter is warranted. However, with the increase of feed temperature, water flux significantly increases. Moreover, the downstream alteration along the membrane is significant. Therefore, it is crucial to study ways to lessen the significant decrease of water flux along the membrane such as by using solar-assisted membrane distillation to localize the heat transfer. Further, the improved model can be used to compare different MD configurations, such as AGMD, which is the focus of our future work.