HCR-stimulated formation of DNAzyme concatamers on gold nanoparticle for ultrasensitive impedimetric immunoassay.
A novel signal-amplified impedimetric immunosensing strategy was successfully developed for ultrasensitive detection of low-abundance proteins (carcinoembryonic antigen, CEA, used as a model) based on hybridization chain reaction (HCR)-stimulated formation of DNAzyme concatamers on nanogold particle accompanying enzyme-triggered biocatalytic precipitation. The assay was carried out on capture antibody-modified electrode by using gold nanoparticle heavily functionalized with initiator strand and detection antibody as the signal-transduction tag with a sandwich-type immunosensing format. In the presence of target CEA, the formed immunocomplex underwent an unbiased strand-displacement reaction by the initiator strand on the gold nanoparticle between two auxiliary single-stranded DNA with the hemin aptamer. Upon hemin introduction, numerous DNAzyme molecules were formed on the concatamers and nanogold particle, which could catalyze 4-chloro-1-naphthol to produce an insoluble precipitation on the electrode, thereby resulting in the amplification of impedimetric signal. Under the optimal conditions, the immuno-HCR assay exhibited good impedimetric responses for the detection of target CEA in the working range from 1.0 pg mL(-1) to 20 ng mL(-1) with a detection limit of 0.42 pg mL(-1). In addition, the immuno-HCR assay was validated by measuring six human serum specimens for target CEA, receiving a highly matched correction between the obtained results by the immuno-HCR assay and the commercialized ELC-based immunoassay method.
['Hou|Li|L|', 'Wu|Xiaoping|X|', 'Chen|Guonan|G|', 'Yang|Huanghao|H|', 'Lu|Minghua|M|', 'Tang|Dianping|D|']
D055910:Antibodies, Immobilized D015374:Biosensing Techniques D002272:Carcinoembryonic Antigen D021881:DNA, Catalytic D055664:Electrochemical Techniques D006046:Gold D006801:Humans D007118:Immunoassay D057230:Limit of Detection D053768:Metal Nanoparticles D009693:Nucleic Acid Hybridization
DNAzyme concatamer Carcinoembryonic antigen Biocatalytic precipitation Immuno-HCR assay Impedimetric immunosensor