Fabrication Of Disposable Ultrasensitive Electrochemical Biosensor Using DNA Functionalized Nanomaterial

DNA functionalized nanomaterial combined the coding property of DNA with unique properties of nanoparticles are widely used in the fabrication of ultrasensitive biosensors. DNA can be engineered easily on nanoparticle surface under designed ways to bring high amounts of biological recognition sites and signal molecules on the surface of nanoparticle. Comparing with traditional signal probes, the DNA nanomaterial based probe has advantages of easy preparation, ability to loading high amounts of signal molecules, and good biocompatibility. So it has potential application in clinical diagnosis and environmental and food quality monitoring. This paper focuses on the development of novel DNA functionalized nanoprobe and construction of ultrasensitive electrochemical biosensors using screen printed electrodes, and done the following work:A DNA nanopolylinker was designed as a three dimensional nanoprobe with high loading of signal molecules for amplifying the biosensing signal. The nanoprobe was prepared by hybridization chain reaction engineering dsDNA polymerization on initiator DNA modified Au nanoparticle with two kinds of small molecule (for example, FITC)-labeled assistant DNA hairpins. The formed core-shell conjugate contained approximately320FITC molecules for further binding of signal molecules. With sandwich-type immunoreaction and biotin-streptavidin affinity reaction, the biotinylated core-shell nanoprobe was immobilized on immunosensor surface, and the FITC molecules then bound enzyme labeled anti-FITC antibody to catalyze a silver deposition process, leading to a novel cascade signal amplification strategy. By combining the proposed strategy with stripping analysis of the deposited silver, an ultrasensitive immunoassay method for biomarker detection was developed. Under optimal conditions, this method showed a linear detection range over5orders of magnitude for carcinoembryonic antigen with a detection limit of1.2fg mL-1(about 18molecules in5.0μL sample). The preparation of DNA nanopolylinker was simple and economic, and it could be used as a universal and multifarious probe for different bioanalytical techniques, showing a promising potential of the signal amplification strategy in future design of biosensing methodology.