Research On The Construction Of Built-in Excitation Source Biosensors Based On Metals And Metal Oxides

Biosensors have been widely used in many application areas including clinical diagnosis, environmental monitoring and food quality control. Using external power sources to generate detection signal is the common drawback of these biosensors, which limit their development. Thus, establishing simple operation, low cost, high sensibility and precision biosensors without using external power sources is on the hand.In this paper, we combine the features of metals and metal oxides with electrochemistry and biofuel cell to realize the establishment of electrochemical and built-in excitation source biosensors. The main research is as follows:（1） A novel electrochemical immunosensor for sensitive detection of carcinoembryonic antigen（CEA） was designed, which using poly（diallyldimethylammonium chloride） functionalized graphene and 3D trepang-like AuNPs（3D-TG） as hybrid platform and nanogold functionalized flower-like hierarchical carbon material（AuNPs/FCM） labeled with horseradish peroxidase-secondary antibodies as signal amplification label. The highly sensitive detection was achieved by the increased HRP-electrocatalyzed reduction of hydrogen peroxide. The proposed electrochemical immunosensor displayed a detection limit of 0.026 pg·m L-1.（2） FrGO was synthesized utilizing flower-like ZnO as template with electrochemical method. Based on the FrGO, Au/FrGO/Au-PWE sensing platform was established, which respected large specific surface area and good electrical conductivity. Meanwhile, The Mn₂O₃ nanoparticle-assembled hierarchical hollow spheres（H-Mn₂O₃） was synthesized by template method and served as nanocarrier to immobilize GOx, HRP and signal strand（S3）, resulting to the formation of S3/H-Mn₂O₃/HRP/GOx bioconjugations. Aniline was catalyzed by active enzyme and changed to PANI as a result. The developed biosensor exhibited a good linear response toward target DNA over a wide range of concentration from 0.005 to 2000 nM.（3） A paper-based analytical device, which was powered by visible-light enhanced biofuel cells（BFCs）, was proposed for sensitive detection of the carbohydrate antigen 15-3（CA15-3）. The gold nanoparticles modified paper electrode possessed large surface area and well conductibility. Glucose dehydrogenase（GDH） modified gold-silver bimetallic nanoparticles were used as bioanodic biocatalyst and signal magnification label;Poly（terthiophene）（pTTh）, a photo-responsive conducting polymer, served as catalysts in cathode for the reduction of oxygen upon illumination by visible light. In the bioanode, electrons were generated through the oxidation of glucose catalyzed by GDH, and then transfered to the cathode and combined with the generated-holes in the HOMO energy level of cathode catalysts pTTh as a result. Meanwhile, the high energy level photo excited electrons were generated in the LUMO energy level and involved in the oxygen reduction reaction, finally resulting to an increasing current and a decreasing overpotential, which could be used for simple and efficient detection of CA15-3.