Study On Biosensors Based On Silver Nnao-Materials And Chitosan Composite Films

Electrochemical biosensors play an important role in food, pharmaceutical and clinical fields because of the advantages such as good accuracy, fast analysis, hign sensitivity and simple detection process. In this thesis, we constructed some deffierent types of electrochemical biosensors based on the silver nanomaterials and personal glucose meters, and investigated their application in the bioanalysis of DNA, D-glucose and CEA, respectively.1、An amperometric glucose biosensor based on silver nanowires (AgNWs) and chitosan (CS)-glucose oxidase (GOD) film was prepared. The fabricated process was characterized by scanning electron microscopy (SEM), and the electrochemical behaviors of the biosensor were characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Under the optimal conditions, the proposed biosensor could detect glucose in the linear range from10μM to0.8mM, with a detection limit of2.83μM (S/N=3). The glucose biosensor showed high sensitivity, low detection limit, fast response, and good stability.2、An electrochemical biosensor for the detection of DNA was developed based on the silver nanocubes (AgNCs). The silver nanocubes (AgNCs) were prepared by simple chemical route. The formation of the AgNCs was confirmed by SEM and TEM analysis. The presence of Ag nanoparticles provided desirable microenvironment for the immobilization of probe DNA with controlled orientation leading to increased hybridization efficiency with target DNA.3. To expand the range of targets that can be detected by personal glucose meters (PGM), a sandwich-type immunesensor for carcinoembryonic antigen (CEA) was fabricated. Glucose oxidase (GOD) was fixed through the biospecific interaction of sugar-lectin between concanavalin A (ConA) and glucose oxidase (GOD). The fabricated process was characterized by differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). The concentration of targeting CEA antigen was albe to be detected by the immunesensor, and the results were shown in the PGM. The proposed biosensor could detect CEA in the linear range from20to140ng mL-1, with a detection limit of3.08ng mL-1(S/N=3).The methods demonstrated here can expand the range of target detection by PGMs significantly.