Studies Of Biomolecular Immobilization And Signal Transduction In Electrochemical Immunosensors

Biosensors play a significant role in clinical diagnosis,food and environment monitoring and so on. It is one of the frontier areas in analytical chemistry. The primary subject of biosensing studies is the immobilization of biomolecules at sensing interface and the signaling of specific events of bioligical interaction. Seeking for novel materials and techniques to develop biosensors with improved selectivity and enhanced sensitivity has been a subject of keen interest in analytical chemistry. The present thesis focuses on the following three aspects:1. A novel piezoelectric immunosensor for Schistosoma-Japonicum (Sj)has been developed, on the basis of a new biomolecular immobilization matrix using self-assembled cystamine film and SiO2 nanoparticles. The formed sensitized nanoparticles of SjAg@SiO2 were immobilized onto the sensor that was modified with self-assembled cystamine film, resulting in a new piezoelectric immunosensor for detecting Sj antibodies (SjAb). The results showed that the three-dimensional (3D) spacial structures of SiO2 nanoparticle matrix can facilitate enhanced antigen-antibody immunoreaction, achieving high sensitivity for the detection of SjAb analytes. Under the optimized experimental conditions, the developed piezoelectric immunosensor is proved be capable of quantitatively determining SjAb in the concentration (dilution ratio) range of 1 : 88 ~ 1 : 3144 with a determination limit of 1 : 4853 (S/N = 3).2. Construction of a nano-based gold and the gold surface to enhance the new type of electrochemical analysis of the voltage sensor immune. The method to human immunoglobulin G (h IgG) model for the analysis of the material, the use of the sandwich so that the immobilized antibody response and analysis of the target h IgG and the gold nano-h IgG antibody binding to the electrode surface, so that the gold electrodes deposited on the surface of Gold nano-particles increase in diameter, and to study the electrochemical behavior before and after the gold to strengthen. And strengthen the traditional silver, to accelerate the speed of analysis. The results show that the law of the high sensitivity and selectivity, reproducibility, and easy to operate, is expected to have the potential to become a new type of highly sensitive immune sensing technology.3. A gold electrode with step-assembly of 10-play CuS was obtained, and then direct-absorption of CuS in the preparation of the surface metal / insulator / identification-layer capacitance sensor-based immunization. Copper sulfide film characterization experiments show that the assembly will be step by step through the insulation, and ultra-thin control of the thickness of the copper sulfide film. When people immunoglobulin A analysis of the material under test at 1.81 ng / mL ~ 90.5 ng / mL concentration can be a good linear relationship between the detection limit of 0.905 ng / mL, and that the sensor has a good Regeneration performance.