Electrochemical Immunosensor For The Rapid Diagnosis Of Tuberculosis

Tuberculosis is one of the major infectious diseases that threat to human health. In recent years, the morbidity and the number of infections have continued to rise, and tuberculosis infection rate in China ranks second in the world. Traditional methods for tuberculosis detection can not meet the demands of diagnosis. Novel tuberculosis detection technologies featured with fast, efficient and low-cost are in urgent need.In this thesis, application of a multichannel electrochemical immunosensor in tuberculosis detection is studied. High specific TB antigens were immobilized on the electrodes of chips by localized co-electro-polymerization. The change of peak currents of electrochemical immunosensors before and after the combination of antibody and antigen were applied for tuberculosis diagnosis and screening.A novel multichannel electrochemical chip with integrated electrodes were designed and fabricated. The average peak current of the six-channel bare electrodes was 2.59 uA. The consistency error among six channels was smaller than 2.84%. The repeatability error was less than 2.66% in multiple scans. The results showed that the chip could provide repeatable and stable detection. Improvement of chip packaging and detection system was carried out. As a result, diagnosis costs were reduced. The detection process was significantly simplified and could be fulfilled within 40 minutes.Parameter optimization of the immobilization of specific antigens were studied. The antigens were embedded onto the electrodes by using cyclic voltammetry method to produce copolymer of o-phenylenediamine (PoPD) and antigens. The optimal parameters were as follows. Scanning voltage ranged from OV to 0.8V with a scan rate of 100mv/s and 8 sections of scanning. The concentration of PoPD was 5mM. After immobilization, the reduction peak current was around 2.2 uA.A large number of antibody was detected for research. The detection results of antibodies of known concentration showed a linear response when the antibody concentration was in the range of 0-23ng/ml, with a detection sensitivity of 0.9886. The detection results of human serum showed a specificity of 58.33%, a sensitivity of 69.23%, and a total detection accuracy of 62%. Such accuracy is much higher than that of traditional methods, which is averagely around 40%. The electrochemical immunoassay developed in this thesis still has some rooms for improvement in stability and consistency of multi-channel detection and sensitivity. Great quantity of clinical detection to infectious serums are necessary for appropriate statistical analysis in the future. The research result indicates a broad application prospect of sensor detection system.