Design Of Ultrasensitive Immunosensors For The Detection Of Protein Biomarkers

As the emerging field of bioelectronics, biosensors utilize the use of biologically active molecules(such as antigens, antibodies, proteins, enzymes, DNA, cells, etc.)to transform the biochemical signal into the useable output signal. Immunosensor that combine chemical analysis with immune technology is a valuable analytical device. It is easy to operate with good selectivity, high sensitivity, and rapid detection. As a significance branch of the biosensors, the immunosensor combined chemistry, materials, biology, medicine, physics, imformation technology, and microelectronic technology together. The application of immunosensors can extend to medical diagnosis, environmental monitoring, food industry and national defense, etc. This paper mainly did the researches as follows:1.Application of hydrogel prepared from ferrocene functionalized amino acid in the design of novel electrochemical immunosensing platformRedox hydrogel was prepared from ferrocene functionalized amino acid and utilized for the fabrication of electrochemical immunosensing platform for the detection of human IgG. We discovered that H2O2could oxidize Fc groups on the amino acid and destroy the structure of the hydrogel. The electrodes were modified with hydrogel and the CNT-GOx-Ab2compound was synthesized as immunosensor label. H2O2generated due to the reaction of glucose oxidase (GOx) with glucose will cause the decrease of the redox activity of the electrode. Based on this novel hydrogel, the immunosensing platform achieved high sensitivity, good selectivity and reproductively for the detection of human IgG with linear range from0.1pg/mL to100pg/mL. We also studied recovery test of human IgG in real serum samples,which indicated this immunosensor can be used in real sample analysis.2.Paper based colorimetric biosensing platform utilizing cross-linked siloxane as probe. Paper based colorimetric biosensing platform utilizing cross-linked siloxane3-aminoproyltrimethoxysilane-glutaraldehyde(APTMS-GA) as probe was developed for the detection of H2O2, glucose and protein biomarker. We discovered when APTMS was cross-linked with GA, the resulting complex(APTMS-GA) displays brick-red color, and a visual color change was observed when the complex was reacted with H2O2. APTMS-GA was used for the modification of filter papers, and the modified paper enables quantitative detection of H2O2through the monitoring of the color intensity change of paper via software Image J. Then, with the immobilization of GOx onto the modified paper, glucose can be detected through the detection of enzymatically generated H2O2. For protein biomarker prostate specific antigen (PSA) assay, we synthesized complex CNT-GOx-Ab2and constructed the immunosensor with sandwich method. The detection of PSA was also achieved via the liberated H2O2when the GOx label was reacted with glucose. The resulting immunosensor displays high sensitivity, good selectivity and stability. These attractive properties plus the low cost and simplicity of the immunosensor enables wide applications of the paper based immunosensor for the detection of different analytes.