Manufacture And Application Of Electrochemical Biosensor Detecting Tumor Cells And Tumor Markers

Tumor cell, a cell of abnormal reproduction in the body, which is one of the most threatening diseases of the human being, plays an essential role in modern medicine. Therefore, early diagnosis and prevention is the main way to reduce the mortality, but also it is the key to improve patient survival. In recent years, many assay methods and sensors as currently popular techniques are being developed for the detection of tumor-related biomarkers.This thesis studied a novel electrochemical biosensor based on nanoporous gold electrode and the signal of amplification of nanoparticles (NPs) was constructed for the determination of tumor cell and achieved satisfying results. This thesis mainly consists of the following issues:1. A novel electrochemical biosensor based on gold nanoparticles and 6-ferrocenylhexanethiol provides a direct method for quantitative detection of cell surface carbohydrate of K562 human leukemia cells. First, 11-mercaptoundecanoic acid (MUA) and 6-ferrocenylhexanethiol were respectively modified on the surface of Au electrode and gold nanoparticles. Besides, concanavalin A (Con A) reacted to MUA and MHA. Au electrode, K562 cell and gold NPs could fabricate a"sandwich-type"assay structure by the lectin/carbohydrate interactions of Con A and carbohydrate on the surface of cell. The CV peak current was proportional to the logarithmic value of the cell concentration ranging from 1.0×10² to 1.0×10⁷ cells mL^-1, and the peak height were found to be dependent on the amount of gold NPs and K562 cells number, the detection limit for cells concentration was calculated to be 73 cells mL^-1, the glycosyl number of single cell were 4.7×10⁹. To sum up, the biosensors which were designed assembly in the experiment have good sensitivity and reproducibility. 2. A novel electrochemical biosensor based on the signal of amplification of gold nanoparticles (NPs) and the sequence-specific DNA was constructed for the determination of Hela cell. Sequence-specific DNA which combined with Ru(bpy)2(dcbpy)NHS and MHA were respectively modified on the gold nanoparticles and Au electrode. Used gold nanoparticles on signal amplifying function and hybridized between survivin DNA and quenching DNA. The system of Ru(bpy)2(dcbpy)NHS has strong intensity and good stability. This biosensor provides a direct method for quantitative detection of Hela cells and has good sensitivity and selectivity. It provides the basis to detecte tumor by using this electrochemical method.3. A new electrochemical biosensor was built based on nanoporous gold electrode to detect the mRNA of Hela cells by using the signal of amplification of gold nanoparticles and interaction of sequence-specific DNA. With the use of Tat, gold nanoparticles could quickly penetrate the membrane and enter into the cell. The Tat not only achieved probe transferring from outside to inside cell, but also amplified the signal, enhanced the signal of sensivity and stability. Using the Tat, the nanoparticles which carried drugs could enter into the cells effective and could be used in the treatment of tumor cells, the clinical application prospect was very good.