| Tumor is one of the serious threats to human’s health, according to a certain research, if the early diagnosis and treatment can be carried, 30% of the cancer patients can be cured at least, which is an important significance for the reduction of cancer mortality. Tumor markers in tumor cells or tissues are significantly different from those in normal, the quantitative detection of tumor markers have important reference value on the risk assessment, diagnosis, prognosis of tumor therapy, toxicity, recurrent, etc.Recent years, a wordwide concern is rising anong the tumor cells and tumor markers in diagnosis. How to develop a high detection sensitivity, selectivity and low cost method on clinical detection of tumor cells and tumor markers has become a global hot topic.This thesis mainly studied a new type of electrochemical biosensor based on nanoparticles which well fit with aptamer, DNA enzyme and bio-bar code technology.The application on the analysis of tumor markers: thrombin and two kinds of micro RNA also gained well result. This thesis cantains the following issues:1. The optimized synthesis of CdS and PbS quantum dots, gold nanoparticles and bio-bar code. Synthesis the well appearance, stabled and same sized CdS and PbS quantum dots by controlling the amount of thioglycolic acid. Synthesis the gold nanoparticles with different particle size by controlling the proportion of sodium citrate and gold chloride acid. One end of the bio-bar code DNA modified wih amino, which could take reaction with carboxyl modified on the surface of the CdS quantum dots,the other end of bio-bar code DNA modified with thiol, which could forming gold-sulphur bond in the surface of gold nanoparticles. By controlling the amount of bio-bar code DNA and capture DNA, a bio-bar code was synthesized cantaining with gold nanoparticles and hundreds of CdS quantum dots and capture DNA.Nanoparticles and the compounds were successful synthesized according to the characterization of transmission electron microscopy(SEM) and UV. The appilication of nanoparticles to biochemical analysis are comprehensive, dissolved the CdS and PbS quantum dots with HNO3 solution and detect Cd2+ and Pb2+ by anodic stripping voltammetry, which could lead to the purpose of detecting targets. The amont of quantum dots on gold nanoparticles, nanoparticle elements in one quantum dot are incomputable, which be able to significantly improve the electrochemical signals.2. An electrochemical sensor based on aptamer and bio-bar code technology was designed for detection of thrombin. Using polymerase to identify the specific characteristics of the site on DNA and repair the sticky end, connected with the electrochemical signal amplification method of bio-bar code to achieve the purpose of the multiple amplification electrochemical detection of thrombin. The linear range of detecting thrombin was 0.1-10 pmol/L, which showing high sensitivity. In addition,this method has good performence under the interference of BSA, telomerase and other substances, which showing high selectivity. Results of electrochemical signals in serum and buffer solution were similar, which proved this method colud be further used in clinical detection.3. A novel electrochemical biosensor was built based on the specificity of double-stranded nucleic acid enzyme and CdS, PbS quantum dots for detection of two kinds of micro RNA. Took good advantage of the properties of DSN specific recognition DNA chain in DNA-RNA hybridization, which caused the DNA along with quantum dots leave magnetic bead into the solution, besides the micro RNAs have no change after the reaction. Finally, the anodic stripping voltammetry technology was employed for the elemental detection of two kinds of quantum dots free in the solution for further assay the amount of two kinds of micro RNA, achieved the purpose of trace detection of two kinds of target RNA. The linear range of detecting microRNA-21 and mi RNA-203 were 1.0-100 pmol/L, which showing high sensitivity. A variety of base mismatch of micro RNA detection proved this method has good selectivity. The application in the extract of Hela and MCF-7 cells gained good effect, which provide good way for further clinical detection of multiple tumor markers. |
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