The Study Of Portable Cholesterol Biosensor Based On Enzymatic Silver Deposition

Cholesterol is an essential ingredient in mammals,and the cholesterol in serum is a major component of atherosclerotic plaques.The level of cholesterol in human serum has become an important index for clinical diagnosis and prevention of cardiovascular disease.Thus,it is important to develop a high specificity,sensitivity and low cost method for the diagnosis of serum cholesterol.In this paper,we have designed two kinds of portable cholesterol biosensor based on the principle of enzyme catalyzed silver deposition and the graphene and enzyme catalyzed silver synergistically.These studies were listed as follows:(1)A Portable detection system was designed for the detection of cholesterol by using the FPGA as the control center,and it was applied to the actual detection.(2)A cholesterol electrochemical biosensor based on enzyme catalyzed silver deposition was designed by immobilizing cholesterol oxidase(CHOD)and cholesterol esterase(CHER)onto the surface of gold nanoparticles modified screen-printed carbon electrode(SPE).By the catalytic action of CHER and CHOD,the cholesterol was hydrolyzed to generate hydrogen peroxide(H2O2)which can reduced the Ag ions in the solution for the deposition of metallic Ag on the electrode surface.The ultrasensitive detection of cholesterol was achieved by anodic stripping voltammetry measurement of the enzymatically deposited Ag.The anodic stripping peak current of Ag depended linearly on the concentration of cholesterol in the range of 5~5000 ?g/m L with the linear regression equation was Y=138.9550+0.0610 X and the regression correlation coefficient of 0.9983,the minimum detection limit is 3.0 ?g/mL.The sensor has high specificity,good reproducibility and high sensitivity.(3)A cholesterol electrochemical biosensor based on the graphene and enzyme catalyzed silver synergistically was designed by immobilizing CHOD,CHER and graphene onto the surface of gold nanoparticles modified SPE.By the catalytic action of CHER,CHOD and graphene,the cholesterol was hydrolyzed to generate H2O2 which can reduced the Ag ions in the solution for the deposition of metallic Ag on the electrode surface.The ultrasensitive detection of cholesterol was achieved by anodic stripping voltammetry measurement of the enzymatically deposited Ag.The anodic stripping peak current of Ag depended linearly on the concentration of cholesterol in the range of 0.01~5000 ?g/mL with the linear regression equation was Y=478.7030+0.0840 X and the regression correlation coefficient of 0.9991,the minimum detection limit is 0.001 ?g/mL.