以亚甲基蓝为电子媒介,通过壳聚糖固定胆固醇氧化酶和辣根过氧化酶在丝网印刷电极表面,制成了一种新型胆固醇生物传感器,实现了低电位下对胆固醇的间接测定.循环伏安法和恒电位法用于研究修饰电极的电化学特性,在优化的试验条件下,安培法对胆固醇响应的线性范围为2.0×10-5~3.0×10-3 mol·L-1,检出限(3S/N)为5.0×10-6mol·L-1.用同一支电极对6.0×10-4 mol·L-1胆固醇溶液进行10次连续测定,测定值的相对标准偏差为4.6%,用3支电极做相同试验,测得相对标准偏差为6.2%.应用此传感器测定了血清样品中胆固醇含量,测定值的相对标准偏差(n=5)以及回收率试验结果依次在2.3%~6.1%之间及94.3%~105.2%之间.

Cholesterol biosensor was prepared by adding 3 μL of a mixed solution containing cholesterol oxidase,horseradish peroxidase (HRP) and chitosan onto the surface of a screen-printed carbon electrode modified with methylene blue,which was used as an electron mediator between HRP and the electrode.Electrochemical behavior of this new biosensor was studied by cyclic voltammetry and constant potentiometry.Under the optimum condition,the biosensor behaved to have a quick current response which achieved to a maximum and stable value within 20 s.Linear relationship was kept between values of response current and concentration of cholesterol in the range of 2.0×10-5-3.0×10-3mol·L-1.Detection limit (3S/N) of the method was found to be 5.0×10-6mol·L-1.Repeatability of the biosensor was tested with cholesterol solution of 6.0×10-4mol·L-1 for 10 determinations,values of RSD obtained were 4.6% (with a same biosensor) and 6.2% (among 3 biosensors).The biosensor was used in the indirect determination of cholesterol in serum samples at low working potential.Values of RSD′s (n=5) and recovery found were in the ranges of 2.3%-6.1% and 94.3%-105.2% respectively.