基于电化学电容检测的新型钙离子传感器

通过金-硫共价键,将巯基十六羧酸以自组装的方式固定到金电极表面。再通过EDC、NHS的活化作用,对钙调蛋白的氨基与巯基十六羧酸暴露于自组装层外的羧基进行共价键和,从而将钙调蛋白固定到电极表面,制成一种新型的钙离子电容传感器。首先对传感器进行了等效电路分析,并分别考察了不同浓度电解质溶液对基底电容的影响,确定了进行实验所需的合适电解质浓度。用本实验室自行开发研制的电化学电容分析仪研究了该传感器对钙离子的响应能力,并进一步考察了其再生能力及稳定性。实验结果表明,在10-8~3×10-6mol/L的较宽范围内,钙离子浓度的对数值与总电容信号值之间呈线性关系,而且检出限可以达到10-9mol/L。制备好的传感器浸泡在0.02 mol/L,pH 7.0的磷酸缓冲溶液中在4℃冰箱中可以保存一个月而其对钙离子的响应能力未发现有显著的下降,说明其具有良好的稳定性。使用过的传感器用EDTA进行再生后基底电容的变化不超过0.3%,说明其具有良好的再生可逆性,可以被重复利用。本工作为对钙离子进行定量检测提供了一种新方法。

A New Type of Ca2+ Sensor Based on Direct Electrochemical Capacitance Method

First,16-mercaptohexadecanoic acid was self-assembled onto the gold electrode surface via Au-S covalent bond.Then calmodulin was covalently immobilized onto the 16-mercaptohexadecanoic acid monolayer under the activation of EDC and NHS.Thus a new type of capacitance Ca2 sensor was constructed.The equivalent circuit analysis of the testing system also was performed.Using the home-made "Electrochemical Capacitance Analyzer",concentration effect of the supporting electrolyte to the basis capacitance and the total capacitance change resulted from the combination of calmodulin with Ca2 were studied.The stability and re-productability of the sensor also were examined.The results showed that for the determination of Ca2 ,the linear range extended from 10-8 mol/L to 3 10-6 mol/L and the detection limit was 1 10-9 mol/L.The sensor would kept its stability for one month by immersed in 0.02 mol/L(pH 7.0) PBS and stored at 4 C.The sensor also could be re-produced by EDTA and the basis capacitance varied less than 0.3% after reproduction.This work provides a new method for the determination of Ca2 .