Thürer Reto, Vigassy Tamás, Hirayama Martina, Wang Joseph, Bakker Eric, Pretsch Ernö
Laboratorium für Organische Chemie, ETH Zürich, CH-8093 Zürich, Switzerland.
Anal Chem. 2007 Jul 1;79(13):5107-10. doi: 10.1021/ac070932m. Epub 2007 May 26.
Potentiometric sensors based on polymer membrane electrodes, if properly optimized, are useful for measurements at trace levels. The expected independence of the electrochemical signal of the sample size makes them extremely attractive for measurements in small volumes. Here, we report on electrodes for the potentiometric detection of cadmium ions that reach a detection limit of 6 nM and utilize a Na(+)-selective electrode as pseudoreference in order to facilitate measurements in 150-microL samples. A potentiometric immunoassay of mouse IgG is performed via CdSe quantum dot labels on a secondary antibody according to a sandwich immunoassay protocol in a microtiter plate format. The CdSe quantum dots are found to be easily dissolved/oxidized in a matter of minutes with hydrogen peroxide, allowing us to maintain the pH at a near-neutral value. The potentiometric protein immunoassay exhibits a log-linear response ranging from 0.15 to 4.0 pmol of IgG, with a detection limit of <10 fmol in 150-microL sample wells.
基于聚合物膜电极的电位传感器，若经过适当优化，可用于痕量水平的测量。样品量的电化学信号预期具有独立性，这使得它们在小体积测量中极具吸引力。在此，我们报告了用于镉离子电位检测的电极，其检测限达到6 nM，并利用钠选择性电极作为伪参比电极，以便于在150 μL样品中进行测量。根据微孔板形式的夹心免疫分析方案，通过在二抗上标记CdSe量子点，对小鼠IgG进行电位免疫分析。发现CdSe量子点在几分钟内很容易被过氧化氢溶解/氧化，这使我们能够将pH维持在接近中性的值。电位蛋白质免疫分析在150 μL样品孔中对IgG的响应呈对数线性，范围为0.15至4.0 pmol，检测限<10 fmol。
