丝素膜修饰电极pH电荷选择效应的研究

pH-Responsive Charge Selective Recognition Based on Silk Fibroin Membrane Modified Graphite Electrodes

研究了丝素膜的带电特性 ,其等电点在pH 4.5附近 ,利用丝素膜在等电点前后的两性荷电特性和电荷之间的静电作用 ,研制了丝素膜修饰石墨电极 .多巴胺在膜中的表观扩散系数为 2 .65× 10 -7cm2 /s ,其电极反应异相电子转移速率常数为 8.9× 10 -6 cm/s .电极用于神经递质类化合物体系的测定中 。

The silk fibroin protein membrane is an amphoteric ion - exchange membrane composed of both weak acidic and weak basic groups. Its isoelectric point is pH 4.5 and the charge thereof is dependent on pH of the solution. This characteristics of the membrane was exploited in a chemical modified electrode in this paper. Silk fibroin protein membrane was modified on a graphite electrode, the pH - responsive function of the modified electrode was investigated. The apparent diffusion coefficient of DA in the fibroin membrane was 2.65 x 10(-7) cm(2)/s. The rate constant of the heterogeneous electron transfer was calculated to be 8.9 x 10(-6) cm/s by computer fitting. When the modified electrode was applied to detect neurotransmitters, some metabolites and ascorbic acid did not interfere with the measurement.