摘要
p-Nitrophenylphosphate （PNPP） is usually employed as the substrate for enzyme-linked immunosorbent assays, p-Nitrophenol （PNP）, the product of PNPP, with the catalyst alkaline phosphatase （ALP）, will passivate an electrode, which limits applications in electrochemical analysis. A novel anti-passivation ink used in the preparation of a graphene/ionic liquid/chitosan composited （rGO/IL/Ghi） electrode is proposed to solve the problem. The anti-passivation electrode was fabricated by directly writing the graphene-ionic liquid-chitosan composite on a single-side conductive gold strip. A glassy carbon electrode, a screen-printed electrode, and a graphene-chitosan composite-modified screen-printed electrode were investigated for comparison. Scanning electron microscopy was used to characterize the surface structure of the four different electrodes and cyclic voltammetry was carried out to compare their performance. The results showed that the rGO/IL/Ghi electrode had the best performance according to its low peak potential and large peak current. Amperometdc responses of the different electrodes to PNP proved that only the rGO/IL/Chi electrode was capable of anti-passivation. The detection of cardiac troponin I was used as a test example for electrochemical immunoassay. Differential pulse voltammetry was performed to detect cardiac troponin I and obtain a calibration curve. The limit of detection was 0.05 ng/ml.
目的:酶联免疫分析常用底物对硝基苯磷酸盐分解后产生对硝基苯酚(PNP),该物质对电极具有钝化作用,限制了该体系在电化学免疫分析领域的应用。因此,需要开发一种具有抗钝化作用的电极浆料。创新点:石墨烯-子液体-壳聚糖(rGO/IL/Chi)电极浆料不仅具有抗钝化作用,且拥有良好的电化学性能,制备过程中无需使用任何有机溶剂,安全环保。方法:制备rGO/IL/Chi复合浆料,涂布于单面导电金箔上,75℃,10 min,将其作为工作电极;背面涂布自制的银浆,作为参比电极和对电极;0.03 g/ml壳聚糖溶液作为绝缘浆料。结论:本研究表明,在比较商品化的玻碳电极、自制丝网印刷电极、石墨烯修饰的丝网印刷电极和rGO/IL/Chi电极对PNP的循环伏安响应时,rGO/IL/Chi电极具有最大的峰电流响应和最小的峰电位。同时,对四种电极进行性能表征时,rGO/IL/Chi电极具有最小的峰电位差和最大的峰电流。这表明rGO/IL/Chi电极具有较好的电化学性能,且对PNP有较大的响应。比较四种电极对PNP的安培响应之后,发现只有rGO/IL/Chi电极具有抗钝化作用。可将该电极用于肌钙蛋白I的检测,其检测限为0.05ng/ml。
基金
Project supported by the National Natural Science Foundation of China(No.31571918)
