A novel label-free electrochemical immunosensor for neutrophil gelatinase-associated lipocalin (NGAL) detection has been developed. The immunosensor has been constructed by immobilization of NGAL capture antibodies to electropolymerized aniline deposited on top of an electrosprayed graphene/polyaniline (G/PANI) modified screen printed carbon electrode. Electrospraying of G/PANI increases the electrode surface area while electropolymerization of aniline increases the number of amino groups (-NH₂) for antibody immobilization. The factors affecting the sensor sensitivity (i.e. aniline concentration, scan number and scan rate of electropolymerization) have been optimized. In a prior report, Kannan et al. reported a broad oxidation peak in cyclic voltammetry upon the binding between NGAL with its antibody. In this study, a dramatic increase (58-fold) in the oxidation current upon the binding between NGAL and its antibody is obtained when compared to an unmodified electrode, verifying a substantial improvement in the electrochemical sensitivity of this system. Under optimal conditions, this system exhibits high sensitivity with a limit of detection (LOD) of 21.1ngmL⁻¹, wide linearity (50–500ngmL⁻¹) and high specificity toward NGAL detection from small samples (10μL). As an example application, the sensor is tested for the detection of NGAL in human urine, and the results correspond well with the values obtained from a standard ELISA. Compared to the ELISA method, our system requires less analysis time (≤30min/sample), less sample and less operating cost.

中文翻译：

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基于石墨烯/聚苯胺纳米复合材料的无标记免疫传感器，用于中性粒细胞明胶酶相关脂钙蛋白的检测

开发了一种新型的无标记电化学免疫传感器，用于中性粒细胞明胶酶相关的脂蛋白（NGAL）检测。通过将NGAL捕获抗体固定在电沉积的石墨烯/聚苯胺（G / PANI）修饰的丝网印刷碳电极上的电聚合苯胺上，可以构建免疫传感器。G / PANI的电喷雾增加了电极的表面积，而苯胺的电聚合增加了氨基的数量（-NH ₂）用于固定抗体。已经优化了影响传感器灵敏度的因素（即苯胺浓度，电聚合的扫描次数和扫描速率）。在以前的报告中，Kannan等人。NGAL与抗体结合后，在循环伏安法中报道了一个宽的氧化峰。在这项研究中，与未修饰的电极相比，在NGAL及其抗体之间结合时，氧化电流显着增加（58倍），证明该系统的电化学灵敏度有了实质性的提高。在最佳条件下，该系统显示出高灵敏度，检测限（LOD）为21.1ngmL ^-1，线性范围宽（50-500ngmL ^-1）和对小样本（10μL）中NGAL检测的高特异性。作为示例应用程序，对传感器进行了检测，以检测人尿中的NGAL，结果与从标准ELISA获得的值非常吻合。与ELISA方法相比，我们的系统需要更少的分析时间（≤30min /样品），更少的样品和更低的操作成本。