基于还原型半抗体构建新型冠状病毒检测的电化学免疫传感器

Development of Electrochemical Immunosensor for SARS-CoV-2 Detection Using Reduced Half-Antibody Fragments

摘要: 新型冠状病毒(SARS-CoV-2)抗原快速检测作为基于核酸的分子生物学检测方法的有益补充，有效提高了SARS-CoV-2筛查的效率。本研究以丝网印刷碳电极为基础电极，纳米金沉积电极表面，SARS-CoV-2核衣壳蛋白包被半抗体通过Au-S自组装功能化电极，SARS-CoV-2核衣壳蛋白检测半抗体和辣根过氧化双标记纳米金作为放大元。循环伏安法和阻抗谱法表征电极逐步修饰过程，建立SARS-CoV-2电化学免疫检测方法：检测范围0.05~50 pg/mL，最低检测限为9.04 fg/mL，与全抗体建立的检测方法相比，检测限降低了10倍。批内和批间差异系数均小于9.3%，另外在血清样本中的加标回收率可达86%~109.4%。以上结果表明所构建的电化学免疫分析方法对COVID-19诊断具有重要意义。

Abstract: Rapid antigen tests for diagnosis of SARS-CoV-2 are broadly employed for screening approaches, and have potential to be used as alternatives to standard laboratory-based molecular assays. Here, the electrochemical immune-sensor was constructed on screen-printed carbon electrode deposited with gold nanoparticles, and the half-antibody specific SARS-CoV-2 nucleocapsid protein was self-assembly via Au-S bond formation. The modified SPCEs was characterized with cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The signal was amplified with gold nanoparticles (AuNPs) dual-modified with detecting half-antibody fragments and horseradish peroxidase (HRP). With a sandwich immunoassay format, the obtained electrochemical responses were proportional to the SARS-CoV-2 level in the sample. The proposed assay had a dynamic range for SARS-CoV-2 NP quantification of 0.05~50 pg/mL. With a detection limit of 9.04  fg/mL, which was almost 10-fold lower than that obtained using AuNPs/SPCE electrode vs. conventional whole antibody. Both the intra- and inter-assay coefficients of variation were less than 9.3%. Moreover, the recovery rates are found to range from 86% to 109.4% in the spiked samples. The results show that the proposed electrochemical immunoassay is a highly promising approach for COVID-19 diagnosis.