College of Chemistry and Chemical Engineering, China University of Petroleum (East China), Qingdao 266580, P. R. China.
The Affiliated Hospital of Qingdao University, Qingdao University, Qingdao 266003, China.
Anal Chem. 2022 Jun 14;94(23):8466-8473. doi: 10.1021/acs.analchem.2c01286. Epub 2022 Jun 3.
Immunoglobulin detection is essential for diagnosing progression of SARS-CoV-2 infection, for which SARS-CoV-2 IgG is one of the most important indexes. In this paper, Ag nanoparticles with ultrathin Au shells (∼2 nm) embedded with 4-mercaptobenzoic acid (MBA) (Ag@Au) were manufactured via a ligand-assisted epitaxial growth method and integrated into lateral flow immunoassay (LFIA) for colorimetric and SERS dual-mode detection of SARS-CoV-2 IgG. Ag@Au possessed not only the surface chemistry advantages of Au but also the superior optical characteristics of Ag. Moreover, the nanogap between the Ag core and the Au shell also greatly enhanced the Raman signal. After being modified with anti-human antibodies, Ag@Au recognized and combined with SARS-CoV-2 IgG, which was captured by the SARS-CoV-2 spike protein on the T line. Qualitative analysis was achieved by visually observing the color of the T line, and quantitative analysis was conducted by measuring the SERS signal with a sensitivity four orders of magnitude higher (detection limit: 0.22 pg/mL). The intra-assay and inter-assay variation coefficients were 7.7 and 10.3%, respectively, and other proteins at concentrations of 10 to 20 times higher than those of SARS-CoV-2 IgG could hardly produce distinguishable signals, confirming good reproducibility and specificity. Finally, this method was used to detect 107 clinical serum samples. The results agreed well with those obtained from enzyme-linked immunosorbent assay kits and were significantly better than those of the colloidal gold test strips. Therefore, this dual-mode LFIA has great potential in clinical practical applications and can be used to screen and trace the early immune response of SARS-CoV-2.
免疫球蛋白检测对于诊断 SARS-CoV-2 感染的进展至关重要，其中 SARS-CoV-2 IgG 是最重要的指标之一。在本文中，通过配体辅助外延生长方法制造了具有超薄 Au 壳（约 2nm）嵌入 4-巯基苯甲酸（MBA）（Ag@Au）的 Ag 纳米粒子，并将其整合到侧向流动免疫分析（LFIA）中，用于 SARS-CoV-2 IgG 的比色和 SERS 双模检测。Ag@Au 不仅具有 Au 的表面化学优势，而且还具有 Ag 的优越光学特性。此外，Ag 核和 Au 壳之间的纳米间隙也大大增强了拉曼信号。经过与人抗体修饰后，Ag@Au 识别并与 SARS-CoV-2 IgG 结合，然后被 SARS-CoV-2 刺突蛋白捕获在 T 线上。通过观察 T 线的颜色进行定性分析，通过测量 SERS 信号进行定量分析，灵敏度提高了四个数量级（检测限：0.22pg/mL）。内分析和间分析的变异系数分别为 7.7%和 10.3%，而浓度比 SARS-CoV-2 IgG 高 10 到 20 倍的其他蛋白质几乎不会产生可区分的信号，证实了良好的重现性和特异性。最后，该方法用于检测 107 份临床血清样本。结果与酶联免疫吸附试剂盒的结果吻合良好，明显优于胶体金测试条的结果。因此，这种双模 LFIA 在临床实际应用中具有很大的潜力，可用于筛选和跟踪 SARS-CoV-2 的早期免疫反应。
