COVID-19 is a widespread and highly contagious disease in the human population. COVID-19 is caused by SARS-CoV-2 infection. There is still a great demand for point-of-care tests for detection, epidemic prevention and epidemiological investigation, both now and after the epidemic. We present a lateral flow immunoassay kit based on a selenium nanoparticle-modified SARS-CoV-2 nucleoprotein, which detects anti-SARS-CoV-2 IgM and anti-SARS-CoV-2 IgG in human serum, and the results can be read by the naked eye in 10 minutes. We expressed and purified the SARS-CoV-2 nucleoprotein in HEK293 cells, with a purity of 98.14% and a concentration of 5 mg mL⁻¹. Selenium nanoparticles were synthesized by L-ascorbic acid reduction of seleninic acid at room temperature. After conjugation with the nucleoprotein, a lateral flow kit was successfully prepared. The IgM and IgG detection limits of the lateral flow kit reached 20 ng mL⁻¹ and 5 ng mL⁻¹, respectively, in human serum. A clinical study sample comprising 90 COVID-19-diagnosed patients and 263 non-infected controls was used to demonstrate a sensitivity and specificity of 93.33% and 97.34%, respectively, based on RT-PCR and clinical results. No cross-reactions with rheumatoid factor and positive serum for anti-nuclear antibodies, influenza A, and influenza B were observed. Moreover, the lateral flow kit remained stable after storage for 30 days at 37 °C. Our results demonstrate that the selenium nanoparticle lateral flow kit can conveniently, rapidly, and sensitively detect anti-SARS-CoV-2 IgM and IgG in human serum and blood; it can also be suitable for the epidemiological investigation of COVID-19.

中文翻译：

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基于护理点硒纳米粒子的测试，用于组合检测人血清和血液中的抗SARS-CoV-2 IgM和IgG

COVID-19是人类中一种广泛传播且高度传染的疾病。COVID-19是由SARS-CoV-2感染引起的。在现在和之后，仍然存在对用于检测，防疫和流行病学调查的即时检验的巨大需求。我们提出一种基于硒纳米粒子修饰的SARS-CoV-2核蛋白的侧向流免疫分析试剂盒，该试剂盒可检测人血清中的抗SARS-CoV-2 IgM和抗SARS-CoV-2 IgG，其结果可读取用肉眼在10分钟内。我们在HEK293细胞中表达和纯化了SARS-CoV-2核蛋白，纯度为98.14％，浓度为5 mg mL ^-1。硒纳米粒子由合成大号-抗坏血酸在室温下还原硒酸。与核蛋白结合后，成功制备了侧流试剂盒。横向流动试剂盒的IgM和IgG检测极限分别达到20 ng mL ^-1和5 ng mL ^-1分别在人血清中。根据RT-PCR和临床结果，使用包含90位经COVID-19诊断的患者和263位未感染对照的临床研究样本，证明其敏感性和特异性分别为93.33％和97.34％。没有观察到与类风湿因子和阳性血清抗核抗体，甲型流感和乙型流感的交叉反应。此外，侧向流动套件在37°C下储存30天后仍保持稳定。我们的结果表明，硒纳米粒子侧向流动试剂盒可以方便，快速，灵敏地检测人血清和血液中的抗SARS-CoV-2 IgM和IgG。它也可能适合于COVID-19的流行病学调查。