The establishment of a simple, low-cost, high-sensitive and rapid immunoassay for detecting SARS-CoV-2 antigen in human blood is an effective mean of discovering early SARS-CoV-2 infection and controlling the pandemic of COVID-19. Herein, a smartphone based nanozyme linked immunochromatographic sensor (NLICS) for the detection of SARS-CoV-2 nucleocapsid protein (NP) has been developed on demand. The system is integrated by disposable immunochromatography assay (ICA) and optical sensor devices. Immunoreaction and enzyme-catalyzed substrate color reaction were carried out on the chromatographic strip in a device, of which the light signal was read by a photometer through a biosensor channel, and the data was synchronously transmitted via the Bluetooth to the app in-stored smartphone for reporting the result. With a limit of detection (LOD) of 0.026 ng/mL NP, NLICS had the linear detection range (LDR) between 0.05 and 1.6 ng/mL NP, which was more sensitive than conventional ICA. NLICS took 25 min for reporting results. For detection of NP antigen in clinical serum samples from 21 COVID-19 patients and 80 healthy blood donor controls, NLICS and commercial enzyme linked immunosorbent assay (ELISA) had 76.2% or 47.6% positivity, and 100% specificity, respectively (P = 0.057), while a good correlation coefficient (r = 0.99) for quantification of NP between two assays was obtained. In conclusion, the NLICS was a rapid, simple, cheap, sensitive and specific immunochromatographic sensing assay for early diagnosis of SARS-CoV-2 infection.

建立一种简单、低成本、高灵敏度和快速的免疫检测方法来检测人血液中的 SARS-CoV-2 抗原，是发现早期 SARS-CoV-2 感染和控制 COVID-19 大流行的有效手段。在此，根据需要开发了一种基于智能手机的纳米酶联免疫层析传感器（NLICS），用于检测 SARS-CoV-2 核衣壳蛋白（NP）。该系统由一次性免疫层析分析 (ICA) 和光学传感器设备集成。在设备中对色谱条进行免疫反应和酶催化底物显色反应，光信号通过生物传感器通道由光度计读取，数据通过蓝牙同步传输到内置的智能手机应用程序用于报告结果。检测限 (LOD) 为 0。026 ng/mL NP，NLICS 的线性检测范围 (LDR) 在 0.05 和 1.6 ng/mL NP 之间，比传统 ICA 更灵敏。NLICS 用了 25 分钟来报告结果。对于 21 名 COVID-19 患者和 80 名健康献血者对照的临床血清样本中的 NP 抗原检测，NLICS 和商业酶联免疫吸附试验 (ELISA) 分别具有 76.2% 或 47.6% 的阳性率和 100% 的特异性（P  = 0.057)，同时获得了两个测定之间 NP 定量的良好相关系数 (r = 0.99)。总之，NLICS 是一种用于早期诊断 SARS-CoV-2 感染的快速、简单、廉价、灵敏和特异的免疫层析传感检测方法。