Lateral flow immunoassays (LFIAs) are an essential and widely used point-of-care test for medical diagnoses. However, commercial LFIAs still have low sensitivity and specificity. Therefore, we developed an automatic ultrasensitive dual-color enhanced LFIA (DCE-LFIA) by applying an enzyme-induced tyramide signal amplification method to a double-antibody sandwich LFIA for antigen detection. The DCE-LFIA first specifically captured horseradish peroxidase (HRP)-labeled colored microspheres at the Test line, and then deposited a large amount of tyramide-modified signals under the catalytic action of HRP to achieve the color superposition. A limit of detection (LOD) of 3.9 pg/mL and a naked-eye cut-off limit of 7.8 pg/mL were achieved for detecting severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleoprotein. Additionally, in the inactivated virus detections, LOD equivalent to chemiluminescence (0.018 TCID/mL) was obtained, and it had excellent specificity under the interference of other respiratory viruses. High sensitivity has also been achieved for detection of influenza A, influenza B, cardiac troponin I, and human chorionic gonadotrophin using this DCE-LFIA, suggesting the assay is universally applicable. To ensure the convenience and stability in practical applications, we created an automatic device. It provides a new practical option for point-of-care test immunoassays, especially ultra trace detection and at-home testing.

中文翻译：

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基于颜色增强信号放大策略的自动超灵敏侧流免疫分析

侧流免疫分析 (LFIA) 是一种重要且广泛使用的医疗诊断现场检测。然而，商业 LFIA 的敏感性和特异性仍然较低。因此，我们通过将酶诱导的酪酰胺信号放大方法应用于双抗体夹心LFIA进行抗原检测，开发了自动超灵敏双色增强LFIA（DCE-LFIA）。 DCE-LFIA首先在测试线上特异性捕获辣根过氧化物酶（HRP）标记的彩色微球，然后在HRP的催化作用下沉积大量的酪酰胺修饰信号，实现颜色叠加。检测严重急性呼吸综合征冠状病毒 2 (SARS-CoV-2) 核蛋白的检测限 (LOD) 为 3.9 pg/mL，肉眼截止限为 7.8 pg/mL。此外，在灭活病毒检测中，获得了与化学发光相当的LOD（0.018 TCID/mL），并且在其他呼吸道病毒的干扰下具有优异的特异性。使用该 DCE-LFIA 检测甲型流感、乙型流感、心肌肌钙蛋白 I 和人绒毛膜促性腺激素也实现了高灵敏度，表明该检测方法具有普遍适用性。为了保证实际应用中的方便性和稳定性，我们创建了一个自动装置。它为即时检测免疫分析，特别是超痕量检测和家庭检测提供了一种新的实用选择。