A gold nanoparticles (AuNPs) enhancement strategy for lateral flow immunoassays (LFIAs) was previously reported to improve assay sensitivity. The multi-steps of detection resulted in a tedious procedure. In this report, to reduce this limitation, a sequential flow LFIA was introduced to perform the AuNPs enhancement in only single step operation using C-reactive protein (CRP) as a model analyte. The delay and non-delay channels created on nitrocellulose membrane (NCM) using wax-printing method were used to deliver immunoassay and AuNPs enhancement reagents to the detection zone sequentially. For the enhancing step, AuNPs were enlarged by the catalytic reaction of KAuCl₄ and NH₂OH⋅HCl. Under optimal conditions, a calibration curve was found in a range of 0.1−5 μg⋅mL⁻¹ with a good linear correlation (R² = 0.9953). The limits of detection (LOD) were found to be 0.1 and 0.001 μg⋅mL^-1 for naked eye observation and calculation (3SD/slope), respectively. Furthermore, the device shows no cross-reactivity with common interferences for CRP. The platform was successfully applied to detect CRP in certified human serum samples within 15 min, demonstrating the simplicity and speed of the AuNPs enhancement strategy platform. These promising results suggest that the new device may be used as an alternative tool for CRP detection and other biomarkers for POCT analysis.

先前已报道了用于侧向流免疫测定（LFIA）的金纳米颗粒（AuNPs）增强策略可提高测定灵敏度。检测的多步骤导致繁琐的过程。在本报告中，为减少此限制，引入了顺序流LFIA，以使用C反应蛋白（CRP）作为模型分析物的单步操作进行AuNPs增强。使用蜡印法在硝酸纤维素膜（NCM）上创建的延迟和非延迟通道用于将免疫测定和AuNPs增强试剂依次输送到检测区。对于增强步骤，通过KAuCl ₄和NH ₂ OH·HCl的催化反应使AuNPs扩大。在最佳条件下，发现校准曲线的范围为0.1−5μg·mL ^-1具有良好的线性相关性（R ² = 0.9953）。对于肉眼观察和计算（3SD /斜率），检测限（LOD）分别为0.1和0.001μg·mL ^-1。此外，该设备与CRP的常见干扰没有交叉反应。该平台已成功应用于15分钟内检测认证的人类血清样品中的CRP，证明了AuNPs增强策略平台的简便性和速度。这些有希望的结果表明，该新设备可用作CRP检测和POCT分析的其他生物标记物的替代工具。