A new paper-based lateral flow immunoassay configuration was engineered and investigated. The assay is intended for the detection of a model protein in human serum, that is, human immunoglobulin G, with the aim to demonstrate a virtually universal protein detection platform. Once the sample is added in the strip, the analyte is selectively captured by antibody-decorated silica beads (Ab-SiO₂) onto the conjugate pad and the sample flows by capillarity throughout the strip until reaching the test line, where a sandwich-like immunocomplex takes place due to the presence of antibody-functionalized QDs (Ab-QDs) onto the test line. Eventually, GO is added as a revealing agent and the photoluminescence of those sites protected by the complex Ab-SiO₂/Antigen/Ab-QDs will not be quenched, whereas those photoluminescent sites directly exposed are expected to be quenched by GO, including the control line, made of bare QDs, reporting that the assay occurred successfully. Hence, the photoluminescence of the test line is modulated by the formation of sandwich-like immunocomplexes. The proposed device achieves a limit of detection (LOD) of 1.35 ng mL⁻¹ in standard buffer, which is lower when compared with conventional lateral flow technology reported by gold nanoparticles, including other amplification strategies. Moreover, the resulting device was proven useful in human serum analysis, achieving a LOD of 6.30 ng mL⁻¹ in this complex matrix. This low-cost disposable and easy-to-use device will prove valuable for portable and automated diagnostics applications, and can be easily transferred to other analytes such as clinically relevant protein biomarkers.

设计并研究了一种新的基于纸张的侧向流免疫分析配置。该测定法旨在检测人血清中的模型蛋白，即人免疫球蛋白G，目的是证明一种几乎通用的蛋白检测平台。一旦将样品添加到试纸条中，被抗体修饰的硅胶珠（Ab-SiO ₂）就会选择性地将分析物捕获到结合垫上，并且样品会通过毛细作用流过试纸条，直至到达测试线，在此处呈三明治状由于在测试线上存在抗体功能化的QD（Ab-QD），因此发生了免疫复合物。最终，加入GO作为显像剂，并通过复合Ab-SiO ₂保护那些位点的光致发光/ Antigen / Ab-QD不会被淬灭，而直接暴露的那些光致发光位点有望被GO淬灭，包括由裸露的QD制成的对照品系，报告检测成功。因此，通过夹心样免疫复合物的形成来调节测试线的光致发光。所提出的装置在标准缓冲液中实现了1.35 ng mL ^-1的检测限（LOD），与金纳米颗粒报道的常规侧向流技术（包括其他扩增策略）相比，该限度更低。此外，事实证明，所得装置可用于人体血清分析，LOD为6.30 ng mL ^-1在这个复杂的矩阵中。这种低成本的一次性易用设备将证明对便携式和自动化诊断应用很有价值，并且可以轻松转移到其他分析物，例如临床相关的蛋白质生物标志物。