Sadler Christy J, Sandler Jan P, Shamsabadi André, Frenette Leah C, Creamer Adam, Stevens Molly M
Department of Materials, Department of Bioengineering, Institute of Biomedical Engineering Imperial College London, London SW7 2AZ, U.K.
Department of Physiology, Anatomy and Genetics, Department of Engineering Science, Kavli Institute for Nanoscience Discovery, University of Oxford, Oxford OX1 3QU, U.K.
ACS Sens. 2025 Jun 27;10(6):4622-4633. doi: 10.1021/acssensors.5c00995. Epub 2025 May 20.
Early diagnosis is vital for effective disease management, selection of appropriate treatment regimes, and surveillance and control of disease transmission. There is a growing need for point-of-need diagnostic platforms, such as lateral flow immunoassays (LFIAs), to reduce healthcare burdens, particularly in low-resource settings. However, LFIAs often suffer from inadequate sensitivity and exhibit limited dynamic ranges, leading to late-stage diagnosis or misdiagnosis. Here, we present a signal enhancement platform for use in both plate- and paper-based immunoassays, based on the formation of a coupled nanoparticle network. We demonstrate the coupling of an antigen-targeting detection probe with a secondary, catalytically active nanoparticle by utilizing secondary antibody interactions. Here, we show that signal enhancement is achieved through two functional mechanisms: network formation, facilitated by the secondary nanoparticle increasing the relative concentration of nanoparticles immobilized at the test zone; and the inclusion of catalytically active nanoparticles, which catalyze the oxidation of a chromogenic substrate at the test zone. Through this approach, we yielded a 40-fold improvement in the limit of detection (LOD) using 40 nm gold nanoparticle detection probes in spiked pooled human saliva. Further, the signal enhancement platform can be utilized alongside a range of detection probes, including gold nanoparticles, commonly employed for use in LFIAs. This work concludes by showcasing that the signal enhancement mechanism is compatible for use with complex sample matrices, such as human saliva.
早期诊断对于有效管理疾病、选择合适的治疗方案以及监测和控制疾病传播至关重要。对即时诊断平台（如侧向流动免疫分析（LFIA））的需求日益增长，以减轻医疗负担，特别是在资源匮乏地区。然而，LFIA常常灵敏度不足且动态范围有限，导致晚期诊断或误诊。在此，我们基于耦合纳米颗粒网络的形成，展示了一种用于基于平板和纸质免疫分析的信号增强平台。我们通过利用二抗相互作用，证明了抗原靶向检测探针与具有催化活性的二级纳米颗粒的耦合。在此，我们表明信号增强通过两种功能机制实现：网络形成，由二级纳米颗粒促进，增加了固定在测试区的纳米颗粒的相对浓度；以及包含催化活性纳米颗粒，其在测试区催化显色底物的氧化。通过这种方法，我们在加标的混合人唾液中使用40纳米金纳米颗粒检测探针时，检测限（LOD）提高了40倍。此外，该信号增强平台可与一系列检测探针一起使用，包括常用于LFIA的金纳米颗粒。这项工作最后展示了信号增强机制与复杂样品基质（如人唾液）兼容。
