Coordination/Assembly Twin-Boosted Lateral Flow Immunochromatographic Assay: Metal–Organic Framework-Mediated Visual Signal Programming for On-Site Ultrasensitive Diagnostics

Lateral flow immunochromatographic assay (LFIA) is a classic point-of-care testing technique. However, its sensitivity is commonly constrained by the signal intensity of conventional probes, restricting the detection of low-abundance biomarkers. Herein, we report an ultrasensitive LFIA platform based on coordination/assembly-regulated signal programming enabled by metal–organic frameworks (MOFs), termed Coordination/Assembly Twin-Boosted LFIA (CATB-LFIA). Zeolitic imidazolate framework-8 (ZIF-8) is employed as the core bifunctional scaffold. Based on a novel coordination-driven signal enhancement strategy, the exposed Zn 2+ sites within the ZIF-8 framework act as active centers to trigger coordination reactions with zinc indicators under mild conditions, enabling rapid generation and localized deposition of chromogenic products. Meanwhile, the confinement effect of ZIF-8 allows high-density loading of gold nanoparticles, further enhancing the colorimetric signal intensity of probes. Using carcinoembryonic antigen as model targets, CATB-LFIA achieved a 25–50-fold reduction in the limit of detection compared to conventional LFIA. In clinical serum samples, CATB-LFIA demonstrated accurate quantitative capability with good discriminatory performance. Overall, this work demonstrates the advantages of MOFs as multifunctional carriers in LFIA, providing a novel design for constructing sensitive and modular diagnostic platforms.