Spatially Layered Dual-Porous Nanohybrids Enabling a Colorimetric-Fluorometric-Catalytic Continuous Gradient Signal Response for High-Performance Immunochromatographic Diagnosis

Achieving high sensitivity, a broad linear range, and accurate quantification in lateral flow immunoassays (LFIAs) remains a significant challenge, particularly due to limitations in signal mode integration. Herein, we report a novel multifunctional "three-in-one" nanohybrid (SQF@ZIF-8/Pt) that addresses these issues by spatially integrating colorimetric, fluorometric, and catalytic functionalities within a single probe. Unlike conventional LFIA probes, this nanohybrid features a well-defined hierarchical architecture constructed through dendritic and mesoporous dual scaffolds, enabling continuous and overlapping signal output across a wide concentration range. Applied to SARS-CoV-2 nucleocapsid protein detection, the developed LFIA enables colorimetric quantification over 4 orders of magnitude (0.025–100 ng/mL) with a detection limit of 0.0302 ng/mL. Furthermore, fluorescence-based secondary quantification within the overlapping concentration range (0.5–10 ng/mL) allows internal signal cross-validation, improving result accuracy. Clinical validation demonstrated that this assay not only outperforms conventional colloidal gold-based LFIAs in sensitivity but also exhibits superior resistance to matrix interference, demonstrating strong potential for reliable point-of-care diagnostics.