Confinement‐Enhanced Ultrabright AIE Nanoparticles With Broad Emission for Ultrasensitive Lateral Flow Immunoassay

ABSTRACT Fluorescent lateral flow immunoassay (LFIA) has emerged as a critical point‐of‐care (POC) diagnostic platform for in vitro diagnosis. However, the analytical sensitivity of conventional fluorescent LFIA is constrained by the suboptimal quantum yield (QY) and photostability of conventional fluorophores. Here, we developed a class of fluorescent nanoparticles by encapsulating butterfly‐shaped aggregation‐induced emission (AIE) luminogens with polystyrene microspheres, achieving a remarkable QYs of 91%—representing a 2.2‐fold enhancement compared to previous AIEgens (42% QY). In addition, the broad emission spectrum characteristic of AIE fluorophores enables significant improvements in detection sensitivity and system stability of LFIAs through strategic optimization of optical filter configurations. Comparative performance evaluation revealed that the optimized 30 nm filter‐AIE LFIAs platform presents outstanding performance relative to conventional, in which 85‐folds and 43‐folds improvements in detection limits for cardiac troponin I is achieved with excellent reproducibility (coefficient of variation < 15%). Overall, the synergistic combination of high‐manufacturing efficiency, high sensitivity, and good biocompatibility of the developed AIE‐RNPs enables it as an efficiency and broadly applicable signal amplifier for LFIA applications, which is expected to extend the application of LFIA for trace and quantitative detection, paving the way for more reliable POC testing in clinical and resource‐limited setting.