Molecular Engineering and Confinement Effect Powered Ultrabright Nanoparticles for Improving Sensitivity of Lateral Flow Immunoassay

The application of traditional lateral flow immunoassay (LFIA)-based gold nanoparticles (AuNPs) to measure traces of target chemicals is usually challenging. In this study, we developed an integrated strategy based on molecular engineering and the spatial confinement of nanoparticles (NPs) to obtain ultrahigh quantum yields (QYs) of aggregation-induced emission (AIE) fluorescence NPs and employed them for the highly sensitive detection of T-2 toxin on the LFIA platform. Tetraethyl-4,4',4″,4‴-(ethene-1,1,2,2-tetrayl)tetrabenzoate (TCPEME), an AIE luminogen, was designed using molecular engineering to lower the energy gap, achieving higher QYs (26.26%) than previous AIEgens (13.02%). Subsequently, TCPEME-doped fluorescence NPs (TFNPs) achieved ultrahigh QYs, up to 84.55%, which were generated from the strong restriction of the NP state, efficiently suppressing nonradiative relaxation channels verified by ultrafast electron dynamics. On the LFIA platform, the sensitivity of the designed TFNP-based LFIA (TFNP-LFIA) was 10.4-fold and 4.3-fold more sensitive than that of the AuNP-LFIA and TPENP-LFIA for detecting the T-2 toxin, respectively. In addition, TFNP-LFIA was used for detecting T-2 toxin in samples and showed satisfactory recoveries (79.5 to 122.0%) with CV (1.49 to 11.75%), which implied excellent application potential for TFNP-LFIA. Overall, dual improvement of the molecule in fluorescence performance originating from the molecular engineering and spatial confinement of NPs could be an efficient tool for promoting the development of high-performance reporters in LFIA.