Crescent-shaped Janus nanoassemblies of gold nanoparticles and AIEgens: Enhancing plasmonic and fluorescent activities for colorimetric and ratiometric fluorescence lateral flow immunoassay

Abstract

Herein, crescent-shaped Janus nanoassemblies (Au-AIENPs) with high plasmonic and fluorescent activities are prepared by co-assembling oleylamine-coated gold nanoparticles (OA-AuNPs) and red-emitting aggregation-induced emission luminogens (AIEgens) in separate compartments of polymer nanoparticles. The obtained Au-AIENPs show typical Janus heterostructures, where AIEgens preferentially aggregate to form fluorescent core and OA-AuNPs are distributed in the polymer matrix to form a crescent-shaped plasmonic shell, thus resulting in effective spatial separation of OA-AuNPs and AIEgens to achieve the balance between plasmonic and fluorescent signals and reduce the mutual interference between signals. Taking advantage of the excellent plasmonic and fluorescent activities of Au-AIENPs, we successfully established a colorimetric and ratiometric fluorescence dual-mode lateral flow immunoassay (Au-AIENPs-RLFIA) for the visual and quantitative detection of aflatoxin B1 (AFB1) in corn sample. Under the developed conditions, the visual detection limit (vLOD) of the Au-AIENPs-RLFIA for colorimetric and ratiomentic fluorescence detection was 0.62 ng/mL and 0.02 ng/mL, respectively, while the quantitative LOD (qLOD) for ratiomentic fluorescence mode was as low as 0.0076 ng/mL. The above results indicate that the designed Janus Au-AIENPs are promising as dual-signal output probes and hold great potential for improving flexible dual-mode detection of various targets on the LFIA platform.