Dual-Spectrum Fluorescence Quenching of Aggregation-Induced Emission Nanoparticles for Dual-Signal Lateral Flow Immunoassay of Danofloxacin in Meat Samples

Abstract

The conventional gold nanoparticle-based lateral flow immunoassay (AuNPs-LFIA) is hampered by single colorimetric signal readout and insufficient sensitivity, restricting its broad application in trace detection for food safety. Herein, an AuNPs-triggered dual-spectrum fluorescence quenching LFIA (DSFQ-LFIA) was constructed for colorimetric and fluorescent detection of danofloxacin (DAN) in meat samples. Aggregation-induced emission nanoparticles (AIENPs) were synthesized using tetramethyl 4′,4‴,4‴″,4‴″″-(ethene-1,1,2,2-tetrayl)tetrakis([1,1′-biphenyl]-4-carbomethoxy) (TCBPE) as an AIE luminogen (AIEgen). The engineered TCBPE molecules with a low highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) gap were featured for the notable AIE effect, conferring AIENPs with a high quantum yield (67.2%). AuNPs acted as an efficient fluorescence quencher owing to the substantial dual-spectrum overlap between the absorption band of AuNPs and excitation/emission spectra of AIENPs. In the absence of DAN, antibody-labeled AuNPs (AuNPs-Ab) were bound to the test (T) line, causing the notable fluorescence quenching of AIENPs. Conversely, the presence of DAN left AIENPs largely unquenched. The limits of detection (LODs) of DSFQ-LFIA were 0.012 ng mL⁻¹ (fluorescence mode) and 0.032 ng mL⁻¹ (colorimetric mode). It presents a rapid and sensitive approach for detecting trace contaminants in food matrices.