Fabrication of PAA coated green-emitting AuNCs for construction of label-free FRET assembly for specific recognition of T-2 toxin

In view of numerous encouraging requisitions, toxins quantification is an imperative research field of food safety. Herein, we synthesized a green-emitting L-arginine@6-aza-2-thiothymine-protected gold nanocluster (Arg@ATT-AuNCs) through host-guest assemblages. The Arg@ATT-AuNCs were capped with polyacrylic acid (PAA) to construct the PAA@Arg@ATT-AuNCs nanoparticles (NPs). The fluorescent and visual detection of T-2 (trichothecenes A) is based on PAA@Arg@ATT-AuNCs NPs and PDDA-aggregated-AuNPs assembly. In the absence of a target, electrostatic interaction of the aptamer-PDDA complex prevents the aggregation of AuNPs. The scattered AuNPs (absorbance at 520 nm) can quench the fluorescence intensity (F.I) of PAA@Arg@ATT-AuNCs NPs (emission at 530 nm) following FRET (Fluorescence resonance energy transfer) mechanism. The target addition leads in toxin-aptamer assemblies and succeeding PDDA is free to aggregate AuNPs (absorbance at 665 nm), resulted in recovered F.I. The developed bioassay sensitively used for quantification of T-2 with LOD of 0.57 pg mL⁻¹ (0.001−100 ng mL⁻¹). Spiking analysis reveals the robustness and efficiency of bioassay in maize and highly correlated with the standard ELISA method. We envision that the present study will substantively contribute to synthesize new core-shell NCs and may be considered as a new method for onsite detection.