Aptamer induced multi-colored AuNCs-WS "Turn on" FRET Nano platform for dual-color simultaneous detection of aflatoxin B and zearalenone.

Mycotoxins posit serious threats to human and animal health, and numerous efforts have been performed to detect the multiple toxins by a single diagnostic approach. For the first time, we synthesized a novel aptamer induced "turn on" fluorescence resonance energy transfer (FRET) biosensor using dual color gold nanoclusters (AuNCs), L-proline and BSA synthesized AuNCs (Lp-AuNCs and BSA-AuNCs), with WS nanosheet for simultaneous recognition of aflatoxin B (AFB and zearalenone (ZEN) by single excitation. Here, AFB aptamer stabilized blue-emitting AuNCs (AFB-apt-Lp-AuNCs) (at 442 nm) and ZEN aptamer functionalized with red colored AuNCs (ZEN-apt-BSA-AuNCs) (at 650 nm) were employed as an energy donor and WS2 nanosheet as a fluorescence quencher. With the addition of AFB and ZEN, the change in fluorescence intensity (F.I) was recorded at 442 nm and 650 nm and can be used for simultaneous recognition with a detection limit of 0.34 pg mL-1 (R= 0.9931) and 0.53 pg mL-1 (R= 0.9934), respectively. Most importantly, the semi-quantitative determination of AFB and ZEN can also be evidently realized through photo-visualization. The current approach paves a new aspect to develop sensitive, selective and convenient metal nanocluster based fluorescent "switch-on" probes with potential applications in multipurpose biosensing.