Bi-color FRET from two nano-donors to a single nano-acceptor: A universal aptasensing platform for simultaneous determination of dual targets

Emerging nano-donor and nano-receptor FRET pairs are more advantageous to broad biosensing applications. However, those reported FRET system generally containing a single pair cannot afford multiplexed analysis. Herein, bi-color FRET from two nano-donors to a single nano-acceptor has been adopted to fabricate a simple-to-use aptasensor for simultaneous determination of dual targets in a single run. Aflatoxin B1 (AFB1) and ochratoxin A (OTA) were selected as the analytes because they have synergistic effect to induce enhanced toxicity. Specially, carbon dots (CDs) and CdZnTe quantum dots (QDs), with unambiguous separation of emission peaks, were used as nano-donors to label the aptamers specific for AFB1 and OTA, respectively. These single-stranded aptamers with labels could be stably adsorbed on a single nano-acceptor MoS2 nanosheets surface due to van der Waals force, leading to the occurrence of FRET. When the aptasensor incubated with AFB1 and OTA, the specific binding between aptamers and targets resulted in partial release of the nano-donor labeled aptamers which disturb the FRET process and ultimately led to the fluorescence recovery to some extent. This aptasensor exhibited a wide detection range of 0.01–10 ng mL−1 for AFB1 and 0.02–5 ng mL−1 for OTA with low detection limits (3.3 pg mL−1 for AFB1 and 7.1 pg mL−1 for OTA). This aptasensor provides a new avenue for simultaneous determination of dual mycotoxins due to its advantages of simple operation, good selectivity and high sensitivity. By simply changing the specific aptamer, our strategy will certainly provide a universal aptasensing platform in advancing multiplexed analysis.