Enhanced nanoflare for sensitive and rapid detection of ampicillin

The development of accurate and simple detection system for antibiotics is of paramount importance for food safety and human health due to the abuse in clinical practice and animal husbandry. In this work, we have constructed a novel enhanced nanoflare by incorporating another organic quencher BHQ-2 into conventional spherical nucleic acid nanoconstruct. The fluorescence of donor TAMRA was quenched simultaneously by AuNPs and BHQ-2 due to fluorescence resonance energy transfer (FRET). Compared to traditional nanoflare, the one-donor-two-acceptor strategy enhanced the energy transfer efficiency and increased the detection sensitivity of ampicillin (AMP) owing to reducing background signal. In the presence of AMP, the specific binding of aptamer on the enhanced nanoflare to the target triggered a fluorescence recovery in a concentration-dependent manner. With this approach, the detection limit of 0.65 ng/mL and the linear dynamic range of 1.8-20 ng/mL were achieved for AMP. Moreover, this method also displayed high specificity, good reproducibility, and acceptable accuracy for detection of AMP in the spiked milk samples and pharmaceutical products. The principle of the present nanoflare can be extended to other antibiotics for which aptamer is available, providing new insights into the fabrication of nanoscale energy transfer-based aptsensor for antibiotics analysis.