High Throughput Signal-Off-On Fluorescent Aptasensor for Pb2+ Detection Based on Fluorescence Resonance Energy Transfer Between Graphite-Phase Carbon Nitride Nanosheets and Gold Nanoparticles

Heavy metal Pb2+ is widely distributed in several environmental media, and exposure to Pb2+ through various channels can seriously endanger the health of residents. Therefore, it is very important to detect Pb2+ in high throughput, accurately and specifically. Fluorescent sensors have obvious advantages in heavy metal detection. In comparison with the bulk phase, graphite-phase carbon nitride nanosheets (g-CNNs) of atomic thickness and nanometer size can conspicuously improve the quantum yield and water solubility. The aptamer offers the benefits of exceptional specificity, robust stability, minimal toxicity, cost-effectiveness, straightforward synthesis and modification, and absence of immunogenicity. In this study, an high throughput signal-off-on fluorescent aptasensor was designed for detecting Pb2+ on the basis of fluorescence resonance energy transfer (FRET) mechanism between gold nanoparticles (AuNPs) and g-CNNs. Under the optimum experimental conditions, a linear correlation was established between (F-F0)/F0 and Pb2+ concentration within the range of 0– $1000~\mu $ g/mL. The linear equation was (F-F0)/ $F_{{0}}=0.0002$ C +0.0278, with an ${R} ^{{2}}$ value of 0.9744 and the detection limit was $0.8~\mu $ g/mL. The proposed fluorescent aptasensor had strong anti-interference ability, high sensitivity, and good reproducibility, and the recoveries of spiked samples were between 90.32% and 103.99%. The detection results of Pb2+ in actual samples confirmed that this fluorescent aptasensor had good application potential.