A graphene quantum dots-Pb2+ based fluorescent switch for selective and sensitive determination of D-penicillamine

Taking consideration of metal-induced fluorescence quenching and excellent coordination effect of D-penicillamine (D-PA), a graphene quantum dots (GQDs)-based fluorescent switch for D-PA detection was designed and established firstly with the help of lead ions . GQDs obtained from citric acids made them rich in carboxyl and hydroxyl groups , giving GQDs the ability to combine with lead ions. As anticipated, the fluorescence intensity was quenched by Pb 2+ through electron transfer process. Further, the addition of D-PA effectively recovered the fluorescence due to the departure of Pb 2+ from GQDs aroused by the strong coordination between D-PA and Pb 2+ . Thus, a fluorescent switch was activated for D-PA detection. The fluorescence recovery efficiencies were found to be proportional to the concentration of D-PA in the range of 0.6–50 μmol L − 1 and the detection limit was 0.47 μmol L − 1 . The real sample detection was performed in human urea sample and satisfactory recoveries of 96.84%–102.13% were obtained. The GQDs-Pb 2+ based fluorescent switch sensing method was firstly established with low detection limit and wide linear range, making it a supplement and improvement for D-PA detection.