A dual-mode nanosensor based on the inner filter effect of gold nanoparticles on the fluorescence of CdS quantum dots for sensitive detection of arginine

In this work, we developed a low-cost, rapid, simple and sensitive analytical method for the visual and fluorescence detection of arginine based on the inner filter effect (IFE) of gold nanoparticles (AuNPs) on the fluorescence of CdS quantum dots (QDs). The proposed sensing system consists of AuNPs and fluorescent CdS QDs, where CdS QDs function as fluorometric reporters, and AuNPs serve a dual function as fluorescence quenchers and colorimetric reporters in the probe. The fluorescence of L-cysteine capped CdS QDs was significantly quenched by citrate-stabilized AuNPs via the IFE. Upon addition of arginine the IFE of AuNPs on the fluorescence of CdS QDs was weakened and the fluorescence intensity was recovered, since arginine could induce the aggregation of AuNPs accompanied by a color change from red to blue, which resulted in turn-on of the IFE-decreased fluorescence of CdS QDs. Under the optimum conditions, the fluorescence intensity of the CdS QDs/AuNP system was proportional to the concentration of arginine in the range of 7-215 mu g L-1, with a detection limit of 2.4 mu g L-1. The sensing platform had been used for arginine detection in human serum and arginine injection samples with satisfactory results.