Poly(thymine)-templated fluorescent copper nanoparticles for label-free detection of N-acetylcysteine in pharmaceutical samples

In this paper, a novel and label-free fluorescence sensing strategy has been developed for thiol-containing drug detection by using poly(thymine) (poly T)-templated copper nanoparticles (Cu NPs) as fluorescent probes. N-acetylcysteine (NAC), one of the thiol-containing drugs, was selected as a model case in this strategy. The fluorescence intensity of poly T-templated Cu NPs was found to be quenched effectively with the increasing concentration of NAC, due to the formation of a coordination complex by the Cu-S metal- ligand bond between NAC and poly T-templated Cu NPs. However, the fluorescence intensity was not nearly changed in the presence of other analytes at a 10-fold higher concentration. Under optimized conditions, the label-free fluorescent sensor achieved highly sensitive and selective detection of NAC with a linear range of 0.2 mu M to 100 mM and a detection limit of 50 nM. Furthermore, the method was successfully applied to the detection of NAC in pharmaceutical samples. The strategy was free of any fluorescence dye label or complex DNA sequence design, and all the processes were performed within 20 minutes at room temperature. Therefore, it could offer a simple, cost-effective, selective and label-free sensing platform for fluorescence detection of thiol-containing drugs in clinical diagnostics.