One-pot green synthesis of l-proline-stabilized copper nanoclusters for quercetin sensing

Herein, a simple, green and low-cost method was established to synthesize l-proline-stabilized copper nanoclusters (l-Pro-Cu NCs) with good water solubility, excellent photostability and resistance to sodium chloride. A series of methods including fluorescence spectroscopy, UV–Vis absorption spectroscopy, Fourier transform infrared spectroscopy, transmission electron microscopy and X-ray photoelectron spectroscopy were used to characterize the structure and optical performance of the Cu NCs. The as-prepared Cu NCs showed green fluorescence with the excitation wavelength of 373 nm. Under the optimal detection conditions, an excellent linear relationship was observed between relative fluorescence intensity (F0/F) and the concentrations of quercetin ranging from 0.5 to 50 μM, and the detection limit (LOD) was 0.012 μM. Moreover, the proposed method provided an excellent platform for the detection of quercetin in the real samples.