Microwave-assisted fabrication of copper-functionalized carbon quantum dots for sensitive detection of histidine

Fluorescent carbon quantum dots are emerging as a new class of fluorescent probes due to their unique optical properties. Herein, we presented a simple, one-pot and effective preparation strategy for copper-functionalized carbon quantum dots (Cu-CDs). The Cu-CDs demonstrated excitation-independent emissions, high fluorescent quantum yield (similar to 24.4%) and excellent fluorescent stability. The fluorescence of Cu-CDs could be quenched efficiently in the presence of histidine (His) due to the coordination occurring between surface Cu and imidazole side chains of His. Thus, the Cu-CDs could be used as an efficient fluorescent probe for His detection. Under optimal conditions, the fluorescent signals of Cu-CDs decreased linearly with the concentrations of His over a range of 0.1-15 mu M. The detection limit was 30 nM. The proposed method provided obvious advantages of rapid response, convenience, simplicity, high selectivity and sensitivity. Moreover, good results also have been obtained for His detection in real biological fluid samples.