Cu2+-doped carbon dots as fluorescence probe for specific recognition of Cr(VI) and its antimicrobial activity

A simple and low-cost fabrication of water-soluble Cu2+-doped carbon dots (Cu2+–CDs) was reported in the paper. The preparation method was mainly via a one-step hydrothermal carbonization of mixture containing cupric acetate monohydrate (Cu(Ac)2•H2O) and waste tea extract. During pyrolysis process, the waste tea extract underwent simultaneous carbonization and doping of Cu2+ onto carbon dots surfaces. Cu2+–CDs was characterized by FTIR, XRD, TEM, XPS, UV-visible and fluorescence. Cu2+–CDs appeared blue fluorescence under UV-light and the fluorescence could be specifically quenched by Cr(VI). The phenomenon was not disturbed by other metal ions, common anions and amino acids. Cu2+–CDs successfully detected Cr(VI) in real samples (tap water and mineral spring water) by standard adding methods. Besides, Cu2+–CDs was highly sensitive to staphylococcus aureus, and the minimum inhibitory concentration was 0.156 mg/mL. Results showed Cu2+–CDs had outstanding biocompatibility and low cytotoxicity. Therefore, Cu2+–CDs could serve as nanoprobe and potential antibiotics.