Synthesis of N, Zn-doped carbon dots for the detection of Fe3+ ions and bactericidal activity against Escherichia coli and Staphylococcus aureus

Abstract

A simple and one-step microwave digestion method was utilized to synthesize the highly photoluminescent glucosamine derived nitrogen and zinc doped carbon dots (N, Zn-CDs) with a bluish-green luminescence property. The synthesized N, Zn-CDs inherited a good photoluminescence property with a quantum yield of 74% and which were characterized by XPS, XRD, TEM, FT-IR, UV–Vis, and fluorescence spectrometry. More importantly, N, Zn-CDs served as a fluorescence sensor for the detection of Fe3+ ions, under optimal conditions, a good linear relationship was established in the concentration range of 0.25–125 μM. Also, the experimental results showed the detection limit of N, Zn-CDs against Fe3+ was 0.15 μM, this could be a promising assay for sensing Fe3+ ions. Also, the role of zinc doping was explored by conducting the detection under similar experimental conditions in the absence of zinc, and reports revealed that the reason for high photoluminescence was due to the zinc doping. Along with the sensing application, our group had investigated the bactericidal property of synthesized N, Zn-CDs against gram-negative (Escherichia coli), and gram-positive pathogens (Staphylococcus aureus). N, Zn-CDs displayed good bactericidal activity against both pathogens under light conditions, but Escherichia coli, even under the dark condition proved its activity. Besides, the morphology of both the strains was displayed before and after the treatment via a scanning electron microscopic images. Also, a plausible mechanism for bactericidal activity was also explained. The reported synthesis method could provide a novel approach for the design of high photoluminescent N, Zn–CDs with good sensing and bactericidal property towards Fe3+ ions, gram-negative and positive bacterial strains.