Carbon dots co-doped with nitrogen and sulfur (NSCDs) were obtained from thiourea and TAE (Tris-acetate-ethylenediamine) buffer using microwave assisted hydrothermal synthesis. The synergistic presence of nitrogen and sulfur as a dopant results in teasing fluorescence properties and a fluorescence quantum yield of 57%. An HR-TEM study showed the NSCDs to be mono-dispersed and seemingly spherical with an average hydrodynamic diameter of 3.6 ± 0.88 nm. The NSCDs are nontoxic as proven by an MTT assay for cytotoxicity. The optical characterization was done by using UV-Vis absorption and fluorescence spectroscopy which revealed excitation wavelength-dependent multicolor emissions. The characterization of surface topology was done by using X-ray diffraction, FTIR, and X-ray photoelectron spectroscopy. The NSCDs were used to image various pathogenic bacteria (E. coli, Klebsiella, Pseudomonas & Staphylococcus) and human buccal epithelial cells by applying multicolor fluorometry. Graphical abstract Schematic presentation of microwave-assisted hydrothermal synthesis of nitrogen and sulfur doped carbon dots (NSCD) based on Thiourea and 50X Tris-acetate-ethylenediamine (TAE) buffer having multicolor fluorescence, used for tagging and imaging pathogenic bacteria and Human buccal epithelial cells using fluorescence microscope.
A. Pathak, Dr. Suneesh P. V., Stanley, J., and Dr. Satheesh Babu T. G., “Multicolor Emitting N/S-doped Carbon Dots as a Fluorescent Probe for Imaging Pathogenic Bacteria and Human Buccal Epithelial Cells”, Mikrochim Acta, vol. 186, no. 3, p. 157, 2019.