Amino acid derived highly luminescent, heteroatom-doped carbon dots for label-free detection of Cd2+/Fe3+, cell imaging and enhanced antibacterial activity

A facile, economic and one-step synthesis strategy was applied for the synthesis of highly fluorescent water-soluble heteroatom doped carbon dots (CDs) from eight different amino acids viz., arginine, cysteine, glutamic acid, glutamine, aspartic acid, lysine, tyrosine, and methionine. Based on the higher quantum yield (38%) cysteine derived CDs were selected to explore their multi-functional behavior viz., sensing of metal ions, cell imaging and cytocompatibility study for MCF7 cancer cells. The cysteine derived CDs exhibit high sensitivity and selectivity toward Cd2+ and Fe3+ ions with a detection limit as low as 2.0 and 3.0 mu g L-1 in the linear range of 6.0-268.0 mu g L-1 and 6.0-250.0 mu g L-1, respectively. In addition, the CDs were applied for cell imaging, demonstrating their potential as excellent probes for high contrast cell imaging. Moreover, to explore an entirely different application of CDs (i.e. antibacterial and photocatalytic activity); a nanocomposite of Au/CDs was also prepared. It was observed that a very low minimum inhibition concentration value (20.0 ng mL(-1)) was required to inhibit the growth of E. coli. Similarly, the photocatalytic activity of Au/CDs nanocomposite was also studied for H2O2 decomposition.