Highly luminescent N-doped carbon dots from black soya beans for free radical scavenging, Fe3+ sensing and cellular imaging.

The novel N doped carbon dots (N-CDs) were readily fabricated through one-step pyrolysis method from black soya beans. The obtained N-CDs possessed excellent photoluminescence properties with quantum yield of 38.7 ± 0.64% and dual responsive properties towards free radical and Fe3+. The N-CDs exhibited favorable radical scavenging activity (RSA) against 1,1-diphenyl-2-picrylhydrazyl (DPPH) and superoxide anion radicals. Fe3+ could induce photoluminescence quenching of N-CDs through static quenching characteristics. The possible quenching mechanism was presented. Combining with negligible toxicity and preferable biocompatibility, the N-CDs were extended to imaging intracellular Fe3+. As an attractive candidate, the N-CDs demonstrated a great potential in free radical scavenging, sensing and cellular imaging.