Preparation of Codonopsis Carbon Quantum Dots and Their Scavenging Effect on Hydroxyl Radicals

Abstract The Carbon quantum dots (CQDs) were produced by a simple hydrothermal method from Codonopsis, Astragalus, Forsythia, and Polygala—the authentic medicinal materials in Shanxi province. The synthesized Codonopsis CQDs (C‐CQDs) showed bright‐blue fluorescence. It exhibits a quantum yield of 3.02% at an excitation wavelength of 345 nm with maximum emission at 440 nm. Ascorbic acid solution was used as a control to investigate the scavenging efficiency of hydroxyl free radicals in CQDs. The synthesized CQDs had varying degrees of ability to scavenge hydroxyl radicals. Among them, C‐CQDs showed the best hydroxyl radical scavenging ability. It was found that C‐CQDs had a scavenging rate of 82.94% for hydroxyl free radicals, which is similar to that of ascorbic acid solution (95.60%). The EC 50 value of C‐CQDs scavenging hydroxyl radical was 27.23 µg/mL, which is lower than that of ascorbic acid solution (36.57 µg/mL). Further, the C‐CQDs with good biocompatibility and low cytotoxicity can be well internalized into Hela cells and carry out hydroxyl radical scavenging in them. This provides a new way for the human body to clear excrescent hydroxyl free radicals.