Novel polysaccharide-derived carbon dots doped with N, S, P: Synthesis, characterization, in vitro antioxidant, fluorescence sensor for chromium (VI) detection and cellular imaging

In this work, for the first time, biomass-derived carbon dots (AMP-CDs) with strong water solubility, antioxidant activity and good biocompatibility were synthesized by a one-step microwave method using Allium macrostemon Bunge polysaccharides (AMP) as the main carbon source, L-cysteine as the nitrogen and sulfur source, and phosphoric acid as the phosphorus source. The results showed that sphere-like AMP-CDs with an average particle size of about 2.34 ± 0.49 nm were successfully prepared, with good resistance to salt and photobleaching, and maintained high fluorescence intensity under normal pH conditions in human body. AMP-CDs were highly resistant to 2,2-diphenyl-1-pycrylhydrazyl (DPPH), 2,2′-Azinobis- (3-ethylbenzthiazoline-6-sulphonate) (ABTS) and hydroxyl radical (·OH) with significantly higher scavenging ability than AMP , with IC 50 (μg/mL) of 10.240, 7.265, and 574.730, respectively. In addition, AMP-CDs can be selectively used for the sensitive detection of Cr 6+ with the limit of detection was 5.25 μM, and satisfactory results were obtained for the Cr 6+ recovery experiments of actual environmental samples. In vitro cytotoxicity and hemolytic activity assays showed that AMP-CDs have good biocompatibility and can smoothly enter cells for clear imaging. Therefore, AMP-CDs are likely expected to be applied as a potential antioxidant and metal ion detection probe in the field of drug and food, environmental and biological scenario samples for metal ion detection analysis.