Green synthesis of weissella-derived fluorescence carbon dots for microbial staining, cell imaging and dual sensing of vitamin B12 and hexavalent chromium

Due to small size, strong fluorescence and low cytotoxicity, fluorescent carbon dots (CDs) attract people's attention. The CDs- Ws derived from Weissella sp. Kl-3 with bright blue photoluminescent were obtained via hydrothermal method . The CDs- Ws could selectively label dead bacterial and yeast cells, and show the potential for the differentiation of live/dead microbe. It showed that the prepared CDs- Ws had multicolor fluorescence emission properties, excellent biocompatibility and low biotoxicity with cell and in vivo imaging. In addition, CDs- Ws sensitized by ampicillin sodium was employed as fluorescence nanosensor (CDs- Ws -Amp Na) to detect Cr(VI) and VB 12 based on inner filter effet mechanism. The linear correction was obtained for VB 12 detection in 0–25 μM with 51.50 nM detection limit, and the linear range was 0–50 μM with 106.57 nM detection limits for Cr(VI) by CDs- Ws -Amp Na. The fluorescent nanosensor was used for detection of Cr(VI) in water and VB 12 in serum and milk. It shows excellent potential in bioimaging , Cr(VI) and VB 12 detection.