Multifunctional Biomedical Applications of Nitrogen and Sulfur Co-Doped Carbon Dots

Multifunctional carbon dots have drawn considerable attention due to their potential biomedical application value. We report the preparation of blue-green fluorescence-emitting, multifunctional, nitrogen-and-sulfur co-doped carbon dots (N, S-CDs) synthesized via a one-step process using 1-thioglycerol as a sulfur source, glucose and citric acid as carbon sources, and polyethyleneimine as a nitrogen source. Because of abundant amino and sulfur content, the CDs exhibited high sensibility and selectivity for detecting Cu2+ (detection limit: 0.01 mu M, linear range: 0.025 to 50 mu M). Fast and sensitive detection of tiopronin was also achieved on the basis of the fluorescence off-on mode considering the strong affinity between tiopronin and Cu2+. The N, S-CDs exhibited good biocompatibility as determined by fluorescence imaging using onion epidermal cells and gram-positive bacteria. The CDs also exhibited excellent antimicrobial ability against the gram-positive bacteria. Our results indicate that these novel N, S-CDs could be ideal candidates for several biochemical applications such as antibacterial treatment and detection of small biomolecules.

Automated summary

Novel N, S-CDs with blue-green fluorescence emission were successfully synthesized and showed high sensitivity and selectivity for detecting Cu2+ and tiopronin. These CDs exhibited good biocompatibility in fluorescence imaging and excellent antimicrobial ability against gram-positive bacteria, indicating their potential for biomedical applications such as antibacterial treatment and detection of small biomolecules.