Versatile Fluorescent Carbon Dots from Citric Acid and Cysteine with Antimicrobial, Anti-biofilm, Antioxidant, and AChE Enzyme Inhibition Capabilities

Suner S., ŞAHİNER M., Ayyala R. S., Bhethanabotla V. R., ŞAHİNER N.

JOURNAL OF FLUORESCENCE, vol.31, no.6, pp.1705-1717, 2021 (SCI-Expanded) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 31 Issue: 6
  • Publication Date: 2021
  • Doi Number: 10.1007/s10895-021-02798-x
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, Biotechnology Research Abstracts, Chimica, Compendex, EMBASE, MEDLINE
  • Page Numbers: pp.1705-1717
  • Keywords: Cysteine-based carbon dots, Antimicrobial, Anti-biofilm, Antioxidant, Acetylcholinesterase enzyme inhibitor
  • Çanakkale Onsekiz Mart University Affiliated: Yes


Nanostructured fluorescent particles derived from natural molecules were prepared by a green synthesis technique employing a microwave method. The precursors citric acid (CA) and cysteine (Cys) were used in the preparation of S- and N-doped Cys carbon dots (Cys CDs). Synthesis was completed in 3 min. The graphitic structure revealed by XRD analysis of Cys CDs dots had good water dispersity, with diameters in the range of 2-20 nm determined by TEM analysis. The isoelectric point of the S, N-doped CDs was pH value for 5.2. The prepared Cys CDs displayed excellent fluorescence intensity with a high quantum yield of 75.6 +/- 2.1%. Strong antimicrobial capability of Cys CDs was observed with 12.5 mg/mL minimum bactericidal concentration (MBC) against gram-positive and gram-negative bacteria with the highest antimicrobial activity obtained against Staphylococcus aureus. Furthermore, Cys CDs provided total biofilm eradication and inhibition abilities against Pseudomonas aeruginosa at 25 mg/mL concentration. Cys CDs are promising antioxidant materials with 1.3 +/- 0.1 mu mol Trolox equivalent/g antioxidant capacity. Finally, Cys CDs were also shown to inhibit the acetylcholinesterase (AChE) enzyme, which is used in the treatment of Alzheimer's disease, even at the low concentration of 100 mu g/mL.