One-pot microbial approach to synthesize carbon dots from baker's yeast-derived compounds for the preparation of antimicrobial membrane

Multifunctional carbon dots (CDs) were synthesized hydrothermally from secreted metabolites (so-called postbiotics) of baker's yeast. The CDs were verified and characterized by particle size analyzer, transmission electronic microscopy, UV-visible/fluorescence, Fourier-transform infrared, and X-ray photoelectron spectroscopic. Homogeneous N and P-doped CDs (~4.1 nm) with abundant functional groups showed a dose-dependent antimicrobial activity on Gram-positive, Gram-negative, and fungal strains. A concentration-dependent antioxidant power based on reducing the power of iron in the presence of CDs was reported. CDs were found to be non-toxic at concentrations below 3.5 mg/mL in the human colon cancer cell line (HCT-116) and TM4 cells (mouse Sertoli cell line). Moreover, CDs were used for the fabrication of antimicrobial bacterial nanocellulose membranes. Biocellulose-CDs membrane depicted broad-spectrum antimicrobial activity on nine selected bacterial and fungal strains. Taken together, the synthesized CDs and biocellulose membrane could be considered as potential antimicrobial/antioxidant additive and antimicrobial packaging material, respectively.

Automated summary

In this study, multifunctional carbon dots (CDs) were synthesized from the secreted metabolites of baker's yeast. The CDs exhibited antimicrobial and antioxidant activities and were found to be non-toxic. Furthermore, the CDs were used to fabricate antimicrobial bacterial nanocellulose membranes, which showed broad-spectrum antimicrobial activity.