Dual-functional nitrogen-doped carbon dot/copper oxide nanocomposites for electrochemical sensing of ascorbic acid...

Antimicrobial resistance poses a growing threat to effective infection treatment, while imbalances in ascorbic acid (AA) levels are linked to various health issues. Nanotechnology offers innovative solutions, with carbon dot-based nanocomposites emerging as promising materials for both antimicrobial applications and sensitive detection of biomolecules. This study aimed to synthesize nitrogen-doped carbon dots (NCDs), copper oxide nanoparticles (CuO NPs), and their nanocomposites (CuO-NCDs), and to evaluate their electrochemical sensing of AA and antimicrobial activity.

NCDs were prepared via a hydrothermal treatment of citric acid and urea, and CuO NPs by precipitation of copper nitrate. Characterization by Ultraviolet-Visible (UV-Vis) spectroscopy, Fourier Transform Infrared (FT-IR) spectroscopy, X-ray Diffraction (XRD), and Scanning Electron Microscopy (SEM) confirmed their optical properties, functional groups, crystallinity, and morphology.

The CuO-NCD nanocomposite exhibited enhanced optical absorption with a reduced energy band gap (2.6 eV) compared to individual components. Electrochemical tests revealed a detection limit of 2.56 µM for AA and increased electrode surface area, indicating improved sensitivity and selectivity. Antimicrobial assays showed significant activity against Staphylococcus aureus, with a 24 mm inhibition zone at 200 mg/mL after 24 h.

These results demonstrate that CuO-NCD nanocomposites hold potential as dual-function materials for effective AA detection and combating microbial infections.