Carbon quantum dots (CQDs) are known for their antibacterial properties and ability to inhibit bacteria growth. In the current study, we observed a dopant and concentration-dependency on the antibacterial effect of CQDs. High concentrations of CQDs completely inhibited bacteria growth yet low concentrations enhanced growth. Unlike undoped CQDs, nitrogen-doped CQDs (N-CQDs) enhanced bacteria growth in a concentration-dependant manner and nitrogen/iron co-doped CQDs (Fe/N-CQDs) resulted in growth profiles similar to untreated bacteria. N-CQDs also exhibited the strongest photoluminescence (PL) signal which was quenched by bacteria, and the reduction in the maximum PL intensity was linear over the concentration range tested until saturation. N-CQDs were found to be located around the bacteria cell periphery suggesting intimate interactions. Illumination prior to interaction with bacteria had little influence on these growth effects. Absorbance measurements of colloidal CQD, N-CQD and Fe/N-CQD confirmed long-term stability (7 days). Such materials have potential for incorporation into rapid sensing and diagnostic systems for bacteria detection in liquids for biomedical applications.
@article{arxiv.2510.06454,
title = {Nitrogen-doped carbon quantum dots enhance bacteria growth and biosensing signals},
author = {David Rutherford and Marketa Šlapal Bařinková and Jaroslav Kuliček and Jelena Kozic and Jovana Prekodravac Filipović and Bohuslav Rezek},
journal= {arXiv preprint arXiv:2510.06454},
year = {2025}
}