Carbon Dots as Multifunctional Nanomaterials: A Review on Antimicrobial Activities and Fluorescence-Based Microbial Detection

The increasing prevalence of antimicrobial resistance and the persistent challenge of infectious diseases highlight the critical necessity for novel approaches that integrate pathogen management with swift detection methods. Carbon dots (CDs) are a versatile class of fluorescent nanomaterials that have garnered increasing attention owing to their tunable surface chemistry, strong photoluminescence, high stability, and biocompatibility. Recent studies demonstrate that CDs possess broad-spectrum antibacterial and antifungal activities via multiple mechanisms, including the generation of reactive oxygen species, disruption of membranes, inhibition of biofilms, and synergistic interactions with conventional antimicrobials. The performance is significantly affected by precursor selection, heteroatom doping, and surface functionalization, with minimum inhibitory concentrations reported to range from highly potent at the microgram level to moderate at elevated concentrations. The intrinsic fluorescence of CDs, in addition to their antimicrobial activity, facilitates their use as sensitive and selective probes for microbial detection, allowing for rapid and real-time monitoring in biomedical, food safety, and environmental settings. This review summarizes recent advancements in the antimicrobial properties of carbon dots (CDs) and their fluorescence-based applications in microbial detection. It emphasizes their theranostic potential and future prospects as multifunctional nanomaterials for combating infectious diseases and ensuring microbial safety.