Insights Into the Antibiofilm Activity of Carbon Quantum Dots Against a Panel of Different Microorganisms: A Review

Biofilm-associated infections account for a majority of chronic bacterial diseases. These infections also present a therapeutic challenge due to their intrinsic tolerance to conventional antibiotics. Carbon dots (CDs) have emerged as a versatile nanoplatform with the potential to combat these resilient structures. This review critically evaluates the burgeoning field of CD-based antibiofilm agents. We move beyond a catalog of studies to analyze how the physicochemical properties of CDs dictate their mechanisms of action against a panel of microorganisms. The antibiofilm activity of CDs is multi-sided, stemming from their ability to (1) electrostatically interact with and disrupt the biofilm matrix and bacterial cell envelopes, (2) penetrate deep into biofilms due to their ultrasmall size, (3) generate ROS that degrade the extracellular polymeric substance (EPS) and kill embedded cells, and (4) downregulate key genes involved in quorum sensing and biofilm formation. An analysis of the literature reveals an efficacy bias towards Gram-positive bacteria, highlighting the barrier posed by the outer membrane of Gram-negative pathogens. We dissect how synthetic strategies and surface passivation techniques (e.g., with cationic polymers, lysozyme, or targeting ligands) are being deployed to overcome these challenges. While CDs represent a frontier in antibiofilm therapy, the field faces hurdles, including a lack of standardized testing protocols, limited in vivo validation, and unresolved questions about toxicity. This review identifies these critical gaps and proposes future research directions focused on the rational design of next-generation CDs with enhanced specificity, potency, and translational potential for treating recalcitrant biofilm infections.