Targeting the Antifungal Activity of Carbon Dots against Candida albicans Biofilm Formation by Tailoring Their Surface Functional Groups

Carbon dots (CDs) are an emerging class of carbon nanoparticles,which for their characteristics have found applications in manyfields such as catalysis, materials and biomedicine. Within thiscontext, the application of CDs as antibacterial agents has receivedmuch attention in very recent years, while their use as antifungalnanoparticles has been scarcely investigated. Here we report asystematic investigation of the surface functional groups of CDs tostudy their influence on these nanoparticles’ against Candidaalbicans. Three classes of CDs have been synthesised and fullycharacterized. A thorough in vitro and in vivo biological screeningagainst C. albicans was performed to test their antifungal,antiadhesion and antibiofilm formation activities. Moreover, theinteraction with C. albicans cells was investigated by microscopicanalysis. Our results evidence how the presence of a positivelypolarised surface results crucial for the internalization into COS-7cells. Positively charged nanoparticles were also able to inhibitadhesion and biofilm formation, to interact with the cellularmembrane of C. albicans, and to increase the survival of G.mellonella infected larvae after the injection with positive nano-particles. The antifungal activity of CDs and their extremely lowtoxicity may represent a new strategy to combat infectionssustained by C.albicans.