Influence of the iodine content of nitrogen- and iodine-doped carbon dots as a peroxidase mimetic nanozyme exhibiting antifungal activity against C. albicans

Nitrogen- and iodine-doped carbon dots (I-CDs) were synthesized as peroxidase mimics for the antifungal disinfection of Candida albicans (C. albicans). The prepared I-CDs samples exhibited peroxidase-like activity in the presence of exogenous H2O2. The peroxidase-like activities and antifungal effects of the I-CDs samples were enhanced by increasing their iodine content from 0.1599 g to 0.4796 g. The antifungal activity of the I-CDs (i.e., 2.72 mg/mL) against C. albicans reached > 90% in the presence of exogenous H2O2 (0.5 mM) under visible light irradiation for 120 min. The in vitro experimental results showed the excellent photocatalytic antifungal activity of the designed system against C. albicans. It was theorized that this system promotes the formation of reactive oxygen species, including hydroxyl radicals (·OH), which can successfully inhibit the growth of C. albicans. The antifungal effect of the synergistic I-CDs/H2O2 system on C. albicans could be attributed to the combined effects of its peroxidase-like and photocatalytic activities; the increased activities appeared to be closely related to the iodine content. The results of the present study are expected to broaden the biological applications of the I-CDs and elucidate the relationship between the iodine content and peroxidase-like enzymatic and antifungal activities of the I-CDs.