Anticandidal Effect of a Fluconazole-carrier Nanosystem

Objectives: The aim of this study was to synthesize a fluconazole (FLZ)-carrier nanosystem using iron oxide nanoparticles (IONPs) and chitosan (CS), as well as to evaluate the anticandidal effect of this nanosystem on Candida albicans and Candida glabrata.
Methods: FLZ was conjugated to CS-coated IONPs, and the generated nanosystem was physicochemically characterized by transmission electron microscopy, X-ray diffraction, infrared spectroscopy, and thermogravimetric analysis. The minimum inhibitory concentration (MIC) of the nanosystem was determined by the broth microdilution method. Biofilms of all strains were formed for 48 h in 96-well plates, and treated during 24 h with FLZ-containing nanosystem at 250 (IONPs-CS-FLZ250), 500 (IONPs-CS-FLZ500), and 1250 μg/mL (IONPs-CS-FLZ1250). The antibiofilm effect was evaluated by counting colony-forming units (CFUs), total biomass (crystal violet staining), and metabolic activity (XTT reduction assay). IONPs, CS, and FLZ alone were included in all analyzes as controls, and untreated biofilms were used as negative controls (NCs). Data were analyzed by one-way ANOVA or Kruskal-Wallis test, followed by Fisher LSD or Student-Newman-Keuls tests, respectively (α = 0.05).
Results: Physicochemical results confirmed that the incorporation of CS and FLZ did not modify the crystalline properties of the IONPs, and the resulting nanosystem had a size smaller than 320 nm. The nanosystem was able to reduce MIC values compared to FLZ alone, at 25 and 50 μg/mL. FLZ and IONPs-CS-FLZ1250 promoted significant reductions in the number of CFUs compared to NCs. IONPs-CS-FLZ1250 was more effective than FLZ in reducing the biofilm biomass of C. glabrata. For all biofilms, CS, FLZ, and IONPs-CS-FLZ1250 significantly reduced the metabolic activity compared to NCs.
Conclusions: In conclusion, the nanosystem was more effective than FLZ in inhibiting Candida species in the planktonic state. For biofilms, the nanosystem showed an antimicrobial effect equal to or greater than FLZ alone, depending on the strain and parameter tested.