Fluconazole-carrier Nanosystem: Effect on Matrix and Structure of Candida Biofilms

Objectives: The aim of this study was to assess the effect of a fluconazole (FLZ)-carrier nanosystem on the extracellular matrix composition and structure of Candida albicans and Candida glabrata biofilms.
Methods: The nanosystem was prepared by loading FLZ on chitosan-coated iron oxide nanoparticles and characterized by transmission electron microscopy, X-ray diffraction, infrared spectroscopy, and thermogravimetric analysis. Biofilms of both species were developed for 48 h in 96-well plates and treated during 24 h with FLZ-containing nanosystem at 250, 500, and 1250 μg/mL. After, protein, carbohydrate, and DNA from the extracellular matrix were quantified, while the biofilms’ structure was analyzed by scanning electron microscopy (SEM). Iron oxide nanoparticles, chitosan, 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 and Fisher LSD test (α = 0.05).
Results: Characterization results confirmed the formation of a nanosystem with size smaller than 320 nm. Overall, FLZ alone and FLZ-containing nanosystem at 1250 μg/mL promoted significant increases in protein, carbohydrate, and DNA contents of the extracellular matrix compared to NCs. SEM observations showed that treatments with FLZ alone and FLZ-containing nanosystem at 1250 μg/mL resulted in the highest disruptions of mono-species biofilms of C. albicans and C. glabrata, generating less dense and compact structures compared to NCs. In addition, energy dispersive spectroscopy mapping revealed the presence of well-distributed Fe and F atoms in the biofilm treated with FLZ-containing nanosystem at 500 and 1250 μg/mL.
Conclusions: Therefore, it was possible to conclude that the nanosystem showed a similar effect to FLZ on the matrix and structure of the biofilms evaluated. Increases in the extracellular matrix components may be associated with the antibiofilm effect of those compounds.