Antibiofilm activity of silver nanoparticles against Candida sp. isolated from the oral cavity.

Candida biofilm is difficult to control due to the poor penetration and unspecificity of antifungal drugs against the microorganisms associated with this structure. Nanoparticles have been investigated for their antimicrobial potential. In this context, the present study evaluated the antibiofilm activity of silver nanoparticle colloids (AgNPs) against candida isolated from the oral cavity. AgNPs were prepared in two different ethanolic syntheses - without and with ammonium hydroxide: AgNP-1 and AgNP-2, respectively. AgNPs were characterized by atomic absorption spectroscopy (AAS), UV-visible (UV-vis) absorption electron spectroscopy, zeta potential, dynamic light scattering (DLS), and transmission electron microscopy (TEM). Subsequently, they were evaluated against biofilm formation by clinical isolates of Candida albicans and Candida krusei by determining the minimum inhibitory concentration (MIC), minimum fungicidal concentration (MFC), and minimum biofilm formation inhibitory concentration (MBIC50). AgNPs inhibited biofilm formation of tested C. albicans and C. krusei and showed antibiofilm activity at subinhibitory concentrations against all yeasts. AgNP-1 inhibited biofilm formation at concentrations between 7.55 and 60.46 µg/mL and AgNP-2 between 7.71 and 30.80 µg/mL. The characterization of AgNP showed that AgNP-1 and AgNP-2 differ mainly in size and dispersion, with AgNP-2 being monodisperse, indicating that these characteristics could be related to the activity against the formation of C. albicans and C. krusei biofilm, and the silver nanoparticles may represent innovative and complementary alternatives to the available antifungal arsenal.