Antimycotic nail polish based on humic acid-coated silver nanoparticles for onychomycosis

Abstract

Background: The objective of this work has been the development of silver nanoparticles (AgNPs) coated with humic acid (HA) and their incorporation into an enamel for antifungal activity. AgNPs were synthesized by chemical reduction using sodium borohydride (NaBH4) as a reducing agent and coated with HA. Uncoated AgNPs were synthesized as control. AgNPs and HAAgNPs were characterized by ultravioletvisible spectrophotometry (UVVis), differential scanning calorimetry (DSC), dynamic light scattering (DLS), Fouriertransform infrared spectroscopy (FTIR), atomic force microscopy (AFM) and Xray diffraction (XRD). Size of AgNPs and HAAgNPs was recorded within the nanorange, showing HAAgNPs higher stability than noncoated particles by presenting a single plasmatic band around 400 nm.

Results Thermal analysis showed conjugated endothermic peaks, which confirms the compatibility HAAgNPs. FTIR depicted absorptions between 1300 and 1000 cm1 (C = C, Ar H, respectively) demonstrating that HA is adsorbed onto AgNPs. TGA showed that HA does not alter the reduction in mass loss of AgNPs, while it was found by XRD that adding HA promoted the formation of more amorphous AgNPs. The effectiveness of HAAgNPs was evaluated against three different fungal species. Minimum inhibitory concentration (MIC) assays showed that ca. 0.5mM of AgNPs were able to inhibit dermatophyte species growth. HAAgNPs were incorporated into a commercial enamel at a concentration of 8% and their organoleptic characteristics, drying time, centrifugation test and thermal stress, were evaluated. Enamels with AgNPs kept their physicochemical properties over 21days of storage.

Conclusion HAAgNPs nail polish is thus proposed as an innovative material for onychomycosis infections.