Functionalized zirconia compounds as antifungal additives for hygienic waterborne coatings

The addition of silver (Ag) into the chemical synthesis of materials, transform them into materials technologically relevant to be used as antimicrobial additives. In this work, the sol-gel method was used to obtain materials based on silica and zirconia, with the inclusion of Ag. The solids were characterized by potentiometric titration, specific surface area (S-BET ), X-Ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) and, the antifungal activity of the additives was assessed by agar plate inhibition against Chaetomiwn globosum and Alternaria alternate. In addition, the resistance to fungal growth on waterborne coatings was evaluated after the incorporation of the solids into paint formulation. Amorphous materials with different acidic and textural properties were obtained. Most of the tested solids showed antifungal activity at the highest concentration used, and the presence of Ag increased the percentage of inhibition. The mixed oxides Ag-additives improved the antifungal activity compare with the pure Ag-oxides (silica or zirconia). In this sense, a synergic effect between zirconia/silica and silver would be a promising result that would reduce the amount of silver in these bioactive materials. This work was performed as a preliminary study, in order to guide the selection of a suitable additive from a list of possible antifungal agents.