Síntese e caracterização de materiais vítreos com capacidade biocida

Abstract

This work consisted in the synthesis and characterization of borophosphate glasses doped with silver ions obtained through the traditional melting-quenching technique and subsequent growth of self-supported silver metal nanoparticles using a simple annealing process under H2 (g) atmosphere at relatively low temperatures. In order to improve the chemical stability of the glass, the effect of the Al3+ ions concentration added as modifiers in the matrix in the ratios of 0 to 15 mol% was evaluated. The effect of the aluminum concentration on the SERS substrate and antimicrobial agent applications was also evaluated. Infrared and Raman spectroscopy revealed that the addition of aluminum ions in the glass matrix leads to depolymerization of the original bonds with subsequent formation of phosphate-aluminum structures. It has been observed that the addition of aluminum ions promotes an increase in the glass transition temperature, improving the chemical stability of the glass, causing the nanoparticles to become firmly grafted on the glass surface. The presence of silver ions and mettalic silver was confirmed by X-ray photoelectron spectroscopy (XPS). Moreover the powder X-ray diffraction (PXRD) analysis confirms the metallic character of the silver nanoparticles. The antimicrobial potential of silver-doped glasses was dependent on the concentration of aluminum in the matrix, and its efficacy was conditioned to the release of silver ions, thus inversely proportional to the concentration of Al3+ ions. Silverdoped glasses were highly efficient for application as a SERS substrate. Residual soda-lime glasses were submitted to a sintering process, giving rise to glass-ceramics with surprising antimicrobial potential, attributed to the crystalline structure present in the amorphous matrix surface, verified by electron diffraction experiment (Selected Area Electron Diffraction- SAED).