Silicato de prata sintetizado por micro-ondas: correlação entre estrutura, propriedades eletrônicas e atividade biológica

Abstract

MICROWAVE-SYNTHESIZED SILVER SILICATE: CORRELATION BETWEEN STRUCTURE, ELECTRONIC PROPERTIES, AND BIOLOGICAL ACTIVITY. Infectious diseases and the increasing resistance of microorganisms to antimicrobial treatments remain among the major challenges to global public health. The COVID-19 pandemic highlighted the vulnerability of healthcare systems to emerging pathogens, reinforcing the need for new strategies for the prevention and control of infectious diseases. Within this context, nanomaterials and, particularly, silver-based semiconductors have attracted considerable attention due to their broad antimicrobial activity and their potential to act through multiple mechanisms, such as the generation of reactive oxygen species and disruption of cell membranes. In this context, silver silicate stands out as a promising material for antimicrobial applications due to its physicochemical properties and potential for reactive oxygen species generation. In this work, silver silicate was synthesized by coprecipitation followed by microwave-assisted hydrothermal treatment, with irradiation times ranging from 0 to 64 min. Although all samples exhibited an amorphous character by X-ray diffraction, spectroscopic and electron diffraction analyses revealed progressive changes in structural organization and the development of semicrystalline regions with increasing synthesis time. Microscopic analyses showed a reduction in particle size associated with dissolution and recrystallization dynamics during microwave irradiation. Elemental analyses revealed a progressive increase in silver incorporation. The antimicrobial activity of the materials increased with synthesis time, with the sample obtained after 64 min exhibiting the highest performance against Staphylococcus aureus, Escherichia coli, and Candida albicans. The effective concentrations against these microorganisms remained below the toxicity levels observed in NIH/3T3 fibroblasts. The generation of reactive oxygen species was experimentally confirmed and increased with irradiation time. Therefore, microwave-assisted synthesis proved to be an effective strategy for controlling the structure, composition, and defects of silver silicate, resulting in a material with high antimicrobial activity and favorable biological compatibility.