INFLUÊNCIA DO DIRECIONADOR DE POROS NA SÍNTESE DA SÍLICA MESOPOROSA A PARTIR DO MÉTODO SOL-GEL DOPADA COM NANOPARTÍCULAS DE PRATA

INFLUENCE OF THE PORE-DIRECTING AGENT ON THE SYNTHESIS OF MESOPOROUS SILICA VIA THE SOL-GEL METHOD DOPED WITH SILVER NANOPARTICLES. Mesoporous silica particles were obtained using the sol-gel method, based on hydrolysis and condensation reactions of alkoxides. This technique enables the production of powders with high purity and chemical homogeneity at low temperatures and reduced costs. Silica was chosen for its biocompatibility and absence of contamination risk. Its versatile structure allows modifications that expand its applications in catalysis, chromatography, luminescent materials, and controlled drug release. The main objective of this study was to obtain mesoporous silica particles from the tetraethyl orthosilicate (TEOS) alkoxide precursor in a basic medium, varying the concentration of the surfactant cetyltrimethylammonium bromide (CTAB), giving rise to the S1 and S2 samples, with lower and higher surfactant concentrations, respectively. These particles were then modified with silver nanoparticles (AgNPs), synthesized by reducing silver nitrate using sodium borohydride as a reducing agent. The obtained materials were characterized by vibrational infrared spectroscopy, where bands at 3740, 3540, and 948 cm–1 were observed, associated with silanol groups (Si–OH). Bands at 1089, 803, and 450 cm–1 correspond to Si–O–Si bond vibrations. X-ray diffraction confirmed the presence of a halo at approximately 22° in 2θ, indicating that the synthesized mesoporous silica does not exhibit an ordered crystalline structure. Ultraviolet-visible absorption spectroscopy confirmed the formation and incorporation of silver nanoparticles with the presence of a band around 400 nm. Dynamic light scattering analysis showed hydrodynamic radii ranging from 400 to 600 nm, and zeta potential analysis indicated a negative surface charge below –30 mV, characterizing the sample as unstable. Microbiological analyses against Escherichia coli and Staphylococcus aureus bacteria revealed that at a concentration of 2000 µg mL–1, the S2, S2 + 1 mgAgNPs, and S2 + 5 mgAgNPs samples exhibited bactericidal properties, while at 1000 µg mL–1, the S2 + 10 mgAgNPs sample demonstrated bactericidal activity against S. aureus, indicating microorganism death.