Síntese e caracterização de microcápsulas de sílica e sílica com óxido de ferro contendo o fármaco sulfametoxazol

Abstract

Bacterial resistance has led to an increase in the number of studies aimed at improving antibiotics, causing thousands of deaths per year. This study aimed to improve the stability of the drug sulfamethoxazole by encapsulating it in magnetic silica. Thus, two types of microcapsules were prepared, one with mesoporous silica and another with mesoporous silica with iron oxide, which showed magnetic properties. Silica is a stable, inert and biocompatible compound, thus not harming human metabolism. The materials obtained were characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and nitrogen adsorption-desorption. The set of these analyses evidenced the encapsulation of sulfamethoxazole for both microcapsules, characteristic bands of the drug were verified in the vibrational spectrum in the infrared region and the improvement in thermal stability by thermogravimetric analysis. Furthermore, nitrogen adsorption analysis showed a 51% reduction in the pore volume of the mesoporous silica microcapsules, which indicates the presence of sulfamethoxazole in the pores. A release kinetics of the drug in aqueous medium with controlled pH and temperature was performed. The results indicated that the drug had a controlled release with a duration of one day, and that this release occurred through surface diffusion, with an average rate constant of 7 x104 g/mol.min at pH 2.8 and 6.7 x103 g/mol.min at pH 7.4. Both materials indicated to be promising for the transport of the drug sulfamethoxazole.