Otimização da síntese de nanopartículas de sílica obtidas a partir da diatomita para aplicação em sistemas de liberação modificada de fármaco

Abstract

Modified drug delivery systems (MDDSs) are valuable allies in the quest for optimizing pharmaceuticals, whether to modulate their release profiles or increase their bioavailability. In this context, silica particles in the nanometric size range stand out as excellent materials for MDDS applications, thanks to their favorable interactions with drugs provided by silanol groups. Experimental planning is a widely applied tool in various scientific fields, and in this study, its relevance is emphasized in the synthesis of silica nanoparticles as promising drug delivery systems. The research details the synthesis process of silica nanoparticles from diatomite using the sol-gel method, along with meticulous material characterization through analytical techniques such as X-Ray Diffraction (XRD), X-Ray Fluorescence (XRF), Fourier-Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy with Energy-Dispersive X-Ray Spectroscopy (SEM-EDS), nitrogen adsorption/desorption (N2), Dynamic Light Scattering (DLS), and Zeta Potential (PZ). Following the successful optimization of the synthesis, particles within the range of 292.5 ± 33.0 nm were obtained, with a yield of 90% and a polydispersity index of 0.218 ± 0,041. The experimental design made it possible to study the parameters (such as the diatomite/NaOH ratio, silicate volume and temperature) that had a direct effect on obtaining particles with the right size, high yield efficiency and low polydispersity. The unique characteristics of amorphous silica particles such as porosity, high specific surface area (291 m2 /g) and, especially, their favorable interactions with the drug (due to the silane groups), point to a remarkable potential for modulating drug release profiles and increasing their bioavailability. Through in vitro release studies, the efficiency of the developed pH-responsive system for the model drug (captopril) was demonstrated, confirming the sustained release capability. Kinetic study evidenced that the model with the best fit was Korsmeyer-Peppas, indicating that the captopril release process is diffusion-controlled.