Modelling the adsorption and controlled release of drugs from the pure and amino surface-functionalized mesoporous silica hosts

Abstract

Several mesoporous silica materials with different structures were investigated as matrices for controlled drug delivery. The aim of this study is correlating the textural and surface chemical properties of these materials with the adsorption and delivery of the drug model methylprednisolone sodium succinate. The materials were synthesized according to different protocols, and employing both cationic and non-ionic surfactants. Additionally, the functionalization of the materials' surface with 1-[3-(trimethoxysilyl)propyl]diethylenetriamine (DT) was accomplished to study the synergistic effect of the incorporation of amine groups and textural properties on the loading and delivery of drug. The thermodynamics and dynamic adsorption behavior of these materials were determined and fitted to several isotherms models to provide information about the drug adsorption processes. The maximum adsorption capacities of the raw silica supports were correlated with the pore size and the results indicated that the drug adsorption ability improved as the material pore size increases. Moreover, it is observed that the drug adsorption on materials with mesoporous size higher than 10 nm are very close to the theoretical saturation capacity. Regarding amino-modified materials, isotherms models confirmed that the factor governing the adsorption process were mainly the electrostatic interactions, hydrogen bonding and/or hydrophobic-hydrophilic interactions between the drug moieties and amino-functionalized silica surfaces, and in a lesser degree the textural properties of the support. Furthermore, the kinetics of the drug release from these materials functionalized with amino groups were also modelled to finally obtain a correlation between the adsorption and release drug cargo from the host pure and surface-functionalized materials.