Mesoporous silica-based nanomaterials for drug delivery: evaluation of structural properties associated with release rate.

We present here a study of the controlled release of amino acid-derived amphiphilic molecules from the internal pore structure of mesoporous nanoparticle drug delivery systems with different structural properties, namely cubic and hexagonal structures of various degrees of complexity. The internal pore surface of the nanomaterials presented has been functionalised with amine moieties through a one-pot method. Release profiles obtained by conductivity measurements are interpreted in terms of specific structural and textural parameters of the porous nanoparticles, such as pore geometry and connectivity. Results indicate that diffusion coefficients are lower by as much 4 orders of magnitude in two-dimensional structures in comparison to three-dimensional mesoporous solids. A fast release in turn is observed from mesocaged materials AMS-9 and AMS-8, where the presence of structural defects is thought to lead to a slightly lower diffusion coefficient in the latter. We conclude that the use of single or mixed phases of these porous systems can be utilized to provide sustained release over long time periods and expect their use in a variety of formulations.