Synthesis of a highly hydrophobic silica mesostructure by a modified co-condensation procedure and evaluation of its drug release capability
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A highly hydrophobic silica mesostructure was synthesized by a modification on the conventional co-condensation procedure that involved the partial substitution of hexadecytltrimethylammonium, used as mesostructure directing agent, by hexadecyltrimethoxysilane. That modification allowed the production of a highly ordered hexagonal silica mesostructure with the mesopores partially filled with high amounts of hexadecyl chains, covalently bonded to inorganic framework. After extracting the reminiscent template molecules, ibuprofen was loaded into the mesostructure in order to evaluate its drug release properties. The drug loading amount (21 wt%) was comparable to the one reported for MCM-41 with grafted propylamine groups (25 wt%), indicating that C16-chains were not fully compacted occluding the pores. A slow ibuprofen release was observed in simulated body fluid (pH 7.2) by a process controlled by an anomalous transport with contribution of diffusional and relaxational components, according to the Korsmeyer-Peppas kinetics model. That hydrophobic mesostructure produced has the potential of being use as a carrier for low water soluble drugs with an extended delivery effect, but without the disadvantages of co-releasing toxic surfactant molecules or the need of non-toxic specific templates to be prepared.
KeywordsHexadecyltrimethoxysilane functionalization Hydrophobic mesoporous silica Drug delivery Molecular nanocontainer Ibuprofen release
Authors are thankful to Prof. Vera R. L. Constantino (IQ-USP) and Ricardo Couto (IQ-USP) for the support on X-ray diffractometry and thermogravimetric experiments. M. A. Bizeto is thankful to the financial support from Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) (Grant 2011/50318-1). M. B. Costa is thankful to Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) for the research fellowship.