Improving the Adsorption and Release Capacity of Organic-Functionalized Mesoporous Materials to Drug Molecules with Temperature and Synthetic Methods

In this report we show that drug incubation temperature, methods used for removing surfactant templates from mesoporous materials and solvents used for placing surface organic functional groups on the materials can improve or affect the adsorption capacity and drug release properties of potentially useful nanoporous silica and organosilica as drug delivery vehicles. This is demonstrated by investigating the adsorption and release properties toward rhodamine 6G (R6G) and an anticancer drug, cisplatin, of various solvent-extracted and calcined mesoporous silicas (MCM-41 and SBA-15), organic-functionalized mesoporous silicas containing terminal organoamine, organothiol and vinyl groups, and bridging organic-functionalized ethane periodic mesoporous organosilica (ethane PMO) under various conditions. Two different solvents, isopropanol and toluene, were used to graft the terminal organic groups from their corresponding organosilanes, producing materials with slightly different adsorption and release properties. The adsorption capacities of the organic-functionalized mesoporous silicas that were prepared from a well solvent-extracted MCM-41 increased significantly as the temperature was raised from room temperature to 50 and 75 degrees C. Furthermore, samples with a higher percent adsorption of R6G and cisplatin also showed higher overall percent release of the adsorbed R6G or cisplatin molecules in a simulated body fluid (SBF) solution. Interestingly, the ethane PM also showed significantly higher adsorption capacity for both R6G and cisplatin than the control samples, MCM-41 or SBA-15. Raising the temperature improved the adsorption capacity of ethane PMO, for both R6G and cisplatin. The method used to remove the surfactant templates from the parent mesostructured materials was also found to affect the materials' adsorption properties.