Construction of pH responsive periodic mesoporous organosilica with histidine framework (His-PMO) for drug delivery

Abstract pH-responsive drug delivery material based on histidine periodic mesoporous organosilica (His-PMO) was constructed by the condensation of histidine bissilylated organosilica precursor (His-BOP) and TEOS in acidic medium under the template P123. The organosilica precursor His-BOP was prepared by selecting histidine as the main reactant via multi-step reactions. Histidine is first introduced as the skeletal constituents of PMO to improve flexibility of the robust framework and sensitivity of pH response. The materials His-PMO maintain ordered meso-structure and facilitate entrance or exit of compounds during application process. Paclitaxel (PTX) is used as the cargo molecules to observe drug delivery in vitro. The results indicate that the maximum loading amounts of drugs are up to 28 mg/g on the material His-PMO-10% under the same conditions. In the release experiments, the different release percentage and speed of PTX are observed with the variation of pH values (pH 5.2, 6.8 and 7.4), which exhibits nonlinear over the time. Rapid accumulation of drugs at low pH are maybe helpful for improving the performance of conquering cancer.