Mesoscale porous silica as drug delivery vehicles: Synthesis, characterization, and pH-sensitive release profiles

Mesoporous silica nanoparticles (MSN) have potential as drug delivery and controlled release devices due to their high surface area and absorption capabilities. The effect of surface charge and pH on the release of the fluorescent dye, rhodamine 6G, from MSN has been studied. Release profiles of rhodamine 6G from bare and amine-coated MSN at pH 5.0 and 7.4 are very different and demonstrate that electrostatic interactions between entrapped rhodamine 6G molecules and the charged surface of the MSN have a significant effect on release kinetics. Release of rhodamine 6G from amine-coated MSN can be fit to a single exponential function, while release from bare MSN can be fit to a double exponential function—indicating that the release of rhodamine 6G from bare MSN is a two-phase process. In addition, it was determined that MSN need to be sonicated in dye solution to maximize their loading capacity.

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► Sonication of MSN in dye solution is necessary to maximize the loading capacity of the MSN.
► Electrostatic interactions between entrapped R6G molecules and the charged surface of the MSN are responsible for differences in release profiles of bare and APTES-functionalized MSN.
► Release profiles from APTES-coated MSN better fit a single exponential function while release profiles from bare MSN better fit a double exponential function—indicating that the release of R6G from bare MSN is a two-phase process.