Design of thermoresponsive polymeric gates with opposite controlled release behaviors

Stimuli-responsive devices are novel tools widely studied in the nanomedicine research field. In this work, magnetic-responsive mesoporous silica nanoparticles (MMSNs) were coated with an engineered thermoresponsive co-polymer. Magnetic cores are used as heating sources when they are exposed to an alternating magnetic field. The polymer structure suffers a change from hydrophilic to hydrophobic state when the temperature is raised above the lower critical solution temperature (LCST) or volume phase transition temperature (VPTT), acting as a gate-keeper of a model drug trapped inside the silica matrix. Fluorescein departure can be tuned employing two different polymer structures on the silica surface which exhibit the same transition temperature (42 degrees C) but a different grafting density: one of them being a dense crosslinked polymer network and the other one a hairy linear polymer layer. The release profile reveals to be the opposite between these two different coatings, allowing suitable drug release behavior for different clinical situations