Thermo-Sensitive Poly(N-Isopropylacrylamide)/Mesoporous Silica Nanocomposites as Controlled Delivery Carriers: Loading and Release Behaviors for Drug Ibuprofen

Thermo-sensitive nanocomposites based on mesoporous silica SBA-15 and poly(N-isopropylacrylamide) (PNIPAAm) have been synthesized via in situ radical polymerization in mesopores. The resultant materials were used as carriers to construct temperature-responsive controlled drug delivery systems. Loading of model drug ibuprofen (IBU) was ascertained by IR and UV-vis/DRS spectroscopy, and the mesostructure and pore properties of the delivery system were characterized by small-angle XRD and N2 adsorption-desorption experiment. Study on drug uptake indicated that higher polymer content in the composite, higher IBU concentration in loading solution and lower loading temperature below the lower critical solution temperature (LCST) could increase the loading amount of IBU by means of interaction between IBU and polymer and trap effect of the polymer chains in pores. Different from the uptake of IBU, however, the release of drug followed a positive temperature-responsive manner, that is, the release was accelerated upon heating above the LCST, while decelerated and lasted for a longer period of time below the LCST. This feature allows the material to function as a reversible fast/slow transition switch or rate regulator responsive to environmental temperature and to be potentially interesting in controlled delivery and other smart application fields.