The selective immobilization of curcumin onto the internal surface of mesoporous hollow silica particles by covalent bonding and its controlled release

Mesoporous-type spherical hollow silica nanoparticles were prepared by using a self-assembled alanine-based amphiphile as a template and then were functionalized with curcumin molecules attached to the internal surface of the nanostructure by covalent bonding. The curcumin-immobilized mesoporous hollow silica nanoparticle (C-MHSP) was characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), BET isotherms, FT-IR, Solid C-13 CP/MAS NMR and powder-XRD. SEM and TEM images revealed spherical structures (100-150 nm outer diameter) containing 90-140 nm hollow cavities with a worm-like structure. The N-2 adsorption-desorption isotherms obtained at 77 K showed a typical type IV isotherm with 4.7 nm of pore size and 448.66 m(2) g(-1) of surface area, respectively. Approximately 35% of the curcumin was selectively immobilized onto the internal surfaces of the mesoporous hollow silica particles by covalent bonds. The curcumin attached onto the internal surface of C-MHSP was efficiently released into the aqueous phase over 120 min at pH 10, indicating that the curcumin that was attached to the inside of the silica particle was effectively hydrolyzed by strong base. Our work provides a method by which the surface of the porous silica can be functionalized in a well-defined manner.