Fabrication of functionalized porous silica nanoparticles and their controlled release behavior

Thiol and amine difunctionalized porous silica (pSiO 2 -SH/NH 2 ) nanoparticles (NPs) were prepared by condensation. The obtained pSiO 2 -SH/NH 2 NPs present uniform spheres with size of 55  nm . Folic acid (FA) as a tumor targeting agent was conjugated on the surface of pSiO 2 NPs by amide linkage (pSiO 2 -SH/FA NPs), and captopril (Cap) as test drug was used to evaluate the releasing behavior. Results indicated that Cap is easily encapsulated into the pores of pSiO 2 -SH/FA NPs, which can further react with the inner thiols to form disulfide bonds . The Cap release from pSiO 2 -Cap/FA nanocarriers can be controlled by dithiothreitol (DTT) or reduced glutathione (GSH). The pSiO 2 -SH/FA nanocarriers showed low cytotoxicity and redox-responsive drug release.