Redox- and enzyme-responsive fluorescent porous silica nanocarriers for drug delivery

In this work, redox/enzyme-responsive fluorescent porous silica (pSiO2) nanoparticles (NPs) were constructed for drug delivery. The resultant pSiO2 NPs have large-pore core and mesoporous shell with size of 75 nm and present high specific surface area (605 m2 g−1). Oxidized glutathione (GSSG) as linker was conjugated on the surfaces of amino-functionalized porous silica (pSiO2-NH2) NPs by the amide bonds for redox-responsive drug release. Dox is served as model drugs to evaluate the release performance of carriers. After loading Dox molecules, both carbon dots (CDs) as fluorescent label and hyaluronic acid (HA) as gatekeepers are capped on the surface of carries (pSiO2-ss-CDs/HA) so as to endow the delivery system with fluorescent monitoring and enzyme-responsive properties. The pSiO2-ss-CDs/HA carriers displayed redox/enzyme-responsive and sustained release behavior. The controlled release of drug from the pSiO2-ss-CDs/HA delivery system was realized by the reduction of disulfide bonds in GSSG linker and degrading HA molecules. The incorporated CDs presented novel redox-dependent fluorescence, which could be used to trace the drug release.