Preparation of Triple-Responsive Porous Silica Carriers and Carbon Quantum Dots for Photodynamic-/Chemotherapy and Multicolor Cell Imaging

Photosensitive carbon quantum dots (CQDs) provide a new route to treat cancer owing to their ability to produce singlet oxygen. In this paper, pH/redox/enzyme-responsive porous silica-based carriers with CQDs were constructed for photodynamic-chemical combination therapy. The porous silica (pSiO(2)) sample comprises uniform spheres with center-radial channels, which is favorable for drug loading and delivery. CQDs with a size of 2.5 nm were synthesized and have the excellent ability to generate singlet oxygen. After loading CQDs and drug molecules, the channels of pSiO(2) carrier were blocked with hyaluronic acid (HA)/chitosan (CHI) layer. The disulfide bonds, conjugating HA to the surface of pSiO(2) carrier, would achieve redox-responsive drug release, while breaking disulfide bonds and the HA/CHI layer could endow the pSiO(2) carrier enzyme/pH-responsive drug release. The prepared pSiO(2) carriers display low cytotoxicity and good biocompatibility for multicolor imaging and photodynamic-/chemotherapy.