Mesoporous silica nanorods intrinsically doped with photosensitizers as a multifunctional drug carrier for combination therapy of cancer

Mesoporous silica nanoparticles (MSNs) have attracted tremendous attention in recent years as drug delivery carriers due to their large surface areas, tunable sizes, facile modification and considerable biocompatibility. In this work, we fabricate an interesting type of MSNs which are intrinsically doped with photosensitizing molecules, chlorin e6 (Ce6). By increasing the amount of Ce6 doped inside the silica matrix, it is found that the morphology of MSNs changes from spheres to rod-like shapes. The obtained Ce6-doped mesoporous silica nanorods (CMSNRs) are not only able to produce singlet oxygen for photodynamic therapy, but can also serve as a drug delivery platform with high drug loading capacity by utilizing their mesoporous structure. Compared to spherical nanoparticles, it is found that CMSNRs with a larger aspect ratio show much faster uptake by cancer cells. With doxorubicin (DOX) employed as a model drug, the combined photodynamic and chemotherapy is carried out, achieving synergistic anti-tumor effects both in vitro and in vivo. Our study presents a new design of an MSN-based drug delivery platform, which intrinsically is fluorescent and able to serve as a photodynamic agent, promising for future imaging-guided combination therapy of cancer.