Controlled co-release of doxorubicin and reactive oxygen species for synergistic therapy by NIR remote-triggered nanoimpellers

How to encapsulate and transport the payload of multiple therapeutic compounds avoiding premature leakage, and simultaneously co-release them rapidly at specific lesions still remains the major concern in clinic. Herein, we designed the UCN@mSiO₂-(Azo+RB) (azobenzene groups and Rose Bengal) nanoimpellers, which used the multicolor-emission capability of the core-shell upconverting nanoparticles (UCNs) at a single excitation wavelength to co-release anticarcinogen doxorubicin (Dox) and reactive oxygen species (ROS) for combined chemotherapy and photodynamic therapy (PDT). The nanoimpeller was formed from UCN inner core, mesoporous silica shell, and light triggers Azo and RB molecules. The UCNs emitting UV/blue and green/red multiband light were used to activate the photoresponsive Azo and photosensitizer RB molecules; The mesoporous silica shell offered the possibilities to load anticancer drug and conjugate the light triggers; As there are strong charge interaction and hydrogen bonds between Dox and surface silanols of mesoporous silica, the azobenzene molecules worked as "gatekeeper" and "molecular stirrer" to precisely trap and propel the release of Dox under the external stimuli. The time-dependent drug release analysis, ROS production test and PDT test suggested that the nanoparticles may serve as a useful multifunctional nanoplatform for synergistic therapy and cancer diagnostic.