A versatile gas-generator promoting drug release and oxygen replenishment for amplifying photodynamic-chemotherapy synergetic anti-tumor effects.

Excellent efficiency of combinational therapy of chemotherapy and photodynamic therapy (PDT) highly depends on the amounts of drug and oxygen in tumor tissue. However, how to cleverly promote drug release accompanied with improving oxygen concentration remains a challenge. Herein, we proposed a gas-generator that realized a high drug loading and integrated facilitation of drug release with oxygen replenishment into a single and simple system, utilizing huge cavities and mesoporous channels of hollow mesoporous silica nanoparticles (HMSNs) for encapsulating oxygen (O2) saturated perfluoropentane (PFP) droplets, indocyanine green (ICG) and doxorubicin (DOX), biocompatible polydopamine (PDA) as the gatekeepers. Under irradiation of 808 nm laser, the thermal effect of PDA caused PFP droplets occur liquid-gas phase transition that triggered the burst release of DOX and O2, finally amplifying the synergetic effects of PDT and chemotherapy both in vitro and in vivo. The influence of PFP, GSH and laser on drug release kinetic was explored through mathematical models. Notably, the mechanism of gas-generator on accelerating drug release under irradiation based on doing volume work and enhancing diffusion coefficient was clarified by researching the relation between DOX release, PFP release and temperature change. Additionally, the way of replenishing O2 did not rely on intracellular components but timely offered abundant "fuels" for producing reactive oxygen species (ROS) when compared with traditional manners. This work provides a new research strategy for boosting drug release and opens an avenue for constructing multifunctional controlled delivery systems.