Dually responsive mesoporous silica nanoparticles regulated by upper critical solution temperature polymers for intracellular drug delivery.

We synthesized a new type of upper critical solution temperature (UCST) thermally responsive polymers (TRPs) with varying responsive temperatures (cloud points). We then grafted one of the TRPs with a cloud point of 42°C on the surface of mesoporous silica nanoparticles (MSN) using disulfide bonds to achieve a novel, dual responsive release system. With this system, the cargo release profiles are responsive to both temperature and reducing agents. When loaded with doxorubicin hydrochloride (DOX), the system could deliver DOX into breast cancer cells (SK-BR-3) in a controlled fashion and present high toxicity.