Chitosan/polyvinyl alcohol-based magnetic hydrogel microspheres with controlled retention and regulated drug release for intravesical instillation

As a clinically effective treatment for bladder cancer (BC), intravesical instillation still suffers from the debilitating efficacy triggered by frequent urination. Herein, the magnetic hydrogel microspheres (DOX-mMSs) with the incorporation of magnetic nanoparticles (MNPs) and doxorubicin (DOX) into polyvinyl alcohol (PVA)/chitosan (CS) are developed for intravesical instillation. The magnetic force initiated by the applied magnetic field (AMF) enables the long-term retention of DOX-mMSs in the bladder, and the convenient injection and excretion from the bladder can be accomplished in virtue of the micron size of the DOX-mMSs. Additionally, the pHsensitive dissociation of CS and hydrazone bonds via which DOX is loaded into DOX-mMSs endows the possibility of controlled drug release by tuning the pH of the urine in the bladder. This dual control strategy is promising in intravesical treatment.