ROS-Activated nanoscale coordination polymers for enhanced ultrasound-mediated therapy for the treatment of cancer.

Stimuli-responsive nanoplatforms for efficient delivery of drugs in an on-demand manner show promising potential for killing cancer cells with high accuracy and minimal invasiveness. Herein, taking advantage of the good tissue-penetrating depth of sonodynamic therapy (SDT), reactive oxygen species (ROS)-responsive nanoscale coordination polymers (NCPs) were designed through self-assembly of porphyrins (PP) and platinum, which contained ROS-cleavable thioketal (TK) linkers to enhance the release of doxorubicin (Dox) during SDT. Upon exposure to the ultrasound (US), the Dox-loaded NCPs (PTK@PEG/Dox) could generate high amounts of cytotoxic ROS and heat, which not only induced the apoptosis of MCF-7 cells but also facilitated the efficient release of Dox due to the decomposition of the ROS-sensitive TK linkers, achieving the synergistic therapy of US-induced therapy and chemotherapy. After being modified with Arg-Gly-Asp (RGD) peptide, RGD/PTK@PEG exhibited a good targeting ability to cancer cells. Importantly, using the multicellular tumor spheroids (MCTS) derived from MCF-7 cells as a model, the RGD/PTK@PEG/Dox exhibited an efficient and controlled release behavior of Dox under the US irradiation, accompanying a tremendous anti-cancer effect for inducing apoptosis in the solid tumor tissues. This work provided a potential strategy to design controllable and stimuli-responsive nanoplatforms for synergistic/enhanced US-induced cancer therapy. STATEMENT OF SIGNIFICANCE: Stimulus-responsive nanoplatforms can deliver drugs efficiently in an on-demand manner, showing the potential to kill cancer cells with high accuracy and minimal invasiveness. Taking advantage of the good penetration ability of ultrasound (US), nanoscale coordination polymers (NCP) composed of porphyrin (PP), thioketal (TK) linkers, and platinum(II) were prepared via a coordination-driven self-assembly procedure. After doxorubicin (Dox) was loaded on the NCP (PTK@PEG/Dox), the nanoplatform responded to reactive oxygen species (ROS) under the stimulation of US, and induced the on-demand release of Dox, thereby achieving the combined therapeutic effect of sonodynamic therapy (SDT) and chemotherapy for cancer. This work provides a potential strategy for the development of controllable and stimuli-responsive nanoplatforms for enhanced ultrasound-induced cancer therapy.