A Near‐Infrared Light‐Activated Photocage Based on a Ruthenium Complex for Cancer Phototherapy

Conventional photocages only respond to short wavelength light, which is a significant obstacle to developing efficient phototherapy in vivo. The development of photocages activated by near‐infrared (NIR) light at wavelengths from 700 to 950 nm is important for in vivo studies but remains challenging. Herein, we describe the synthesis of a photocage based on a ruthenium (Ru) complex with NIR light‐triggered photocleavage reaction. The commercial anticancer drug, tetrahydrocurcumin (THC), was coordinated to the RuII center to create the Ru‐based photocage that is readily responsive to NIR light at 760 nm. The photocage inherited the anticancer properties of THC. As a proof‐of‐concept, we further engineered a self‐assembled photocage‐based nanoparticle system with amphiphilic block copolymers. Upon exposure to NIR light at 760 nm, the Ru complex‐based photocages were released from the polymeric nanoparticles and efficiently inhibited tumor proliferation in vivo. A Ru complex‐based photocage that can be activated by NIR light was designed and was engineered into amphiphilic block copolymers which self‐assembled into nanoparticles. Upon irradiation, Ru complexes are released from the nanoparticles and effectively inhibit tumor proliferation in mice via combined chemotherapy and photodynamic therapy, demonstrating the promising anticancer applications of the Ru‐based photocage in vivo.