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 Ru^II 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.