A tri-component semiconducting polymer with ultrahigh photothermal conversion efficiency as a biodegradable photosensitizer for phototheranostics

Semiconducting polymers usually with high photostability, reactive oxygen species (ROS) generation ability, photothermal conversion efficiency hold tremendous promise for phototherapy. In this paper, a biodegradable tri-component semiconducting polymer (NDT) has been designed and synthesized for phototheranostics. NDT nanoparticles (NPs) obtained by nano-precipitation with an ultrahigh photothermal conversion efficiency (65.6%) are able to be degraded in the presence of hydrogen peroxide in the tumor microenvironment (TME). Such NPs show high phototoxicity towards human cervial cancer cells (HeLa) with laser irradiation as well as negligible dark toxicity. Furthermore, in vivo study demonstrates that tumor growth was inhibited efficiently when the mice were injected with NDT NPs even with low power laser irradiation (0.2 W/cm2). In contrast, higher power density (0.5 W/cm2) led to the complete tumor suppression. No side effects were observed towards the normal tissues, which was confirmed by the H&E stained pictures of the normal tissues, including heart, liver, spleen, lung and kidney. Further hematological, liver and renal function parameters indicate the biosafety of NDT NPs.