Liposome co-loaded with β-elemene and IR780 for combined chemo-phototherapy

Combinational chemo-phototherapy has shown significant advantages for the treatment of cancer. To achieve this goal, long-circulating liposomes co-loaded with β-elemene (ELE) and IR780 (denoted as IR780-ELE-LCL) were prepared. Herein, ELE is a kind of volatile oil extracted from the plant, Curcumae Rhizoma. Owning to its anti-tumor activity, ELE was exploited as the chemo-agent for chemotherapy. And IR780 was chosen as the photosensitizer to perform photothermal therapy (PTT) and photodynamic therapy (PDT). The obtained IR780-ELE-LCL had an average diameter ca. 130 nm, and the encapsulation efficiency of ELE and IR780 were 90.23% and 85.11%, respectively. The IR780-ELE-LCL exhibited high photothermal conversion efficiency upon the near infrared (NIR) light irradiation. After intravenous injection, the IR780-ELE-LCL could gradually accumulate at the tumor area and elevate tumor temperature by 20 °C under the 808 nm laser irradiation. Moreover, IR780-ELE-LCL also showed excellent photodynamic effect, since it could produce a significant amount of reactive oxygen species (ROS) when exposed to the NIR light. From the in vitro cell viability study, the IR780-ELE-LCL plus laser treated group showed stronger cytotoxicity against the Lewis lung cancer (LLC) cells compared to the IR780-ELE-LCL or the IR780-LCL plus laser treated groups, which demonstrated the enhanced cytotoxicity of combined chemo-phototherapy. And the result of in vivo experiments showed that IR780-ELE-LCL plus laser exhibited the most significant tumor inhibition among all the treatment groups. These results collectively confirmed that IR780-ELE-LCL could achieve combined chemo-phototherapy to enhance the overall anti-tumor efficacy.