Squaraine-containing polymeric nanoparticles enable photodynamic and photothermal therapy of cancer cells

Abstract

Herein, we unveil the synthesis and characterization of a squaraine (Sq1) and Pluronic F127 based Sq1@F127 nanoparticles. These nanoparticles exhibited fascinating photothermal and photodynamic properties. Experimental results showed that Sq1 was efficient photosensitizers that could produce reactive oxygen species (ROS) with singlet oxygen quantum yield of 0.019. Furthermore, we found that Sq1@F127 nanoparticles could increase the local temperature gradually from 24.0 °C to 54.2 °C over the course of 10 min. Sq1@F127 nanoparticles had a photothermal efficiency of 52%. Finally, in vitro phototherapy efficiency of Sq1@F127 nanoparticles were elucidated using human melanoma cells (SK-MEL 30/An1). Sq1@F127 nanoparticles did not exhibit any discernible toxicity in the dark. For photodynamic therapy (PDT), SK-MEL 30 cells were illuminated with red light, which was followed by laser irradiation (808 nm, 1.0 W/cm2) for photothermal therapy (PTT). It is noteworthy that up to 57% of melanoma cells could be killed by Sq1@F127 nanoparticles when dual therapy was carried out. Our data clearly showed that the treatment of Sq1@F127 nanoparticles with two different wavelengths produced a combined dual phototherapy effect on cancer cells. Overall, Sq1@F127 nanoparticles were truly efficient photosensitizers for PDT and PTT.