PDA-mediated Mild Photothermal Therapy Combined with Autophagy Inhibitors Kill Breast Cancer Cells

Objective To explore whether inhibiting autophagy can enhance the sensitivity of photothermal treatment under mild photothermal conditions. Methods CQ@PLGA@PDA NPs were prepared by an improved double emulsification method and a PDA-based surface modification method. After basic characterization, CCK-8 method was used to detect the cytotoxicity of nanoparticles; the near-infrared laser irradiation nanoparticle solution was used to detect the heating effect; CCK-8 method and live-dead cell staining were used to detect the killing effect of tumor cells; Western blot was used to detect the expression of autophagy-related proteins. Results The CQ@PLGA@PDA NPs were successfully prepared, with a particle size of 253.10±2.39 nm, a zeta potential of -22.57±0.80 mV, uniform particle size and good dispersion. The temperature of nanoparticle solution increased to 45℃ after the near-infrared laser irradiation for 10 min. CQ@PLGA@PDA NPs had no obvious toxicity to cells. The survival rates of breast cancer cell MDA-MB-231 and mouse embryonic fibroblast NIH-3T3 cell were above 95%. The inhibition of autophagy under mild photothermal conditions could improve the sensitivity of photothermal therapy. Conclusion The prepared CQ@PLGA@PDA NPs have good photothermal performance and high biological safety; by inhibiting autophagy, they can effectively kill tumor cells under mild photothermal conditions(< 50℃).