<i>In Vitro</i> and <i>In Vivo</i> Evaluation of PCL–PEG Nanomicelles for Paclitaxel Drug Release to Treat Breast Cancer

Breast cancer is the primary cause of cancer-related deaths in the female population across the globe. Polycaprolactone (PCL)–polyethylene glycol (PEG) copolymer micelles have been described for different drug delivery applications for breast cancer. Herein, to deliver paclitaxel (PTX), a stable nanomicelle was developed by using a maleic anhydride bridged PCL–PEG copolymer (PCGM) synthesized by a polycondensation reaction. PTX entrapped (PTX-PCGM) nanomicelles were prepared by a thin film hydration method. The spherical PTX-PCGM nanomicelles had a diameter of 235 nm with a negative surface charge, which facilitated their long-term circulation in the bloodstream. Additionally, the PTX-PCGM nanomicelles showed excellent stability in PBS over a period of 30 days. In vitro characterization and cellular experiments showed that the nanomicelles entered MDA-MB-231 cells via passive targeting, and the cytotoxicity of PTX was significantly increased by an enhanced stabilization of tubulin. A steady and sustained release was observed in NOD-SCID mice bearing MDA-MB-231 breast cancer. Moreover, the administration of PTX-PCGM exhibited superior anticancer activity in vivo with a tumor growth inhibition rate of 90.6% with no side effects in major organs. In conclusion, the PTX-PCGM nanomicelle could be a potential breast cancer therapy tool.