Linear–Dendritic Copolymer Composed of Polyethylene Glycol and All-trans-Retinoic Acid as Drug Delivery Platform for Paclitaxel against Breast Cancer

A new linear–dendritic copolymer composed of poly­(ethylene glycol) (PEG) and all-trans-retinoic acid (ATRA) was synthesized as the anticancer drug delivery platform (PEG-G3-RA₈). It can self-assemble into core–shell micelles with a low critical micelle concentration (CMC) at 3.48 mg/L. Paclitaxel (PTX) was encapsulated into PEG-G3-RA₈ to form PEG-G3-RA₈/PTX micelles for breast cancer treatment. The optimized formulation had high drug loading efficacy (20% w/w of drug copolymer ratio), nanosized diameter (27.6 nm), and narrow distribution (PDI = 0.103). Compared with Taxol, PEG-G3-RA₈/PTX remained highly stable in the serum-containing cell medium and exhibited 4-fold higher cellular uptake. Besides, near-infrared fluorescence (NIR) optical imaging results indicated that fluorescent probe loaded micelle had a preferential accumulation in breast tumors. Pharmacokinetics and biodistribution studies (10 mg/kg) showed the area under the plasma concentration–time curve (AUC_0‑∞) and mean residence time (MRT_0‑∞) for PEG-G3-RA₈/PTX and Taxol were 12.006 ± 0.605 mg/L h, 2.264 ± 0.041 h and 15.966 ± 1.614 mg/L h, 1.726 ± 0.097 h, respectively. The tumor accumulation of PEG-G3-RA₈/PTX group was 1.89-fold higher than that of Taxol group 24 h postinjection. With the advantages like efficient cellular uptake and preferential tumor accumulation, PEG-G3-RA₈/PTX showed superior therapeutic efficacy on MCF-7 tumor bearing mice compared to Taxol.