Enzymatic synthesis of PEGylated lactide-diester-diol copolyesters for highly efficient targeted anticancer drug delivery.

PEGylated lactide-diester-diol copolymers were successfully synthesized via lipase-catalyzed copolymerization, the resultant amphiphilic PEG-poly(L-lactate-co-hexamethylene-co-adipate) (PEG-PLLHA) and PEG-poly(D,L-lactate-co-hexamethylene-co-adipate) (PEG-PDLLHA) block copolymers readily undergo self-assembly processes to form nanosized micelles in aqueous medium, which are stable under physiological conditions in the presence of serum proteins. By conjugating folic acid (FA) to enzymatic synthesized poly(hexamethylene adipate-co-hexamethylene 2,3-epoxy succinate), we could formulate FA-bearing PEG-polyester micelles for docetaxel (DTX) targeting delivery. FA-PEG-PLLHA and FA-PEG-PDLLHA micelles possess efficient cell-targeting capability toward FA receptor-positive cancer cells (e.g., CT-26), which significantly enhances their cellular uptake rates and efficacy of drug-loaded formulations toward such cells. During in vivo anticancer treatments, the FA-bearing micelles are highly capable of targeting and accumulating preferentially in tumor tissues by both active cell-targeting mechanism and passive targeting via the EPR effect. All these desirable properties enable the FA-bearing micelles to deliver DTX with 97% tumor-inhibiting efficiency through systemic delivery, which is favorable in comparison to the values of various DTX nanoparticle formulations reported in literature. Importantly, biosafety assays reveal that all DTX-loaded micelles are biocompatible and safe for in vivo antitumor treatment applications. Thus, FA-PEG-PLLHA and FA-PEG-PDLLHA micelles represent new types of promising anticancer drug nanocarriers for targeted chemotherapy.