Ibuprofen-loaded micelles based on star-shaped erythritol-core PLLA-PEG copolymer: effect of molecular weights of PEG

Amphiphilic star-shaped copolymers based on star-shaped poly(L-lactide) (s-PLLA) and poly(ethylene glycol) (PEG) (s-PLLA-PEG) were synthesized with variable molecular weights (M w ) of PEG, and the relationship between the PEG block molecular weight of s-PLLA-PEG copolymers and their micelle properties were investigated. The structure and M w of s-PLLA-PEG were characterized with 1 H NMR, GPC, DSC, and XRD. The ibuprofen (IBU)-loaded s-PLLA-PEG micelles were prepared by dialysis method. The effects of PEG block molecular weight on the morphology, particle size, zeta potential, drug loading content (LC), drug encapsulation efficiency (EE), and in vitro drug release behavior of prepared micelles were investigated. Results indicated that the average diameters, LC, and EE of IBU-loaded s-PLLA-PEG micelles increased with increasing the M w of PEG in s-PLLA-PEG copolymers. The in vitro study showed that the IBU accumulative release can be depressed by increasing the M w of the s-PLLA-PEG, and the release profiles of IBU from s-PLLA-PEG followed the Baker-Lonsdale model equation. The results suggest that structural tailoring of PEG length from s-PLLA-PEG copolymers could provide a new strategy for designing drug carriers of high efficiency.