Thermosensitive P(NIPAM-co-AM)-b-PLA block copolymer micelles for applications in intracellular drug delivery

Thermosensitive poly(N-isopropyl acrylamide-co-acrylamide)-block-poly(d,l-lactide) (P(NIPAM-co-AM)-b-PLA) block copolymers were synthesized and characterized in the current study. The block copolymers could self-assemble into nanosized spherical core-shell micelles in aqueous media. Physicochemical properties were examined by surface tension, UV-vis, TEM and DLS measurements. Three water-insoluble drugs, paclitaxel (PTX), 10-hydroxycamptothecine (HCPT) and prednisone, were encapsulated into the copolymer micelles to obtain an optimal micelle-based drug formulation. The experimental results revealed that the copolymer micelles had a cloud point from 43 to 54 °C, critical aggregate concentration from ca 7 to 16 mg L- 1, and hydrodynamic size from 71 to 81 nm. The PTX-loaded polymer micelle had higher drug loading capacity and entrapment efficiency as well as more excellent thermo-triggered in vitro drug release trait than other two drugs. The MTT cytotoxicity assay indicated that the copolymer micelles exhibited good biocompatibility, and therefore they were potentially feasible as effective target therapy carriers.