pH- and temperature-sensitive, injectable, biodegradable block copolymer hydrogels as carriers for paclitaxel

Paclitaxel (PTX) was loaded into synthetic pH/T-sensitive block copolymer (OSM–PCLA–PEG–PCLA–OSM) solution with various concentrations. The phase diagram of PTX-loaded block copolymer solution shifted to lower temperature region compared to net block copolymer because of the salting-out effect of PTX. Release profiles of PTX showed sustained manner regardless of loading amount of PTX. To evaluate anti-tumor effect of PTX-loaded block copolymer, solutions were injected subcutaneously to tumor-bearing mice and TUNEL assay examined. PTX-loaded block copolymer hydrogel for in vivo use showed good anti-tumor effect for 2 weeks and induced strong apoptosis in tumor tissue. Therefore, we conclude OSM–PCLA–PEG–PCLA–OSM block copolymer as an effective injectable carrier of PTX.