Synthesis of an amphiphilic block copolymer containing zwitterionic sulfobetaine as a novel pH-sensitive drug carrier

pH-sensitive drug carriers offer promise for tumor targeted drug delivery. An amphiphilic triblock copolymer, poly(epsilon-caprolactone)-block-poly(diethylaminoethyl methacrylate)-block-poly(sulfobetaine methacrylate) (PCL-PDEA-PSBMA), was synthesized through click reaction of alkyne end-functionalized poly(sulfobetaine methacrylate) (polySBMA-alkyne) onto azide end-functionalized PCL-PDEA (PCL-PDEA-N-3) and was used as a pH-sensitive drug carrier in the form of micelles. In particular, the micelles exhibited pH dependency as a result of the protonation of the PDEA block. A hydrophobic drug, curcumin, was chosen as a model drug to investigate the potential application of this triblock copolymer in drug-controlled release. The results indicated that the release rate of curcumin-loaded micelles at pH 5.0 was faster than that at pH 7.4. Furthermore, the results of the pharmacokinetics of the curcumin-loaded micelles in vivo showed that the retention time of the curcumin-loaded micelles in blood could extend and the clearance of curcumin in the micelles was delayed, compared with the curcumin solution. This new pH-sensitive triblock copolymer PCL-PDEA-PSBMA has great potential as a hydrophobic anticancer drug carrier.