A new type of amphiphilic block copolymers, poly(ethylene glycol)-block-poly(2-methyl-acrylicacid 2-methoxy-5-methyl-[1,3]dioxin-5- ylmethyl ester) (PEG-b-PMME), bearing acid-labile six-membered ortho ester rings in side chains was synthesized by reversible addition-fragmentation chain-transfer polymerization, and the influence of chain length of the hydrophobic PMME block on micelle properties was investigated. The PEG-b-PMME micelles were stable in aqueous buffer at physiological pH with a low critical micelle concentration. Nile Red as a model drug was encapsulated into the micelles to explore the release profiles. The Nile Red-loaded polymeric micelles showed rapid release of Nile Red in weakly acidic environments (pH 5) but slow release under physiological condition (pH 7.4), due to different hydrolysis rate of ortho ester side chains of PEG-b-PMME. The Paclitaxel (PTX)-loaded micelles retained potency in killing lung cancer cells (A549), compared with the free PTX. No obvious toxicity was found in vitro and in vivo after intraperitoneal injection of the micelles, which confirms that the PEG-b-PMME micelles with unique acid-labile characteristic have great potential as nano-scaled carriers for drug delivery.
Bibliographical noteFunding Information:
This work is financially supported by the Chinese Program for New Century Excellent Talents in Universities [grant number NCET-11-0661]; the National Natural Science Foundation of China [grant numbers 21174054, 21004030]; the Scientific Research Foundation for Returned Scholars from Ministry of Education of China, the Natural Science Foundation of Anhui Province of China [grant number 1408085MB26]; and Jiangsu Key Laboratory of Advanced Functional Polymer Design and Application [grant number KJS1238, Soochow University]. WH Ji and C Wang acknowledge the support by the US National Institutes of Health [grant number R01CA129189].
- drug carriers
- ortho ester