Authors: G. Li, P. Ghoroghchian, W. Qi, N. Christian, P.R. Frail, D.A. Hammer, M.J. Therien
Affilation: Carestream Health Inc., United States
Pages: 661 - 664
Keywords: nanostructured polymersomes, synthesis, self-assembly, poly(ethylene oxide)-b-polycaprolactone (PEO-b-PCL) diblock copolymers, biodegradable polymersomes
A series of amphiphilic poly(ethylene oxide)-b-polycaprolactone (PEO-b-PCL) diblock copolymers with various PEO blocks (number-average molecular weight (Mn): 750~5800), PEO weight fraction (fPEO) from 7.7% to 33.3%, and Mn of the copolymers from 3.6k to 57k, had been synthesized by ring-opening polymerization or sequential anionic living polymerization. Nuclear Magnetic Resonance (NMR) and gel permeation chromatography (GPC) were used to characterize chemical structure, molecular weights and molecular weight distribution of these copolymers. All copolymers have polydispersity index (PDI) from 1.14 to 1.37 by GPC. Two self-assembly techniques, film rehydration and organic solvent extraction, had been employed to process polymersomes. The perfect nanostructured polymersomes were processed by freeze-thaw-sonication film rehydration technique. Cryo-TEM and confocal laser fluorescence microscopy was used to study self-assembly morphology of the copolymers. The polymersomes with sizes from a hundred nanometer to several microns were obtained from PEO(2k)-b-PCL(12k). Polymersomes could only be made from the copolymers with PEO blocks (Mn: 2k-3.8k) and fPEO (11.8-18.8%). Molecular weight distribution has almost no influence on formation of the biodegradable polymersomes. Film rehydration is a highly favorable self-assembly method for preparing biodegradable nanostructured polymersomes from PEO-b-PCL diblock copolymers. The nanostructured biodegradable polymersomes which can entrap water soluble drug or imaging agents in their core and encapsulate water-insoluble hydrophobic drug or imaging agents in their bilayer membrane have potential applications for drug delivery and molecular imaging probes.