Sterilizable Gels from Thermoresponsive Block Copolymer Worms

Adam Blanazs, Robert Verber, Oleksandr O. Mykhaylyk, Anthony J. Ryan, Jason Z. Heath, C. W. Ian Douglas, and Steven P. Armes*

J. Am. Chem. Soc., Article ASAP
DOI: 10.1021/ja3024059
Publication Date (Web): May 14, 2012
Copyright © 2012 American Chemical Society


Biocompatible hydrogels have many applications, ranging from contact lenses to tissue engineering scaffolds. In most cases, rigorous sterilization is essential. Herein we show that a biocompatible diblock copolymer forms wormlike micelles via polymerization-induced self-assembly in aqueous solution. At a copolymer concentration of 10.0 w/w %, interworm entanglements lead to the formation of a free-standing physical hydrogel at 21 °C. Gel dissolution occurs on cooling to 4 °C due to an unusual worm-to-sphere order–order transition, as confirmed by rheology, electron microscopy, variable temperature 1H NMR spectroscopy, and scattering studies. Moreover, this thermo-reversible behavior allows the facile preparation of sterile gels, since ultrafiltration of the diblock copolymer nanoparticles in their low-viscosity spherical form at 4 °C efficiently removes micrometer-sized bacteria; regelation occurs at 21 °C as the copolymer chains regain their wormlike morphology. Biocompatibility tests indicate good cell viabilities for these worm gels, which suggest potential biomedical applications.

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