Original Research ARTICLE
Controlling topological entanglement in engineered protein hydrogels with a variety of thiol coupling chemistries
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
Topological entanglements between polymer chains are achieved in associating protein hydrogels through the synthesis of high molecular weight proteins via chain extension using a variety of thiol coupling chemistries, including disulfide formation, thiol-maleimide, thiol-bromomaleimide and thiol-ene. Coupling of cysteines via disulfide formation results in the most pronounced entanglement effect in hydrogels, while other chemistries provide versatile means of changing the extent of entanglement, achieving faster chain extension, and providing a facile method of controlling the network hierarchy and incorporating stimuli responsivities. The addition of trifunctional coupling agents causes incomplete crosslinking and introduces branching architecture to the protein molecules. The high-frequency plateau modulus and the entanglement plateau modulus can be tuned by changing the ratio of difunctional chain extender to the trifunctional branching unit. Therefore, these chain extension reactions show promise in delicately controlling the relaxation and mechanical properties of engineered protein hydrogels in ways that complement their design through genetic engineering.
Keywords: engineered protein hydrogels, coiled-coil, thiol-X click chemistries, entanglement, branching
Citation: Tang S and Olsen BD (2014) Controlling topological entanglement in engineered protein hydrogels with a variety of thiol coupling chemistries. Front. Chem. 2:23. doi: 10.3389/fchem.2014.00023
Received: 03 March 2014; Accepted: 22 April 2014;
Published online: 14 May 2014.
Edited by:Carissa M. Soto, Naval Research Laboratory, USA
Reviewed by:Paola Laurienzo, Italian Research Council (CNR), Italy
Yanli Zhao, Nanyang Technological University, Singapore
Copyright © 2014 Tang and Olsen. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Bradley D. Olsen, Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA e-mail: firstname.lastname@example.org