Photopolymerized Carboxybetaine Hydrogels with a Carboxybetaine Dimethacrylate Crosslinker for Functionalization and High Mechanical Strength

Thursday, October 20, 2011: 1:35 PM
L100 F (Minneapolis Convention Center)
Louisa R. Carr, Lei Zhang, Yibo Zhou, Jordan B. Krause and Shaoyi Jiang, Chemical Engineering, University of Washington, Seattle, WA

Hydrophilic crosslinked polymer networks, or hydrogels, are commonly studied systems for many biological applications ranging from corneal implants to drug delivery and wound dressings.  The key attributes of hydrogels that make them particularly well-suited to biological applications are their high water content, biological stability, optical transparency, permeability to metabolites, and sufficient crosslinking to prevent dissolution.  In order to expand the scope of hydrogels’ impact in the biomedical arena, several challenges must be addressed, primarily improving mechanical properties, without reducing its high water content and permeability. 

Hydrogels made from zwitterionic materials have many interesting properties.  Zwitterionic hydrogels have been studied as superabsorbants[1], with particular attention being paid to their swelling properties[2].  We have previously reported low protein adhesion on sulfobetaine methacrylate and mixed charge hydrogels[3] and low cell adhesion on carboxybetaine methacrylate gels[4].  The zwitterionic gels studied so far have shown low mechanical strength[5],3, which limits their potential biological uses, but we have achieved high mechanical properties by designing and synthesizing a carboxybetaine dimethacrylate crosslinker.  Thermally polymerized hydrogels with a compressive modulus of 8 MPa and 60% water content were made[6].

Photopolymerizing these hydrogels, on the other hand, improves the uniformity of the polymer network and results in an order-of-magnitude improvement in compressive modulus.  With 50% water, hydrogels were made with a compressive modulus of 90 MPa.  Furthermore, a redesign of the crosslinker to enable it to be more functionalizable allows for uniformly functionalizable hydrogels regardless of crosslinker content or physical properties, with a completely nonfouling background.  These hydrogels were implanted subcutaneously into mice for 4 weeks to monitor their ability to reduce the foreign body response and minimize capsule formation.  pHEMA hydrogels were used as a control.

[1]Slaughter, B.V., Khurshid, S.S., Fisher, O.Z., Khademhosseini, A. & Peppas, N.A. Hydrogels in Regenerative Medicine. Advanced Materials 21, 1-23 (2009).

[2]Didukh, A.G., Koizhaiganova, R.B., Khamitzhanova, G., Bimendia, L.A. & Kudaibergenov, S.E. Stimuli-sensitive behaviour of novel betaine-type polyampholytes. Polymer International 52, 883-891 (2003).

[3] Chen, S. & Jiang, S. A New Avenue to Nonfouling Materials. Advanced Materials 20, 335-338 (2008).

[4] Zhang, Z., Chen, S. & Jiang, S. Dual-Functional Biomimetic Materials: Nonfouling Poly(carboxybetaine) with Active Functional Groups for Protein Immobilization. Biomacromolecules 7, 3311-3315 (2006).

[5] Kabiri, K., Faraji-Dana, S. & Zohuriaan-Mehr, M.J. Novel sulfobetaine-sulfonic acid-contained superswelling hydrogels. Polymers for Advanced Technologies 16, 659-666 (2005).

[6] Carr, L., Xue, H. & Jiang, S. Functionalizable and nonfouling zwitterionic carboxybetaine hydrogels with a carboxybetaine dimethacrylate crosslinker. Biomaterials 32, 961-968 (2011).

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See more of this Session: Hydrogel Biomaterials II
See more of this Group/Topical: Materials Engineering and Sciences Division