pubs.acs.org/Langmuir © 2010 American Chemical Society
Engineering the Polymer Backbone To Strengthen Nonfouling Sulfobetaine Hydrogels Louisa Carr, Gang Cheng, Hong Xue, and Shaoyi Jiang* Department of Chemical Engineering, University of Washington, Seattle, Washington 98195 Received July 13, 2010. Revised Manuscript Received August 10, 2010 We have demonstrated that molecularly engineering the chemical structure of a monomer can lead to hydrogels with improved mechanical strength. In this case, hydrogels from zwitterionic sulfobetaine methacrylate monomers were compared to sulfobetaine vinylimidazole (pSBVI) hydrogels. We show that the introduction of the vinylimidazole backbone improves the tensile and compressive mechanical properties of the sulfobetaine hydrogel by an order of magnitude over the same properties of a methacrylate hydrogel. Zwitterionic groups have been shown to create surface coating materials with ultralow fouling properties, and we demonstrate here that the presence of the imidazole group does not compromise the nonfouling properties attributed to the zwitterionic sulfobetaine: surfaces coated with pSBVI exhibited exceptionally low nonspecific protein adsorption, and cell adhesion was reduced by 97% relative to lowfouling poly(2-hydroxyethyl methacrylate) (pHEMA) hydrogels.
Introduction Zwitterionic materials have garnered interest for their extremely low fouling properties and versatility.1 Their ability to resist nonspecific protein adsorption from complex media, bacterial adhesion, and biofilm formation2,3 makes them of interest for ex vivo biosensor background coatings and in vivo applications such as wound dressings, biosensors, contact lenses, and prosthetic coatings. Undesirable adsorption of biomacromolecules and attachment of cells onto surfaces is one of the leading causes of device and equipment failure in both biomedical and industrial applications. Over 1 million cases per year, ∼60% of all hospitalassociated infections, are caused by biofouling on indwelling medical devices.4 These medical device-related infections typically require removal of the device, increase hospital stays, and add over 1 billion dollars per year to U.S. hospitalization costs. The foreign body response, which leads to the encapsulation and the failure of many implanted biomaterials, is the result of nonspecific adsorption of complement proteins onto the implant surface. The deposition of blood proteins on the surface of nanomedicine carriers also leads to short circulation times. Hydrophilic materials, such as dextran, poly(ethylene glycol) (PEG) derivatives, and more recently zwitterionic polymers, have been widely used to modify surfaces in order to reduce the adsorption of protein. However, only PEG and zwitterionic polymers are able to effectively resist nonspecific protein adsorption (e.g., at the level of
