(293d) Multifunctional Polyampholyte Hydrogels With Nonfouling and Protein Conjugation Capacity

Materials that are resistant to nonspecific protein adsorption are critical to reduce the undesirable, but natural, foreign body response. Our recent investigations have demonstrated that materials comprised of a mixture of positively and negatively charged monomer subunits mimic zwitterionic polymer systems and resist nonspecific protein adsorption.

The purpose of this study is to demonstrate that polyampholyte hydrogels prepared with equimolar quantities of positively charged [2-(acryloyloxy)ethyl] trimethylammonium chloride (TMA) and negatively charged 2-carboxyethyl acrylate (CAA) monomers with various amounts of a triethylene glycol dimethacrylate (TEGDMA) cross-linker are a feasible nonfouling hydrogel platform. TMA:CAA hydrogels were synthesized and their physical properties were characterized as a function of the cross-linker density through experiments analyzing percent hydration, compressional properties, and swelling behavior in phosphate- buffered saline as well as DI water. The nonfouling properties of the TMA:CAA hydrogels were verified at varying cross-linker densities using enzyme-linked immunosorbant assays (ELISA), which allowed for a qualitative detection of protein adsorption to the surface of the sample.  The results clearly demonstrate the nonfouling characteristics of the TMA:CAA hydrogel material for both negatively charged fibrinogen (FBG) and positively charged lysozyme (LYZ) when compared to a known nonfouling control of N-(3-sulfopropyl)-N-methacryloxyethyl-N,N-dimethylammonium betaine (SBMA).

A unique advantage of the nonfouling TMA:CAA system is that bioactive proteins can be covalently attached to these materials using standard conjugation chemistry of N-hydroxy succinimide (NHS) and N-ethyl-N’-(3-diethylaminopropyl) (EDC). This was demonstrated through a combination of modified ELISA experiments and short term cell adhesion assays, confirming successful fibrinogen conjugation to TMA:CAA samples. The multifunctional properties of the TMA:CAA polyampholyte hydrogels shown in this work indicate a high potential for this system to serve as a tissue regeneration scaffold for various biomedical applications.