Molecular engineering of poly(HEMA-co-PEGMA)-based hydrogels: Role of minor AEMA and DMAEMA inclusion

Hydrogel membranes of in-dwelling pH-responsive devices are of interest for the development of biomedical sensors that must measure small changes in pH associated with tissue acidosis. Poly(2-hydroxyethyl methacrylate)-based hydrogels possessing minor amounts of the cationogenic N-(2-aminoethyl) methacrylamide (AEMA) (4 mol%) or a tertiary amine moiety, N,N-(2-dimethylamino)ethyl methacrylamide (DMAEMA) (4 mol%) or AEMA-DMAEMA (2 mol% each) were UV cross-linked with 1 mol% tetra(ethylene glycol) diacrylate (TEGDA) and the degree of hydration, free and bound water distribution, glass transition temperature, elastic modulus, membrane resistance and protein adsorption were studied. Correlation analysis reveals that each of these biotechnical properties is strongly anti-correlated with total hydration (-0.92) and that the bound water content dominates this anti-correlation (~-0.83). However, free water shows a direct, though only weak correlation with these properties (~+0.5). Thus, minor changes in the hydrogel composition (~4 mol%) can significantly influence biomaterials properties and may be useful in tailoring hydrogel properties for application in biosensors and engineered tissue scaffolds.