Biofunctionalization of Poly(acrylamide) Gels.

Engineering novel biomaterials that mimic closer in vivo scenarios requires the simple and quantitative incorporation of multiple instructive signals to gain a higher level of control and complexity at the cell-matrix interface. Poly(acrylamide) (PAAm) gels are very popular among biology labs as 2D model substrates with defined biochemical and mechanical properties. These gels are cost effective, easy to prepare, reproducible, and available in a wide range of stiffness. However, their functionalization with bioactive ligands (cell adhesive proteins or peptides, growth factors, etc.) in a controlled and functional fashion is not trivial; therefore reproducible and trustable protocols are needed. Amine or thiol groups are ubiquitous in natural or synthetic peptides, proteins, and dyes, and hence routinely used as handles for their immobilization on biomaterials.We describe here the preparation of mechanically defined (0.5-100 kPa, range that approximates the stiffness of most tissues in nature), thin PAAm-based hydrogels supported on a glass substrate and covalently functionalized with amine- or thiol-containing bioligands via simple, robust, and effective protocols.

Bioconjugating Thiols to Poly(acrylamide) Gels for Cell Culture Using Methylsulfonyl Co-monomers.

Poly(acrylamide) P(AAm) gels have become relevant model substrates to study cell response to the mechanical and biochemical properties of the cellular microenvironment. However, current bioconjugation strategies to functionalize P(AAm) gels, mainly using photoinduced arylazide coupling, show poor specificity and hinder conclusive studies of material properties and cellular responses. We describe methylsulfonyl-containing P(AAm) hydrogels for cell culture. These gels allow easy, specific and functional covalent coupling of thiol containing bioligands in tunable concentrations under physiological conditions, while retaining the same swelling, porosity, cytocompatibility, and low protein adsorption of P(AAm) gels. These materials allow quantitative and standardized studies of cell-materials interactions with P(AAm) gels.