Comb Copolymer Biomaterials

An ideal surface for many biomaterials applications would resist nonspecific protein adsorption while at the same time providing specific signals to cells in order to direct their survival, growth, migration and differentiation. The objective of this project is to develop a facile, commercially scalable method for modifying biomaterial surfaces to this end. Our approach exploits amphiphilic comb polymers having polyethylene oxide (PEO) side chains with selectively modified chain ends and poly(methyl methacrylate (PMMA) backbones. The PEO provides general resistance to protein adsorption, while cell-signaling capacity is achieved through the attachment of growth factors or adhesion ligands (such as the peptide sequence RGD) to chain ends.

Our research has shown that comb molecules adjacent to a polymer/water interface self-organize into quasi-2D conformations in which the backbones remain pinned at the interface while the side chains extend into solution, creating a dense brush layer. By varying the number of ligands attached to PEO side chains and/or blending different ratios of ligand-modified to “inert” comb, the spatial distribution of biological ligands can be modified in a controlled fashion on the scale of nanometers to tens of nanometers to investigate the effects on cell behavior. Comb copolymers with polysulfone, polyvinylidene fluoride and biodegradable polycaprolactone backbones have also been developed, for applications in biofiltration and tissue engineering.