Investigations on the secondary structure of polypeptide chains in polyelectrolyte multilayers and their effect on the adhesion and spreading of osteoblasts.

Inspired by the composition of the native extracellular matrix, biomimetic polyelectrolyte multilayers were assembled from polypeptides and the glycosaminoglycan chondroitin sulfate (CS). To investigate whether peptide conformation imposes an effect on the cell biological functions of osteoblasts, the secondary structure was analyzed by in situ infra-red and circular dichroism spectroscopy. Multilayers composed of polypeptides and CS reveal a predominantly random coiled conformation and impede osteoblast spreading. On the contrary, polypeptide chains in assemblies of poly-L-lysine and poly-L-glutamic acid (PGA) primarily adopt an intermolecular β sheet structure and reveal an increased area of spread, which consequently supports the proliferation of osteoblasts. When CS is replaced by PGA in mixed multilayers, we observe a structural rearrangement from random coils to β sheets with a concomitant improved cell response. We conclude that polypeptide conformation in biomimetic multilayer assemblies affects osteoblast response by altering the stiffness of the multilayer.