Layer-By-Layer Assembly of Collagen Thin Films: Controlled Thickness and Biocompatibility

The extracellular matrix molecular collagen is the one of the most widely utilized scaffolding materials in tissue engineering. However, obtaining uniform bioactive collagen films in the nanoscale range and precisely controlling the physical and chemical properties of these biological films is still a challenge for biomedical engineering. Layer-by-layer assembly, i.e., sequential adsorption of oppositely charged macromolecular species, is a powerful new film preparation technique that can be applied to the design of versatile biomaterials, with well-controlled interfacial, mechanical and biological functions. To demonstrate the feasibility of biomaterial design by means of layer-by-layer assembly, type-I collagen thin films were prepared by using this technique with poly(styrene) sulfonate as a partner polyelectrolyte. The gradual build-up of the collagen films was confirmed by UV-vis spectroscopy and ellipsometry, while their surface morphology was assessed by atomic force microscopy. The thickness of the collagen layers can be changed by increasing the number of bilayers adsorbed with an increment of 13 nm. It was found that the layer-by-layer assembled collagen scaffolds can support the attachment and growth of C2C12 myoblast cells and PC12 pheochromocytoma cells. Accurate thickness control and compatibility with nerve cell precursors indicate the utility of layer-by-layer assembled films in neuroprosthesis.