Optimizing the osteogenicity of nanotopography using block co‐polymer phase separation fabrication techniques

Both temporary and permanent orthopedic implants have, by default or design, surface chemistry, and topography. There is increasing evidence that controlling nanodisorder can result in increased osteogenesis. Block co‐polymer phase separation can be used to fabricate a nanotopography exhibiting a controlled level of disorder, both reproducibly and cost‐effectively. Two different topographies, produced through the use of block co‐polymer phase separation, were embossed onto the biodegradable thermoplastic, polycaprolactone (PCL). Analysis of the topography itself was undertaken with atomic force microscopy, and the topography's effect on human osteoblasts studied through the use of immunocytochemistry and fluorescence microscopy. Planar controls had a surface roughness 0.93 nm, and the substrates a high fidelity transfer of a disordered pattern of 14 and 18 nm. Cytoskeletal organization and adhesion, and increased expression of Runx2 were significantly greater on the smallest nanotopography. Expression of osteopontin and osteocalcin protein, and alizarin red staining of bone nodules were greatest on the smallest feature nanopatterns. Highly osteogenic, disordered nanotopographies can be manufactured into thermoplastics in a rapid and cost‐effective way through the use of block co‐polymer phase separation. Osteogenic topographies reproducibly and cost‐effectively produced have a potentially useful application to the fields of implant technology and regenerative orthopedics. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 30:1190–1197, 2012