X-ray and neutron investigation of self-assembled lipid layers on a titanium surface

Abstract

Titanium is the most widely preferred metal material for bone reconstruction in orthopedics and dentistry. To improve its biological performance, various coatings can be applied. In this investigation, a biomimetic coating on a model implant surface was studied in X-ray and neutron reflectivity experiments to probe the quality of this coating, which is only few nanometers thick. Titanium was deposited on polished silicon surfaces using a magnetron sputtering technique. To improve the lipid coating’s stability, a stronger van der Waals interaction was first created between the implant surface and the biomimetic coating by adding a phosphonic acid (n-octadecylphosphonic acid – OPA) monolayer onto the surfaces. Then, three monolayers of POPE (phospholipid 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-ethanolamine) were transferred using the Langmuir-Blodgett (LB) and Langmuir-Schaefer (LS) techniques. The analysis of X-ray and neutron specular reflectivity data shows that OPA molecules cover the model implant surface completely and that approximately 50% coverage of POPE can be achieved by LB and LS transfer.