Neutron study of phospholipids 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-ethanolamine spray coating on titanium implants.

Permanent implants made from titanium are widely used and successfully implemented in medicine to address problems related to orthopedic and oral disorders. However, implants that interact in all cases optimally and durably with bone tissue have yet to be developed. Here, the authors suggest a phospholipids 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-ethanolamine (POPE) lipid coating to partially mimic the biological cell membrane. To improve the homogeneity of the POPE distribution on the metal surface, the lipids are applied by spray coating. It is shown that the spray coating leads to two types of multilamellar POPE structures. Our experimental results demonstrate that these coatings are stable in a liquid environment in the range of physiological temperatures due to the unique interbilayer interaction of POPE lipids. Additionally, the interaction of the POPE multilayer structure with human serum albumin is considered. A simultaneous analysis of the specular and off-specular data provides structural information necessary to assess the quality of the coating for future applications.

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

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.