Adam McAteer, Steven DiSpirito, Jonathan Bunn, Jeffrey Hettinger, Rowan University, Glassboro, NJ
Orthopedic implants are frequently manufactured using metal alloys or polymers. While the materials used are non-corrosive and biocompatible by most measures, improvements are needed. Metal alloys are not ideal due to the mismatch in elastic properties between the alloy and bone leading to stress shielding, bone resorption and implant loosening often requiring revision surgery. Polymer materials, such as polyether ether ketone (PEEK) have been found to have a hydrophobic surface which leads to poor cell adhesion and proliferation making these less favorable for applications that require bone adhesion. This presentation outlines preliminary results using a thin film method to search for new alloys with favorable elastic properties that could be used for the full orthopedic implant or as a coating on a polymer implant encouraging cell growth.
Combinatorial approaches are well established in materials research. Using the natural deposition profiles of sputtering cathodes is one method to create hundreds of samples with different compositions in a single deposition on a single substrate expediting the search for new materials with favorable properties. A promising range of compositions including titanium (Ti), niobium (Nb) and tin (Sn) was reported with a minimum in the elastic modulus (~30GPa) in a bulk material with composition Ti_79.5Nb₁₅Sn_5.5. This work has been confirmed by others but has uniformly required bulk processing of a few discrete compositions followed by some form of high-temperature processing making the search time consuming, expensive and not practical as an interfacial layer on most polymers. The currently reported work investigates a process to make these materials in a coating form using magnetron sputtering. The work investigates a combinatorial library of composition near Ti_79.5Nb₁₅Sn_5.5 that forms the desired alloy without post deposition processing.