Ceramic coating of bone implants – A cost-effective process is being developed in the “NanoCoat”Nano Argovia project

The team of the Nano Argovia project “Nanocoat” will develop a new, alternative method for coating of implants. A calcium phosphate phase grows onto the implant and inside a porous layer. (Image: PSI and Meisinger)

An interdisciplinary team at the Paul Scherrer Institute (PSI) and the University of Applied Sciences Northwestern Switzerland (FHNW) is working with three industry partners on the Nano Argovia program. The researchers are developing a protocol for coating titanium implants with calcium phosphates ceramics, which will improve the integration of implants into new bone growth, and therefore ensure a better stability of the implant.

Integration in the bones essential
Thanks to new technologies, increased prosperity, and an ever-ageing population, the demand for bone implants is continually growing. Implants are primarily comprised of metallic materials; titanium is particularly popular due to its excellent mechanical properties and its optimal biological compatibility, and is often used in dentistry, plastic surgery and orthopedics.

In order to guarantee the long-term integration of a titanium implant into the bone, bone-building cells (osteoblasts) must be able to settle on the implant’s surface. They form new bone cells and the implant is then gradually incorporated into the existing bone. In the past, different methods were developed to encourage the forming of bone cells on the implant surface as well as the implant’s incorporation into the bone. Coating with hydroxyapatite has proven to be a promising method. Hydroxyapatite is a calcium phosphate compound and a main constituent of bone. In the market of orthopedic implants, plasma spray has been established as coating process.

An energy-saving method is being developed
In the “NanoCoat” Nano Argovia Project, a team of scientists under the lead of Dr. Andrea Testino from the Paul Scherrer Institute is now investigating a more cost- and energy-efficient method for coating titanium surfaces with calcium phosphate. Alongside Dr. Andrea Testino, the team comprises Dr. Elisabeth Müller (PSI), Professor Michael de Wild (FHNW) as well as Philipp Gruner (Medicoat AG, Mägenwil, Aarau), Dr. Burkard Höchst (Hager & Meisinger GmbH, Neuss, Deutschland) and Dr. Walter Moser (Atesos Medical AG, Aarau).

In the first phase of the project, the researchers are using a chemical and thermal treatment to transform the smooth titanium surface of the implant into a raw and porous one. In the subsequent coating stage, the implant is placed into a coating reactor where a special solution, containing the calcium phosphate precursors, was poured. The researchers were able to prove that, under controlled conditions, the calcium phosphate phase grows both onto the implant and inside a porous layer, ensuring an optimal grafting of the thin calcium phosphate phase on titanium. As a results, the titanium implant is already coated with a synthetic bone.

“In the Nano Argovia project, we are optimistic that we will develop a new cost-efficient, alternative method for coating of implants which support integration into natural bone material. We hope to open new market fields that our plasma spray technique cannot access” says Philipp Gruner, one of the “NanoCoat” project’s three industry partners.