Lotus leaf inspires novel orthopaedic implant surface

Fereydoon Namavar, Sc.D.

When a drop of water hits a lotus leaf, the water becomes a self-cleaning mechanism as it rolls off the surface and washes away dirt and dust.

Researchers at UNMC mimicked properties of the lotus leaf and created a novel nanostructure coating that will maximize the lifetime of orthopaedic implants and minimize the possibility of wear and surgery.

Fereydoon Namavar, Sc.D., professor and director of the nano-biotechnology laboratory in the UNMC Department of Orthopaedic Surgery, and his team published the findings in the April issue of Nano Letters journal, a leading forum for nanoscale research.

The manuscript, “The Lotus Effect in Engineered Zirconia,” demonstrates how the group mimicked the same nanostructural properties that make the lotus leaf hydrophobic — or water repellant — to create ultra-hydrophilic — or water attracting — surfaces for use in orthopaedic implant devices.

Nano Letters article Click here to see the manuscript as it appears in Nano Letters.

“Applying the same principal, we have engineered a nanocrystalline cubic zirconia coating with super hydrophilic properties,” Dr. Namavar said. “These coatings have the potential to be used for many applications including orthopaedic artificial implants, tissue engineering and cell adhesion and proliferation.”

Dr. Namavar said one of the two joint surfaces that contact each other in movement must have the ability to stay wet to reduce friction and wear. The new surface coating his lab has designed has this ability to stay wet.

Dr. Namavar’s research group alters the structure of the zirconia by using a technique called ion-bombardment to produce the novel coating.

Ion bombardment involves exposing a substance to a large amount of ions — atoms that have gained an electrical charge by either adding or losing an electron. These charged ions are able to alter substances at an atomic level.

Dr. Namavar’s team has used a special ion beam assisted deposition (IBAD) process to enhance the zirconia’s hardness and ability to stay wet. Dr. Namavar and his team are one of the few groups in the country capable of using the IBAD process.

“In orthopaedic terms, this translates into prolonged life of orthopaedic implants and fewer revision surgeries due to reduced friction and wear of the implant, as well as enhanced bone growth,” Dr. Namavar said. “Biointegration failure is one of the primary concerns with orthopaedic devices because it prevents long-term stability, which contributes to pain, implant loosening and infection that usually necessitates revision.”

Revision surgery is required when the device fails. It is generally less successful than the primary surgery and costly in terms of patient hardship and expense. Extending the life of artificial implants would eliminate patient suffering and save substantial health care dollars, Dr. Namavar said.

Kevin Garvin, M.D., professor and chair of orthopaedic surgery, and Hani Haider, Ph.D., associate professor and director of the department’s biomechanics laboratory, are co-authors on the manuscript. In addition, researchers from the Nebraska Center for Materials and Nanoscience and the department of chemistry at the University of Nebraska-Lincoln, and the department of physics at the University of Nebraska at Omaha, assisted with the manuscript. A grant from the Nebraska Research Initiative funded the project. The group is seeking further funding to begin testing the coating in animal models.

“We are excited for the possibilities this holds for the future of orthopaedic implants,” Dr. Garvin said. “In the long run, there is potential for much improved outcomes for patients undergoing joint replacement, and that goal is always at the forefront of our work.”