Australian Researchers Bling It On with Diamond-Coated 3D Printed Titanium Implants

As the song says, diamonds are forever – and not just in terms of jewelry. New research coming out of Australia this week illustrates that the stone has been successfully used as a coating for SLM 3D printed titanium implants. Coatings can be used to protect 3D prints, and we’ve seen materials like wax and carbon nanotubes used as coatings, and even an electroluminescent coating that makes prints glow, but this is reportedly the first time in the world that diamonds have been used.

Aside from the really cool notion that people could one day sport blinged-out implants, a diamond coating on 3D printed titanium implants could actually improve how the human body accepts implants for orthopedic and biomedical uses.

3D printed titanium covered with the diamond coating developed by RMIT researchers.

Titanium, as we know by now, is an accurate and reliable metal to use in medical-grade and patient-specific implants. But, it’s not without its own set of issues, as the chemical compounds on titanium can prevent bone and tissue from interacting with biomedical implants, causing the body to reject the material. Using inexpensive, synthetic diamond to coat the implants can solve this problem.

Biomedical engineer Dr. Kate Fox, and her team at RMIT University’s School of Engineering, made the breakthrough with the 3D printed, diamond-coated titanium implants, though it would not have been possible without some new advances in 3D printed titanium scaffolds by the university’s Advanced Manufacturing Precinct.

Dr. Fox explained, “Currently the gold standard for medical implants is titanium but too often titanium implants don’t interact with our bodies the way we need them to.

“To work around this, we have used diamond on 3D scaffolds to create a surface coating that adheres better to cells commonly found in mammals. We are using detonation nanodiamonds to create the coating, which are cheaper than the titanium powder. This coating not only promotes better cellular attachment to the underlying diamond-titanium layer, but encouraged the proliferation of mammalian cells. The diamond enhances the integration between the living bone and the artificial implant, and reduces bacterial attachment over an extended period of time. Not only could our diamond coating lead to better biocompatibility for 3D-printed implants, but it could also improve their wear and resistance. It’s an exceptional biomaterial.”

The collaborative team is made up of researchers from many different disciplines from RMIT University, the University of Melbourne, the RMIT Microscopy and Microanalysis Facility (RMMF), Swinburne University of Technology, and the Institute of Health and Biomedical Innovation at Queensland University of Technology.

Together, they published a paper on their work, titled “Polycrystalline Diamond Coating of Additively Manufactued Titanium for Biomedical Applications,” in the journal ACS Applied Materials and Interfaces; co-authors include Aaqil Rifai, Nhiem Tran, Desmond W. Lau, Aaron Elbourne, Hualin Zhan, Alastair D. Stacey, Edwin L. H. Mayes, Avik Sarker, Elena P. Ivanova, Russell J. Crawford, Phong A. Tran, Brant C. Gibson, Andrew D. Greentree, Elena Pirogova, and Dr. Fox.

Graphical abstract

The abstract reads, “Additive manufacturing using selective laser melted titanium (SLM-Ti) is used to create bespoke items across many diverse fields such as medicine, defense, and aerospace. Despite great progress in orthopedic implant applications, such as for ‘just in time’ implants, significant challenges remain with regards to material osseointegration and the susceptibility to bacterial colonization on the implant. Here, we show that polycrystalline diamond coatings on these titanium samples can enhance biological scaffold interaction improving medical implant applicability. The highly conformable coating exhibited excellent bonding to the substrate. Relative to uncoated SLM-Ti, the diamond coated samples showed enhanced mammalian cell growth, enriched apatite deposition, and reduced microbial S. aureus activity. These results open new opportunities for novel coatings on SLM-Ti devices in general and especially show promise for improved biomedical implants.”

Diamond has been used to coat cardiovascular stents, and bionics and prosthetics, and now orthopaedic implants. According to Rifai, a PhD researcher working with Dr. Fox, diamond is an effective material for these types of purposes because carbon is already one of the main components in the human body.

“Carbon has an incredible level of biocompatibility. Our body readily accepts and thrives off diamond as a platform for complex material interfacing,” said Rifai.

3D printed titanium in a plasma microwave. When removed the titanium is covered by the nanodiamond surface coating.

A microwave plasma process at the Melbourne Centre for Nanofabrication was used to create the biomaterial coating, made by combining diamonds and titanium scaffolds. Once it’s removed from the microwave, the titanium is completely covered by the nanodiamond coating.

“It will be a number of years before a technology like this is rolled out, and there are many steps to take until we see it available to patients,” Dr. Fox said.

“But what we have done is taken the first crucial step in a long and potentially incredible journey.”

The team will continue its concentration on how this technology can be used to improve orthopaedics.

“3D printing is a groundbreaking revolution in the modern era. With 3D printing we can design patient specific implants of medical grade. The technology is fast, accurate, reliable and saves labour time,” Rifai said.

“The scalability of 3D printing is growing rapidly, so we can expect to see diamond coatings to become common in orthopaedics sometime in the near future.”

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