Researchers from the Fraunhofer Institute for Surface Engineering and Thin Films (IST) have developed a process for 3D printing plastic bone implants that are patient-specific and stable. The print process, developed in collaboration with seven other EU-based partners, uses a novel cold plasma treatment at every print layer to enhance the bonding of bone-forming cells.
The process pioneered at Fraunhofer IST relies on a plasma jet technique that effectively blows a cold jet of plasma-containing reactive groups onto the individual printed layers of the bone implant. The amino groups from the plasma bond with the surface of the printed layers. This enables bone cells to adhere to a “convenient substrate.”
The process could be used as an alternative to conventional surface treatments which often use low-pressure or atmospheric pressure methods that result in a limited penetration of the cell-growth-promoting coating to the implants.
Notably, the 3D printing and plasma jet coating process are combined into a single machine, making it relatively straightforward to use. Additionally, the researchers say the process does not require any chemical pretreatment, making it environmentally friendly.
Looking more closely at the 3D printing technology used in the process, we see that the bone implants are made up of a copolymer scaffold. The material used was developed to mimic bone closely and the print process offers the ability to create tailored, highly precise implants.
Dr. Jochen Borris, the head of the Life Science and Ecology business unit at Fraunhoger IST, commented: “Our goal is for the bone cells to grow into the synthetic structure as quickly as possible and finally replacing the implant which is broken down gradually by the body’s own enzymes.”
The process can be further customized by adding special fillers to the printed copolymer. That is, by adding a higher filler concentration, the researchers achieved a higher stability for the implant scaffold. Ingredients such as antibiotics can also be added to the filler to reduce risk of infection when implanted.
“This development by our project partners from Maastricht University makes it possible to individually vary the stability inside the implant,” added Fr. Thomas Neubert, manager of the EU project at Fraunhofer IST. “Like natural bones, implants can now have areas with different strengths.”
Presently, the researchers and their partners from outside the Fraunhofer Institute are working on improving the implant printing process to bring it to maturity. At this stage, the team says the technology is still experimental and limited within a laboratory setting.
“We’re currently working on simplifying the process and making it more stable,” Dr. Borris elaborated. “To be able to further pursue development and carry out clinical studies, we’re on the search for industrial partners. With our method, we’re able to control the shape, porosity, mechanical stability and biomechanical characteristics well and vary them within the implants. This means that we can produce areas with different strengths or porosities, which can also be coated with various functional groups.”
Ultimately, the plasma jet 3D printing process could enable doctors to produce patient-specific bone implants with superior fits and bone regeneration potential.
The eight project partners for the innovative research project include: Abalonyx AS, Norway; Fraunhofer Institute for Surface Engineering and Thin Films IST, Germany; Fundacion Tecnalia Research & Innovation, Spain; GeSIM Gesellschaft für Silizium-Mikrosysteme mbH, Germany; Maastricht University, The Netherlands; Polyvation BV, The Netherlands; Prolabin & Tefarm S. r. l., Italy; and University of Padova, Italy.