A multifaceted biomimetic interface to improve the longevity of orthopedic implants

Michiel Croes; Behnam Akhavan; Omid Sharifahmadian; Haiyang Fan; Raya Mertens; Richard P Tan; Aliza Chunara; Arifah A Fadzil; Steven G Wise; Moyo C Kruyt; Sebastiaan Wijdicks; Wim E Hennink; Marcela M M Bilek; Saber Amin Yavari

doi:10.1016/j.actbio.2020.04.020

A multifaceted biomimetic interface to improve the longevity of orthopedic implants

Acta Biomater. 2020 Jul 1:110:266-279. doi: 10.1016/j.actbio.2020.04.020. Epub 2020 Apr 25.

Authors

Affiliations

¹ Department of Orthopedics, University Medical Center Utrecht, Utrecht 3508GA, the Netherlands.
² School of Biomedical Engineering, University of Sydney, Sydney, NSW 2006, Australia; School of Physics, University of Sydney, Sydney, New South Wales 2006, Australia. Electronic address: behnam.akhavan@sydney.edu.au.
³ School of Physics, University of Sydney, Sydney, New South Wales 2006, Australia.
⁴ PMA, Department of Mechanical Engineering, KU Leuven & Member of Flanders Make, Celestijnenlaan 300, Leuven B-3001, Belgium.
⁵ School of Medical Sciences, Dept of Phsyiology, University of Sydney, NSW 2006, Australia; Charles Perkins Centre, University of Sydney, Sydney, New South Wales 2006, Australia.
⁶ School of Biomedical Engineering, University of Sydney, Sydney, NSW 2006, Australia; School of Physics, University of Sydney, Sydney, New South Wales 2006, Australia.
⁷ Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences (UIPS), Utrecht University, Utrecht 3512JE, the Netherlands.
⁸ School of Biomedical Engineering, University of Sydney, Sydney, NSW 2006, Australia; School of Physics, University of Sydney, Sydney, New South Wales 2006, Australia; Charles Perkins Centre, University of Sydney, Sydney, New South Wales 2006, Australia; Sydney Nano Institute, University of Sydney, Sydney, New South Wales 2006, Australia.

PMID: 32344174
DOI: 10.1016/j.actbio.2020.04.020

Abstract

The rise of additive manufacturing has provided a paradigm shift in the fabrication of precise, patient-specific implants that replicate the physical properties of native bone. However, eliciting an optimal biological response from such materials for rapid bone integration remains a challenge. Here we propose for the first time a one-step ion-assisted plasma polymerization process to create bio-functional 3D printed titanium (Ti) implants that offer rapid bone integration. Using selective laser melting, porous Ti implants with enhanced bone-mimicking mechanical properties were fabricated. The implants were functionalized uniformly with a highly reactive, radical-rich polymeric coating generated using a unique combination of plasma polymerization and plasma immersion ion implantation. We demonstrated the performance of such activated Ti implants with a focus on the coating's homogeneity, stability, and biological functionality. It was shown that the optimized coating was highly robust and possessed superb physico-chemical stability in a corrosive physiological solution. The plasma activated coating was cytocompatible and non-immunogenic; and through its high reactivity, it allowed for easy, one-step covalent immobilization of functional biomolecules in the absence of solvents or chemicals. The activated Ti implants bio-functionalized with bone morphogenetic protein 2 (BMP-2) showed a reduced protein desorption and a more sustained osteoblast response both in vitro and in vivo compared to implants modified through conventional physisorption of BMP-2. The versatile new approach presented here will enable the development of bio-functionalized additively manufactured implants that are patient-specific and offer improved integration with host tissue. STATEMENT OF SIGNIFICANCE: Additive manufacturing has revolutionized the fabrication of patient-specific orthopedic implants. Although such 3D printed implants can show desirable mechanical and mass transport properties, they often require surface bio-functionalities to enable control over the biological response. Surface covalent immobilization of bioactive molecules is a viable approach to achieve this. Here we report the development of additively manufactured titanium implants that precisely replicate the physical properties of native bone and are bio-functionalized in a simple, reagent-free step. Our results show that covalent attachment of bone-related growth factors through ion-assisted plasma polymerized interlayers circumvents their desorption in physiological solution and significantly improves the bone induction by the implants both in vitro and in vivo.

Keywords: Bone integration; Bone morphogenetic proteins; Metal 3D printing; Multi-functional biomaterials; Plasma polymer films; Scaffolds.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Biomimetics*
Humans
Osteoblasts
Porosity
Prostheses and Implants*
Titanium / pharmacology

Substances

Titanium