Plasma ion implantation enabled bio-functionalization of PEEK improves osteoblastic activity

Abstract

Slow appositional growth of bone in vivo is a major problem associated with polyether ether ketone (PEEK) based orthopaedic implants. Early stage promotion of osteoblast activity, particularly bone nodule formation, would help to improve contact between PEEK implantable materials and the surrounding bone tissue. To improve interactions with bone cells, we explored here the use of plasma immersion ion implantation (PIII) treatment of PEEK to covalently immobilize biomolecules to the surface. In this study, a single step process was used to covalently immobilize tropoelastin on the surface of PIII modified PEEK through reactions with radicals generated by the treatment. Improved bioactivity was observed using the human osteoblast-like cell line, SAOS-2. Cells on surfaces that were PIII-treated or tropoelastin-coated exhibited improved attachment, spreading, proliferation, and bone nodule formation compared to cells on untreated samples. Surfaces that were both PIII-treated and tropoelastin-coated triggered the most favorable osteoblast-like responses. Surface treatment or tropoelastin coating did not alter alkaline phosphatase gene expression and activity of bound cells but did influence the expression of other bone markers including osteocalcin, osteonectin, and collagen I. We conclude that the surface modification of PEEK improves osteoblast interactions, particularly with respect to bone apposition, and enhances the orthopedic utility of PEEK.

Bioinspired Modifications of PEEK Implants for Bone Tissue Engineering

“…Functionalizing cell-interfacing surfaces with cell-modulatory proteins can also improve the biological properties of the implant. For example, the ECM protein tropoelastin has been shown to promote the biological behavior of human osteoblast-like osteosarcoma cells (SAOS-2) on PEEK via plasma immersion ion implantation (PIII) treatment (Wakelin et al, 2018 ). Adiponectin (APN), which is adipocyte-secreted adipokine, has been confirmed to increase the osteogenic ability in vitro and osseointegration in vivo of sPEEK implants (Wang et al, 2019 ; Deng et al, 2020 ).…”

Plasma ion implantation of 3D‐printed PEEK creates optimal host conditions for bone ongrowth and mineralisation

“…[14] Some of the performance deficits may arise from the relatively low surface energy of PEEK that makes it more hydrophobic than titanium, other metals and other polymers. [17] A range of modifications of PEEK has been examined, including wet chemistry, plasma treatments, coating or blending with biomaterials known for their osteoconductive properties, such as titanium and hydroxyapatite. [13,18] Plasma immersion ion implantation (PIII) is a form of plasma treatment that imparts significantly more energy to the ions bombarding the surface than conventional plasma treatments and implants them at depth in the treated material.…”

“…PIII can modify the flat surface of commercially available PEEK sheets to promote bone cell adhesion and spread. [17] It has been shown that the high energy of ion bombardment available in PIII allows covalent binding to take place when an initially adsorbed molecule reacts with a radical diffusing to the surface, as shown for tropoelastin to PEEK. [17,21] Covalency of protein binding to PIII-treated PEEK has been demonstrated by the resistance to attempted removal of the bound protein with a detergent solution containing 5% sodium dodecyl sulphate at 80°C for 10 min.…”

“…However, certain restrictions for highly hydrophobic surfaces apply. [17,[22][23][24] Recently, 3D-printing methods such as fused filament deposition modelling and selective laser sintering (SLS) offer reduced cost and increased fabrication speed over traditional subtractive machining methods, and they enable the implant to be readily customised for individual patients using their computed tomography scan data. 3D printing offers a greater range of possible structures including porous scaffolds, many of which are unavailable using traditional subtractive machining.…”

Interfacial Nanostructure of 2D Ti3C2/Graphene Quantum Dots Hybrid Multicoating for Ultralow Wear

“…Generally, polymer materials are divided into universal polymer (such as polypropylene and polymethyl methacrylate), engineering polymer (such as polyamide 66 and polyformaldehyde), and special polymer (such as polyetheretherketone and polytetrafluoroethylene [PTFE]). Polypropylene, polymethyl methacrylate, polyamide 66, polyformaldehyde, polyetheretherketone, and PTFE all have brilliant tribological performances for applications. Hence, the polymer bearing balls might be suitable for tribological applications due to their excellent tribological nature.…”