The Surface Characterisation of Fused Filament Fabricated (FFF) 3D Printed PEEK/Hydroxyapatite Composites.

Krzysztof Rodzeń,Preetam K. Sharma,Alistair McIlhagger,Adrian R. Boyd,Aoife McFerran,Jonathan G. Acheson,Mary Josephine McIvor,Joanna Ward,Mozaffar Mokhtari,Brian J. Meenan

doi:10.3390/polym13183117

Krzysztof Rodzeń, Preetam K. Sharma + Show 8 more

Open Access

https://doi.org/10.3390/polym13183117

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Journal: Polymers	Publication Date: Sep 15, 2021
Citations: 14	License type: CC BY 4.0

Affiliation: University of Ulster, Loughborough University

Abstract

Polyetheretherketone (PEEK) is a high-performance thermoplastic polymer which has found increasing application in orthopaedics and has shown a lot of promise for ‘made-to-measure’ implants via additive manufacturing approaches. However, PEEK is bioinert and needs to undergo surface modification to make it at least osteoconductive to ensure a more rapid, improved, and stable fixation that will last longer in vivo. One approach to solving this issue is to modify PEEK with bioactive agents such as hydroxyapatite (HA). The work reported in this study demonstrates the direct 3D printing of PEEK/HA composites of up to 30 weight percent (wt%) HA using a Fused Filament Fabrication (FFF) approach. The surface characteristics and in vitro properties of the composite materials were investigated. X-ray diffraction revealed the samples to be semi-crystalline in nature, with X-ray Photoelectron Spectroscopy and Time-of-Flight Secondary Ion Mass Spectrometry revealing HA materials were available in the uppermost surface of all the 3D printed samples. In vitro testing of the samples at 7 days demonstrated that the PEEK/HA composite surfaces supported the adherence and growth of viable U-2 OS osteoblast like cells. These results demonstrate that FFF can deliver bioactive HA on the surface of PEEK bio-composites in a one-step 3D printing process.

Highlights

There is increasing interest in the use of Polyetheretherketone (PEEK) in orthopaedic implant devices due to its excellent biocompatibility, its radiolucency, chemical resistance, sterilizability, ability to be processed, and its favourable mechanical properties [1,2]
A range of different bioactive agents have been studied as additives for PEEK based composites, namely the likes of hydroxyapatite [HA—Ca10 (PO4 )6 (OH)2 ], [13] strontium (Sr) substituted apatites [14], fluoro-hydroxyapatite [15], β-tricalcium phosphate [β-tissue culture plastic (TCP)
PEEK sample (0HA), several peaks were observed in the Fourier Transform Infrared Spectroscopy (FTIR) spectrum (Figure 2a), including the carbonyl stretching vibrational modes at 1655, 1485, 1415 cm−1, and a corresponding shoulder at 1252 cm−1

Summary

Introduction

There is increasing interest in the use of Polyetheretherketone (PEEK) in orthopaedic implant devices due to its excellent biocompatibility, its radiolucency, chemical resistance, sterilizability, ability to be processed, and its favourable mechanical properties (in comparison to human cortical bone) [1,2]. To date it has found applications in spinal fusions cages, dental implants, and maxillofacial reconstruction [1,3,4]. These different additives all offer obvious advantages when added to the PEEK matrix to create a composite material, the use of these materials could potentially alter bone homeostasis and depending on their concentration and scale (micro versus nanoparticles) they could prove toxic to osteoblasts and this needs to be considered when designing the composite material of choice [13,14,15,16,17,18,19,20]

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