title: Surface phosphonation enhances hydroxyapatite coating adhesion on polyetheretherketone and its osseointegration potential.
abstract: Polyetheretherketone (PEEK) has excellent mechanical properties, biocompatibility, chemical resistance and radiolucency, making it suitable for use as orthopedic implants. However, its surface is hydrophobic and bioinert, and surface modification is required to improve its bioactivity. In this work, we showed that grafting phosphonate groups via diazonium chemistry enhances the bioactivity of PEEK. Decreased contact angle indicated reduced hydrophobicity as a result of the treatment and X-ray photoelectron spectroscopy (XPS) confirmed the attachment of phosphonate groups to the surface. The surface treatment not only accelerated hydroxyapatite (HA) deposition after immersion in simulated body fluid but also significantly increased the adhesion strength of HA particles on PEEK. MC3T3-E1 cell viability, metabolic activity and deposition of calcium-containing minerals were also enhanced by the phosphonation. After three months of implantation in a critical size calvarial defect model, a fibrous capsule surrounded untreated PEEK while no fibrous capsule was observed around the treated PEEK. Instead, mineral deposition was observed in the region between the treated PEEK implant and underlying bone. This work introduces a simple method to improve the potential of PEEK-based orthopedic implants.
  
  
  
  We have introduced phosphonate groups on the surface of PEEK substrates using diazonium chemistry. Our results show that the treatment not only increased the adhesion strength of hydroxyapatite particles deposited on PEEK in vitro by approximately 40% compared to unmodified PEEK, but also improved the metabolic activity and mineralization of MC3T3-E1 cells. When implanted in cranial defects in rats, the phosphonate coating enhanced the osseointegration of PEEK by successfully preventing the formation of a fibrous capsule and favoring mineral deposition between the implant and the surrounding bone. This work introduces a simple method to improve the potential of PEEK-based orthopedic implants, particularly those with complex shapes.
authors.affiliation: Materials Engineering, McGill University, Montreal, Quebec H3A 0C5, Canada.
authors.forename: Hesameddin
authors.initials: H
authors.lastname: Mahjoubi
authors.affiliation: Materials Engineering, McGill University, Montreal, Quebec H3A 0C5, Canada.
authors.forename: Emily
authors.initials: E
authors.lastname: Buck
authors.affiliation: Materials Engineering, McGill University, Montreal, Quebec H3A 0C5, Canada.
authors.forename: Praveena
authors.initials: P
authors.lastname: Manimunda
authors.affiliation: Department of Ophthalmology, McGill University, Montreal, Quebec H3A 1A1, Canada.
authors.forename: Reza
authors.initials: R
authors.lastname: Farivar
authors.affiliation: Materials Engineering, McGill University, Montreal, Quebec H3A 0C5, Canada.
authors.forename: Richard
authors.initials: R
authors.lastname: Chromik
authors.affiliation: Division of Experimental Medicine, Department of Medicine, McGill University, Montreal, Quebec H3G 1Y6, Canada.
authors.forename: Monzur
authors.initials: M
authors.lastname: Murshed
authors.affiliation: Materials Engineering, McGill University, Montreal, Quebec H3A 0C5, Canada. Electronic address: marta.cerruti@mcgill.ca.
authors.forename: Marta
authors.initials: M
authors.lastname: Cerruti
mesh_terms: D000818:Animals; D001577:Benzophenones; D001826:Body Fluids / Q000737:chemistry; D002448:Cell Adhesion; D002460:Cell Line; D020099:Coated Materials, Biocompatible / Q000737:chemistry*; D017886:Durapatite / Q000737:chemistry*; D007659:Ketones / Q000737:chemistry*; D051379:Mice; D016348:Osseointegration; D010757:Phosphorous Acids / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry*; D011108:Polymers; D017207:Rats, Sprague-Dawley; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties
chemical_list: D001577:Benzophenones; D020099:Coated Materials, Biocompatible; D007659:Ketones; D010757:Phosphorous Acids; D011108:Polymers; C570063:phosphonic acid; C063834:polyetheretherketone; D011092:Polyethylene Glycols; D017886:Durapatite
keywords: Adhesion strength; Biomineralization; Diazonium chemistry; In vivo osseointegration; PEEK