Polyetheretherketone Surface Research Articles

Effects of Surface Topography and Chemistry on Polyether-Ether-Ketone (PEEK) and Titanium Osseointegration.

An in vivo study examining the functional osseointegration of smooth, rough, and porous surface topographies presenting polyether-ether-ketone (PEEK) or titanium surface chemistry. To investigate the effects of surface topography and surface chemistry on implant osseointegration. Interbody fusion devices have been used for decades to facilitate fusion across the disc space, yet debate continues over their optimal surface topography and chemistry. Though both factors influence osseointegration, the relative effects of each are not fully understood. Smooth, rough, and porous implants presenting either a PEEK or titanium surface chemistry were implanted into the proximal tibial metaphyses of 36 skeletally mature male Sprague Dawley rats. At 8 weeks, animals were euthanized and bone-implant interfaces were subjected to micro-computed tomography analysis (n = 12), histology (n = 4), and biomechanical pullout testing (n = 8) to assess functional osseointegration and implant fixation. Micro-computed tomography analysis demonstrated that bone ingrowth was 38.9 ± 2.8% for porous PEEK and 30.7 ± 3.3% for porous titanium (P = 0.07). No differences in fixation strength were detected between porous PEEK and porous titanium despite titanium surfaces exhibiting an overall increase in bone-implant contact compared with PEEK (P < 0.01). Porous surfaces exhibited increased fixation strength compared with smooth and rough surfaces regardless of surface chemistry (P < 0.05). Across all groups both surface topography and chemistry had a significant overall effect on fixation strength (P < 0.05), but topography accounted for 65.3% of the total variance (ω = 0.65), whereas surface chemistry accounted for 5.9% (ω = 0.06). The effect of surface topography (specifically porosity) dominated the effect of surface chemistry in this study and could lead to further improvements in orthopedic device design. The poor osseointegration of existing smooth PEEK implants may be linked more to their smooth surface topography rather than their material composition. N/A.

ASSESSMENT OF VARIOUS SURFACE TREATMENTS ON PULL OFF OF POLYETHERETHERKETONE ANTERIOR CROWN

ABSTRACT Objectives: to assess the pull off of Polyetheretherketone (PEEK) anterior crown after various surface treatments. Materials& Methods: Twenty Polyetheretherketone (PEEK) full coverage crown were constructed on prepared human maxillary central incisors. All of the crowns (n=20) were divided into four groups according to the surface treatment used group I ) Control , 2) 98% Sulphric acid, 3) 9.5% Hydrofluoric acid (HF ) 4) Air Abrasion with 50 μm AL2 O3 .( n=5 in each ) Afterwards, each crown specimens were cementeded to corresponding abutments using self-adhesive resin cement RelyX U200. Then, subjected to thermo cycling (5°C - 55°C,5000 cycles,). A universal testing machine was used to assess pull-off test. Data were collected, tabulated and statistically evaluated. Results: The mean pull off values were ranked as follows: group II (253.81±7.67 N) > group IV (221.18±3.91N) ≥ group III (203.20±8.23N) > group I (135.91±9.92N). The highest and lowest Pull off values was obtained in group II (253.81±7.67 N) and group I (135.91±9.92N), respectively. Conclusions: 98% sulphric acid PEEK surface treatment is recommended to achieve high retentive strength.

Enhanced osteogenic activities of polyetheretherketone surface modified by poly(sodium p‐styrene sulfonate) via ultraviolet‐induced polymerization

AbstractPolyetheretherketone (PEEK) is a promising bone and dental tissue engineering material with excellent mechanical properties and biocompatibility, but its biological inertness deficiency limits its clinical applications. In this study, poly(sodium p‐styrene sulfonate) (pNaSS) was grafted onto PEEK surface by ultraviolet (UV) induced polymerization to enhance its osteogenic activities. Attenuated total reflectance Fourier transformed Infrared (ATR‐FTIR) spectroscopy, scanning electron microscopy (SEM), and contact angle (CA) analysis were carried out to prove the success of grafting polymerization. Toluidine blue O (TBO) colorimetric assay was utilized to quantify the graft amounts of pNaSS. Results showed that the amounts of grafted pNaSS on the PEEK surface could be well‐controlled from 0.59 ± 0.07 mmol/cm2 to 5.08 ± 0.20 mmol/cm2, through adjusting the UV irradiation time and monomer concentration. The hydrophilicity of PEEK surface was increased and the in vitro mineralization ability was promoted with the introduction of pNaSS. Besides, this surface modification method did not influence the intrinsic mechanical properties of PEEK. in vitro biological studies revealed that cell adhesion, proliferation, and osteogenic differentiation of MC3T3‐E1 cells were enhanced with the increase of graft amounts.

In vitro study of surface alterations to polyetheretherketone and titanium and their effect upon human gingival fibroblasts

Statement of problemSoft-tissue attachment to different surfaces may play a pivotal role in the long-term success of dental implants. However, studies on the issue, especially on newer materials, are sparse. PurposeThe purpose of this in vitro study was to evaluate the viability and adhesion of human gingival fibroblasts (HGFs) on different implant abutment materials with specific surface modifications. Material and methodsOne hundred and fifty specimens in 6 experimental groups were evaluated: smooth-machined titanium alloy (Ti), laser-modified titanium (TiL), smooth-machined polyetheretherketone (PEEK) (P), laser-modified PEEK (PL), plasma-treated PEEK (PP), laser- and plasma-treated PEEK (PLP). Machined Ti was considered as the control group. Surface roughness (Sa), water contact angle (WCA), and X-ray photoelectron spectroscopy (XPS) were measured. HGF attachment and proliferation were observed at 1, 3, and 7 days after cell seeding. Comparison of the means among the groups was performed with 1-way analysis of variance (ANOVA) with post hoc comparison using the Tukey test (α=.05). ResultsSa values of the laser modified groups were significantly higher than those of the nonmodified (smooth-machined) groups (P<.001). WCAs were significantly different among PEEK groups, and plasma-sprayed groups had the lowest WCAs. XPS analysis of both Ti and PEEK groups showed laser treatment did not have any significant effect on the surface composition of the PEEK as the same bonds with similar ratio/fraction were detected in the spectrum of the modified specimens. Scanning electron microscopy (SEM) revealed more functionally oriented HGF cells on the laser-grooved surfaces. On the first, third, and seventh day of proliferation, the titanium groups showed no significant differences (P>.05). On the first and third days of proliferation, the plasma sprayed groups (PP, PLP) showed significantly greater proliferation than all experimental groups (P<.001). On the seventh day of proliferation, statistically significant differences were observed between all PEEK groups and between all PEEK groups and the Ti group (P<.001), with the exception of the PL and P groups and the PLP and Ti groups (P>.05). ConclusionsLaser-modified titanium and PEEK surfaces led to guided gingival fibroblast attachment. Plasma treatment of PEEK surfaces increased the wettability of this polymer and improved proliferation of HGF.

Streamer characteristics of PEEK surface in nitrogen driven by positive repetitive pulse voltage

In this work, we present a detailed analysis on the observed streamer characteristics of PEEK (polyetheretherketone) surface in nitrogen at atmospheric pressure driven by positive repetitive pulse voltage, including the forward discharge streamer and the back discharge streamer. Fast oscilloscopic technique and digital photographic technique were employed to observe the streamers of surface discharges, and current pulse waveform analysis technique and image analysis technique were used to analyze the characteristics of the observed streamers. The experimental results show that the current pulse of forward discharge streamer has a shorter rise time, a higher current amplitude, a faster current rising rate, a shorter fall time, a faster current falling rate and a smaller charge quantity than those of back discharge streamer at the same voltage amplitude. Besides, the forward discharge streamer has a longer stopping length, a faster propagation velocity and a stronger maximum light intensity than back discharge streamer at the same voltage amplitude. Furthermore, the correlation between the electrical characteristics and optical characteristics of the streamer was analytically derivated, and the current rising rate of the streamer is proportionally correlated to the product of the streamer stopping length and the streamer velocity square.

PEEK surface modification methods and effect of the laser method on surface properties

Polyether ether ketone (PEEK) is one the most interesting polymeric materials used in the industry today, such as aerospace, nuclear reactors, polymer electrolyte membranes and especially in biomedical applications like bone implants. PEEK’s desirable properties like mechanical strength, biocompatibility, chemical resistance, radiation resistance and high thermal stability in the body make this suitable polymer choice for a bone implant. Besides these useful properties, PEEK is bio-inert in the biological environment, which is a big problem in implant application. Fortunately, there are several methods to improve the surface bioactivity of such materials. Here surface modification methods of the PEEK, including laser and their effect on the surface bioactivity were studied. Laser techniques are one of the exciting methods for PEEK surface modification because of being a secure processing method, time-consuming, easy to control the laser parameter, which leads to the control of surface properties. Several kinds of laser with different settings is used for the enhancement of the surface of PEEK, were described here. Here different surface modification techniques to enhance the adhesion and wettability of the PEEK surface studied. Along with varying categories of laser were introduced and different laser methods, which used for PEEK surface treatment is collected, that is the exciting point of this review paper.

Comparison of the Bond Strength of Composite Resin to Zirconia and Composite Resin to Polyether Ether Ketone: An In Vitro Study.

ABSTRACTAim:The aim of the study was to compare the shear bond strength of composite resin bonded to polyether ether ketone (PEEK) and zirconia, and also to evaluate the effect of thermocycling on the shear bond strength.Materials and Methods:A total of 22 zirconia (Group 1) and 22 PEEK (Group 2) specimens (disks of 10 mm in diameter and 10 mm in thickness) were machine milled using computer-aided design (CAD)/computer-aided manufacturing (CAM) from commercially available zirconia and PEEK. These specimens were air abraded with 110-μm aluminum oxide. Following which these two groups were subdivided into four groups, that is, Group 1A: 11 zirconia specimens before thermocycling, Group 1B: 11 zirconia specimens after thermocycling, Group 2A: 11 PEEK specimens before thermocycling, and Group 2B: 11 PEEK specimens after thermocycling. These four groups of specimens were embedded in an acrylic block, and bonding agent was applied over the upper surfaces of the disks of each of these specimens. Composite resin was then cured, and then Group 1B and group 2B were thermocycled under a standard temperature. The bond strength of the specimen was tested using universal testing machine.Result:The result showed that there was no significant difference in shear bond strength between the groups, although higher shear bond strength was observed in the PEEK group.Conclusion:Shear bond strength of PEEK is similar to zirconia. The results suggest that the pretreatment method and primers used were effective in improving the bonding of resin cements to zirconia ceramic and the bonding properties of the veneering resin to the PEEK surface.

Surface sulfonation and nitrification enhance the biological activity and osteogenesis of polyetheretherketone by forming an irregular nano-porous monolayer.

Polyether-ether-ketone (PEEK) is becoming a popular component of clinical spinal and orthopedic applications, but its practical use suffers from several limitations. In this study, irregular nano-porous monolayer with differently functional groups was formed on the surface of PEEK through sulfonation and nitrification. The surface characteristics were detected by field-emission scanning electron microscopy, atomic force microscopy, energy-dispersive X-ray spectrometry, water contact angle measurements and Fourier transform infrared spectroscopy. In vitro cellular behaviors were evaluated by cell adhesion, morphological changes, proliferation, alkalinity, phosphatase activity, real-time RT-PCR and western blot analyses. In vivo osseointegration was examined through micro-CT and histological assessments. Our results reveal that the irregular nano-porous of PEEK affect the biological properties. High-temperature hydrothermal NP treatment induced early osteogenic differentiation and early osteogenesis. Modification by sulfonation and nitrification can broaden the use of PEEK in orthopedic and dental applications. This study provides a theoretical basis for the wider clinical application of PEEK. a To obtain a uniform porous structure, PEEK samples were treated by concentrated sulfuric acid and fuming nitric acid (82-80%) with magnetic stirring sequentially. b Effects of nanopores on biological behavior of bMSCS.

Preparation and Biocompatibility of Polydopamine Modified Porous Polyetheretherketone Implants

Polyetheretherketone (PEEK), as a new polymer biomaterial, became a potential candidate for orthopedic and dental implant, however its application was limited by bioinert surface. The surface modification method had achieved remarkable results in improving the bioactivity of the implant surface. In this work, PEEK was firstly etched by sulfuric acid of different time and then the optimal group was modified with polydopamine coating. All the specimens including the control group were characterized by scanning electron microscopy (SEM), contact angle goniometer and X-ray photoelectron spectrometer (XPS). As a result, the surface of PEEK was corroded by sulfuric acid to obtain a relatively stable porous structure at 6 minutes and polydopamine coating significantly reduced the surface contact angle. In subsequent biocompatibility study, the non-toxicity and the promotion of cell adhesion and proliferation of the modified PEEK-based substrates were verified by MC3T3 cells, laying a foundation for the wider application of PEEK in medical implantation.

Tuning the surface immunomodulatory functions of polyetheretherketone for enhanced osseointegration

The adverse macrophage-mediated immune response elicited by the surface of polyetheretherketone (PEEK) is responsible for the formation of fibrous encapsulation and resulting inferior osseointegration of PEEK implants in the dental and orthopedic fields. Therefore, endowing the PEEK surface with immunomodulatory ability is an appealing strategy to enhance implant-bone integration. Herein, a reliable and cost-effective method to construct adherent films with tunable nanoporous structures on PEEK is described. The functionalized surface not only suppresses the acute inflammatory response of macrophages, but also provides a favorable milieu for osteogenic differentiation of human bone marrow mesenchymal stem cells (hBMSCs). Whole genome expression analysis reveals that the suppression effect arises from synergistic inhibition of focal adhesion, Toll-like receptor, and NOD-like receptor signaling pathways, as well as the attenuating loop through the JAK-STAT and TNF signaling pathways in macrophages. Further in vivo studies confirm that the functionalized surface induces less fibrous capsule formation and an improved bone regeneration. The nanoporous films fabricated on PEEK harmonize the early macrophage-mediated inflammatory response and subsequent hBMSCs-centered osteogenic functions consequently yielding superior osseointegration.

Effect of nitrogen plasma treatment on the crystallinity and self-bonding of polyetheretherketone (PEEK) for biomedical applications.

Polyetheretherketone (PEEK) is a thermoplastic material with outstanding properties and high potential for biomedical applications, including hermetic encapsulation of active implantable devices. Different biomedical grade PEEK films with initial degree of crystallinity ranging from 8% to 32% (with or without mineral filling) were inspected. PEEK surfaces were treated with nitrogen RF plasma and the effects on materials crystallinity and self‐bonding were evaluated. In particular, the relationship between auto‐adhesive properties and crystalline content of PEEK before and after plasma treatment was examined.PEEK samples showed different bonding strength depending on their degree of crystallinity, with higher self‐bonding performance of mineral‐filled semi‐crystalline films. XRD did not show any modification of the PEEK microstructure as a result of plasma treatment, excluding a significant influence of crystallinity on the self‐bonding mechanisms. Nevertheless, plasma surface treatment successfully improved the self‐bonding strength of all the PEEK films tested, with larger increase in the case of semi‐crystalline unfilled materials. This could be interpreted to the increase in chain mobility that led to interfacial interpenetration of the amorphous phase.

Investigation on gas plasma and liquid plasma treatment for polyether ether ketone (PEEK) surface for wettability enhancement

The results of liquid and gas plasma treatment on polyether ether ketone PEEK surfaces are reported. The experiments were conducted by using variation of treatment time (5 s to 60 s) using Helium as its working gas. The results were obtained by measuring the water contact angle (WCA) and the studying the surface morphology of the PEEK surface. Comparisons of WCA and Scanning Electron Microscopy (SEM) analysis were conducted for samples which undergone gas plasma treatment and liquid plasma treatment. After gas plasma treatment, WCA of the PEEK surface decreased from 65° to 21°. Results of WCA for liquid plasma treatment showed decrement from 65° to 45°. Images from SEM showed PEEK surface area after gas and liquid plasma showed surface area increment of 40% for gas plasma and 20% for liquid plasma. The decrement of WCA and increment of surface area showed that PEEK surface properties changed from hydrophobic to hydrophilic via wettability enhancement.

Adhesion Behaviour of Primary Human Osteoblasts and Fibroblasts on Polyether Ether Ketone Compared with Titanium under In Vitro Lipopolysaccharide Incubation.

The aim of this in vitro pilot study was to analyse the adhesion behaviour of human osteoblasts and fibroblasts on polyether ether ketone (PEEK) when compared with titanium surfaces in an inflammatory environment under lipopolysaccharide (LPS) incubation. Scanning electron microscopy (SEM) images of primary human osteoblasts/fibroblasts on titanium/PEEK samples were created. The gene expression of the LPS-binding protein (LBP) and the LPS receptor (toll-like receptor 4; TLR4) was measured by real-time polymerase chain reaction (PCR). Immunocytochemistry was used to obtain evidence for the distribution of LBP/TLR4 at the protein level of the extra-cellular-matrix-binding protein vinculin and the actin cytoskeleton. SEM images revealed that the osteoblasts and fibroblasts on the PEEK surfaces had adhesion characteristics comparable to those of titanium. The osteoblasts contracted under LPS incubation and a significantly increased LBP gene expression were detected. This was discernible at the protein level on all the materials. Whereas no increase of TLR4 was detected with regard to mRNA concentrations, a considerable increase in the antibody reaction was detected on all the materials. As is the case with titanium, the colonisation of human osteoblasts and fibroblasts on PEEK samples is possible under pro-inflammatory environmental conditions and the cellular inflammation behaviour towards PEEK is lower than that of titanium.

Effect of Surface Treatments on Shear Bond Strength of Polyetheretherketone to Autopolymerizing Resin.

These days, new prosthodontic materials are appearing with the development of digitalization. Among these, the use of polyetheretherketone (PEEK) as the clasp of removable partial dentures has been proposed. The adhesive strength between the PEEK and acrylic resin influences the probability of denture fracture. To investigate the effect of PEEK surface treatments on the shear bond strength to acrylic resin, five surface treatment conditions of PEEK were analyzed: 1. no treatment; 2. ceramic primer application; 3. Al2O3 sandblasting; 4. Rocatec; and 5. Rocatec with ceramic primer application, comparing with a metal primer-treated Co-Cr alloy. Two kinds of autopolymerizing resin (Unifast II and Palapress Vario) were used as bonding materials. The specimens were evaluated to determine the bond strength. Rocatec treatment with ceramic primer application yielded the highest bond strengths (12.71 MPa and 15.32 MPa, respectively, for Unifast II and Palapress Vario). When compared to a metal primer-treated Co-Cr alloy, the bond strength of PEEK to Unifast II was similar, whereas it was about 60% of that to Palapress Vario. Rocatec treatment, combined with ceramic primer, showed the highest bond strength of PEEK to acrylic resin. Treatment of PEEK will enable its use as the clasp of removable dentures and the fixation of PEEK prostheses.

Osteoblast/bone-tissue responses to porous surface of polyetheretherketone-nanoporous lithium-doped magnesium silicate blends' integration with polyetheretherketone.

The porous surface of a polyetheretherketone (PK)–nanoporous lithium-doped magnesium silicate (NLS) blend (PKNLS) was fabricated on a PK surface by layer-by-layer pressuring, sintering, and salt-leaching. As controls, porous surfaces of a PK/lithium-doped magnesium silicate blend (PKLS) and PK were fabricated using the same method. The results revealed that porosity, water absorption, and protein absorption of the porous surface of PKNLS containing macropores and nanopores were obviously enhanced compared to PKLS and PK containing macropores without nanopores. In addition, PKNLS, with both macroporostiy and nanoporosity, displayed the highest ability of apatite mineralization in simulated body liquid, indicating excellent bioactivity. In vitro responses (including adhesion, proliferation, and differentiation) of MC3T3E1 cells to PKNLS were significantly enhanced compared to PKLS and PK. In vivo implantation results showed that new bone grew into the macroporous surface of PKNLS, and the amount of new bone for PKNLS was the highest. In short, PKNLS integration with PK significantly promoted cells/bone-tissue responses and exhibited excellent osteogenesis in vivo, which might have great potential for bone repair.

An In Vitro Study of Osteoblast Response on Fused-Filament Fabrication 3D Printed PEEK for Dental and Cranio-Maxillofacial Implants.

Polyetheretherketone (PEEK) is a prime candidate to replace metallic implants and prostheses in orthopedic, spine and cranio-maxillofacial surgeries. Fused-filament fabrication (FFF) is an economical and efficient three-dimensional (3D) printing method to fabricate PEEK implants. However, studies pertaining to the bioactivity of FFF 3D printed PEEK are still lacking. In this study, FFF 3D printed PEEK samples were fabricated and modified with polishing and grit-blasting (three alumina sizes: 50, 120, and 250 µm) to achieve varying levels of surface roughness. In vitro cellular response of a human osteosarcoma cell line (SAOS-2 osteoblasts, cell adhesion, metabolic activity, and proliferation) on different sample surfaces of untreated, polished, and grit-blasted PEEK were evaluated. The results revealed that the initial cell adhesion on different sample surfaces was similar. However, after 5 days the untreated FFF 3D printed PEEK surfaces exhibited a significant increase in cell metabolic activity and proliferation with a higher density of osteoblasts compared with the polished and grit-blasted groups (p < 0.05). Therefore, untreated FFF 3D printed PEEK with high surface roughness and optimal printing structures might have great potential as an appropriate alloplastic biomaterial for reconstructive cranio-maxillofacial surgeries.

Triple-functional polyetheretherketone surface with enhanced bacteriostasis and anti-inflammatory and osseointegrative properties for implant application

Polyetheretherketone (PEEK) is considered a potential orthopedic/dental material because of its excellent mechanical and chemical properties (e.g., similar elastic modulus to that of human bone). However, the poor bacteriostasis and anti-inflammatory and osseointegrative properties of bioinert PEEK impede its clinical application. We previously developed a facile and versatile surface modification method using dexamethasone plus minocycline-loaded liposomes (Dex/Mino liposomes) bonded by a mussel-inspired polydopamine coating, which effectively modulated cell inflammatory response and discouraged bacterial colonization in vitro. Herein, we report the application of this multifunctional surface modification method to improve bioinert PEEK, aimed at further studying the in vitro osteogenesis and in vivo properties of Dex/Mino liposome-modified PEEK to prevent bacterial contamination, attenuate the inflammatory response, and enhance ossification for physiologic osseointegration. Our study established that the Dex/Mino liposome-modified PEEK surface presented favorable stability and cytocompatibility. Compared with bare PEEK, improved osteogenic differentiation of human mesenchymal stem cells under both osteoinductive and osteoconductive conditions was found on the functionalized surface due to the liposomal Dex releasing. In vivo bacteriostasis assay confirmed that Mino released from the functionalized surface provided an effective antibacterial effect. Moreover, the subcutaneous foreign body reaction and beagle femur implantation models corroborated the enhanced anti-inflammatory and osteointegrative properties of the functionalized PEEK. Our findings indicate that the developed Dex/Mino liposome-modified PEEK with enhanced antibacterial, anti-inflammatory, and osseointegrative capacity has great potential as an orthopedic/dental implant material for clinical application.

In Vitro Effect of Modified Polyetheretherketone (PEEK) Implant Abutments on Human Gingival Epithelial Keratinocytes Migration and Proliferation.

Improving soft tissue attachment to implant abutments is a crucial factor for enduring health and maintenance of soft peri-implant tissue health. In this in vitro study we aimed to compare the biocompatibility of three different abutment surfaces: titanium, zirconia and modified polyetheretherketone (PEEK). Surface topography, roughness and wettability were investigated with scanning electron microscopy, profilometer and contact angle meter, respectively. Human gingival epithelial keratinocytes were examined for viability, morphology, proliferation and migration by using tetrazolium salt colorimetric assay, scanning electron microscopy imaging, immunofluorescence bromodeoxyuridine analysis and scratch wound healing assays. Roughness measurements revealed differences between the investigated surfaces. Keratinocytes cultured on all examined surfaces indicated adhesion and attachment by means of scanning electron microscopy imaging. Cell viability assays showed no significant differences between the groups (p > 0.05). The modified PEEK surface similarly improved surface roughness in comparison to titanium and zirconia, which resulted in greater and equivalent cell proliferation and migration. The study methodology showed here may emphasize the importance of cell interactions with different abutment materials, which in part increases the changes of implant success. PEEK, titanium and zirconia surface types used in this study showed mostly similar epithelial biological responses.

Silicon nitride enhances osteoprogenitor cell growth and differentiation via increased surface energy and formation of amide and nanocrystalline HA for craniofacial reconstruction

The bioactive silicon nitride (Si3N4) has been FDA cleared for use as spinal intervertebral arthrodesis devices. Because its surface properties promote bone ongrowth and ingrowth, it also has the potential to benefit craniofacial reconstruction. Thus, the aim of this work was to determine whether the surface properties of Si3N4 could enhance the osteoblast cell growth, differentiation and nucleation of hydroxyapatite (HA) crystals compared to conventional implant materials such as titanium (Ti) and polyether ether ketone (PEEK). X-ray absorbance near-edge structure analysis (XANES) indicated the presence of Si-Si, Si-O and Si-N bonding. Surface wettability studies confirmed that Si3N4 exhibits the lowest contact angle and highest surface energy. Cell culture studies showed that osteoblast growth was enhanced on Si3N4 after 1 day and up to 7 days. Si3N4 surface induced highest surface coverage and thickness of nanocrystalline HA (211) and (203) in cell-free in vitro studies after 7 days of culture. Raman spectroscopy analysis confirmed the presence of surface functional groups consisting of phosphate and carbonate species. Interestingly, Si3N4 surface showed amide and hydroxyproline groups, the precursors to collagen, which were not observed on Ti and PEEK surfaces. Furthermore, Si3N4 surface indicated high expression of RUNX2, enhanced cell differentiation and dense collagenous ECM after 30 days of the in vitro study. The present study concluded that Si3N4 surface enhances osteoprogenitor cell adhesion, growth, RUNX2 expression and ECM formation via the coupled effects of higher surface energy and the presence of amide and nanocrystalline HA functional groups.

Wetting Properties of Polyetheretherketone Plasma Activated and Biocoated Surfaces

Polyetheretherketone (PEEK) biomaterial is a polymer which has been widely used since the early 90s as a material for human bone implant preparations. Nowadays it is increasingly used due to its high biocompatibility and easily modeling, as well as better mechanical properties and price compared to counterparts made of titanium or platinum alloys. In this paper, air low-temperature and pressure plasma was used to enhance PEEK adhesive properties as well as surface sterilization. On the activated polymeric carrier, biologically-active substances have been deposited with the Langmuir-Blodgett technique. Thereafter, the surface was characterized using optical profilometry, and wettability was examined by contact angle measuring. Next, the contact angle hysteresis (CAH) model was used to calculate the surface free energy of the modified surface of PEEK. The variations of wettability and surface free energy were observed depending on the deposited monolayer type and its components.