Polyetheretherketone Substrate Research Articles

Biomedical Device Surface Treatment by Laser-Driven Hydroxyapatite Penetration-Synthesis Technique for Gapless PEEK-to-Bone Integration.

Polyetheretherketone (PEEK), a bioinert polymer known for its mechanical properties similar to bone, is capable of averting stress shielding. Due to these attributes, it finds applications in diverse fields like orthopedics, encompassing cervical disc replacement for the neck and spine, along with dentistry and plastic surgery. However, due to insufficient bonding with bone, various methods such as hydroxyapatite (HA) coating on the surface are attempted. Nonetheless, the interface between the polymer and ceramic, two different materials, tended to delaminate after transplantation, posing challenges in preventing implant escape or dislodgement. This research delves into the laser-driven hydroxyapatite penetration-synthesis technique. Differing from conventional coating methods that bond layers of dissimilar materials like HA and PEEK, this technology focuses on synthesizing and infiltrating ionized HA within the PEEK substrate resulting in an interface-free HA-PEEK surface. Conversely, HA-PEEK with this technology applied achieves complete, gap-free direct bone-implant integration. Our research involved the analysis of various aspects. By means of these, we quantitatively assesed the enhanced bone bonding characteristics of HA-PEEK surfaces treated with this approach and offered and explanation for the mechanism responsible for direct bone integration.

Wear-Resistant Low-friction Atmospheric Pressure Plasma Spray Coatings for Sustainable (Bio-based Recyclable) Materials

Coatings from polyetheretherketone (PEEK), polyamide 12 (PA12), molybdenumdisulfide (MoS2), zinc (Zn), and graphite (C) powder mixtures were deposited on PA6, PA12, and PEEK substrates by an atmospheric pressure plasma (APP) spray jet system. Several tenth of µm thick coatings on PA6 and PA12 substrates result in an almost halved surface roughness Ra ~8 µm, Rq ~10 µm and Rz ~60 µm, whereas a significant increase of all surface roughness parameters is observed for PEEK substrates (Ra < 1 µm → 4 µm, Rq < 1 µm → 5 µm, Rz < 5 µm → 20 µm). The surface roughness, powder composition, and selected APP process parameter strongly influence the coefficient of friction (COF) and specific wear rate ki of the APP coatings in rotational ball-on-disc tribological testing. The COF of PA12/MoS2/C coatings on PA6 substrates manufactured by selective laser sintering (SLS) is ~0.2 after 628 m sliding distance, resulting in a very low calculated ki of 6.3 × 10−7 mm3/Nm. A similarly low COF and ki was observed for PEEK coatings deposited at a current of 75 A and 60 mm jet–substrate distance on SLS PA12 substrate. Although the COF of Zn/C/MoS2 coatings on PEEK drops down below 0.1 after 1884 m sliding distance under nitrogen atmosphere the corresponding ki of 5.6 × 10−5 mm3/Nm is higher. Still all calculated specific wear rates are significantly lower than the reported values of polyamide-polytetrafluorethylene (PTFE)-polyethylene composites (1.9–8.0 × 10−2 mm3/Nm) and partly even outperform PEEK-PTFE composites (1.0 × 10−7–2.5 × 10−6), currently applied in demanding wear regimes.

An investigation of methods to enhance adhesion of conductive layer and dielectric substrate for additive manufacturing of electronics

Additive manufacturing of conductive layers on a dielectric substrate has garnered significant interest due to its promise to produce printed electronics efficiently and its capability to print on curved substrates. A considerable challenge encountered is the conductive layer’s potential peeling due to inadequate adhesion with the dielectric substrate, which compromises the durability and functionality of the electronics. This study strives to facilitate the binding force through dielectric substrate surface modification using concentrated sulfuric acid and ultraviolet (UV) laser treatment. First, polyetheretherketone (PEEK) and nanoparticle silver ink were employed as the studied material. Second, the surface treatment of PEEK substrates was conducted across six levels of sulfuric acid exposure time and eight levels of UV laser scanning velocity. Then, responses such as surface morphology, roughness, elemental composition, chemical bonding characteristics, water contact angle, and surface free energy (SFE) were assessed to understand the effects of these treatments. Finally, the nanoparticle silver ink layer was deposited on the PEEK surface, and the adhesion force measured using a pull-off adhesion tester. Results unveiled a binding force of 0.37 MPa on unmodified surface, which escalated to 1.99 MPa with sulfuric acid treatment and 2.21 MPa with UV laser treatment. Additionally, cross-approach treatment investigations revealed that application sequence significantly impacts results, increasing binding force to 2.77 MPa. The analysis further delves into the influence mechanism of the surface modification on the binding force, elucidating that UV laser and sulfuric acid surface treatment methods hold substantial promise for enhancing the binding force between heterogeneous materials in the additive manufacturing of electronics.

Enhancing interfacial bond strength between PEEK and inkjet-printed silver film through laser surface modification for additive manufacturing of electronics

Electronic 3D printing is a very promising technology, which is widely used in the manufacturing of conformal antennas, flexible electronics and sensors. Polyether ether ketone (PEEK) is one of the most popular substrate materials for electronic 3D printing due to its superior fatigue resistance, heat tolerance, chemical resistance, and mechanical properties. However, the deficient bond between the PEEK substrate and the conductive ink leads to the peeling and shedding of the conductive pattern. This paper investigated the enhancement of the bond strength between the PEEK substrate and the conductive layer through PEEK surface modification. A 355 nm ns solid-state laser was used to treat the PEEK surface with different values of laser scanning spacing (S) and spot overlap rate (R). The surface microstructure, surface roughness, wettability, and functional groups of the treated substrates have been measured. Then the nanoparticle silver ink was printed and cured on the treated substrate. After that, the bonding strength was measured using a pull-off adhesion tester. Results showed that regular grooves were generated and the content of active oxygen atoms was increased on the PEEK surface through laser modification. The mechanical interlocking between the grooves and silver particles and hydrogen bonds induced by the active oxygen atoms and the hydroxyl groups contribute to the enhancement of bond strength between PEEK and silver film. The bond strength for the laser treated PEEK reached the maximum of 1.9 MPa, which was 413.51% higher than that of the untreated PEEK. The laser modification can effectively enhance the interfacial bond strength for additive manufacturing of reliable electronics.

45S5/PEEK Coatings by Cold Gas Spray with In Vitro Bioactivity, Degradation, and Cellular Proliferation

This study evaluated the biological response of cold-sprayed coatings composed of bioactive glass 45S5 and polyetheretherketone (PEEK). The functional coatings were produced by cold gas spray (CGS) technology, a technique that allows the deposition of powders at significantly low temperatures, avoiding heat damage to polymeric surfaces. By CGS, blends with different ratios of bioactive glass and PEEK powders have been deposited onto PEEK substrates to improve the response of the bio-inert polymer. The bioactivity of the coatings when immersed in a simulated body fluid solution was evaluated by observation with scanning electron microscopy (SEM) and x-ray diffraction (XRD). Results verify that bioactive glass particles in the composite coatings enhance their bioactivity. A degradation test was performed with Tris–HCl solution. From the results obtained by inductively coupled plasma optical emission spectroscopy (ICP-OES) and the weight loss of the samples, it was noticed that the degradation was directly related to the amount of glass in the coatings. Finally, the ability of bone-forming cells to adhere and proliferate on the coatings was evaluated. These experiments showed that the presence of glass particles does not cause a significant increase in cell proliferation. Combining a bioactive material with PEEK leads to forming a final component that provides suitable bioactivity to the final implant.

Bioinspired Hard–Soft Composite Scaffold with Excellent Lubrication and Osteogenic Properties for the Treatment of Osteochondral Defect

AbstractNatural articular cartilage is a typical self‐healing and superlubrication system capable of maintaining extremely low friction under physiological loadings. Cartilage wear and accidental trauma can cause irreversible defects to cartilage and subchondral bone with a significant decrease in intra‐articular lubrication, leading to the development of severe osteoarthritis and osteochondral defect. To address the important clinical problem of osteochondral defect, a bioinspired hard–soft (PEEK‐lubrication hydrogel) composite scaffold is designed and developed. The polymerization of polyethylene glycol diacrylamide (PEGDAA) and 2‐methacryloyloxyethyl phosphorylcholine (MPC) on polyetheretherketone (PEEK) substrate is achieved by UV initiation to form a strong interfacial bonding, and nano‐hydroxyapatite is deposited on porous PEEK substrate via polydopamine coating to improve osteogenic capability. Accordingly, the composite scaffold is successfully developed with lubrication and osteogenic activity. The tribological tests show that the lubrication performance of the composite scaffold is based on the hydration lubrication mechanism of the upper hydrogel layer, and the in vitro and in vivo experiments demonstrate that the composite scaffold is endowed with excellent biocompatibility and bioactivity. In conclusion, the bioinspired strategy for preparing a hard–soft composite scaffold shows a promising way in the treatment of osteochondral defect and provided a guideline for designing functional PEEK‐based biomaterials in tissue engineering scaffolds.

MnFe2O4/graphene oxide modified PEEK with phototherapeutic and GPx-mimetic potential for anti-bacterial treatment

Polyetheretherketone (PEEK) as a promising orthopaedic alternative possesses excellent mechanical properties and biocompatibility. However, the scarcity of anti-pathogenic property limits its clinical application. In this work, the MnFe2O4/graphene oxide (MFO/GO) nanosheets were hydrothermally fabricated and further decorated on sulfonated PEEK (SP) substrate mediated by polydopamine for the preparation of SP-P-MFO/GO. The results show that the sample exhibits glutathione oxidase-mimetic activity, which can catalyze glutathione to oxidized glutathione for reactive oxide species accumulation to kill bacteria. Additionally, the favorable photothermal effect can generate a local hyperthermic microenvironment for enhancing bacterial inhibition. The antibacterial tests in vitro reveal that the SP-P-MFO/GO possesses about 99.99% bactericidal rate against both E. coli and S. aureus with near infrared laser irradiation. This work provides a potential strategy for the healing of bacteria-invaded bone tissue.

Oral microbial colonization on titanium and polyetheretherketone dental implant healing abutments: An in vitro and in vivo study

Although polyetheretherketone (PEEK) implant healing abutments have become popular because of their esthetic, mechanical, and chemical properties, studies analyzing oral polymicrobial adhesion to PEEK abutments are lacking. The purpose of this in vitro and in vivo study was to evaluate oral microbial adhesion and colonization on titanium (Ti) and PEEK healing abutments. Ti (N=35) and PEEK substrates (N=35) were evaluated in vitro in terms of the initial adhesion (1 hour) or biofilm accumulation (48 hours) of Candida albicans and a polymicrobial inoculum using stimulated human saliva to mimic a diverse oral microbiome. Surface decontamination ability was evaluated after 24 hours of in vitro biofilm formation after exposure to an erbium-doped yttrium aluminum garnet (Er:YAG) laser. Conventional and flowable composite resin veneering on PEEK was also tested for microbial adhesion. In addition, an in vivo model with 3 healthy volunteers was conducted by using a palatal appliance containing the tested materials (3 or 4 specimens of each material per appliance) for 2 days to evaluate the effect of substrate on the microbial profile. Biofilms were evaluated by live cell counts and scanning electron microscopy images, and the microbial profile by Checkerboard deoxyribonucleic acid (DNA)-DNA hybridization. The t test and Mann-Whitney test were used to compare the groups (α=.05). PEEK and Ti materials showed similar fungal adhesion (P>.05). Although the PEEK surface limited the initial in vitro polymicrobial adhesion (approximately 2 times less) compared with Ti (P=.040), after 48 hours of biofilm accumulation, the microbial load was statistically similar (P=.209). Er:YAG laser decontamination was more effective on PEEK than on Ti surfaces, reducing approximately 11 times more microbial accumulation (P=.019). Both composite resins tested showed similar microbial adhesion (1 hour). In vivo, the PEEK material showed reduced levels of 6 bacterial species (P<.05), including the putative pathogen Treponema denticola. Although PEEK and Ti had similar bacterial and fungus biofilm attachment and accumulation, PEEK promoted a host-compatible microbial profile with a significantly reduced T. denticola load.

Keratinocyte Proliferation and Hemidesmosome Formation on Surfaces for Dental Implants: In Vitro Study.

To demonstrate the likelihood of the polyetheretherketone (PEEK), zirconia (ZrO2), and titanium (Ti) disks to support proliferation and hemidesmosome formation of gingival cells. Water contact angle was performed on each material, and surface roughness (Ra) was measured. Scanning electron microscopy and x-ray photoelectron spectroscopy were used. Later, oral keratinocyte cells were cultured on disks, and metabolic activity and expression of hemidesmosome markers, integrin α6 and β4, in relation to the biomaterial disks at 1, 3, and 5 days of cell culture were quantified. Tissue culture polystyrene was used as the control. Statistical analysis was performed with analysis of variance (ANOVA) with Tukey post hoc comparison test. A P value of < .05 was considered statistically significant. The water contact angle ranged from 70.2 degrees (Ti) to a maximum of hydrophobicity of 93.3 degrees (PEEK). Ra was highest on ZrO2, followed by PEEK. Ti showed the most keratinocyte metabolic activity at 1, 3, and 5 culture periods. Contrarily, ZrO2 and PEEK disks had lower keratinocyte metabolic activity at all observation times, with no statistical differences between both groups. Integrin α6 and β4 expression was highest on TCPS and ZrO2 compared to Ti and PEEK. Keratinocytes proliferated faster on Ti than on ZrO2 and PEEK substrates, and expression of hemidesmosome formation markers, integrin α6 and β4, were higher on ZrO2 than either Ti or PEEK. Int J Oral Maxillofac Implants 2023;38:496-502. doi: 10.11607/jomi.9894.

Fabrication of polyetheretherketone (PEEK)-based 3D electronics with fine resolution by a hydrophobic treatment assisted hybrid additive manufacturing method

Additive manufacturing (AM) is a free-form technology that shows great potential in the integrated creation of three-dimensional (3D) electronics. However, the fabrication of 3D conformal circuits that fulfill the requirements of high service temperature, high conductivity and high resolution remains a challenge. In this paper, a hybrid AM method combining the fused deposition modeling (FDM) and hydrophobic treatment assisted laser activation metallization (LAM) was proposed for manufacturing the polyetheretherketone (PEEK)-based 3D electronics, by which the conformal copper patterns were deposited on the 3D-printed PEEK parts, and the adhesion between them reached the 5B high level. Moreover, the 3D components could support the thermal cycling test from −55 °C to 125 °C for more than 100 cycles. Particularly, the application of a hydrophobic coating on the FDM-printed PEEK before LAM can promote an ideal catalytic selectivity on its surface, not affected by the inevitable printing borders and pores in the FDM-printed parts, then making the resolution of the electroless plated copper lines improved significantly. In consequence, Cu lines with width and spacing of only 60 µm and 100 µm were obtained on both as-printed and after-polished PEEK substrates. Finally, the potential of this technique to fabricate 3D conformal electronics was demonstrated.

Mechanical and bioactive properties of PVD TiO2 coating modified PEEK for biomedical applications

Polyetheretherketone (PEEK) is gaining popularity in the biomedical field due to its excellent mechanical properties, chemical resistance and biocompatibility. Although PEEK is an excellent biomaterial, it may require bulk surface modification to tailor its properties for specific biomedical applications. In this study, the surface modification of PEEK was achieved by depositing titanium dioxide (TiO2) by PVD method. The microstructure and mechanical properties of TiO2 coatings were studied by SEM/EDS and nanoindentation tests. Conventional scratch tests were performed to determine the adhesion and tribological properties of the TiO2 films. An in vitro study was performed in simulated body fluids to evaluate the osteocompatibility of TiO2 coated PEEK. According to the results The TiO2 coating has a dense microstructure and good adhesion, the critical cohesive load Lc1 is greater than 1N. The TiO2 film improved the mechanical properties of the PEEK substrate: hardness and elastic modulus increased from ∼0.33 to ∼4.03 GPa to ∼3.6 and ∼21.85 GPa, respectively. In addition, compared with the PEEK substrate, the coating showed a 61% improvement in wear resistance and a reduction in the coefficient of friction from 0.38 to 0.09. The results also showed that the TiO2 coating induces the formation of hydroxyapatite on the surface, which promotes the osteocompatibility of PEEK.

A novel method to combine fused deposition modelling and inkjet printing in manufacturing multifunctional parts for aerospace application

Nowadays, the fabrication of smart product with sensing capability is still an arduous task due to the difficulties in integrating multifunctional materials using conventional method. To address this problem, this study presents a novel method to manufacture the multifunctional parts using fused deposition modeling (FDM) and inkjet printing (IJP) technologies. Firstly, the influence of process parameters on building time (BT), surface roughness (SR) and ultimate tensile strength (UTS) of poly-ether-ether-ketone (PEEK) samples manufactured by FDM was studied. Then, IJP was used to fabricate conductive lines on the surface of printed PEEK substrates. Finally, the process-structure–property relationship of PEEK parts before and after printing the conductive line was investigated. It is concluded that the BT and the SR of PEEK parts are significantly increased with an increased layer thickness, while the UTS increases steadily with an increase of nozzle temperature. Moreover, the maximum SR of 35.352 μm and the maximum UTS of 73.649 MPa are obtained at the infill angle of 45°. Furthermore, the warping deformation of PEEK samples will greatly affect SR during the real manufacturing, especially at both ends of the printed parts. Printed lines showing good aesthetic quality and the lowest electrical resistance (6.838 Ω/cm) are obtained on PEEK samples with the infill angle of 90°. This study demonstrates the possibility of manufacturing structure-integrated antenna by the combination of FDM and IJP processes.

Design and In Situ Additive Manufacturing of Multifunctional Structures

Multifunctional structures (MFSs) integrate diverse functions to achieve superior properties. However, conventional design and manufacturing methods—which generally lack quality control and largely depend on complex equipment with multiple stations to achieve the integration of distinct materials and devices—are unable to satisfy the requirements of MFS applications in emerging industries such as aerospace engineering. Motivated by the concept of design for manufacturing, we adopt a layer regulation method with an established optimization model to design typical MFSs with load-bearing, electric, heat-conduction, and radiation-shielding functions. A high-temperature in situ additive manufacturing (AM) technology is developed to print various metallic wires or carbon fiber-reinforced high-melting-point polyetheretherketone (PEEK) composites. It is found that the MFS, despite its low mass, exceeds the stiffness of the PEEK substrate by 21.5%. The embedded electrics remain functional after the elastic deformation stage. Compared with those of the PEEK substrate, the equivalent thermal conductivity of the MFS beneath the central heat source area is enhanced by 568.0%, and the radiation shielding is improved by 27.9%. Moreover, a satellite prototype with diverse MFSs is rapidly constructed as an illustration. This work provides a systematic approach for high-performance design and advanced manufacturing, which exhibits considerable prospects for both the function expansion and performance enhancement of industrial equipment.

Study on the Performance of Flexible Memory Device Based on Antimony Film

Antimony films and devices based on polyether-ether-ketone (PEEK) flexible substrates were fabricated. After bending at different radii for 24 hours, the antimony film still achieved a complete phase transition after heating. When the bending cycle was more than 10000 times, the resistance difference between amorphous and crystalline states kept more than one order of magnitude. With the increase of bending times, grains tended to be refined, resulting in a wider band gap. The good ductility of antimony film made it have small resistance drift in tensile state. The reversible SET and RESET operations were realized in bending phase change memory device. Antimony films based on PEEK substrates had great potential applications in flexible phase change memories.

Influence of Irregular Al2O3 Content on Electrical Conductivity, Adhesion Strength, and Tribological Properties of Cold Sprayed Al-Al2O3 Coatings on Polyether Ether Ketone Substrate

Influence of Irregular Al2O3 Content on Electrical Conductivity, Adhesion Strength, and Tribological Properties of Cold Sprayed Al-Al2O3 Coatings on Polyether Ether Ketone Substrate

Structural, mechanical and cytotoxic properties of Ta-doped diamond-like carbon films deposited via radio frequence magnetron sputtering on polyether ether ketone

Diamond-like carbon (DLC) films has excellent mechanical, tribological and biological properties. These properties can be further improved by doping transition metals to DLC films. The aim of this study is to enhance the tribological, mechanical and biological properties of polyether ether ketone (PEEK), which has been used in dental implant studies in recent years, with Ta doped DLC (Ta-DLC) thin films. In this study, Ta-DLC thin films were deposited on PEEK and Si substrates using Radio Frequency Magnetron Sputter. The DLC thin films were characterized using scanning electron microscopy, energy-dispersive spectroscopy, X-ray diffraction, Raman spectroscopy, scratch test and microhardness tester. Biological properties of Ta-DLC thin films were examined by cytotoxicity assays with using L929 mouse fibroblast cells. According to the results, Ta-DLC films deposited on the PEEK surface showed a promising critical load value (Lc=150 N). The ID/IG was 1.04, D and G peaks were positioned at 1384.7 cm−1 and 15,714 cm−1 respectively. Ta-DLC thin films deposited on PEEK substrate were found to be more favorable for cell viability and attachment.

Polyetheretherketone implants with hierarchical porous structure for boosted osseointegration

BackgroundGood osseointegration is the key to the long-term stability of bone implants. Thermoplastic polyetheretherketone (PEEK) has been widely used in orthopedics; however, its inherent biological inertia causes fibrous tissue to wrap its surface, which leads to poor osseointegration and thus greatly limits its clinical applications.MethodsHerein, we developed a facile yet effective surface modification strategy. A commonly used sulfonation coupled with “cold pressing” treatment in the presence of porogenic agent formed a three-dimensional hierarchical porous structure on PEEK surface. Subsequently, the effects of porous surface on the in vitro adhesion, proliferation and differentiation of rat bone marrow-derived mesenchymal stem cells (BMSCs) were evaluated. Finally, the osteoinduction and osseointegration of surface-porous PEEK implant were examined in the rat distal femoral defect model.ResultsIn vitro results showed that the surface modification did not significantly affect the mechanical performance and cytocompatibility of PEEK substance, and the porous structure on the modified PEEK substrate provided space for cellular ingrowth and enhanced osteogenic differentiation and mineralization of BMSCs. In vivo tests demonstrated that the surface-porous PEEK implant could effectively promote new bone formation and had higher bone-implant contact rate, thereby achieving good bone integration with the surrounding host bone. In addition, this modification technique was also successfully demonstrated on a medical PEEK interbody fusion cage.ConclusionThe present study indicates that topological morphology plays a pivotal role in determining implant osseointegration and this facile and effective modification strategy developed by us is expected to achieve practical applications quickly.Graphical

Surface modification of polyether ether ketone implant with a novel nanocomposite coating containing poly (vinylidene fluoride) toward improving piezoelectric and bioactivity performance

Polyether ether ketone (PEEK) is an appropriate biomaterial for orthopedic implant applications due to its superior mechanical properties, chemical resistance, nontoxicity, and Magnetic resonance imaging (MRI) compatibility. Unfortunately, the inherent bio-inertness of PEEK restricted its application and required some modification to provide better bioactivity. Besides it, the generated electrical signals in the bone due to its piezoelectricity features have a vital role in regulating bone repair and regeneration. We aimed to modify the surface of PEEK with a dual-functionality nanocomposite that provides surface bioactivity and simulates the piezoelectricity of bone. So, we introduced a novel piezoelectric-bioactive nanocomposite of dispersed poly (vinylidene fluoride) (PVDF) in a sulfonated PEEK (SPEEK) matrix containing Nanohydroxyapatite (nHA) and Carbon nanofiber (CNF) fillers for coating on PEEK substrate to improve its biological activity and simulate the electrical microenvironment for bone tissue. Furthermore, sulfonation of the PEEK surface was conducted as an intermediate layer to prepare better adhesion between the coating nanocomposite and the PEEK sublayer. Surface and cross-section morphology, apatite formation, and cell attachment were investigated on the different treated PEEK surfaces using field-emission scanning electron microscopy (FESEM) and energy dispersive X-ray analysis (EDX). Also, piezoelectric performance, electrical conductivity, contact angle, and mechanical properties were examined on the prepared samples. Moreover, cell viability and cell morphology were investigated for biological evaluation with human osteoblast-like MG-63 cells. Collectively, the hydrophilicity of modified PEEK (mPEEK) coated with nanocomposite was improved due to the synergistic effects of SPEEK functional groups and nHA. Also, comprehensive investigation on the mPEEK treated with nanocomposite indicated a noticeably better bone-like apatite formation, cell proliferation, and cell attachments in the presence of nHA. The transfer of induced piezoelectric charges from dispersed PVDF in the matrix to the surface of nanocomposite containing 2 wt% of CNF increased output voltage to 1893 mV. On the other hand, the presence of CNF in nanocomposites enhanced tensile strength and Young's modulus by 92% and 117%, respectively.

Enhancement of surface properties of polyetheretherketone implant material by fractional laser texturing

Background: Polyetheretherketone (PEEK) is a promising implant material due to its superior biomechanical strength. However, due to its hydrophobic nature and lack of cellular adhesion properties, it has poor integration with bone tissue. Methods: A fractional CO2 laser was used with various parameters for surface texturing of PEEK substrate to enhance its surface properties. An optical microscope and field-emission scanning electron microscope (FESEM) were used to examine the surface morphology of untextured and laser-textured samples. Energy dispersive X-ray spectroscopy (EDX) was performed to determine the effect of the laser on the microstructure of PEEK. Surface microroughness, atomic force microscopy (AFM), and wettability were investigated. Results: There were significant increases in microroughness, nanoroughness, surface area ratio, and wettability after laser texturing with no change in the elemental composition. The best results were obtained by using 400 µs laser pulse duration with a dot separation distance of 0.2 mm and a 60° staggered dots pattern. Conclusions: Laser surface texturing of PEEK implant material by fractional CO2 laser is an easy and fast method of introducing patterned topographical features with no need for additional devices. With further investigations, this method of PEEK modification might have the potential to be used in the implant field.

Synergetic adsorption-photocatalysis process of titania-silica photocatalysts and their immobilization on PEEK nonwoven filter for VOC removal

Studying the synergistic mechanisms of removing volatile organic compounds (VOCs) in an adsorption-photocatalytic oxidation process, remains a major challenge. This study explores the synergistic effects of SiO2 nanoparticles and anatase TiO2 nanocomposites in removing ethyl acetate, as a VOC test model, under solar irradiation in a photo-reactor. The physiochemical properties of the synthesized TiO2/SiO2 nanocomposites (70/30 and 50/50, molar ratio) and pure TiO2 nanoparticles were systematically characterized. It was found that the TiO2/SiO2 nanocomposite with 30% SiO2 showed the best synergistic adsorption and photocatalytic activity for the elimination of ethyl acetate among the tested samples. The integrated adsorption-photocatalytic mechanisms of TiO2/SiO2 nanocomposites were revealed by inverse gas chromatography (IGC), electron paramagnetic resonance (EPR), photoluminescence (PL) techniques and kinetic analysis. Moreover, a facile ambient-temperature immobilization method was successfully developed to load photocatalysts onto poly-ether ether-ketone (PEEK) nonwoven. In addition, the photo-induced chemiluminescence (PICL) analysis confirmed that the TiO2/SiO2 coating prevented the photodegradation of PEEK substrate under UVA radiation and improved its photostability. These results provided new understanding on designing highly adsorptive photocatalysts which are commercially applicable on filter materials for efficient VOC removal and air purification.