Controllable and durable release of BMP-2-loaded 3D porous sulfonated polyetheretherketone (PEEK) for osteogenic activity enhancement

Strategies to improve the performance of polyetheretherketone (PEEK) as orthopedic implants: from surface modification to addition of bioactive materials

Polyetheretherketone (PEEK), as a high-performance polymer, is widely used for bone defect repair due to its homogeneous modulus of elasticity of human bone, good biocompatibility, excellent chemical stability and projectability. However, the highly hydrophobic surface of PEEK is biologically inert, which makes it difficult for cells and proteins to attach, and is accompanied by the development of infections that ultimately lead to failure of PEEK implants. In order to further enhance the potential of PEEK as an orthopedic implant, researchers have explored modification methods such as surface modification by physical and chemical means and the addition of bioactive substances to PEEK-based materials to enhance the mechanical properties, osteogenic activity and antimicrobial properties of PEEK. However, these current modification methods still have obvious shortcomings in terms of cost, maneuverability, stability and cytotoxicity, which still need to be explored by researchers. This paper reviews some of the modification methods that have been used to improve the performance of PEEK over the last three years in anticipation of the need for researchers to design PEEK orthopedic implants that better meet clinical needs.

A self-assembling graphene oxide coating for enhanced bactericidal and osteogenic properties of poly-ether-ether-ketone

Poly-ether-ether-ketone (PEEK) is a biomedical plastic that can be used for orthopedic implants, but it offers poor antibacterial properties and bioactivity. In this study, PEEK was sulfonated with the obtained porous structure adsorbing graphene oxide (GO). The surface microstructures and properties of the original PEEK, sulfonated PEEK (SPEEK), and GO-grafted PEEK (GO-SPEEK) were characterized. The results revealed that the GO-SPEEK surface is a 3D porous structure exhibiting superior hydrophilicity to the original PEEK. Although SPEEK was shown to possess antimicrobial properties against both Escherichia coli and Staphylococcus aureus, the bactericidal effect was even more significant for GO-SPEEK, at about 86% and 94%, respectively. In addition, the in vitro simulated-body-fluid immersion and cell experiments indicated that GO-SPEEK had much better hydroxyapatite (HA)-precipitation induction capacity and cell-material interactions (e.g., cell adhesion, proliferation, osteodifferentiation, and extracellular matrix mineralization. The tensile test revealed that the mechanical properties of PEEK were maintained after surface modification, as GO-SPEEK has comparable values of elastic modulus and tensile strength to PEEK. Our investigation sought a method to simultaneously endow PEEK with both good antimicrobial properties and bioactivity as well as mechanical properties, providing a theoretical basis for developing high-performance orthopedic implants in the clinic.

Chemically heparinized PEEK via a green method to immobilize bone morphogenetic protein-2 (BMP-2) for enhanced osteogenic activity

Osseointegration remains one of the major challenges in the success of bone-related implants. Recently, polyetheretherketone (PEEK) has emerged as an alternative material in orthopedic and dental applications due to its bone-mimicking mechanical properties. However, its bioinertness resulting in poor osseointegration has limited its potential application. So, the surface modification of PEEK with bone morphogenetic protein-2 (BMP-2) can be a potential approach for improving osseointegration. In this study, we proposed the chemical modification of heparin onto PEEK through an environmentally benign method to exploit the BMP-2 binding affinity of heparin. The heparin was successfully functionalized on the PEEK surface via a combination of ozone and UV treatment without using organic solvents or chemicals. Furthermore, BMP-2 was efficiently immobilized on PEEK and exhibited a sustained release of BMP-2 compared to the pristine PEEK with enhancement of bioactivity in terms of proliferation as well as osteogenic differentiation of MG-63. The significant synergistic effect of BMP-2 and heparin grafting on osteogenic differentiation of MG-63 was observed. Overall, we demonstrated a relatively safe method where no harsh chemical reagent or organic solvent was involved in the process of heparin grafting onto PEEK. The BMP-2 loaded, heparin-grafted PEEK could serve as a potential platform for osseointegration improvement of PEEK-based bone implants.

Enhancing PEEK surface bioactivity: Investigating the effects of combining sulfonation with sub-millimeter laser machining

Due to its superior mechanical properties and chemical stability, Polyetheretherketone (PEEK) has emerged as an alternative to conventional metal implants. However, the bio-inertness of PEEK's surface has limited its applications. Ambient sulfonation has been adopted to enhance bioactivity, but its nanoscale topographic changes are insufficient for implant-bone interlock. To further improve bone-implant interlock, this study employs CO2 laser machining to create sub-millimeter (0.5 mm) grooves on PEEK's surface, aiming to encourage bone ingrowth and strengthen the implant-bone interface. This research investigated the physical and chemical properties and bio-interaction of PEEK surface modified by sulfonation (SPEEK), laser machining (L-PEEK), and combination of both technique (L-SPEEK). X-ray photoelectron spectroscopy (XPS) spectra revealed that sulfonation compensates for the surface chemical shift instigated by laser ablation, aligning the surface chemistry of L-SPEEK with that of SPEEK. Furthermore, L-PEEK surfaces presented pores with sizes ranging from 1 to 600 μm, while SPEEK surfaces exhibited pores between 5 and 700 nm. All tested samples demonstrated non-cytotoxicity, with L-SPEEK exhibiting the highest mineralization and ALP activity as 2 and 2.1 times that of intrinsic PEEK, after 21 days of incubation. Microscopic imaging reveals a notably higher extracellular content on L-SPEEK compared to the other groups. This study underscores the potential of combining sub-millimeter laser machining with sulfonation in enhancing early osteogenic markers, providing a promising pathway for future PEEK-based orthopedic applications.

Research progress and future prospects of antimicrobial modified polyetheretherketone (PEEK) for the treatment of bone infections

Infection of the bone is a difficult problem in orthopedic diseases. The key and basis of the treatment of bone infection is the effective control of local infection, as well as the elimination of infection focus and dead cavities. The most commonly used approach utilized for the prevention and management of bone infection is the application of antibiotic bone cement. However, the incorporation of antibiotics into the cement matrix has been found to considerably compromise the mechanical characteristics of bone cement. Moreover, some investigations have indicated that the antibiotic release rate of antibiotic bone cement is relatively low. Polyetheretherketone (PEEK) and its composites have been considered to perfectly address the challenges above, according to its favorable biomechanical characteristics and diverse surface functionalizations. This article provides a comprehensive overview of the recent advancements in the antimicrobial modification of PEEK composites in the field of antibacterial therapy of bone infection. Furthermore, the potential application of PEEK-modified materials in clinical treatment was discussed and predicted.

Current surface modification strategies to improve the binding efficiency of emerging biomaterial polyetheretherketone (PEEK) with bone and soft tissue: A literature review

PURPOSE

The aim of this study was to review the literature on current surface modification strategies used to improve the binding efficiency of an emerging biological material, polyetheretherketone (PEEK), with bone and soft tissues.

STUDY SELECTION

This review was based on articles retrieved from PubMed, Google Scholar, Web of Science, and ScienceDirect databases. The main keywords used during the search were "polyetheretherketone (PEEK)," "implant," "surface modification," "biomaterials," "bone," "osseointegration," and "soft tissue."

RESULTS

The suitability of PEEK surface modification strategies has been critically analyzed and summarized here. Many cell and in vivo experiments in small animals have shown that the use of advanced modification technologies with appropriate surface modification strategies can effectively improve the surface inertness of PEEK, thereby improving its binding efficiency with bone and soft tissues.

CONCLUSIONS

Surface modifications of PEEK have revealed new possibilities for implant treatment; however, most results are based on in vitro or short-term in vivo evaluations in small animals. To achieve a broad application of PEEK in the field of oral implantology, more in vivo experiments and long-term clinical evaluations are needed to investigate the effects of various surface modifications on the tissue integration ability of PEEK to develop an ideal implant material.

Preparation and characterization of different micro/nano structures on the surface of bredigite scaffolds

The preparation of controllable micro/nano structures on the surface of the bredigite scaffold is expected to exhibit the same support and osteoconductive capabilities as living bone. However, the hydrophobicity of the white calciμm silicate scaffold surface restricts the adhesion and spreading of osteoblasts. Furthermore, during the degradation process of the bredigite scaffold, the release of Ca2+ results in an alkaline environment around the scaffold, which inhibits the growth of osteoblasts. In this study, the three-dimensional geometry of the Primitive surface in the three-periodic minimal surface with an average curvature of 0 was used as the basis for the scaffold unit cell, and a white hydroxyapatite scaffold was fabricated via photopolymerization-based 3D printing. Nanoparticles, microparticles, and micro-sheet structures with thicknesses of 6 μm, 24 μm, and 42 μm, respectively, were prepared on the surface of the porous scaffold through a hydrothermal reaction. The results of the study indicate that the micro/nano surface did not affect the morphology and mineralization ability of the macroporous scaffold. However, the transition from hydrophobic to hydrophilic resulted in a rougher surface and an increase in compressive strength from 45 to 59-86 MPa, while the adhesion of the micro/nano structures enhanced the scaffold's ductility. In addition, after 8 days of degradation, the pH of the degradation solution decreased from 8.6 to around 7.6, which is more suitable for cell growth in the hμman body. However, there were issues of slow degradation and high P element concentration in the degradation solution for the microscale layer group during the degradation process, so the nanoparticle and microparticle group scaffolds could provide effective support and a suitable environment for bone tissue repair.

Strategies of immobilizing BMP-2 with 3D-printed scaffolds to improve osteogenesis

The management and definitive treatment of critical-size bone defects in severe trauma, tumor resection and congenital malformation are troublesome for orthopedic surgeons and patients worldwide without recognized good treatment strategies. Researchers and clinicians are working to develop new strategies to treat these problems. This review aims to summarize the techniques used by additive manufacturing scaffolds loaded with BMP-2 to promote osteogenesis and to analyze the current status and trends in relevant clinical translation. Optimize composite scaffold design to enhance bone regeneration through printing technology, material selection, structure design and loading methods of BMP-2 to advance the clinical therapeutic bone repair field.

Antibacterial properties of antimicrobial peptide HHC36 modified polyetheretherketone

Introduction

Polyetheretherketone (PEEK) is considered to be a new type of orthopedic implant material due to its mechanical properties and biocompatibility. It is becoming a replacement for titanium (Ti) due to its near-human-cortical transmission and modulus of elasticity. However, its clinical application is limited because of its biological inertia and susceptibility to bacterial infection during implantation. To solve this problem, there is an urgent need to improve the antibacterial properties of PEEK implants.

Methods

In this work, we fixed antimicrobial peptide HHC36 on the 3D porous structure of sulfonated PEEK (SPEEK) by a simple solvent evaporation method (HSPEEK), and carried out characterization tests. We evaluated the antibacterial properties and cytocompatibility of the samples in vitro. In addition, we evaluated the anti-infection property and biocompatibility of the samples in vivo by establishing a rat subcutaneous infection model.

Results

The characterization test results showed that HHC36 was successfully fixed on the surface of SPEEK and released slowly for 10 days. The results of antibacterial experiments in vitro showed that HSPEEK could reduce the survival rate of free bacteria, inhibit the growth of bacteria around the sample, and inhibit the formation of biofilm on the sample surface. The cytocompatibility test in vitro showed that the sample had no significant effect on the proliferation and viability of L929 cells and had no hemolytic activity on rabbit erythrocytes. In vivo experiments, HSPEEK can significantly reduce the bacterial survival rate on the sample surface and the inflammatory reaction in the soft tissue around the sample.

Discussion

We successfully loaded HHC36 onto the surface of SPEEK through a simple solvent evaporation method. The sample has excellent antibacterial properties and good cell compatibility, which can significantly reduce the bacterial survival rate and inflammatory reaction in vivo. The above results indicated that we successfully improved the antibacterial property of PEEK by a simple modification strategy, making it a promising material for anti-infection orthopedic implants.

Amyloid-Mediated Nanoarchitectonics with Biomimetic Mineralization of Polyetheretherketone for Enhanced Osseointegration

Polyetheretherketone (PEEK), a widely used implant material, has attracted the attention of scientific researchers because of its bone-matched elastic modulus, radiolucency, and chemical resistance. However, the bioinert chemical properties of PEEK do not promote bone apposition once implanted. In this study, using a phase-transitioned lysozyme (PTL) nanofilm as a sandwiched layer, a robust hydroxyapatite (HAp) coating on PEEK (HAp@PTL@PEEK) is constructed. The PTL nanofilm shows strong adhesion to the PEEK surface and induces biomimetic mineralization to form a compact HAp coating on PEEK in simulated body fluids. This HAp coating not only shares a higher adhesion strength and better stability but can also be applied to implants with complex 3D structures. HAp@PTL@PEEK showed significantly enhanced osteogenic capacity when cultured with rat bone marrow mesenchymal stem cells by promoting initial cell adhesion, proliferation, and osteogenic differentiation in vitro. In vivo evaluations utilizing models of femoral condyle defects and skull defects confirm that the HAp coating substantially augments bone remodeling and osseointegration ability. Compared with the traditional method, our modified method is simpler, more environmentally friendly, and uses less hazardous components. Furthermore, the obtained HAp coating shares a higher adhesion strength to PEEK and a better osteogenic capacity. The study offers a novel method to improve the osseointegration of PEEK-based implants in biointerfaces and tissue engineering.

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.

Biomimetic Strategy to Enhance Epithelial Cell Viability and Spreading on PEEK Implants

Polyetheretherketone (PEEK) is a biocompatible material widely used in spinal and craniofacial implants, with potential use in percutaneous implants. However, its inertness prevents it from forming a tight seal with the surrounding soft tissue, which can lead to infections and implant failure. Conversely, the surface chemistry of percutaneous organs (i.e., teeth) helps establish a strong interaction with the epithelial cells of the contacting soft tissues, and hence a tight seal, preventing infection. The seal is created by adsorption of basement membrane (BM) proteins, secreted by epithelial cells, onto the percutaneous organ surfaces. Here, we aim to create a tight seal between PEEK and epithelial tissues by mimicking the surface chemistry of teeth. Our hypothesis is that collagen I, the most abundant tooth protein, enables integration between the epithelial tissue and teeth by promoting adsorption of BM proteins. To test this, we immobilized collagen I via EDC/NHS coupling on a carboxylated PEEK surface modified using diazonium chemistry. We used titanium alloy (Ti-6Al-4V) for comparison, as titanium is the most widely used percutaneous biomaterial. Both collagen-modified PEEK and titanium showed a larger adsorption of key BM proteins (laminin, nidogen, and fibronectin) compared to controls. Keratinocyte epithelial cell viability on collagen-modified PEEK was twice that of control PEEK and ∼1.5 times that of control titanium after 3 days of cell seeding. Both keratinocytes and fibroblasts spread more on collagen-modified PEEK and titanium compared to controls. This work introduces a versatile and biomimetic surface modification technique that may enhance PEEK-epithelial tissue sealing with the potential of extending PEEK applications to percutaneous implants, making it competitive with titanium.

Strategies to improve bioactive and antibacterial properties of polyetheretherketone (PEEK) for use as orthopedic implants

Polyetheretherketone (PEEK) has gradually become the mainstream material for preparing orthopedic implants due to its similar elastic modulus to human bone, high strength, excellent wear resistance, radiolucency, and biocompatibility. Since the 1990s, PEEK has increasingly been used in orthopedics. Yet, the widespread application of PEEK is limited by its bio-inertness, hydrophobicity, and susceptibility to microbial infections. Further enhancing the osteogenic properties of PEEK-based implants remains a difficult task. This article reviews some modification methods of PEEK in the last five years, including surface modification of PEEK or incorporating materials into the PEEK matrix. For surface modification, PEEK can be modified by chemical treatment, physical treatment, or surface coating with bioactive substances. For PEEK composite material, adding bioactive filler into PEEK through the melting blending method or 3D printing technology can increase the biological activity of PEEK. In addition, some modification methods such as sulfonation treatment of PEEK or grafting antibacterial substances on PEEK can enhance the antibacterial performance of PEEK. These strategies aim to improve the bioactive and antibacterial properties of the modified PEEK. The researchers believe that these modifications could provide valuable guidance on the future design of PEEK orthopedic implants.

Small extracellular vesicles with nanomorphology memory promote osteogenesis

Nanotopographical cues endow biomaterials the ability to guide cell adhesion, proliferation, and differentiation. Cellular mechanical memory can maintain the cell status by retaining cellular information obtained from past mechanical microenvironments. Here, we propose a new concept “morphology memory of small extracellular vesicles (sEV)” for bone regeneration. We performed nanotopography on titanium plates through alkali and heat (Ti8) treatment to promote human mesenchymal stem cell (hMSC) differentiation. Next, we extracted the sEVs from the hMSC, which were cultured on the nanotopographical Ti plates for 21 days (Ti8-21-sEV). We demonstrated that Ti8-21-sEV had superior pro-osteogenesis ability in vitro and in vivo. RNA sequencing further confirmed that Ti8-21-sEV promote bone regeneration through osteogenic-related pathways, including the PI3K-AKT signaling pathway, MAPK signaling pathway, focal adhesion, and extracellular matrix-receptor interaction. Finally, we decorated the Ti8-21-sEV on a 3D printed porous polyetheretherketone scaffold. The femoral condyle defect model of rabbits was used to demonstrate that Ti8-21-sEV had the best bone ingrowth. In summary, our study demonstrated that the Ti8-21-sEV have memory function by copying the pro-osteogenesis information from the nanotopography. We expect that our study will encourage the discovery of other sEV with morphology memory for tissue regeneration.

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Nanotopography fabricated on titanium plates has superior promoted hMSCs differentiation ability.

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sEV extracted from hMSCs which were cultured on Ti8 plates for 21 days had the superior pro-osteogenesis ability.

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Ti8-21-sEV have memory function through copy the pro-osteogenesis information from nanotopography.

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RNA sequencing confirmed that Ti8-21-sEV promote bone regeneration through osteogenic-related pathways.

Peek dental implants coated with boron-doped nano-hydroxyapatites: Investigation of in-vitro osteogenic activity

BACKGROUND

PEEK is a high-performance thermoplastic that has many potential uses in orthopaedics and dentistry, and it has been shown to be a substitute for titanium (Ti) implants. However, PEEK is an inherently inert material, and that characteristic limits its cellular adhesion and bone integration. The aim of this study is to determine a suitable surface modification method for increasing the osteogenic potential of polyetheretherketone (PEEK) implants used in periodontal applications.

METHODS

In this work, a nanostructured porous surface is created on PEEK material by sulfonation, in sulfuric acid at room temperature for 20 min, and thus SPEEK samples were obtained. Then, PEEK and SPEEK samples were coated with boron (B) doped hydroxyapatite (HAp) nanoparticles (B-nHAp) precipitated from concentrated synthetic body fluid (10xSBF) by a microwave-assisted method conducted at 600 W. In vitro cell culture studies were carried out with periodontal ligament cells (PDL) on the samples. Osteogenic differentiation of PDL cells on PEEK, SPEEK and SPEEK-B-nHAp was evaluated using ALP activity assay, hydroxyproline assay, and RT-qPCR.

RESULTS

In vitro cell culture studies disclosed improved adhesion and proliferation of PDL cells on the SPEEK and B-nHAp coated SPEEK surfaces (SPEEK-B-nHAp). Results of these assays confirmed that treated PEEK surfaces, especially SPEEK-B-nHAp, significantly enhanced osteogenic differentiation of PDL cells in vitro compared with untreated PEEK surfaces.

CONCLUSION

Here a simple, easy to-use, and efficient modification method based on the properties of boron is proposed for increasing osteogenic potential of PEEK implants.

Application of biomolecules modification strategies on PEEK and its composites for osteogenesis and antibacterial properties

As orthopedic and dental implants, polyetheretherketone (PEEK) is expected to be a common substitute material of titanium (Ti) and its alloys due to its good biocompatibility, chemical stability, and elastic modulus close to that of bone tissue. It could avoid metal allergy and bone resorption caused by the stress shielding effect of Ti implants, widely studied in the medical field. However, the lack of biological activity is not conducive to the clinical application of PEEK implants. Therefore, the surface modification of PEEK has increasingly become one of the research hotspots. Researchers have explored various biomolecules modification methods to effectively enhance the osteogenic and antibacterial activities of PEEK and its composites. Therefore, this review mainly summarizes the recent research of PEEK modified by biomolecules and discusses the further research directions to promote the clinical transformation of PEEK implants.

Modification of polyether ether ketone for the repairing of bone defects

Bone damage as a consequence of disease or trauma is a common global occurrence. For bone damage treatment - bone implant materials are necessary across three classifications of surgical intervention (i.e. fixation, repair, and replacement). Many types of bone implant materials have been developed to meet the requirements of bone repair. Among them, polyether ether ketone (PEEK) has been considered as one of the next generation of bone implant materials, owing to its advantages related to good biocompatibility, chemical stability, X-ray permeability, elastic modulus comparable to natural bone, as well as the ease of processing and modification. However, as PEEK is a naturally bioinert material, some modification is needed to improve its integration with adjacent bones after implantation. Therefore, it has become a very hot topic of biomaterials research and various strategies for the modification of PEEK including blending, 3D printing, coating, chemical modification and the introduction of bioactive and/or antibacterial substances have been proposed. In this systematic review, the recent advances in modification of PEEK and its application prospect as bone implants are summarized, and the remaining challenges are also discussed.

Antibacterial Activity Studies of 3D-Printing Polyetheretherketone Substrates with Surface Growth of 2D TiO2/ZnO Rodlike Arrays

Heterogeneous metal implants have been applied in clinical treatments of skeletal wounds, but their low antibacterial properties and the possibility of a release of metal ions may have harmful influences on the human body. Therefore, a polymer implant with low cost, high safety, an elastic modulus similar to that of human bone, and a good antibacterial property must be produced for orthopedic treatments. In this study, the surface of a 3D-printed polyetheretherketone (PEEK) disk was grown with ZnO/TiO₂ rodlike arrays using a chemical bath deposition. X-ray diffraction patterns and transmission electron microscopy images showed that TiO₂/ZnO rodlike arrays were deposited onto the PEEK substrate. With the direct absorption of antibiotic agents onto the surface of TiO₂/ZnO/PEEK samples, their antibacterial performances greater than the values of minimum inhibitory concentration required to inhibit the growth of 90% of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) remained for around 10 days. The concentration of Zn²⁺ ions in a buffer solution is reduced with the coating of a TiO₂ layer on a ZnO rodlike array. The sample with absorption from a mixture containing ampicillin and vancomycin salts with a weight ratio of 1:1 had the best inhibitory effect on the growth of E. coli and S. aureus.

Rational integration of defense and repair synergy on PEEK osteoimplants via biomimetic peptide clicking strategy

Polyetheretherketone (PEEK) has been widely used as orthopedic and dental materials due to excellent mechanical and physicochemical tolerance. However, its biological inertness, poor osteoinduction, and weak antibacterial activity make the clinical applications in a dilemma. Inspired by the mussel adhesion mechanism, here we reported a biomimetic surface strategy for rational integration and optimization of anti-infectivity and osteo-inductivity onto PEEK surfaces using a mussel foot proteins (Mfps)-mimic peptide with clickable azido terminal. The peptide enables mussel-like adhesion on PEEK biomaterial surfaces, leaving azido groups for the further steps of biofunctionalizations. In this study, antimicrobial peptide (AMP) and osteogenic growth peptide (OGP) were bioorthogonally clicked on the azido-modified PEEK biomaterials to obtain a dual-effect of host defense and tissue repair. Since bioorthogonal clicking allows precise collocation between AMP and OGP through changing their feeding molar ratios, an optimal PEEK surface was finally obtained in this research, which could long-term inhibit bacterial growth, stabilize bone homeostasis and facilitate interfacial bone regeneration. In a word, this upgraded mussel surface strategy proposed in this study is promising for the surface bioengineering of inert medical implants, in particular, achieving rational integration of multiple biofunctions to match clinical requirements.

Icariin-loaded Sulfonated Polyetheretherketone with Osteogenesis Promotion and Osteoclastogenesis Inhibition Properties via Immunomodulation for Advanced Osseointegration

Preventing prosthesis loosening due to insufficient osseointegration is critical for patients with osteoporosis. Endowing implants with immunomodulatory function can effectively enhance osseointegration. In this work, we loaded icariin (ICA) onto...

Fabrication of Dexamethasone-Loaded Dual-Metal-Organic Frameworks on Polyetheretherketone Implants with Bacteriostasis and Angiogenesis Properties for Promoting Bone Regeneration

Polyetheretherketone (PEEK) is a biocompatible polymer, but its clinical application is largely limited due to its inert surface. To solve this problem, a multifunctional PEEK implant is urgently fabricated. In this work, a dual-metal-organic framework (Zn-Mg-MOF74) coating is bonded to PEEK using a mussel-inspired polydopamine interlayer to prepare the coating, and then, dexamethasone (DEX) is loaded on the coating surface. The PEEK surface with the multifunctional coating provides superior hydrophilicity and favorable stability and forms an alkaline microenvironment when Mg²⁺, Zn²⁺, 2,5-dihydroxyterephthalic acid, and DEX are released due to the coating degradation. In vitro results showed that the multifunctional coating has strong antibacterial ability against both Escherichia coli and Staphylococcus aureus; it also improves human umbilical vein endothelial cell angiogenic ability and enhances rat bone marrow mesenchymal stem cell osteogenic differentiation activity. Furthermore, the in vivo rat subcutaneous infection model, chicken chorioallantoic membrane model, and rat femoral drilling model verify that the PEEK implant coated with the multifunctional coating has strong antibacterial and angiogenic ability and promotes the formation of new bone around the implant with a stronger bone-implant interface. Our findings indicate that DEX loaded on the Zn-Mg-MOF74 coating-modified PEEK implant with bacteriostasis, angiogenesis, and osteogenesis properties has great clinical application potential as bone graft materials.

The surface modification of long carbon fiber reinforced polyether ether ketone with bioactive composite hydrogel for effective osteogenicity

Long carbon fiber reinforced polyether ether ketone (LCFRPEEK) is fabricated using a three-dimensional (3D) needle-punched method in our previous work, which is considered as a potential orthopedic implant due to its high mechanical strength and isotropic properties, as well as having an elastic modulus similar to human cortical bone. However, the LCFRPEEK has inferior integration with bone tissue, limiting its clinical application. Thus, a facile surface modification method, using gelatin methacrylate/polyacrylamide composite hydrogel coating (GelMA/PAAM) loading with dexamethasone (Dex) on our newly-developed LCFRPEEK composite via concentrated sulfuric acid sulfonating and ultraviolet (UV) irradiation grafting methods, has been developed to tackle the problem. The results demonstrate that the GelMA/PAAM/Dex coating modified sulfonated LCFRPEEK (SCP/GP/Dex) has a hydrophilicity surface, a long-term Dex release capability and forms more bone-like apatite nodules in SBF. The SCP/GP/Dex also displays enhanced cytocompatibility and osteogenic differentiation in terms of rat bone marrow mesenchymal stem cells (rBMSCs) responses in vitro assay. The in vivo rat cranial defect assay confirms that SCP/GP/Dex boosts bone regeneration/osseointegration, which significantly improves osteogenic fixation between the implant and bone tissue. Therefore, the newly-developed LCFRPEEK modified via GelMA/PAAM/Dex bioactive coating exhibits improved biocompatibility and osteogenic integration capability, which has the basis for an orthopedic implant for clinical application.

Modification of polyetheretherketone implants: From enhancing bone integration to enabling multi-modal therapeutics

Polyetheretherketone (PEEK) is a popular thermoplastic material widely used in engineering applications due to its favorable mechanical properties and stability at high temperatures. With the first implantable grade PEEK being commercialized in 1990s, the use of PEEK has since grown exponentially in the biomedical field and has rapidly transformed a large section of the medical devices landscape. Nowadays, PEEK is a standard biomaterial used across a wide range of implant applications, however, its bioinertness remains a limitation for bone repair applications. The increasing demand for enhanced treatment efficacy/improved patient quality of life, calls for next-generation implants that can offer fast bone integration as well as other desirable therapeutic functions. As such, modification of PEEK implants has progressively shifted from offering desirable mechanical properties, enhancing bioactivity/fast osteointegration, to more recently, tackling post-surgery bacterial infection/biofilm formation, modulation of inflammation and management of bone cancers. Such progress is also accompanied by the evolution of the PEEK manufacturing technologies, to meet the ever increasing demand for more patient specific devices. However, no review has comprehensively covered the recently engaged application areas to date. This paper provides an up-to-date review on the development of PEEK-based biomedical devices in the past 10 years, with particularly focus on modifying PEEK for multi-modal therapeutics. The aim is to provide the peers with a timely update, which may guide and inspire the research and development of next generation PEEK-based healthcare products. STATEMENT OF SIGNIFICANCE: Significant progress has been made in PEEK processing and modification techniques in the past decades, which greatly contributed to its wide applications in the biomedical field. Despite the high volume of published literature on PEEK implant related research, there is a lack of review on its emerging applications in multi-modal therapeutics, which involve bone regeneration, anti-bacteria/anti-inflammation, and cancer inhibition, etc. This timely review covers the state-of-the-art in these exciting areas and provides the important guidance for next generation PEEK based biomedical device research and development.

Surface modifications to enhance osseointegration-Resulting material properties and biological responses

As life expectancy and the age of the general population increases so does the need for improved implants. A major contributor to the failure of implants is poor osseointegration, which is typically described as the direct connection between bone and implant. This leads to unnecessary complications and an increased burden on the patient population. Modification of the implant surfaces through novel techniques, such as varying topography and/or applying coatings, has become a popular method to enhance the osseointegration capability of implants. Recent research has shown that particular surface features influence how bone cells interact with a material; however, it is unknown which exact features achieve optimal bone integration. In this review, current methods of modifying surfaces will be highlighted, and the resulting surface characteristics and biological responses are discussed. Review of the current strategies of surface modifications found that many coating types are more advantageous when used in combination; however, finding a surface modification that utilizes the mutual beneficial effects of important surface characteristics while still maintaining commercial viability is where future challenges exist.

Strontium ranelate incorporated 3D porous sulfonated PEEK simulating MC3T3-E1 cell differentiation

Polyetheretherketone (PEEK) has been used as an implant material because it has similar mechanical properties to natural bone. However, inferior osseointegration and bioinertness hamper the clinical application of PEEK. In this study, the surfaces of sulfonated three-dimensional (3D) PEEK porous structures were loaded with different concentrations of strontium ranelate, a compound commonly used in the treatment or prevention of osteoporosis by promoting bone formation and inhibiting bone resorption. Field-emission scanning electron microscopy was used to characterize the topography of the structures, elemental carbon, oxygen and strontium contents were measured by X-ray photoelectron spectroscopy, and surface zeta potentials and water-contact angle were also measured. The results indicated that strontium ranelate was successfully loaded onto the 3D porous structures. In vitro cellular results showed that strontium ranelate-treated sulfonated PEEK (SP-SR) strengthened the adhesion of MC3T3-E1 cells. The activity of alkaline phosphatase, collagen secretion and extracellular matrix mineralization deposition of MC3T3-E1 cells were also improved on the surface of SP-SR. These results indicate that SP-SR could serve a new implant candidate for surgical treatment.

Bioinspired Modifications of PEEK Implants for Bone Tissue Engineering

In recent years, polyetheretherketone (PEEK) has been increasingly employed as an implant material in clinical applications. Although PEEK is biocompatible, chemically stable, and radiolucent and has an elastic modulus similar to that of natural bone, it suffers from poor integration with surrounding bone tissue after implantation. To improve the bioactivity of PEEK, numerous strategies for functionalizing the PEEK surface and changing the PEEK structure have been proposed. Inspired by the components, structure, and function of bone tissue, this review discusses strategies to enhance the biocompatibility of PEEK implants and provides direction for fabricating multifunctional implants in the future.

Biologically Modified Polyether Ether Ketone as Dental Implant Material

Polyether ether ketone (PEEK) is a non-toxic polymer with elastic modulus close to human bone. Compared with metal implants, PEEK has advantages such as evasion of stress shielding effect, easy processing, and similar color as teeth, among others. Therefore, it is an excellent substitute material for titanium dental orthopedic implants. However, PEEK's biological inertia limits its use as an implant. To change PEEK's biological inertia and increase its binding ability with bone tissue as an implant, researchers have explored a number of modification methods to enhance PEEK's biological activities such as cellular compatibility, osteogenic activity, and antibacterial activity. This review summarizes current biological activity modification methods for PEEK, including surface modification and blending modification, and analyzes the advantages and disadvantages of each modification method. We believe that modified PEEK will be a promising dental and orthopedic implant material.

Effects of different sulfonation times and post-treatment methods on the characterization and cytocompatibility of sulfonated PEEK

Polyetheretherketone (PEEK) has been becoming a popular implant material in orthopaedic applications. The lack of bioactivity affects PEEK's long-term lifetime, and appropriate surface modification is an effective way to enhance its bioactivity. Sulfonation of PEEK can endow PEEK with a 3 D porous network surface and improve its bioactivity. This study is aimed at exploring an optimal sulfonation time and a post-treatment method of PEEK sulfonation. PEEK was immersed into concentrated sulfuric acid for different sulfonation times and experienced different post-treatment methods to turn into sulfonated PEEK (SPEEK). The immersion times were 0.5 min (SPEEK0.5), 1 min (SPEEK1), 3 min (SPEEK3), 5 min (SPEEK5) and 7 min (SPEEK7), and the post-treatment methods were acetone rinsing (SPEEK-T1), hydrothermal treatment (SPEEK-T2) and NaOH immersion (SPEEK-T3). Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy, hydrophilic property, ion release and cell viability evaluations were performed to optimize the sulfonation time, and the SEM, EDS, ion release and cell viability were analysed to optimize the post-treatment method. The results showed a porous network structure was formed on all samples of SPEEK, and the porous structure became more obvious and the S concentration increased with increasing sulfonation time. However, too long of an immersion time (SPEEK7) tended to damage the superficial porous structure and left a higher content of sulfuric acid, which could inhibit the growth of MC3T3E1 cells on its surface. In addition, the surface morphology, residual sulfuric acid and cytocompatibility of SPEEK-T1, SPEEK-T2 and SPEEK-T3 were not distinctly different. In conclusion, a 5-min sulfonation time was considered to be the optimal selection, and acetone rinsing, hydrothermal treatment and NaOH immersion showed the same effect in removing the residual sulfuric acid. The understanding of optimal sulfonation time and post-treatment method can provide a theoretical basis in preparing SPEEK for orthopaedic applications.

Covalently functionalized poly(etheretherketone) implants with osteogenic growth peptide (OGP) to improve osteogenesis activity

Polyetheretherketone (PEEK), as the most promising implant material for orthopedics and dental applications, has bone-like stiffness, excellent fatigue resistance, X-ray transparency, and near absence of immune toxicity. However, due to biological inertness, its bone conduction and bone ingrowth performance is limited. The surface modification of PEEK is an option to overcome these shortcomings and retain most of its favorable properties, especially when excellent osseointegration is desired. In this study, a simple reaction procedure was employed to bind the osteogenic growth peptide (OGP) on the surface of PEEK materials by covalent chemical grafting to construct a bioactive interface. The PEEK surface was activated by N,N′-disuccinimidyl carbonate (DSC) after hydroxylation, and then OGP was covalently grafted with amino groups. The functionalized surface of PEEK samples were characterized by X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FT-IR), water contact angle measurement and biological evaluation in vitro. OGP-functionalized PEEK surface significantly promoted the attachment, proliferation, alkaline phosphatase (ALP) activity and mineralization of pre-osteoblast cells (MC3T3-E1). The in vivo rat tibia implantation model is adopted and micro-CT analyses demonstrated that the OGP coating significantly promoted new bone formation around the samples. The in vitro and in vivo results reveal that the modification by covalent chemical functionalization with OGP on PEEK surface can augment new bone formation surrounding implants compared to bare PEEK and PEEK implant modified by covalently attached OGP is promising in orthopedic and dental applications.

Polyetheretherketone (PEEK), as the most promising implant material for orthopedics and dental applications, has bone-like stiffness, excellent fatigue resistance, X-ray transparency, and near absence of immune toxicity.

Influences of sodium tantalite submicro-particles in polyetheretherketone based composites on behaviors of rBMSCs/HGE-1 cells for dental application

Dental implanted materials require excellent mechanical properties, biocompatibility as well as integration with bone tissue and gingival tissue to achieve early loading and long-term stability. In this study, cubic shape sodium tantalite (ST) submicro-particles with the size of around 180 nm were synthesized by a hydrothermal method, and ST/polyetheretherketone (PEEK) composites (TPC) with ST content of 20 w% (TPC20) and 40 w% (TPC40) were prepared by melting blend. The results showed that the compressive strength, thermal properties, surface roughness, hydrophilicity and surface energy as well as adsorption of proteins on TPC40 were also significantly enhanced compared with TPC20 and PEEK. Moreover, the responses (adhesion and proliferation as well as differentiation) of rat bone marrow mesenchymal stem cells (rBMSCs), and responses (adhesion, and proliferation) of human gingival epithelial (HGE-1) cells to TPC40 were significantly promoted compared with TPC20 and PEEK. The results demonstrated that ST content in TPC had remarkable effects on the surface properties, which played key roles in stimulating the responses of both rBMSCs and HGE-1 cells. TPC40 with increased surface properties and excellent cytocompatibility might have great potential as an implanted material for dental application.

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.

Minocycline hydrochloride loaded graphene oxide enables enhanced osteogenic activity in the presence of Gram-positive bacteria, Staphylococcus aureus

Minocycline hydrochloride loaded graphene oxide films offer a solution for the issues of insufficient osseointegration and bacterial infections on the implants.