A carboxymethyl chitosan and peptide-decorated polyetheretherketone ternary biocomposite with enhanced antibacterial activity and osseointegration as orthopedic/dental implants

Biomaterials science and surface engineering strategies for dental peri-implantitis management

Peri-implantitis is a bacterial infection that causes soft tissue inflammatory lesions and alveolar bone resorption, ultimately resulting in implant failure. Dental implants for clinical use barely have antibacterial properties, and bacterial colonization and biofilm formation on the dental implants are major causes of peri-implantitis. Treatment strategies such as mechanical debridement and antibiotic therapy have been used to remove dental plaque. However, it is particularly important to prevent the occurrence of peri-implantitis rather than treatment. Therefore, the current research spot has focused on improving the antibacterial properties of dental implants, such as the construction of specific micro-nano surface texture, the introduction of diverse functional coatings, or the application of materials with intrinsic antibacterial properties. The aforementioned antibacterial surfaces can be incorporated with bioactive molecules, metallic nanoparticles, or other functional components to further enhance the osteogenic properties and accelerate the healing process. In this review, we summarize the recent developments in biomaterial science and the modification strategies applied to dental implants to inhibit biofilm formation and facilitate bone-implant integration. Furthermore, we summarized the obstacles existing in the process of laboratory research to reach the clinic products, and propose corresponding directions for future developments and research perspectives, so that to provide insights into the rational design and construction of dental implants with the aim to balance antibacterial efficacy, biological safety, and osteogenic property.

Chitosan-based materials for dental implantology: A comprehensive review

Chitosan, a versatile biopolymer, has gained recognition in the discipline of dental implantology due to possessing salient properties. This comprehensive review explores the potential of chitosan in dental implants, focusing on its biocompatibility, bioactivity, and the various chitosan-based materials that have been utilized for dental implant therapy. The review also highlights the importance of surface treatment in dental implants to enhance osseointegration and inhibit bacterial biofilm formation. Additionally, the chemical structure, properties, and sources of chitosan are described, along with its different structural forms. The characteristics of chitosan particularly color, molecular weight, viscosity, and degree of deacetylation are discussed about their influence on its applications. This review provides valuable insights into the promising utilization of polymeric chitosan in enhancing the success and functionality of dental implants. This study highlights the potential applications of chitosan in oral implantology. Chitosan possesses various advantageous properties, including muco-adhesiveness, hemostatic action, biocompatibility, biodegradability, bioactivity, and antibacterial and antifungal activities, which enhance its uses in dental implantology. However, it has limited aqueous solubility at the physiological pH, which sometimes restricts its biological application, but this problem can be overcome by using modified chitosan or chitosan derivatives, which have also shown encouraging results. Recent research suggests that chitosan may act as a promising material for coating titanium-based implants, improving osteointegration together with antibacterial properties.

Methods to improve antibacterial properties of PEEK: A review

As a thermoplastic and bioinert polymer, polyether ether ketone (PEEK) serves as spine implants, femoral stems, cranial implants, and joint arthroplasty implants due to its mechanical properties resembling the cortical bone, chemical stability, and radiolucency. Although there are standards and antibiotic treatments for infection control during and after surgery, the infection risk is lowered but can not be eliminated. The antibacterial properties of PEEK implants should be improved to provide better infection control. This review includes the strategies for enhancing the antibacterial properties of PEEK in four categories: immobilization of functional materials and functional groups, forming nanocomposites, changing surface topography, and coating with antibacterial material. The measuring methods of antibacterial properties of the current studies of PEEK are explained in detail under quantitative, qualitative, andin vivomethods. The mechanisms of bacterial inhibition by reactive oxygen species generation, contact killing, trap killing, and limited bacterial adhesion on hydrophobic surfaces are explained with corresponding antibacterial compounds or techniques. The prospective analysis of the current studies is done, and dual systems combining osteogenic and antibacterial agents immobilized on the surface of PEEK are found the promising solution for a better implant design.

Biomimetic Coatings in Implant Dentistry: A Quick Update

Biomimetic dental implants are regarded as one of the recent clinical advancements in implant surface modification. Coatings with varying thicknesses and roughness may affect the dental implant surface's chemical inertness, cell adhesion, and antibacterial characteristics. Different surface coatings and mechanical surface changes have been studied to improve osseointegration and decrease peri-implantitis. The surface medication increases surface energy, leading to enhanced cell proliferation and growth factors, and, consequently, to a rise in the osseointegration process. This review provides a comprehensive update on the numerous biomimetic coatings used to improve the surface characteristics of dental implants and their applications in two main categories: coating to improve osseointegration, including the hydroxyapatite layer and nanocomposites, growth factors (BMPs, PDGF, FGF), and extracellular matrix (collagen, elastin, fibronectin, chondroitin sulfate, hyaluronan, and other proteoglycans), and coatings for anti-bacterial performance, covering drug-coated dental implants (antibiotic, statin, and bisphosphonate), antimicrobial peptide coating (GL13K and human beta defensins), polysaccharide antibacterial coatings (natural chitosan and its coupling agents) and metal elements (silver, zinc, and copper).

Research and Application of Medical Polyetheretherketone as Bone Repair Material

Polyetheretherketone (PEEK) can potentially be used for bone repair because its elastic modulus is similar to that of human natural bone and good biocompatibility and chemical stability. However, its hydrophobicity and biological inertness limit its application in the biomedical field. Inspired by the composition, structure, and function of bone tissue, many strategies are proposed to change the structure and functionality of the PEEK surface. In this review, the applications of PEEK in bone repair and the optimization strategy for PEEK's biological activity are reviewed, which provides a direction for the development of multifunctional bone repair materials in the future.

Fabricating biodegradable calcium phosphate/calcium sulfate cement reinforced with cellulose: in vitro and in vivo studies

Osteoporosis is a growing public health concern worldwide. To avoid extra surgeries, developing biodegradable bone cement is critical for the treatment of osteoporosis. Herein, we designed calcium phosphate/calcium sulfate cement reinforced with sodium carboxymethyl cellulose (CMC/OPC). It presents an appropriate physicochemical performance for clinical handling. Meanwhile, CMC/OPC bone cement promotes osteogenic differentiation in vitro. Results of the immune response in vitro and in vivo confirmed that increasing the cellulose content triggered macrophage switching into the M2 phenotype and CMC/OPC exhibited significant anti-inflammation. Furthermore, in vitro and in vivo degradation demonstrated that cellulose tailors the degradation rate of composite bone cement, which achieved a linear degradation process and could degrade by more than 90% for 12 weeks. In summary, the composite bone cement CMC/OPC is a promising candidate for bone repair applications.

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.

Treatment methods toward improving the anti-infection ability of poly(etheretherketone) implants for medical applications

Due to its favorable chemical stability, biocompatibility, and mechanical properties, Poly(etheretherketone) (PEEK) is a promising material for repairing bone and dental hard tissue defects. However, there are critical disadvantages: PEEK is biologically and chemically inert, which influences osseointegration of implants and bonding strength of prostheses, and its mechanical properties still cannot meet the requirements for some medical applications. Furthermore, bacterial infections and inflammatory reactions often accompany bone defects caused by trauma or inflammation or teeth loss caused by periodontitis. Previous studies mainly focused on enhancing PEEK's bioactivity and mechanical performance, but PEEK also lacks effective anti-infection ability. Thus, it is necessary to improve its anti-infection ability, and this is considered in this paper from two aspects. The first is to inhibit the attachment and growth of bacteria on the material, and the second is to endow the material with immunoregulatory ability, which means mobilizing the host immune system to protect tissue from inflammation. In this review, we analyze and discuss the existing treatment methods to improve the antibacterial and immunomodulatory abilities of PEEK addressing their limitations, relevant future challenges, and required research efforts.

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.

Facilitating GL13K Peptide Grafting on Polyetheretherketone via 1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide: Surface Properties and Antibacterial Activity

In the present work, the antimicrobial peptide (AMP) of GL13K was successfully coated onto a polyetheretherketone (PEEK) substrate to investigate its antibacterial activities against Staphylococcus aureus (S. aureus) bacteria. To improve the coating efficiency, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) was mixed with a GL13K solution and coated on the PEEK surface for comparison. Both energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS) data confirmed 30% greater peptide coating on PEEK/GL13K-EDC than PEEK without EDC treatment. The GL13K graft levels are depicted in the micrograms per square centimeter range. The PEEK/GL13K-EDC sample showed a smoother and lower roughness (Rq of 0.530 µm) than the PEEK/GL13K (0.634 µm) and PEEK (0.697 µm) samples. The surface of the PEEK/GL13K-EDC was more hydrophilic (with a water contact angle of 24°) than the PEEK/GL13K (40°) and pure PEEK (89°) samples. The pure PEEK disc did not exhibit any inhibition zone against S. aureus. After peptide coating, the samples demonstrated significant zones of inhibition: 28 mm and 25 mm for the PEEK/GL13K-EDC and PEEK/GL13K samples, respectively. The bacteria-challenged PEEK sample showed numerous bacteria clusters, whereas PEEK/GL13K contained a little bacteria and PEEK/GL13K-EDC had no bacterial attachment. The results confirm that the GL13K peptide coating was able to induce antibacterial and biofilm-inhibitory effects. To the best of our knowledge, this is the first report of successful GL13K peptide grafting on a PEEK substrate via EDC coupling. The present work illustrates a facile and promising coating technique for a polymeric surface to provide bactericidal activity and biofilm resistance to medical implantable devices.

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.

Coated electrospun polyamide-6/chitosan scaffold with hydroxyapatite for bone tissue engineering

Polyamide-6 (PA6) is a synthetic polymer that bears resemblance to collagen in its backbone and has excellent stability in human body fluid. Chitosan (CS) with the similar structure to that of the polysaccharides existing in the extracellular matrix (ECM), has a more suitable biodegradation rate for the formation of new-bone. Electrospun fiber have nanoscale structure, high porosity and large specific surface area, can simulate the structure and biological function of the natural ECM. To meet the requirements of mechanical properties and biocompatibility of bone tissue engineering, electrospun PA6/CS scaffolds were fabricated by electrospinning technology. The mineralized PA6/CS scaffolds were obtained through immersion in 1.5× simulated body fluid (1.5SBF), which allowed the hydroxyapatite (HA) layer to grow into the thickness range under very mild reaction conditions without the need of a prior chemical modification of the substrate surface. The results showed that electrospun PA6/CS fibrous scaffolds in the diameter range of 60-260 nm mimic the nanostructure of the ECM. The tensile strength and modulus of 10PA6/CS fibrous scaffolds reach up to 12.67 ± 2.31 MPa and 95.52 ± 6.78 MPa, respectively. After mineralization, HA particles uniformly distributed on the surface of PA6/CS fibrous scaffolds in a porous honeycomb structure, and the content of mineral was about 40%. In addition, cell culture study indicated that the mineralized PA6/CS composite scaffolds were non-cytotoxic, and had a good biocompatibility and an ability to promote MC3T3-E1 cell attachment and proliferation.

Surface Modified Techniques and Emerging Functional Coating of Dental Implants

Dental implants are widely used in the field of oral restoration, but there are still problems leading to implant failures in clinical application, such as failed osseointegration, marginal bone resorption, and peri-implantitis, which restrict the success rate of dental implants and patient satisfaction. Poor osseointegration and bacterial infection are the most essential reasons resulting in implant failure. To improve the clinical outcomes of implants, many scholars devoted to modifying the surface of implants, especially to preparing different physical and chemical modifications to improve the osseointegration between alveolar bone and implant surface. Besides, the bioactive-coatings to promote the adhesion and colonization of ossteointegration-related proteins and cells also aim to improve the osseointegration. Meanwhile, improving the anti-bacterial performance of the implant surface can obstruct the adhesion and activity of bacteria, avoiding the occurrence of inflammation related to implants. Therefore, this review comprehensively investigates and summarizes the modifying or coating methods of implant surfaces, and analyzes the ossteointegration ability and anti-bacterial characteristics of emerging functional coatings in published references.

Chitosan-based drug delivery systems: From synthesis strategy to osteomyelitis treatment - A review

Osteomyelitis is a complex disease in orthopedics mainly caused by bacterial pathogens invading bone or bone marrow. The treatment of osteomyelitis is highly difficult and it is a major challenge in orthopedic surgery. The long-term systemic use of antibiotics may lead to antibiotic resistance and has limited effects on eradicating local biofilms. Localized antibiotic delivery after surgical debridement can overcome the problem of antibiotic resistance and reduce systemic toxicity. Chitosan, a special cationic polysaccharide, is a product extracted from the deacetylation of chitin. It has numerous advantages, such as nontoxicity, biocompatibility, and biodegradability. Recently, chitosan has attracted significant attention in bacterial inhibition and drug delivery. Because chitosan contains many functional bioactive groups conducive to chemical reaction and modification, some chitosan-based biomaterials have been applied as the local antibiotic delivery systems in the treatment of osteomyelitis. This review aims to introduce recent advances in the biomedical applications of chitosan-based drug delivery systems in osteomyelitis treatment and to highlight the perspectives for further studies.

Two-dimensional nanocoating-enabled orthopedic implants for bimodal therapeutic applications

As one of the promising orthopedic materials, polyetheretherketone (PEEK) has high chemical durability and similar mechanical properties to the cortical bone; nevertheless, the inherent bioinert nature of PEEK dramatically impedes its broader clinical applications in the management of bone infection. To address this challenge, herein, we developed a multifunctional two-dimensional (2D) nanocoating to assemble graphene oxide (GO) nanosheets, a polydopamine (pDA) nanofilm, and an oligopeptide onto the surface of porous sulfonated PEEK (SPEEK). The resulting multifunctional PEEK implants exhibited enhanced cytocompatibility, alkaline phosphatase activity, and calcium matrix deposition as well as osteogenesis-associated gene expression. Moreover, the animal experiments based on a rabbit femur defect model confirmed that the 2D nanocoating prominently boosted the in vivo osseointegration and bone remodeling. Besides, the GO/pDA hybrid complex anchoring on the SPEEK surface through π-π stacking can generate robust antibacterial phototherapy resulting from the synergetic photothermal/photodynamic therapeutic effects. Accordingly, this work provides a paradigm to empower inert PEEK implants with bi-/multi-modal therapeutic applications, such as against bone infection treatment.

High-Potential surface on zirconia ceramics for bacteriostasis and biocompatibility

Bacteria easily adhere, colonize, and form biofilm on oral implants subsequently causing periimplantation periarthritis and mechanical loosening. Previous studies show that a high potential surface on polymeric implants can achieve surface bacteriostasis without side effects. In this study, a high surface potential is introduced to zirconia ceramics to mitigate bacterial infection. Carbon and nitrogen plasma immersion ion implantation (C-PIII and N-PIII) are conducted on zirconia ceramic samples sequentially to elevate the surface potential. The surface with a high potential but without ion leaching exhibits excellent antibacterial effects against oral bacteria and little bacterial resistance is triggered. The surface also has high strength and excellent biocompatibility. The nitrogen-containing inorganic structure with high potential can actualize bacteriostasis and biocompatibility on zirconia ceramics simultaneously and this new strategy can enhance the antibacterial ability of oral implants.

From Dermal Patch to Implants-Applications of Biocomposites in Living Tissues

Composites are composed of two or more materials, displaying enhanced performance and superior mechanical properties when compared to their individual components. The use of biocompatible materials has created a new category of biocomposites. Biocomposites can be applied to living tissues due to low toxicity, biodegradability and high biocompatibility. This review summarizes recent applications of biocomposite materials in the field of biomedical engineering, focusing on four areas-bone regeneration, orthopedic/dental implants, wound healing and tissue engineering.

Fabrication of Curcumin-Modified TiO2 Nanoarrays via Cyclodextrin Based Polymer Functional Coatings for Osteosarcoma Therapy

The incomplete removal of bone tumors leads to increased local recurrence and poor prognosis. To prevent ostoperative tumor recurrence and simultaneously repair surgery-caused bone defects, there is a need of great significance to develop implantable biomaterials possessing both cancer cell-killing ability and excellent bioactivity. In this work, a functionalized titanium-based implant is successfully fabricated by loading curcumin (CUR) onto cyclodextrin based polymer (pCD) modified titanium dioxide (TiO₂ ) nanorod arrays. Herein, a polydopamine (pDA) assisted film is implemented as a first coating layer onto the surface of the TiO₂ nanoarrays to guarantee the robust anchorage of the pCD. The pCD coating acts as a reservoir for CUR, allowing for efficient drug loading and sustained release of anticancer drugs. Studies show that the CUR-modified surfaces (TiO₂ /pDA/pCD/CUR) can significantly promote apoptosis of osteosarcoma cells in vitro by inducing mitochondrial dysfunction caused by the ROS overproduction, and meanwhile, effectively inhibit the tumor growth in vivo. Moreover, such functionalized implants with surface density of loaded CUR at 22.48 µg cm^-2 or lower support the attachment and proliferation of osteoblasts in vitro. These results successfully demonstrate that as-prepared TiO₂ /pDA/pCD/CUR constructs have combined anticancer performance and good biocompatibility, which has great promise for the surgical therapy of bone tumors.

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.

Cobalt nanowire-based multifunctional platform for targeted chemo-photothermal synergistic cancer therapy

Cobalt nanowires (CoNWs) simultaneously possessing advantages in photothermal effect, targeting drug delivery and photoacoustic imaging property are hopefully promising strategies to further improve the treatment efficiency and reduce the side effects of cancer chemotherapy. Herein, a unique cobalt-based structure decorated with graphene oxide (GO) and polyethylene glycol (PEG) is fabricated through a facile approach. The resultant nanohybrids show relatively low cytotoxicity, favorable biocompatibility as well as inherit the outstanding properties of cobalt. Moreover, CoNWs decorated with GO and PEG (CoNWs-GO-PEG) can load therapeutic drug molecules (e.g., doxorubicin, DOX) with a high drug loading capacity (992.91 mg/g), and simultaneously they are responsive to pH, NIR (near-infrared) irradiation and magnetism stimulation. Accordingly, CoNWs-GO-PEG-DOX shows the satisfactory effect of eliminating cancer cells with synergistic chemo-photothermal therapy in vitro. Current work provides a solid demonstration of the potential of CoNWs-GO-PEG for serving as a targeted antitumor agent in synergistic chemo-photothermal therapy.

Chitosan-based asymmetric topological membranes with cell-like features for healthcare applications

Chitosan-based guided tissue regeneration (GTR) membranes are extensively used in orthopedic/stomatological regenerative medicine since chitosan shares many chemical and structural similarities with glycosaminoglycans (GAGs) in the extracellular matrix.

Dual Therapy Coating on Micro/Nanoscale Porous Polyetheretherketone to Eradicate Biofilms and Accelerate Bone Tissue Repair

Defective osteogenesis and latent infections continue to be two major issues in the therapy of bone tissue regeneration. In this study, a unique hierarchically micro/nanoscale-architecture is first proposed and produced on polyetheretherketone (PEEK). Besides, a "simvastatin-PLLA film-tobramycin microspheres" delivery system is subsequently fabricated to endow the PEEK implant with osteogenic and antibacterial capabilities. In vitro antibacterial evaluations confirm that the decorated PEEK scaffolds possess excellent resistance against planktonic/adherent bacteria. In vitro cell attachment/proliferation, lactate dehydrogenase (LDH) content, alkaline phosphatase (ALP) activity, calcium mineral deposition experiments, and real-time PCR analysis all exhibit that the superior proliferation rate and osteo-differentiation potential of MC3T3-E1 pre-osteoblasts are presented on the PEEK samples with dual functional decoration. In the mouse calvarial defect model, the micro-CT and histological results demonstrate that our scaffolds display a remarkable bone forming capability. Generally, the PEEK scaffolds co-endowed with simvastatin and tobramycin microspheres possess great potential in clinics.

Novel resin-based dental material with anti-biofilm activity and improved mechanical property by incorporating hydrophilic cationic copolymer functionalized nanodiamond

There is an increasing clinical need to design dental restorative materials that combine excellent mechanical property and anti-biofilm activity. In the current study, photocurable polycation functionalized nanodiamond (QND) was synthesized and proposed as novel filler for dental resins. By reason of increased repulsive force between nanoparticles and enhanced compatibility with resin matrix, QND dispersed uniformly in reinforced resins, which would help to transfer stress and deformation from the matrix to fillers more efficiently, resulting in a significant improvement in mechanical properties. Notably, the Vickers's hardness, flexural strength and flexural modulus of resins containing 1.0 wt% QND were 44.5, 36.1 and 41.3% higher than that of control, respectively. The antibacterial activity against Streptococcus mutans (S. mutans) showed that QND-incorporated resins produced anti-adhesive property due to their hydrophilic surfaces and could suppress bacterial growth as a result of the contact-killing effect of embedded nanocomposites. As the synergistic effect of anti-adhesive and bactericidal performance, resins loading 1.0~1.5 wt% QNDs displayed excellent anti-biofilm activity. Meanwhile, the results of macrophage cytotoxicity showed that the proliferation of RAW 264.7 cells remained 84.3%, even at a concentration of 1.0 wt% QNDs after 7-day incubation. Therefore, the QND-containing dental resin with the combination of high mechanical property, bacteria-repellent capability and antibacterial performance holds great potential as a restorative material based on this scheme.

Simvastatin delivery on PEEK for bioactivity and osteogenesis enhancements

A strategy developed for obtaining positive cellular responses remains to be focused in the filed of functional biomimetics. In this study, a hydrogel covered simvastatin-loaded polyetheretherketone (PEEK) bio-composites was constructed with the purpose of bone tissue regeneration therapy. Briefly, a three-dimensional (3D) porous structure was fabricated on PEEK surface; then the substrate was functionalized with the poly(L-lactic acid)/simvastatin porous film and hyaluronic acid hydrogel subsequently. In vitro cell attachment, proliferation, and cytoskeletal observation experiments reveal that our scaffolds show better bio-affinity due to the layer of hyaluronic acid hydrogel compared with control. Furthermore, the alkaline phosphatase activity, calcium mineral deposition evaluation, and gene expression for osteogenic potential all exhibit that the superior osteogenic differentiation of MC3T3-E1 pre-osteoblasts on our scaffolds. Therefore, our PEEK samples loaded with simvastatin and covered with hyaluronic acid hydrogel hold great potential in clinical applications for bone repair.

Dual Ag/ZnO-Decorated Micro-/Nanoporous Sulfonated Polyetheretherketone with Superior Antibacterial Capability and Biocompatibility via Layer-by-Layer Self-Assembly Strategy

Polyetheretherketone is attractive for dental and orthopedic applications due to its mechanical attributes close to that of human bone; however, the lack of antibacterial capability and bioactivity of polyetheretherketone has substantially impeded its clinical applications. Here, a dual therapy implant coating is developed on the 3D micro-/nanoporous sulfonated polyetheretherketone via layer-by-layer self-assembly of Ag ions and Zn ions. Material characterization studies have indicated that nanoparticles consisting of elemental Ag and ZnO are uniformly incorporated on the porous sulfonated polyetheretherketone surface. The antibacterial assays demonstrate that Ag-decorated sulfonated polyetheretherketone and Ag/ZnO-codecorated sulfonated polyetheretherketone effectively inhibit the reproduction of Gram-negative and Gram-positive bacteria. Owing to the coordination of micro-/nanoscale topological cues and Zn induction, the Ag/ZnO-codecorated sulfonated polyetheretherketone substrates are found to enhance biocompatibility (cell viability, spreading, and proliferation), and hasten osteodifferentiation and -maturation (alkaline phosphate activity (ALP) production, and osteogenesis-related genetic expression), compared with the Ag-decorated sulfonated polyetheretherketone and the ZnO-decorated sulfonated polyetheretherketone counterparts. The dual therapy Ag/ZnO-codecorated sulfonated polyetheretherketone has an appealing bacteriostatic performance and osteogenic differentiation potential, showing great potential for dental and orthopedic implants.

Synthesis, Self-Assembly, and Biomedical Applications of Antimicrobial Peptide-Polymer Conjugates

Antimicrobial peptides (AMPs) have been attracting much attention due to their excellent antimicrobial efficiency and low rate in driving antimicrobial resistance (AMR), which has been increasing globally to alarming levels. Conjugation of AMPs into functional polymers not only preserves excellent antimicrobial activities but reduces the toxicity and offers more functionalities, which brings new insight toward developing multifunctional biomedical materials such as hydrogels, polymer vesicles, polymer micelles, and so forth. These nanomaterials have been exhibiting excellent antimicrobial activity against a broad spectrum of bacteria including multidrug-resistant (MDR) ones, high selectivity, and low cytotoxicity, suggesting promising potentials in wound dressing, implant coating, antibiofilm, tissue engineering, and so forth. This Perspective seeks to highlight the state-of-the-art strategy for the synthesis, self-assembly, and biomedical applications of AMP-polymer conjugates and explore the promising directions for future research ranging from synthetic strategies, multistage and stimuli-responsive antibacterial activities, antifungi applications, and potentials in elimination of inflammation during medical treatment. It also will provide perspectives on how to stem the remaining challenges and unresolved problems in combating bacteria, including MDR ones.

Time-responsive osteogenic niche of stem cells: A sequentially triggered, dual-peptide loaded, alginate hybrid system for promoting cell activity and osteo-differentiation

The efficacy of stem cell-based bone tissue engineering has been hampered by cell death and limited fate control. A smart cell culture system with the capability of sequentially delivering multiple factors in specific growth stages, like the mechanism of the natural extracellular matrix modulating tissue formation, is attractive for enhancing cell activity and controlling cell fate. Here, a bone forming peptide-1 (BFP-1)-laden mesoporous silica nanoparticles (pep@MSNs) incorporated adhesion peptide, containing the arginine-glycine-aspartic acid (RGD) domain, modified alginate hydrogel (RA) system (pep@MSNs-RA) was developed to promote the activity and stimulate osteo-differentiation of human mesenchymal stem cells (hMSCs) in sequence. The survivability and proliferation of hMSCs were enhanced in the adhesion peptide modified hydrogel. Next, BFP-1 released from pep@MSNs induced hMSCs osteo-differentiation after the proliferation stage. Moreover, BFP-1 near the cells was self-captured by the additional cell-peptide cross-linked networks formed by the ligands (RGD) binding to receptors on the cell surface, leading to long-term sustained osteo-stimulation of hMSCs. The results suggest that independent and sequential stimulation in proliferation and osteo-differentiation stages could synergistically enhance the survivability, expansion, and osteogenesis of hMSCs, as compared to stimulating alone or simultaneously. Overall, this study provided a new and valid strategy for stem cell expansion and osteo-differentiation in 2D or 3D culture systems, possessing potential applications in 3D bio-printing and tissue regeneration.

Dopamine self-polymerized along with hydroxyapatite onto the preactivated titanium percutaneous implants surface to promote human gingival fibroblast behavior and antimicrobial activity for biological sealing

The clinical success of dental implants requires not only the optimum osseointegration but also the integration of implant surface with soft tissues to form biological sealing. In this study, alkali-heat treatment was applied to modify the pure titanium surface constructing a unique micro-and nano-structure. Then, poly(dopamine), along and with the additional incorporation of hydroxyapatite and carboxymethyl chitosan have been successfully infiltrated into the preactivated Ti surface during dopamine self-polymerization proceeding. Here, the effects of poly(dopamine)-modified surface coating on the biological behaviors of human gingival fibroblasts (HGFs) and oral pathogens have been systematically studied, which was critical for the early peri-implant soft tissue integration. The results showed that the poly(dopamine)-modified alkali-heat-titanium surface was a superior substrate for human gingival fibroblast adhesion, spread and proliferation. Moreover, further enhancements on cytoskeleton organization, collagen secretion and fibronectin adsorption were generally observed through the additional incorporation of hydroxyapatite. The addition of carboxymethyl chitosan exerted a positive modulation effect on antibacterial activity. Overall, our study demonstrated that combined superior soft tissue integration and antibacterial activity can be achieved by using poly(dopamine)-modified titanium implant, which has great potential in the optimal design of dental implant.

Facile and Versatile Strategy for Construction of Anti-Inflammatory and Antibacterial Surfaces with Polydopamine-Mediated Liposomes Releasing Dexamethasone and Minocycline for Potential Implant Applications

Reducing early nonbacterial inflammation induced by implanted materials and infection resulting from bacterial contamination around the implant-abutment interface could greatly decrease implant failure rates, which would be of clinical significance. In this work, we presented a facile and versatile strategy for the construction of anti-inflammatory and antibacterial surfaces. Briefly, the surfaces of polystyrene culture plates were first coated with polydopamine and then decorated with dexamethasone plus minocycline-loaded liposomes (Dex/Mino liposomes), which was validated by contact angle goniometry, quartz crystal microbalance, and fluorescence microscopy. Dex/Mino liposomes were dispersed on functional surfaces and the drug release kinetics exhibited the sustained release of dexamethasone and minocycline. Our results demonstrated that the Dex/Mino liposome-modified surfaces had good biocompatibility. Additionally, liposomal dexamethasone reduced proinflammatory mediator expression (particularly IL-6 and TNF-α) in lipopolysaccharide-stimulated human gingival fibroblasts and human mesenchymal stem cells. Moreover, liposomal minocycline prevented the adhesion and proliferation of Porphyromonas gingivalis (Gram-negative bacteria) and Streptococcus mutans (Gram-positive bacteria). These findings demonstrate that an anti-inflammatory and antibacterial surface was developed, using dopamine as a medium and combining a liposomal delivery device, which has potential for use to reduce implant failure rates. Accordingly, the surface modification strategy presented could be useful in biofunctionalization of implant materials.

Amino acid-modified chitosan nanoparticles for Cu2+ chelation to suppress CuO nanoparticle cytotoxicity

The extensive development and application of engineered nanoparticles (NPs) in various fields worldwide have been subjected to increasing concern due to their potential hazards to human health and the environment. Therefore, a simple, economical, and effective method for suppressing the toxicity of metal-based nanomaterials is needed. In this study, glutaraldehyde-crosslinked chitosan nanoparticles (CS NPs) were prepared and further modified with lysine (Ly-CS), glutamic acid (Glu-CS), or sodium borohydride reduction (R-CS), and used to suppress cytotoxicity induced by copper oxide NPs (CuO NPs) through chelation with intracellularly released copper ions. All three kinds of CS NPs had similar sizes of ∼100 nm in a dry state and ∼200 nm in cell culture medium, as determined by scanning electron microscopy, transmission electron microscopy, and dynamic light scattering. The chelating efficiency of different CS NPs followed the order Ly-CS > Glu-CS > R-CS. The CS NPs showed minimal or no toxicity to three different cell lines (HepG2, A549, and RAW264.7 cells) at 100 μg mL^-1 with similar cell internalization and exocytosis processes. Comparatively, RAW264.7 cells exhibited higher endocytosis and exocytosis rates, as revealed by flow cytometry and confocal laser scanning microscopy. CS NPs were found as agglomerates inside A549 cells and RAW264.7 cells, with the amount of agglomerates inside RAW264.7 cells decreasing significantly with prolonged incubation. All three CS NPs, especially Ly-CS and Glu-CS NPs, efficiently suppressed the cytotoxicity induced by CuO NPs, and reduced the intracellular level of reactive oxygen species.

Nano-hydroxyapatite reinforced polyphenylene sulfide biocomposite with superior cytocompatibility and in vivo osteogenesis as a novel orthopedic implant

The design of novel functional biomaterials that possess similar mechanical attributes as human bones, accompanied with admirable osteogenesis to replace conventional metallic implants would be an intriguing accomplishment.

Dual functional polylactide–hydroxyapatite nanocomposites for bone regeneration with nano-silver being loaded via reductive polydopamine

In bone tissue engineering, scaffolding materials with antibacterial function are required to avoid failure in treating infected bone defects, and poly(l-lactide) - hydroxyapatite nanocomposites containing silver nanoparticles are good choices for the purpose.

Advances in collagen, chitosan and silica biomaterials for oral tissue regeneration: from basics to clinical trials

Different materials have distinct surface and bulk characteristics; each of them potentially useful for the treatment of a particular wound or disease.