Porous surface with fusion peptides embedded in strontium titanate nanotubes elevates osteogenic and antibacterial activity of additively manufactured titanium alloy

A shellfish-inspired bionic microstructure design for biological implants: Enhancing protection of antibacterial silver-loaded coatings and promoting osseointegration

Implants incorporating multi-level micro-nano structures and antibacterial coatings offer a promising approach to overcoming the shortcomings of titanium and its alloys in stimulating bone growth and preventing bacterial infections. Silver ions have been identified as promising antibacterial agents. However, silver-loaded surface coatings are susceptible to damage from direct friction, and excessive release of silver ions can lead to cytotoxicity, thereby limiting their practical application. Inspired by the wear-resistant surface structure of natural shellfish, this study developed a biomimetic micro/nano multi-level structure on the titanium alloy (TC4) surfaces. The structure incorporated a biomimetic microgroove structure (BMS) with alkaline heat treatment (AH) of sodium titanate and chitosan/silver (CS/Ag) micro-nanostructured coatings (BMS/AH/CS/Ag). The microstructural armor effectively reduced external mechanical friction, safeguarding the coatings from damage. Compared to the unstructured sample, the biomimetic micro-groove armor group with a large micro-groove angle (θ) exhibited significantly reduced wear volume and only a marginal decrease of 1.86% in inhibition against Staphylococcus aureus (S. aureus) post-wear, highlighting the protective effect of this microstructure on the coating. The outstanding improvement was primarily attributed to the increased micro-groove angle, which enhanced the stability of the microstructure and effectively mitigated the friction. Additionally, the biomimetic micro-nano multi-level structure and coating have shown a significant ability to improve the bioactivity for the implant, promoting the adhesion, proliferation, collagen secretion, and extracellular matrix mineralization of human mesenchymal stem cells (hMSCs), which suggests the potential for enhanced osteogenic differentiation and indicates that this method can effectively improve the clinical performance of the implant.

Improved pleiotropic antibacterial activity of Ag(I)-Thiolate coordination polymers via iodide encapsulation in multinuclear silver nano cages

Silver-based nanomaterials have attracted considerable attention due to their antimicrobial properties. In this study, two nano-AgI-cage-based coordination polymers, [Ag6(μ-StBu)6]n (University of South China Coordination Polymer USC-CP-2) and [Ag14(μ-StBu)12I2]n (USC-CP-3), were synthesized via the reaction of AgNO3 and 2-methyl-2-propanethiol (HStBu) with sodium ethylate as a non-toxic base in a water/ethanol mixed solvent, with and without iodide as a coligand. Structural analysis by single-crystal X-ray diffraction revealed that both polymers are one-dimensional Ag(I)-thiolate coordination polymers with distinct secondary building units: USC-CP-2 features Ag6 nano-cages stabilized by μ2-StBu ligands, while USC-CP-3 comprises nanochains formed by iodide-encapsulated Ag16-cages linked through edge-sharing. Antimicrobial studies against Escherichia coli demonstrated that USC-CP-3, featuring iodide-encapsulated Ag16-cages, exhibited superior antibacterial activity compared to the iodide-free Ag6-cages in USC-CP-2. Mechanistic studies, supported by ICP-MS, EPR, TEM, and SEM analyses, suggested that the synergistic bactericidal effects arise from the release of Ag(I) ions, hydroxyl radical generation, and the presence of iodide. This study highlights a rational design strategy for advanced antibacterial materials with potential applications in combating bacterial contamination.

Construction of Mg2+ loaded multifunctional casein phosphopeptide/alendronate sodium antioxidative coating for repairing osteoporotic fracture

Owning to seriously impaired capacity of bone regeneration, the repair of osteoporotic bone defect remains a major clinical challenge in orthopedics. For titanium mesh scaffolds of skull repair, to construct bio-coatings targeting the pathological environment of osteoporosis is significant. Here, tannic acid (TA)/casein phosphopeptide (CPP) based layer-by-layer (LBL) self-assembled coating that loaded with anti-osteoporotic alendronate sodium (AS) and bioactive Mg2+ were prepared. The TA/CPP based LBL coatings showed good antioxidative function to effectively clear ABTS+• free radicals (scavenging rate of 64.29 ± 20.21 %) and inhibited the production of reactive oxygen species (ROS) in bone marrow mesenchymal stem cells (BMSCs) under oxidative stress conditions. All the LBL coatings exhibited good blood compatibility, and promoted early adhesion of BMSCs without affecting cell proliferation. In particular, the (TA/CPP-AS NPs)4 + Mg2+coatings had both good alkaline phosphatase (ALP) activity and in vitro osteogenic mineralization, and could effectively promote the migration of human umbilical vein endothelial cells (HUVECs). In 8-weeks in vivo implantation experiments of osteoporotic skull defects, AS and Mg2+ loaded LBL coating showed significant formation of new bone tissue. The study on the integrated system of antioxidative coating with bisphosphonates and active metal ions will serve as a promising strategy for osteoporotic bone defect repair.

Mussel-inspired bifunctional chimeric peptides macromolecules functionalize 3D-printed porous scaffolds for enhanced antimicrobial and osseointegration properties in bone defect repair

Polyetheretherketone (PEEK) is a promising material for bone defect repair due to its superior mechanical properties and chemical stability. However, its limited bioactivity and susceptibility to infection hinder its clinical use. To address these limitations, we developed antibacterial and osteogenic bifunctional chimeric peptides (CP) and integrated them onto 3D-printed PEEK scaffolds (3DP) using the adhesive properties of 3,4-dihydroxy-L-phenylalanine (DOPA). The CP, composed of antimicrobial peptide (GL13K) and osteogenic peptide (PFS) linked by DOPA, enhances bacterial membrane disruption while promoting bone marrow mesenchymal stem cell (BMSCs) adhesion and osteogenic differentiation. Through DOPA-mediated attachment, a hydrophilic and stable layer is formed on the scaffold surface via a simple immersion process. In vitro studies showed that CP@3DP effectively destroys bacterial membranes of Staphylococcus aureus and Escherichia coli, while promoting BMSCs adhesion, proliferation, and differentiation. In a rat skull defect model infected with S. aureus, CP@3DP demonstrated synergistic antibacterial effects and enhanced bone regeneration. Micro-CT imaging and histologic analysis confirmed that CP@3DP was firmly bound to host bone. This study highlights the potential of DOPA as a versatile adhesion molecule and the CP's bifunctional design for bone defect repair in infected environments, offering a novel approach for tissue engineering applications.

Construction of pH-responsive hydrogel coatings on titanium surfaces for antibacterial and osteogenic properties

Infection is one of the leading causes of failure in titanium-based implant materials during clinical surgeries, often resulting in delayed or non-union of bone healing. Furthermore, the overuse of antibiotics can lead to bacterial resistance. Therefore, developing a novel titanium-based implant material with both antimicrobial and osteogenic properties is of great significance. In this study, chitosan (CS), polydopamine (PDA), and antimicrobial peptides (AMPs) HHC36 were applied to modify the surface of titanium, resulting in the successful preparation of the composite material Ti-PDA-CS/PDA@HHC36 (abbreviated as T-P-C/P@H). CS promotes osteogenesis and cell adhesion, providing an ideal microenvironment for bone repair. PDA enhances the material's biocompatibility and corrosion resistance, offering cell adhesion sites, while both components exhibit pH-responsive characteristics. The HHC36 effectively prevents infection, protecting the bone repair material from bacterial damage. Overall, the synergistic effects of these components in T-P-C/P@H not only confer excellent antimicrobial and osteogenic properties but also improve biocompatibility, offering a new strategy for applying titanium-based implants in clinical settings.

Carboxymethyl chitosan/alendronate sodium/Sr2+ modified TiO2 nanotube arrays enhancing osteogenic activity and antibacterial property

Titanium and its alloys are widely used as orthopedic implants owing to their good mechanical properties and excellent corrosion resistance. However, the insufficient osteogenic activity and antibacterial properties hinder their clinical applications. To address these issues, TiO2 nanotube arrays (TNT) were first fabricated on the TA2 alloy surface via an anodizing technique, and strontium ions (Sr2+) were then loaded by hydrothermal reaction (TNT + Sr) and annealing treatment (TNT + A). Subsequently, the polydopamine layer (TNT + PDA) was constructed to immobilize the carboxymethyl chitosan and alendronate sodium (TNT + CA) mixture. The prepared coatings were thoroughly characterized by scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), X-ray photoelectron spectrometer (XPS), attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), X-ray diffractometer (XRD), and water contact angle measurement. The results confirmed that Sr2+ ions, polydopamine, and carboxymethyl chitosan/alendronate sodium were successfully immobilized on the nanotubes. The coating of TNT + CA significantly enhanced the hydrophilicity, and effectively delayed the release of Sr2+ and alendronate. The TNT + CA coating significantly promoted osteoblast adhesion and proliferation, and up-regulated the expressions of alkaline phosphatase (ALP), osteocalcin (OCN), and osteoblast-specific transcription factor (RUNX2). TNT + CA was able to rapidly induce in situ hydroxyapatite deposition from the simulated body fluid (SBF). Moreover, TNT + CA coating showed inhibition against Escherichia coli and Staphylococcus aureus (especially against Escherichia coli). The prepared TNT + CA coating provides a novel strategy for enhancing bone affinity, improving osteoblast behaviors, and antibacterial properties of titanium-based biomaterials.

Porous metal materials for applications in orthopedic field: A review on mechanisms in bone healing

Background

Porous metal materials have been widely studied for applications in orthopedic field, owing to their excellent features and properties in bone healing. Porous metal materials with different compositions, manufacturing methods, and porosities have been developed. Whereas, the systematic mechanisms on how porous metal materials promote bone healing still remain unclear.

Methods

This review is concerned on the porous metal materials from three aspects with accounts of specific mechanisms, inflammatory regulation, angiogenesis and osteogenesis. We place great emphasis on different cells regulated by porous metal materials, including mesenchymal stem cells (MSCs), macrophages, endothelial cells (ECs), etc.

Result

The design of porous metal materials is diversified, with its varying pore sizes, porosity material types, modification methods and coatings help researchers create the most experimentally suitable and clinically effective scaffolds. Related signal pathways presented from different functions showed that porous metal materials could change the behavior of cells and the amount of cytokines, achieving good influence on osteogenesis.

Conclusion

This article summarizes the current progress achieved in the mechanism of porous metal materials promoting bone healing. By modulating the cellular behavior and physiological status of a spectrum of cellular constituents, such as macrophages, osteoblasts, and osteoclasts, porous metal materials are capable of activating different pathways and releasing regulatory factors, thus exerting pivotal influence on improving the bone healing effect.

The translational potential of this article

Porous metal materials play a vital role in the treatment of bone defects. Unfortunately, although an increasing number of studies have been concentrated on the effect of porous metal materials on osteogenesis-related cells, the comprehensive regulation of porous metal materials on the host cell functions during bone regeneration and the related intrinsic mechanisms remain unclear. This review summarizes different design methods for porous metal materials to fabricate the most suitable scaffolds for bone remodeling, and systematically reviews the corresponding mechanisms on inflammation, angiogenesis and osteogenesis of porous metal materials. This review can provide more theoretical framework and innovative optimization for the application of porous metal materials in orthopedics, dentistry, and other areas, thereby advancing their clinical utility and efficacy.

Quorum sensing inhibiting dihydropyrrol-2-ones embedded polymer/graphene oxide nanocomposite waterborne antimicrobial coatings

With increasing antibiotic resistance and hospital acquired microbial infections, there has been a growing interest to explore alternate antimicrobial approaches. This is particularly challenging when aiming to protect surfaces over a large area to avoid contact mediated infection transmission. Quorum sensing (QS) inhibition has emerged as an alternate antimicrobial approach overcoming evolutionary stress driven resistance observed in antibiotic treatment. However, specific surface orientation requirements and limited work on delivery of small molecule QS inhibiting compounds have limited their widespread applicability certainly when it comes to coating large surfaces. Here, we report antimicrobial nanocomposite coatings overcoming the dependence on molecular orientation of QS inhibiting dihydropyrrol-2-ones (DHP) analogues and release small molecule analogues. In a systematic study, we developed poly(styrene-stat-n-butyl acrylate)/graphene oxide (GO)/DHP analogue nanocomposite antimicrobial coatings that can be easily applied to surfaces of any length scale and studied their efficacy against Staphylococcus aureus. The polymer nanocomposite was designed to undergo coating formation at ambient temperature. The antimicrobial coatings exhibited DHP dose dependent antimicrobial response both in the supernatant growth media with a ∼7-log10 reduction in cell growth and virtually a complete inhibition in cell adhesion on the surface in the best coating compared to controls. When compared, DHP-Br coatings outperformed other DHP analogues (-F and -Ph) both in limiting the cell growth in the media and cellular adhesion on the coating surface. This is the first example of nanocomposite coatings comprising QS inhibiting compounds, and their exceptional performance is expected to pave the way for further research in the field.

Polydopamine-Based Biomaterials in Orthopedic Therapeutics: Properties, Applications, and Future Perspectives

Polydopamine is a versatile and modifiable polymer, known for its excellent biocompatibility and adhesiveness. It can also be engineered into a variety of nanoparticles and biomaterials for drug delivery, functional modification, making it an excellent choice to enhance the prevention and treatment of orthopedic diseases. Currently, the application of polydopamine biomaterials in orthopedic disease prevention and treatment is in its early stages, despite some initial achievements. This article aims to review these applications to encourage further development of polydopamine for orthopedic therapeutic needs. We detail the properties of polydopamine and its biomaterial types, highlighting its superior performance in functional modification on nanoparticles and materials. Additionally, we also explore the challenges and future prospects in developing optimal polydopamine biomaterials for clinical use in orthopedic disease prevention and treatment.

Enhanced vascularization and osseointegration under osteoporotic conditions through functional peptide coating on implant surfaces

Patients with osteoporosis face challenges such as decreased bone density, a sparse trabecular structure, weakened osteogenic ability, and impaired angiogenesis, leading to poor osseointegration and implant failure. Surface modification of implants with biologically active molecules possessing various functions is an effective strategy to improve osseointegration. In this study, we constructed a simple multifunctional coating interface that significantly improves osseointegration. In brief, a multifunctional coating interface was constructed by coupling the Rgd adhesive peptide, Ogp osteogenic peptide, and Ang angiogenic peptide to Lys6 (k6), which self-assembled layer by layer with TA to form the (TA-Rgd@ogp@ang)n composite membrane. This study characterized the surface morphology and biomechanical properties of the coating under both gas and liquid phases and monitored the deposition process and reaction rate of the two peptides with TA using a quartz crystal microbalance. Moreover, (TA-Rgd@ogp@ang)n exhibited a triple synergistic effect on cell migration and adhesion, osteogenic differentiation, and angiogenesis. It also ameliorated the high ROS environment characteristic of osteoporosis pathology, promoted angiogenic bone defect regeneration in osteoporosis, thereby avoiding poor osseointegration. This work provides a new approach for the prevention of implant failure in pathological environments by constructing multifunctional coatings on implants, with tremendous potential applications in the fields of orthopedics and dentistry.

Presenting dual-functional peptides on implant surface to direct in vitro osteogenesis and in vivo osteointegration

The complex biological process of osseointegration and the bio-inertness of bone implants are the major reasons for the high failure rate of long-term implants, and have also promoted the rapid development of multifunctional implant coatings in recent years. Herein, through the special design of peptides, we use layer-by-layer assembly technology to simultaneously display two peptides with different biological functions on the implant surface to address this issue. A variety of surface characterization techniques (ellipsometry, atomic force microscopy, photoelectron spectroscopy, dissipation-quartz crystal microbalance) were used to study in detail the preparation process of the dual peptide functional coating and the physical and chemical properties, such as the composition, mechanical modulus, stability, and roughness of the coating. Compared with single peptide functional coatings, dual-peptide functionalized coatings had much better performances on antioxidant, cellular adhesion in early stage, proliferation and osteogenic differentiation in long term, as well as in vivo osteogenesis and osseointegration capabilities. These findings will promote the development of multifunctional designs in bone implant coatings, as a coping strategy for the complexity of biological process during osteointegration.

The Effect of Antibacterial-Osteogenic Surface Modification on the Osseointegration of Titanium Implants: A Static and Dynamic Strategy

Titanium (Ti) and its alloys are widely used biomaterials in bone repair. Although these biomaterials possess stable properties and good biocompatibility, the high elastic modulus and low surface activity of Ti implants have often been associated with infection, inflammation, and poor osteogenesis. Therefore, there is an urgent need to modify the surface of Ti implants, where changes in surface morphology or coatings loading can confer specific functions to help them adapt to the osseointegration formation phase and resist bacterial infection. This can further ensure a healthy microenvironment for bone regeneration as well as the promotion of immunomodulation, angiogenesis, and osteogenesis. Therefore, in this review, we evaluated various functional Ti implants after surface modification, both in terms of static modifications and dynamic response strategies, mainly focusing on the synergistic effects of antimicrobial activities and functionalized osteogenic. Finally, the current challenges and future perspectives are summarized to provide innovative and effective solutions for osseointegration and bone defect repair.

Study on the Antibacterial Activity and Bone Inductivity of Nanosilver/PLGA-Coated TI-CU Implants

Background

Implants are widely used in the field of orthopedics and dental sciences. Titanium (TI) and its alloys have become the most widely used implant materials, but implant-associated infection remains a common and serious complication after implant surgery. In addition, titanium exhibits biological inertness, which prevents implants and bone tissue from binding strongly and may cause implants to loosen and fall out. Therefore, preventing implant infection and improving their bone induction ability are important goals.

Purpose

To study the antibacterial activity and bone induction ability of titanium-copper alloy implants coated with nanosilver/poly (lactic-co-glycolic acid) (NSPTICU) and provide a new approach for inhibiting implant-associated infection and promoting bone integration.

Methods

We first examined the in vitro osteogenic ability of NSPTICU implants by studying the proliferation and differentiation of MC3T3-E1 cells. Furthermore, the ability of NSPTICU implants to induce osteogenic activity in SD rats was studied by micro-computed tomography (micro-CT), hematoxylin-eosin (HE) staining, masson staining, immunohistochemistry and van gieson (VG) staining. The antibacterial activity of NSPTICU in vitro was studied with gram-positive Staphylococcus aureus (Sa) and gram-negative Escherichia coli (E. coli) bacteria. Sa was used as the test bacterium, and the antibacterial ability of NSPTICU implanted in rats was studied by gross view specimen collection, bacterial colony counting, HE staining and Giemsa staining.

Results

Alizarin red staining, alkaline phosphatase (ALP) staining, quantitative real-time polymerase chain reaction (qRT-PCR) and western blot analysis showed that NSPTICU promoted the osteogenic differentiation of MC3T3-E1 cells. The in vitro antimicrobial results showed that the NSPTICU implants exhibited better antibacterial properties. Animal experiments showed that NSPTICU can inhibit inflammation and promote the repair of bone defects.

Conclusion

NSPTICU has excellent antibacterial and bone induction ability, and has broad application prospects in the treatment of bone defects related to orthopedics and dental sciences.

Dealloyed nano-porous TiCu coatings with controlled copper release for cardiovascular devices

TiCu coatings with controlled copper release and nano-porous structures were fabricated as biocompatible, blood-contacting interfaces through a two-step process. Initially, coatings with 58 % Cu were created using HiPIMS/DC magnetron co-sputtering, followed by immersion in a dilute HF solution for varying durations to achieve dealloying. The presence of Ti elements in the as-deposited TiCu coatings facilitated their dissolution upon exposure to the dilute HF solution, resulting in the formation of nanopores and increased nano-roughness. Dealloying treatment time correlated with higher Cu/(Ti + Cu) values, nanopore size, and nano-roughness in the dealloyed samples. The dealloyed TiCu coatings with 87 % Cu exhibited a controlled release of copper ions and displayed nanopores (approximately 80 nm in length and 31.0 nm in width) and nano-roughness (Ra roughness: 82 nm). These coatings demonstrated inhibited platelet adhesion and suppressed smooth muscle cell behavior, while supporting favorable endothelial cell viability and proliferation, attributed to the controlled release of copper ions and the extent of nanostructures. In contrast, the as-deposited TiCu coatings with 85 % Cu showed high copper ion release, leading to decreased viability and proliferation of endothelial cells and smooth muscle cells, as well as suppressed platelet adhesion. The TiCu coatings met medical safety standards, exhibiting hemolysis rates of <5 %. The technology presented here paves the way for the simple, controllable, and cost-effective fabrication of TiCu coatings, opening new possibilities for surface modification of cardiovascular devices such as vascular stents and inferior vena cava filters.

Titanium modification using bioactive titanate layer with divalent ions and coordinated ciprofloxacin - Assessment of drug distribution using FT-IR imaging

The paper presents a new method of titanium alloy (Ti6Al4V) modification using bioactive titanate layers containing various divalent ions (Ca2+, Mg2+, Sr2+, Zn2+) and surface-coordinated ciprofloxacin. Due to the coordination of ciprofloxacin (antibiotic) on the surface of the alloy, it has great application potential. In the paper, the influence of a given cation on the effectiveness of drug sorption was determined. The most effective cation was zinc and the least effective was calcium. The distribution of the antibiotic on the alloy surface was determined using FT-IR imaging. The antibiotic was evenly distributed on alloys modified with magnesium, strontium and zinc titanates. In the case of calcium titanate, the analysis could not be performed because the amount of the drug was too small. The release profiles of ciprofloxacin indicate that it can be released for as long as 3 h for strontium and zinc titanates. The biocompatibility of the obtained materials is indicated by the results of the BSA adsorption, and HA growth test. The obtained results confirm that the proposed modification can be used in the modification of titanium implants. The big advantage of this layer is that ciprofloxacin is coordinated on the surface of the material and thus will not be removed during the surgical procedure. The creation of this type of layer may in the future allow for fewer perioperative infections, and thus fewer complications.

Tribocorrosion and Surface Protection Technology of Titanium Alloys: A Review

Titanium alloy has the advantages of high specific strength, good corrosion resistance, and biocompatibility and is widely used in marine equipment, biomedicine, aerospace, and other fields. However, the application of titanium alloy in special working conditions shows some shortcomings, such as low hardness and poor wear resistance, which seriously affect the long life and safe and reliable service of the structural parts. Tribocorrosion has been one of the research hotspots in the field of tribology in recent years, and it is one of the essential factors affecting the application of passivated metal in corrosive environments. In this work, the characteristics of the marine and human environments and their critical tribological problems are analyzed, and the research connotation of tribocorrosion of titanium alloy is expounded. The research status of surface protection technology for titanium alloy in marine and biological environments is reviewed, and the development direction and trends in surface engineering of titanium alloy are prospected.