Bone Repair Applications Research Articles

A biodegradable, osteo-regenerative and biomechanically robust polylactide bone screw for clinical orthopedic surgery

Poly (L-lactic acid) (PLLA) has emerged as a promising orthopedic implant material due to its favorable strength and biodegradability. However, challenges such as low toughness and limited osteoinductivity hinder its widespread use in bone fixation. This study focuses on enhancing the toughness and osteogenic activity of PLLA-based orthopedic implants. Inspired by reinforcement techniques in the construction industry, we designed a structure comprising flexible fibers enveloped by PLLA/hydroxyapatite (HA) crystalline phases. Initially, PLLA/poly (butylene succinate-co-adipate) (PBSA)/HA composites with “sea-island” morphology were prepared through melt-compounding. Subsequently, the highly oriented PBSA fibers were in situ formed during microinjection molding for bone screw fabrication. Comprehensive investigation into the structural-mechanical property relationship revealed a significant increase in elongation at break (from 5.4 % to 59.4 % with an optimal PBSA/HA ratio), while maintaining a high stiffness and a slight decrease in tensile strength (from 62 MPa to 56 MPa). The flexural tests of the resulting composite bone screws demonstrated a significant increase in toughness. Additionally, the in vivo studies corroborated the osteogenic potential of the microinjection molded bone screws by using hematoxylin and eosin (HE) and Masson staining. The methodology presented in this study offers a promising approach for advancing PLLA-based fixation devices in bone repair applications.

Role of Ti3AlC2 MAX phase in regulating biodegradation and improving electrical properties of calcium silicate ceramic for bone repair applications

Calcium silicate ceramic is a promising bioceramic for various biomedical applications, but its high biodegradation rate and low strength restrict its clinical utility. As a result, the study devised an innovative solution to address these issues by utilizing the titanium aluminum carbide phase, potentially for the first time in biological applications, in conjugation with hydroxyapatite. Then, using powder metallurgy technology, they added these phases to calcium silicate to create nanocomposites. After soaking in simulated body fluid for ten days, the produced nanocomposites were assessed for bioactivity and biodegradability using scanning electron microscopy, inductively coupled plasma-atomic emission spectroscopy, and weight loss assays. Their electrical and dielectric properties were also measured before and after soaking in the simulated body fluid solution. Furthermore, the tribo-mechanical properties of all sintered samples were measured. Interestingly, adding 40% hydroxyapatite nanoparticles to calcium silicate reduced the porosity from 12 to 6%. However, adding five vol% of the titanium aluminum carbide phase to the same sample increased the porosity to 8%. Importantly, these recorded percentages of porosity were comparable to those of compact bone porosity, which range from 5 to 13%. The addition of hydroxyapatite and titanium aluminum carbide phase significantly improved the rapid biodegradation of calcium silicate, albeit with a slight decrease in its bioactive properties, as evidenced by the incomplete surface coverage of the samples with the hydroxyapatite layer in the scanning electron microscopy images. The electrical properties of the nanocomposites were better with the addition of hydroxyapatite and titanium aluminum carbide phase, which helped the bone heal faster. The addition of a titanium aluminum carbide phase significantly improved the mechanical properties of the resulting nanocomposites. For example, the calculated values for compressive strength of all examined samples were 131, 115, 105, 147, and 135 MPa. Based on the results, the prepared samples can be used in orthopaedic and dental applications.

Cohesion Regulation of Polyphenol Cross‐Linked Hydrogel Adhesives: From Intrinsic Cross‐Link to Designs of Temporal Responsiveness

AbstractPolyphenol hydrogels have found widespread application in wound healing, bone repair, drug delivery, and biosensors due to their robust wet adhesion, high ductility, and excellent self‐healing ability. However, these hydrogels often exhibit low intrinsic cohesion, which limits their overall adhesive strength. Enhancing cohesion is critical for improving both the adhesion and mechanical properties of the hydrogels, thereby expanding their utility in biomedical fields. This review begins by exploring strategies to enhance the cohesion of polyphenol hydrogel adhesives, detailing modifications that act individually or synergistically. The importance of temporally regulating cohesion is emphasized to accommodate various applications and environmental conditions. Finally, this paper discusses remaining challenges in cohesion regulation and outlines prospects for future research. It is hoped that this comprehensive review will provide new insights into the development of advanced polyphenolic hydrogel adhesives and contribute to the design of “smart adhesives” for increasingly complex needs in biomedical applications.

Silver Nanoparticles and Simvastatin-Loaded PLGA-Coated Hydroxyapatite/Calcium Carbonate Scaffolds.

The need to develop synthetic bone substitutes with structures, properties, and functions similar to bone and capable of preventing microbial infections is still an ongoing challenge. This research is focused on the preparation and characterization of three-dimensional porous scaffolds based on hydroxyapatite (HA)-functionalized calcium carbonate loaded with silver nanoparticles and simvastatin (SIMV). The scaffolds were prepared using the foam replica method, with a polyurethane (PU) sponge as a template, followed by successive polymer removal and sintering. The scaffolds were then coated with poly(lactic-co-glycolic) acid (PLGA) to improve mechanical properties and structural integrity, and loaded with silver nanoparticles and SIMV. The scaffolds were characterized by X-ray powder diffraction (XRD), field emission scanning electron microscopy (FE-SEM), ATR FT-IR, and silver and SIMV loading. Moreover, the samples were analyzed by Brillouin and Raman microscopy. Finally, in vitro bioactivity, SIMV and silver release, and antimicrobial activity against Staphylococcus aureus and Staphylococcus epidermidis were evaluated. From the Brillouin spectra, samples showed characteristics analogous to those of bone tissue. They exhibited new hydroxyapatite growth, as evidenced by SEM, and good antimicrobial activity against the tested bacteria. In conclusion, the obtained results demonstrate the potential of the scaffolds for application in bone repair.

Synergetic effect of bioglass and nano montmorillonite on 3D printed nanocomposite of polycaprolactone/gelatin in the fabrication of bone scaffolds

Nowadays, bone injuries and disorders have increased all over the world and can reduce the quality of human life. Bone tissue engineering repair approaches require new biomaterials and methods to construct scaffolds with the required structural properties as well as improved performance. As potential therapeutic strategies in bone tissue engineering, 3D printed scaffolds have been developed. Polycaprolactone/Ceramic composites have attracted considerable attention due to their cytocompatibility, biodegradability, and physical properties. In this study, a 3D printing process was used to create polycaprolactone (PCL)-Gelatin (GEL) scaffolds containing varying concentrations of Bioglass (BG) and Nano Montmorillonite (MMT). This mixture was then loaded into a 3D printer, and the scaffolds were printed layer by layer. After constructing the scaffolds, they were then examined for their physical, chemical, and biological characteristics. Surface appearance was analyzed with a scanning electron microscope (SEM), which revealed that NC increased the diameter of pores from 465 to 480 μm. The elements in the scaffolds were evaluated by EDX analysis, and a uniform dispersion of nano montmorillonite particles was observed. The compressive strength reached 76.43 MPa for PCL/G/35 %MMT/15 %BG scaffold. Also, the rate of water absorption, biodegradability and bioactivity of PCL-GEL scaffolds increased significantly in the presence of NC. According to the MTT cell test results, adding BG and NC increased cell proliferation, adhesion and cell viability to 127.7 %. These findings indicated that the 3D printed PCL/G/35 %MMT/15 %BG scaffold has promising strategies for bone repair applications. Also, polynomial curve fitting shows that scaffold degradability after soaking in PBS can be predicted using the initial weight and soaking time. Adding more variables and data could improve prediction accuracy, reducing the need for experiments and conserving resources.

Tuning the toughness, strength, and biological properties of functionally graded alumina/titania-based composites for use in bone repair applications

In this study, functionally graded composite (FGC) was prepared using a high-energy ball mill by fabricating five layers of alumina (Al2O3), titania (TiO2), hydroxyapatite (HA), and iron oxide (Fe3O4), which were sintered at 1100 °C to create an FGC sample. Scanning electron microscopy (SEM), inductively coupled plasma-atomic emission spectroscopy (ICP-AES), and weight loss measurements were used to assess bioactivity and biodegradation after immersing samples in simulated body fluid (SBF). Also, the antimicrobial activity and biocompatibility of these layers were evaluated. Furthermore, their electrical, dielectric, and mechanical properties were examined. The results revealed that all sintered layers were bioactive, and adding HA and Fe3O4 enhanced this desired property. Also, S. aureus bacterial growth was inhibited by TiO2 and Fe3O4. Fortunately, the sintered layers showed no cytotoxic effect, validating the ICP findings that demonstrated acceptable biodegradation. Adding HA and Fe3O4 enhanced fracture toughness in another hopeful outcome, which is crucial for biomaterial efficacy and long-term therapeutic success. Moreover, the compressive strength of all the layers and the FGC sample was 191.7, 182.2, 171.18, 159.8, 142.5, and 171.1 MPa. Layers 3, 4, and 5 notably had a compressive strength similar to cortical bone. This means that implanting these layers into human bone will protect the bone around them from stress-shielding action. Finally, the successive increase in HA/Fe3O4 contents increased the electrical conductivity. Accordingly, the prepared FGC sample and its layers are attractive bone substitute materials.

Evaluation of biocompatibility and osseointegration of multi-component TiAl6V4 titanium alloy implants.

This study aimed to investigate the biocompatibility and osseointegration of novel titanium (Ti) implants with a perforated part with high surface roughness (Ra >4 μm) and a smooth solid part (test group), as compared to smooth solid Ti implants (control group; Ra < 0.8 μm). Test and control implants were implanted in rabbit femurs. After 4 and 15 weeks, host tissue reaction and quality of tissue formed were evaluated with histopathology, while micro-CT scans were used to quantitatively assess bone-implant contact (BIC), surrounding bone formation, and bone ingrowth. After 4 and 15 weeks, minimal host reaction was found in the test group. Histopathological analysis showed new bone formation around the implants in both the test and control groups after 4 weeks. Furthermore, additional bone growth was often observed within the holes of the test implants. After 15 weeks, the test implants showed high bone ingrowth and the presence of mature bone in direct contact with the implant surface, whereas, bone ingrowth was poorer for the control group with 30% of the control implants, showing larger gaps at the bone-implant interface. Quantitative micro-CT analysis revealed comparable BIC and bone formation in both groups at 4 weeks, but higher BIC and more bone formation in the test group than in the control group after 15 weeks. No significant differences were observed in any of the analyses. In conclusion, partially perforated, high-roughness Ti implants showed excellent osseointegration and minimal host reaction, indicating their potential for orthopedic applications in bone repair and regeneration.

Preparation and osteogenesis of a multiple crosslinking silk fibroin/carboxymethyl chitosan/sodium alginate composite scaffold loading with mesoporous silica/poly (lactic acid-glycolic acid) microspheres.

Large bone defect repair is a striking challenge in orthopedics. Currently, inorganic-organic composite scaffolds are considered as a promising approach to these bone regeneration. Silicon ions (Si4+) are bioactive and beneficial to bone regeneration and Si4+-containing inorganic mesoporous silica (MS) can effectively load drugs for bone repair. To better control the release of drug, we prepared biodegradable MS/PLGA (MP) microspheres. MP loaded organic silk fibroin/carboxymethyl chitosan/sodium alginate (MP/SF/CMCS/SA) composite scaffolds were further constructed by genipin and Ca2+ crosslinking. All MP/SF/CMCS/SA scaffolds had good swelling ability, degradation rate and high porosity. The incorporation of 1% MP significantly enhanced the compressive strength of composite scaffolds. Besides, MP loaded scaffold showed a sustained release of Si4+ and Ca2+. Moreover, the release rate of rhodamine (a model drug) of MP/SF/CMCS/SA scaffolds was obviously lower than that of MP. When culturing with rat bone marrow mesenchymal stem cells, scaffolds with 1% MP displayed good proliferation, adhesion and enhanced osteogenic differentiation ability. Based on the results above, the addition of 1% MP in SF/CMCS/SA scaffolds is a prospective way for drug release in bone regeneration and is promising for further in vivo bone repair applications.

Toward the Production of Hydroxyapatite/Poly(Ether-Ether-Ketone) (PEEK) Biocomposites: Exploring the Physicochemical, Mechanical, Cytotoxic and Antimicrobial Properties.

The development of hydroxyapatite (HAp) and polyether ether ketone (PEEK) biocomposites has been extensively studied for bone repair applications due to the synergistic properties of the involved materials. In this study, we aimed to develop HAp/PEEK biocomposites using high-energy ball milling, with HAp concentrations (20%, 40%, and 60% w/v) in PEEK, to evaluate their physicochemical, mechanical, cytotoxicity, and antimicrobial properties for potential applications in Tissue Engineering (TE). The biocomposites were characterized by structure, morphology, apparent porosity, diametral compression strength, cytotoxicity, and antimicrobial activity. The study results demonstrated that the HAp/PEEK biocomposites were successfully synthesized. The C2 biocomposite, containing 40% HAp, stood out due to the optimal distribution of HAp particles in the PEEK matrix, resulting in higher compression strength (246 MPa) and a homogeneous microstructure. It exhibited antimicrobial activity against Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli, with no cytotoxicity observed. These properties make the C2 biocomposite promising for regenerative medicine applications, combining mechanical strength, bioactivity, and biocompatibility.

Hydroxyapatite-Based Natural Biopolymer Composite for Tissue Regeneration.

Hydroxyapatite (HAp) polymer composites have gained significant attention due to their applications in bone regeneration and tooth implants. This review examines the synthesis, properties, and applications of Hap, highlighting various manufacturing methods, including wet, dry, hydrothermal, and sol-gel processes. The properties of HAp are influenced by precursor materials and are commonly obtained from natural calcium-rich sources like eggshells, seashells, and fish scales. Composite materials, such as cellulose-hydroxyapatite and gelatin-hydroxyapatite, exhibit promising strength and biocompatibility for bone and tissue replacement. Metallic implants and scaffolds enhance stability, including well-known titanium-based and stainless steel-based implants and ceramic body implants. Biopolymers, like chitosan and alginate, combined with Hap, offer chemical stability and strength for tissue engineering. Collagen, fibrin, and gelatin play crucial roles in mimicking natural bone composition. Various synthesis methods like sol-gel, hydrothermal, and solution casting produce HAp crystals, with potential applications in bone repair and regeneration. Additionally, the use of biowaste materials, like eggshells and snails or seashells, not only supports sustainable HAp production but also reduces environmental impact. This review emphasizes the significance of understanding the properties of calcium-phosphate (Ca-P) compounds and processing methods for scaffold generation, highlighting novel characteristics and mechanisms of biomaterials in bone healing. Comparative studies of these methods in specific applications underscore the versatility and potential of HAp composites in biomedical engineering. Overall, HAp composites offer promising solutions for improving patient outcomes in bone replacement and tissue engineering and advancing medical practices.

Investigating the Effect of Carbon Nanomaterials Reinforcing Poly(ε-Caprolactone) Printed Scaffolds for Bone Repair Applications.

Scaffolds, three-dimensional (3D) substrates providing appropriate mechanical support and biological environments for new tissue formation, are the most common approaches in tissue engineering. To improve scaffold properties such as mechanical properties, surface characteristics, biocompatibility and biodegradability, different types of fillers have been used reinforcing biocompatible and biodegradable polymers. This paper investigates and compares the mechanical and biological behaviors of 3D printed poly(ε-caprolactone) scaffolds reinforced with graphene (G) and graphene oxide (GO) at different concentrations. Results show that contrary to G which improves mechanical properties and enhances cell attachment and proliferation, GO seems to show some cytotoxicity, particular at high contents.

Electrospun polycaprolactone-chitosan nanofibers on a zinc mesh as biodegradable guided bone-regeneration membranes with enhanced mechanical, antibacterial, and osteogenic properties for alveolar bone-repair applications

Guided bone-regeneration membrane (GBRM) is commonly used in bone-repair surgery because it blocks fibroblast proliferation and provides spatial support in bone-defect spaces. However, the need for removal surgery and the lack of antibacterial properties of conventional GBRM limit its therapeutic applicability for alveolar bone defects. Here we developed a GBRM for alveolar bone-repair and -regeneration applications through double-sided electrospinning of polycaprolactone and chitosan layers on a Zn mesh surface (denoted DSZM). The DSZM showed a UTS of ∼25.6 MPa, elongation of ∼16.1%, strength-elongation product of ∼0.413 GPa%, and ultrahigh spatial maintenance ability, and the UTS was over 6 times higher than that of commercial Bio-Gide membrane. The DSZM exhibited a corrosion rate of ∼17 µm/y and a Zn ion concentration of ∼0.23 µg/ml after 1 month of immersion in Hanks’ solution. The DSZM showed direct and indirect cytocompatibility with exceptional osteogenic differentiation and calcium deposition toward MC3T3-E1 cells. Further, the DSZM showed strongly sustained antibacterial activity against S. aureus and osteogenesis in a rat critical-sized maxillary defect model. Overall, the DSZM fits the requirements for alveolar bone-repair and -regeneration applications as a biodegradable GBRM material due to its spatial support, suitable degradability, cytocompatibility, and antibacterial and osteogenic capabilities. Statement of significanceThis work reports the mechanical properties, antibacterial ability and osteogenic properties of electrospun PCL-CS nanofiber on Zn mesh as biodegradable guided bone-regeneration membrane for alveolar bone-repair applications. Our findings demonstrate that the DSZM prepared by double-sided electrospinning of PCL-CS layers on Zn mesh showed a UTS of ∼25.6 MPa, elongation of ∼16.1%, strength-elongation product of ∼0.413 GPa%, and ultrahigh spatial maintenance ability, and the UTS was over 6 times greater than that of commercial Bio-Gide® membrane. The DSZM showed direct and indirect cytocompatibility with exceptional osteogenic differentiation and calcium deposition toward MC3T3-E1 cells. Further, the DSZM showed strongly sustained antibacterial activity against S. aureus and osteogenesis in a rat critical-sized maxillary defect model.

Micro/nanostructure constructed by in situ growth of SiC nanowires in porous Si3N4 ceramics

AbstractImplant materials with micro/nanostructures bear a closer resemblance with the features of natural bone, which influences the wettability, bone differentiation, and vascularization of materials. However, it is still technically challenging to design the inner wall and surface micro/nanostructures on macroporous bioceramics due to their brittleness. In this work, micro/nanostructured composites with Si3N4 whiskers as a framework, and the (inner) surface covered with SiC nanowires were prepared, denoted as SiC‐nw@Si3N4‐w bioceramics. The synthesis, adopting the green chemistry concept, was utilized from environmental products (carbon evaporated in the furnace at high temperature) and reaction impurities (carbon obtained by polymer pyrolysis and silicon obtained by Si3N4 decomposition) to synthesize SiC nanowires via a vapor‐solid growth mechanism. The prepared SiC‐nw@Si3N4‐w bioceramics have potential applications in bone repair due to their cell adhesion and proliferation.

Additive manufacturing of bioactive and biodegradable poly (lactic acid)-tricalcium phosphate scaffolds modified with zinc oxide for guided bone tissue repair

Bioactive and biodegradable scaffolds that mimic the natural extracellular matrix of bone serve as temporary structures to guide new bone tissue growth. In this study, 3D-printed scaffolds composed of poly (lactic acid) (PLA)-tricalcium phosphate (TCP) (90-10 wt.%) were modified with 1%, 5%, and 10 wt.% of ZnO to enhance bone tissue regeneration. A commercial chain extender named Joncryl was incorporated alongside ZnO to ensure the printability of the composites. Filaments were manufactured using a twin-screw extruder and subsequently used to print 3D scaffolds via fused filament fabrication (FFF). The scaffolds exhibited a homogeneous distribution of ZnO and TCP particles, a reproducible structure with 300 μm pores, and mechanical properties suitable for bone tissue engineering, with an elastic modulus around 100 MPa. The addition of ZnO resulted in enhanced surface roughness on the scaffolds, particularly for ZnO microparticles, achieving values up to 241 nm. This rougher topography was responsible for enhancing protein adsorption on the scaffolds, with an increase of up to 85% compared to the PLA-TCP matrix. Biological analyses demonstrated that the presence of ZnO promotes mesenchymal stem cell (MSC) proliferation and differentiation into osteoblasts. Alkaline phosphatase (ALP) activity, an important indicator of early osteogenic differentiation, increased up to 29%. The PLA-TCP composite containing 5% ZnO microparticles exhibited an optimized degradation rate and enhanced bioactivity, indicating its promising potential for bone repair applications.

Electrical Responsive Coating with a Multilayered TiO2-SnO2-RuO2 Heterostructure on Ti for Controlling Antibacterial Ability and Improving Osseointegration.

The bacterial infection and poor osseointegration of Ti implants could significantly compromise their applications in bone repair and replacement. Based on the carrier separation ability of the heterojunction and the redox reaction of pseudocapacitive metal oxides, we report an electrically responsive TiO2-SnO2-RuO2 coating with a multilayered heterostructure on a Ti implant. Owing to the band gap structure of the TiO2-SnO2-RuO2 coating, electron carriers are easily enriched at the coating surface, enabling a response to the endogenous electrical stimulation of the bone. With the formation of SnO2-RuO2 pseudocapacitance on the modified surface, the postcharging mode can significantly change the surface chemical state of the coating due to the redox reaction, enhancing the antibacterial ability and osteogenesis-related gene expression of the human bone marrow mesenchymal stem cells. Owing to the attraction for Ca2+, only the negatively postcharged SnO2@RuO2 can promote apatite deposition. The in vivo experiment reveals that the S-SnO2@RuO2-NP could effectively kill the bacteria colonized on the surface and promote osseointegration with the synostosis bonding interface. Thus, negatively charging the electrically responsive coating of TiO2-SnO2-RuO2 is a good strategy to endow modified Ti implants with excellent antibacterial ability and osseointegration.

Organic-inorganic nHA-Gelatin/Alginate high strength macroporous cryogel promotes bone regeneration

Macroporous cryogel has the advantages of nutrient exchange and cell growth, and is an ideal material for tissue regeneration. In order to strengthen the machenical properties of cryogel for the widely use, a high strength gelatin/sodium alginate/nano hydroxyapatite (nHA) porous cryogel (GA-HA cryogel) was prepared by a simple freeze-thaw process. The mechanical strength of GA-HA cryogel increased significantly with the increase of nHA content. In vitro studies showed that GA-HA cryogel had good biocompatibility and no obvious cytotoxicity to MC3T3-E1 cells. The results of alkaline phosphatase activity assay and osteocalcin immunofluorescence staining showed that GA-HA1 porous hydrogel system could significantly increase the expression of MC3T3-E1 alkaline phosphatase and osteocalcin when the content of nHA was 1 ​%. In addition, porous GA-HA cryogel showed good performance in promoting bone regeneration in rat skull defect model. Therefore, the high-strength double network cryogel prepared in this study can provide new applications in bone repair and tissue regeneration.

Additive manufacturing of polylactic acid scaffolds dip-coated with polycaprolactone for bone tissue engineering

Bone tissue engineering aims to create scaffolds that support bone regeneration, addressing the needs of approximately 1.71 billion people with bone structure problems worldwide. This study explores the fabrication and characterization of 3D-printed polylactic acid (PLA) scaffolds dip-coated with polycaprolactone (PCL), producing complex geometries with interconnected pores, specifically RoundBar Sphere and RoundBar Cube. The scaffolds were then coated with PCL solutions of 0.5 % and 1 % concentrations, applying up to three layers. Surface topology analysis indicated that PCL coating slightly reduced pore size (1150 µm to 900) while improving coverage and integrity. After coating, Fourier Transform Infrared Spectroscopy (FTIR) confirmed the presence of PCL on scaffold surfaces (characteristic bands at 1726, 1175 and 728 cm−1), whose a better coverage was obtained with more layers and higher concentrations of PCL. Coated scaffolds showed not significant change in compressive strengths (2–12 MPa), remaining suitable for trabecular bone applications. Hemolysis assays of the 3D scaffolds promoted non-hemolytic properties (0 % hemolysis), ensuring their blood compatibility. Metabolic activity (>70 %) and live/dead cell assays in human dermal fibroblasts (HDF) exhibited biocompatibilities for all samples, with coated scaffolds promoting enhanced cell proliferation compared to uncoated ones. Additionally, osteoblast metabolic activity (>90 %) and osteoblasts scratch assay demonstrated coated scaffolds promoted an area reduction of 1.36 and 1.53-fold higher than the control group and uncoated scaffold, respectively. In short, these coated scaffolds are promising candidates for bone tissue engineering and bone repair applications.

Biomimetic Bi3+ substituted borate bioactive glasses for bone tissue engineering via enhanced biological and antimicrobial activity

Biomimetic borate-based bioactive glasses (BAGs), substituted with metal oxides, serve as prominent candidates for the repair and regeneration of both hard and soft tissues. In the current study, bismuth mixed borate BAGs (60-X) B2O3–25CaO–15Na2O–XBi2O3 (X = 2, 4, 6, 8 & 10 mol.%) were synthesized using melt-quench method and systematically evaluated for their structural properties, followed by in-vitro biological performance and enhanced antimicrobial activity, using various characterization techniques and bioassays. The BAG structure was studied by Fourier transform infrared (FTIR), differential thermal analysis (DTA), and X-ray photoelectron spectroscopy (XPS) methods. The density and mechanical properties of the BAGs were found to increase with increase in bismuth content of the borate glass network. The XPS analysis confirmed the presence of Bi3+ ions embedded in the glass network. From DTA, it is noticed that the glass transition temperature (Tg) decreased and thermal stability (ΔT) values increased, with increased Bi2O3 content. Further, the bioactivity via hydroxy apatite (HAp) layer formation was confirmed by X-ray diffraction (XRD), FTIR, scanning electron microscopy- energy dispersive spectra (SEM-EDS) and Atomic force microscopy (AFM), both before and after soaking the glass samples in simulated body fluid (SBF) for 0, 7, 14, and 21 days. The results revealed that Bi3+ modified borate BAGs exhibited good HAp layer formation on their surfaces upon immersion in SBF solution. Moreover, the pH variation and degradation followed a trend, with increased in immersion time and decrease with Bi2O3 content. Lastly, in vitro cell culture tests on MG-63 osteoblast-like cells demonstrated that the as-developed BAGs were non-toxic and cytocompatible in nature; in addition, they also displayed demonstrable antibacterial activity against S. aureus and E. coli bacterial strains. Thus, the developed Bi2O3 mixed borate BAGs become suitable candidates for bone substitutes, especially for bone tissue regeneration and repair applications.

A hydrogel containing Mg2+ with improved osteogenesis, enhanced endochondral ossification, and modulated inflammation for bone-repair applications

In this study, an injectable, porous, and Mg2+-loaded hydrogel with the ability to scavenge local reactive oxygen species was developed for bone-repair applications. Alendronate sodium with a specific binding affinity to Mg2+ was incorporated into the hydrogel through a Schiff’s base reaction with oxidized dextran. The porous hydrogel, which was cross-linked by catechol-modified chitosan to maintain its mechanical properties, showed enhanced cell viability, proliferation, differentiation of human bone marrow stromal cells in vitro, and osteogenic property in a rat-femur defect model. The hydrogel promoted the regeneration of bone tissue including ossification and particularly endochondral ossification, indicating a progressive healing process. The formed bone tissue exhibited a dense and layered structure, substantiating its effectiveness in osteogenic differentiation. The hydrogel also affected the polarization of macrophages and inhibited the M1 phenotype associated with tissue repair and regeneration, exhibiting the potential to reduce local inflammatory response and benefit bone repair. Overall, the hydrogel can be anticipated as a promising biomaterial for bone repair because of its multiple biofunctions including enhanced osteogenesis and endochondral ossification, and modulation of inflammation.

Highly Stable Amorphous (Pyro)phosphate Aggregates: Pyrophosphate as a Carrier for Bioactive Ions and Drugs in Bone Repair Applications

Highly Stable Amorphous (Pyro)phosphate Aggregates: Pyrophosphate as a Carrier for Bioactive Ions and Drugs in Bone Repair Applications