A review of the biological response to ionic dissolution products from bioactive glasses and glass-ceramics

Achievements in Mesoporous Bioactive Glasses for Biomedical Applications

Nowadays, mesoporous bioactive glasses (MBGs) are envisaged as promising candidates in the field of bioceramics for bone tissue regeneration. This is ascribed to their singular chemical composition, structural and textural properties and easy-to-functionalize surface, giving rise to accelerated bioactive responses and capacity for local drug delivery. Since their discovery at the beginning of the 21st century, pioneering research efforts focused on the design and fabrication of MBGs with optimal compositional, textural and structural properties to elicit superior bioactive behavior. The current trends conceive MBGs as multitherapy systems for the treatment of bone-related pathologies, emphasizing the need of fine-tuning surface functionalization. Herein, we focus on the recent developments in MBGs for biomedical applications. First, the role of MBGs in the design and fabrication of three-dimensional scaffolds that fulfil the highly demanding requirements for bone tissue engineering is outlined. The different approaches for developing multifunctional MBGs are overviewed, including the incorporation of therapeutic ions in the glass composition and the surface functionalization with zwitterionic moieties to prevent bacterial adhesion. The bourgeoning scientific literature on MBGs as local delivery systems of diverse therapeutic cargoes (osteogenic/antiosteoporotic, angiogenic, antibacterial, anti-inflammatory and antitumor agents) is addressed. Finally, the current challenges and future directions for the clinical translation of MBGs are discussed.

Highly water-stable bimetallic organic framework MgCu-MOF74 for inhibiting bacterial infection and promoting bone regeneration

As a typical metal-organic framework (MOF), Mg-MOF74 can release biocompatible Mg²⁺when the framework is degraded, and it has the potential to be used as filler in the field of bone tissue engineering. However, Mg-MOF74 has poor stability in aqueous environment and limited antibacterial ability, which limit its further development and applications. In this work, MgCu-MOF74 particles with different Cu content were synthesized through a facile one-step hydrothermal method. The physicochemical properties and water stability of the synthesized powders were characterized. The osteogenic potential of the MgCu-MOF74 particles on human osteogenic sarcoma cells (SaOS-2) was evaluated. The hybrid MgCu-MOF74 exhibited favorable water stability. These results indicated that MgCu-MOF74 enhanced cellular viability, alkaline phosphatase levels, collagen (COL) synthesis and osteogenesis-related gene expression. Moreover, the samples doped with Cu²⁺were more sensitive to the acidic microenvironment produced by bacteria, and exhibited stronger antibacterial ability than Mg-MOF74. In conclusion, MgCu-MOF-74 with good water stability, osteogenic ability and antibacterial ability, which could be attributed to the doping of Cu²⁺. Hence, MgCu-MOF74 shows great potential as a novel medical bio-functional fillers for the treatment of bone defects.

Poly(Glycerol Succinate) as Coating Material for 1393 Bioactive Glass Porous Scaffolds for Tissue Engineering Applications

BACKGROUND

Aliphatic polyesters are widely used for biomedical, pharmaceutical and environmental applications due to their high biodegradability and cost-effective production. Recently, star and hyperbranched polyesters based on glycerol and ω-carboxy fatty diacids have gained considerable interest. Succinic acid and bio-based diacids similar to glycerol are regarded as safe materials according to the US Food and Drug Administration (FDA). Bioactive glass scaffolds utilized in bone tissue engineering are relatively brittle materials. However, their mechanical properties can be improved by using polymer coatings that can further control their degradation rate, tailor their biocompatibility and enhance their performance. The purpose of this study is to explore a new biopolyester poly(glycerol succinate) (PGSuc) reinforced with mesoporous bioactive nanoparticles (MSNs) as a novel coating material to produce hybrid scaffolds for bone tissue engineering.

METHODS

Bioactive glass scaffolds were coated with neat PGSuc, PGSuc loaded with dexamethasone sodium phosphate (DexSP) and PGSuc loaded with DexSP-laden MSNs. The physicochemical, mechanical and biological properties of the scaffolds were also evaluated.

RESULTS

Preliminary data are provided showing that polymer coatings with and without MSNs improved the physicochemical properties of the 1393 bioactive glass scaffolds and increased the ALP activity and alizarin red staining, suggesting osteogenic differentiation potential when cultured with adipose-derived mesenchymal stem cells.

CONCLUSIONS

PGSuc with incorporated MSNs coated onto 1393 bioactive glass scaffolds could be promising candidates in bone tissue engineering applications.

Influence of Copper-Strontium Co-Doping on Bioactivity, Cytotoxicity and Antibacterial Activity of Mesoporous Bioactive Glass

Mesoporous bioactive glass (MBG) is an extensively studied biomaterial used for the healing of bone defects. Its biological applications can be tailored by introducing metallic ions, such as strontium (Sr) and copper (Cu), which can enhance its functionalities, including osteogenetic, angiogenetic and antibacterial functionalities. In this study, Cu and Sr ions were co-doped (ratio 1:1) with x = 0.5, 1 and 2 mol% each in glass with an intended nominal composition of 80SiO2-(15-2x)CaO-5P2O5-xCuO-xSrO and synthesized with an evaporation-induced self-assembly (EISA)-based sol-gel technique. XRD confirmed the amorphous nature of the glass, while compositional analysis using ICP-OES confirmed the presence of dopant ions with the required amounts. A TEM study of the MBG powders showed fringes that corresponded to the formation of a highly ordered mesoporous structure. The Cu-Sr-doped MBG showed a positive effect on apatite formation when immersed in SBF, although the release of Cu and Sr ions was relatively slow for 1 mol% of each co-dopant, which signified a stable network structure in the glass. The impact of the Cu and Sr ions on the osteoblast-like cell line MG-63 was assessed. At the particle concentrations of 1 wt./vol.% or lower, the cell viability was above 50%. An antibacterial test was conducted against Gram-negative E. coli and Gram-positive S. aureus bacteria. With a sequential increase in the co-doped ion content in the glass, the zone of inhibition for bacteria increased. The results suggest that the doping of MBG with Cu and Sr ions at up to 2 mol% can result in tailored sustained release of ions to enhance the applicability of the studied glass as a functional biomaterial for bone regeneration applications.

Bioactivity Potential of Bioceramic-Based Root Canal Sealers: A Scoping Review

INTRODUCTION

Bioceramic-based root canal sealers are novel materials with a bioactivity potential that stands out compared with conventional root canal sealers. However, the term bioactivity may be overused and is often misunderstood. Hence, the objective of this study was to synthesize and map key concepts related to the bioactivity analysis of bioceramic-based root canal sealers.

METHODS

The present scoping review is reported in accordance with the PRISMA-ScR Statement and is registered in the Open Science Framework. Two blinded reviewers carried out a comprehensive search in six databases up to January 10th, 2022: MEDLINE, Scopus, Embase, Web of Science, Cochrane Library, and Lilacs/BBO. Eligibility was considered for in vitro and in vivo studies that evaluated the bioactivity potential of bioceramic-based root canal sealers.

RESULTS

A total of 53 studies were included in the qualitative synthesis. In vitro bioactivity was evaluated through the mineralization potential, formation of carbonated apatite on the surface, and the gene expression related to proteins involved in the mineralization process. Meanwhile, for in vivo studies, staining techniques associated with immunohistochemical tests were mainly used to detect mineralization on the material-host tissue interface.

CONCLUSIONS

According to the methodology used, the most prevalent methods to assess bioactivity in acellular form were the immersion of the material in Hank's balanced salt solution, followed by surface observation with scanning electron microscopy and energy dispersive X-ray. In cell cultures, the chosen method was usually Alizarin Red staining, followed by the evaluation of alkaline phosphatase enzymatic activity and the use of molecular biology tests.

Gallium containing bioactive materials: A review of anticancer, antibacterial, and osteogenic properties

The incorporation of gallium into bioactive materials has been reported to enhance osteogenesis, to influence blood clotting, and to induce anti-cancer and anti-bacterial activity. Gallium-doped biomaterials prepared by various techniques include melt-derived and sol-gel-derived bioactive glasses, calcium phosphate bioceramics, metals and coatings. In this review, we summarize the recently reported developments in antibacterial, anticancer, osteogenesis, and hemostasis properties of Ga-doped biomaterials and briefly outline the mechanisms leading to Ga biological effects. The key finding is that gallium addition to biomaterials has great potential for treating bone-related diseases since it can be efficiently transferred to the desired region at a controllable rate. Besides, it can be used as a potential substitute for antibiotics for the inhibition of infections during the initial and advanced phases of the wound healing process. Ga is also used as an anticancer agent due to the increased concentration of gallium around excessive cell proliferation (tumor) sites. Moreover, we highlight the possibility to design different therapeutic approaches aimed at increasing the efficiency of the use of gallium containing bioactive materials for multifunctional applications.

MOF-derived CuO@ZnO modified titanium implant for synergistic antibacterial ability, osteogenesis and angiogenesis

Surface modification of titanium implants with antibacterial, osteogenic and even angiogenic capabilities are essential to enhance their clinical applicability. Herein, metal-organic framework (MOF) derived CuO@ZnO composite was grafted onto the polydopamine (PDA) modified titanium alloy to achieve vascularized bone regeneration. The CuO@ZnO-coated titanium effectively inhibits the formation of bacterial biofilms and the sterilization rate of Staphylococcus aureus (S. aureus) reaches 99%. Benefitting from the intrinsic porous architecture of MOFs, the Zn2+ and Cu2+ could be controllably released to facilitate the production of excess intracellular reactive oxygen species (ROS) inside the bacteria, which ensures the excellent antibacterial performance of the composite coating. The CuO@ZnO-coated titanium also exhibits good cytocompatibility, effectively promotes the adhesion and proliferation of the human bone marrow mesenchymal stem cells (hBMSCs) and reduces the level of the cell apoptosis. The up-regulated expression of the osteogenesis-related genes and the superior extracellular matrix mineralization reveals that the CuO@ZnO coating possesses fantastic osteoinductive properties. In addition, the transwell and tube formation assays of the human umbilical vein endothelial cells (HUVECs) suggest the superior angiogenesis ability of the CuO@ZnO-coated titanium. The released Cu2+ stimulated the angiogenesis of the HUVECs in vitro by up-regulating the expression of the vascular endothelial growth factor (VEGF). These findings will provide new insight into the development of multifunctional titanium implants for clinical applications.

Taguchi grey relational optimization of sol-gel derived hydroxyapatite from a novel mix of two natural biowastes for biomedical applications

The comparative study of natural hydroxyapatite (NHAp) from bovine (B) and catfish (C) bones using different fabrication parameters has been extensively researched through traditional investigation. However, the quantitative effect optimization of a novel mix proportion of hydroxyapatite from these bones, and fabrication parameters have not been examined. Hence, this study presents the effect of the powder mixture, compaction pressure, and sintering temperature (as production parameters) on the experimental mechanical properties of naturally derived HAp. The bovine bone and catfish bone biowastes were used in mixed proportions to produce hydroxyapatite via the sol-gel synthesis protocol. The powders were calcined separately at 900 °C to convert the deproteinized biowaste. Next, the powders were combined chemically (sol-gel) in the appropriate ratios (i.e. 45 g of B: 15 g of C (B75/C25), 30 g of B: 30 g of C (B50/C50), and 15 g of B; 45 g of C (B25/C75)). Taguchi design supported by grey relational analysis was employed with an L9 orthogonal array. The Minitab 16 software was employed to analyze the Taguchi design. The result revealed an inconsistency in the powder mixture as the optimum state for individual mechanical properties, but the grey relational analysis (GRA) showed better mechanical properties with a powder mix of B50/C50, 500 Pa compaction pressure, and 900 °C sintering temperature. The obtained result further showed that the novel mix of these powders is a good and promising material for high-strength biomedical applications, having a contribution of 97.79% on hardness and 94.39% on compressive strength of HAp. The obtained experimental grey relational grade of 0.7958 is within the 95% confidence interval, according to confirmation analysis (CA). The optimum powder parameter was examined using X-ray diffraction (XRD), and its structure, size, and elemental makeup were examined using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analysis. The sample had a higher degree of crystallinity and mean crystallite size of 80.42% and 27.3 nm, respectively. The SEM images showed big, gritty grains that are not tightly packed.

Porous biomaterials for tissue engineering: a review

The field of biomaterials has grown rapidly over the past decades. Within this field, porous biomaterials have played a remarkable role in: (i) enabling the manufacture of complex three-dimensional structures; (ii) recreating mechanical properties close to those of the host tissues; (iii) facilitating interconnected structures for the transport of macromolecules and cells; and (iv) behaving as biocompatible inserts, tailored to either interact or not with the host body. This review outlines a brief history of the development of biomaterials, before discussing current materials proposed for use as porous biomaterials and exploring the state-of-the-art in their manufacture. The wide clinical applications of these materials are extensively discussed, drawing on specific examples of how the porous features of such biomaterials impact their behaviours, as well as the advantages and challenges faced, for each class of the materials.

Cancer Inhibition and In Vivo Osteointegration and Compatibility of Gallium-Doped Bioactive Glasses for Osteosarcoma Applications

Traditional osteosarcoma therapies tend to focus solely on eradicating residual cancer cells and often fail to promote local bone regeneration and even inhibit it due to lack of precise control over target cells, i.e., the treatment affects both normal and cancer cells. Typically, multistep procedures are required for optimal efficacy. Here, we found that a silica-based bioactive material containing 3 mol % gallium oxide selectively kills human osteosarcoma cells and presents excellent in vivo osteointegration, while showing no local or systemic toxicity. Cell culture media conditioned with the proposed material was able to kill 41% of osteosarcoma cells, and no significant deleterious effect on normal human osteoblasts was observed. In addition, rats treated with the gallium-doped material showed excellent material-bone integration with no sign of local toxicity or implant rejection. Systemic biocompatibility investigation did not indicate any sign of toxicity, with no presence of fibrosis or cellular infiltrate in the histological microstructure of the liver and kidneys after 56 days of observation. Taken together, these results show that synergistic bone regeneration and targeted cancer therapy can be combined, paving the way toward new bone cancer treatment approaches.

Ameliorative effect of different mesoporous bioactive glass materials in experimental tibial defects in rats

Background

Enhancing the bone healing procedure would resultantly improve the post-recovery life quality, as well as the speed with which the patient returns to their former life quality. Porous structures can provide a large surface area and abundant channels to facilitate mass transfer.

Objective

To evaluate the application of mesoporous materials in the bone healing of surgically created defects on the tibiae of male adult Wistar rats.

Methods

The defect areas were evaluated after implantation of 4 types of bioactive glass histopathologically and immunohistochemically. Fifty adult rats were divided into 5 groups including a control group without material. The used products were mesoporous bioactive glass (MBG), Cu-MBG, Zn-MBG, and Cu-Zn-MBG. Unicortical bone defects with a 3 mm diameter were performed in both tibiae of the animals and filled with 4 types of glass particles. The rats were then euthanized at 15 d and 30 d. Tibial samples were collected and the tissues forwarded for histological processing, and examined using light microscopy. Additionally, bone healing was evaluated by assessing the levels of bone morphogenetic protein BMP2, collagen 1, osteocalcin (OST), and vascular endothelial growth factor (VEGF) using immunohistochemical methods.

Results

Within the 15th day, all groups presented connective tissue septa; at the 30th day, the new bone formation was more intense in the Cu-Zn-MBG group. Additionally, BMP2, collagen 1, OST, and VEGF immune expression were more prominent in the Cu-Zn-MBG group.

Conclusions

The study results indicated that MBG may be used for the repairing of bone defects. Cu-Zn-MBG may be the best choice for this purpose.

In-situ forming hydrogel based on thiolated chitosan/carboxymethyl cellulose (CMC) containing borate bioactive glass for wound healing

Suitable wound dressings for accelerating wound healing are actively being designed and synthesised. In this study, thiolated chitosan (tCh)/oxidized carboxymethyl cellulose (OCMC) hydrogel containing Cu-doped borate bioglass (BG) was developed as a wound dressing to improve wound healing in a full-thickness skin defect of mouse animal model. Thiolation was used to incorporate thiol groups into chitosan (Ch) to enhance its water solubility and mucoadhesion characteristics. Here, the in situ forming hydrogel was successfully developed using the Schiff-based reaction, and its physio-chemical and antibacterial characteristics were examined. Borate BG was also incorporated in the generated hydrogel to promote angiogenesis and tissue regeneration at the wound site. Investigations of in vitro cytotoxicity assays demonstrated that the synthesised hydrogels showed good biocompatibility and promoted cell growth. These results inspired us to investigate the effectiveness of skin wound healing in a mouse model. On the backs of animals, two full-thickness wounds were created and treated utilising two different treatment conditions: (1) OCMC/tCh hydrogel, (2) OCMC/tCh/borate BG, and (3) control defect. The wound closure ratio, collagen deposition, and angiogenesis activity were measured after 14 days to determine the healing efficacy of the in situ hydrogels used as wound dressings. Overall, the hydrogel containing borate BG was maintained in the defect site, healing efficiency was replicable, and wound healing was apparent. In conclusion, we found consistent angiogenesis, remodelling, and accelerated wound healing, which we propose may have beneficial effects on the repair of skin defects.

Smart biomaterials and their potential applications in tissue engineering

Smart biomaterials have been rapidly advancing ever since the concept of tissue engineering was proposed. Interacting with human cells, smart biomaterials can play a key role in novel tissue morphogenesis. Various aspects of biomaterials utilized in or being sought for the goal of encouraging bone regeneration, skin graft engineering, and nerve conduits are discussed in this review. Beginning with bone, this study summarizes all the available bioceramics and materials along with their properties used singly or in conjunction with each other to create scaffolds for bone tissue engineering. A quick overview of the skin-based nanocomposite biomaterials possessing antibacterial properties for wound healing is outlined along with skin regeneration therapies using infrared radiation, electrospinning, and piezoelectricity, which aid in wound healing. Furthermore, a brief overview of bioengineered artificial skin grafts made of various natural and synthetic polymers has been presented. Finally, by examining the interactions between natural and synthetic-based biomaterials and the biological environment, their strengths and drawbacks for constructing peripheral nerve conduits are highlighted. The description of the preclinical outcome of nerve regeneration in injury healed with various natural-based conduits receives special attention. The organic and synthetic worlds collide at the interface of nanomaterials and biological systems, producing a new scientific field including nanomaterial design for tissue engineering.

Therapeutic application of hydrogels for bone-related diseases

Bone-related diseases caused by trauma, infection, and aging affect people’s health and quality of life. The prevalence of bone-related diseases has been increasing yearly in recent years. Mild bone diseases can still be treated with conservative drugs and can be cured confidently. However, serious bone injuries caused by large-scale trauma, fractures, bone tumors, and other diseases are challenging to heal on their own. Open surgery must be used for intervention. The treatment method also faces the problems of a long cycle, high cost, and serious side effects. Studies have found that hydrogels have attracted much attention due to their good biocompatibility and biodegradability and show great potential in treating bone-related diseases. This paper mainly introduces the properties and preparation methods of hydrogels, reviews the application of hydrogels in bone-related diseases (including bone defects, bone fracture, cartilage injuries, and osteosarcoma) in recent years. We also put forward suggestions according to the current development status, pointing out a new direction for developing high-performance hydrogels more suitable for bone-related diseases.

Premixed Calcium Silicate-Based Root Canal Sealer Reinforced with Bioactive Glass Nanoparticles to Improve Biological Properties

Recently, bioactive glass nanoparticles (BGns) have been acknowledged for their ability to promote interactions with the periapical tissue and enhance tissue regeneration by releasing therapeutic ions. However, there have been no studies on calcium silicate sealers with bioactive glass nanoparticle (BGn) additives. In the present study, a premixed calcium silicate root canal sealer reinforced with BGn (pre-mixed-RCS@BGn) was developed and its physicochemical features and biological effects were analyzed. Three specimens were in the trial: 0%, 0.5%, and 1% bioactive glass nanoparticles (BGns) were gradually added to the premixed type of calcium silicate-based sealer (pre-mixed-RCS). To elucidate the surface properties, scanning electron microscopy, X-ray diffraction, and energy-dispersive spectroscopy were used and flowability, setting time, solubility, and radiopacity were analyzed to evaluate the physical properties. Chemical properties were investigated by water contact angle, pH change, and ion release measurements. The antibacterial effects of the bioactive set sealers were tested with Enterococcus faecalis and the viability of human bone marrow-derived mesenchymal stem cells (hMSCs) with this biomaterial was examined. In addition, osteogenic differentiation was highly stimulated, which was confirmed by ALP (Alkaline phosphatase) activity and the ARS (Alizarin red S) staining of hMSCs. The pre-mixed-RCS@BGn satisfied the ISO standards for root canal sealers and maintained antimicrobial activity. Moreover, pre-mixed-RCS@BGn with more BGns turned out to have less cytotoxicity than pre-mixed-RCS without BGns while promoting osteogenic differentiation, mainly due to calcium and silicon ion release. Our results suggest that BGns enhance the biological properties of this calcium silicate-based sealer and that the newly introduced pre-mixed-RCS@BGn has the capability to be applied in dental procedures as a root canal sealer. Further studies focusing more on the biocompatibility of pre-mixed-RCS@BGn should be performed to investigate in vivo systems, including pulp tissue.

Cytotoxicity and Antibacterial Activity of Mineral Trioxide Aggregate Cement with Radiopacity Introduced by ZrO2

The article presents the results of in vitro studies on cytotoxicity and antibacterial activity of new MTA-type cements, developed on the basis of the sintered tricalcium silicate enriched with ZnO, along with an agent introducing the radiopacity in the form of ZrO₂. The new materials have been developed to ensure that their physical and chemical properties are suited for endodontic applications. The cements were evaluated via characterisation of setting time, compressive strength, as well as translucency on X-ray images, and bioactivity in the simulated body fluid (SBF). The μCT was used to test the influence of the ZrO₂ grains in the powder component on the microstructure of the produced cement. Then, the cytotoxic action of the cements was evaluated by applying a reference L-929 cell line. The conditions of the culture upon contact with the tested materials or with extracts from the cements were assessed using image analysis or an MTT colorimetric assay. Two strains of streptococci, Streptococcus mutans and Streptococcus sanguinis, were used to study the antibacterial activity of the tested cements with ZrO₂ acting as the agent introducing the radiopacity. The new cements are characterised by appropriate properties as far as retrograde root canal filling is concerned.

A Bilayer Membrane Doped with Struvite Nanowires for Guided Bone Regeneration

Guided bone regeneration (GBR) therapy demonstrates a prominent curative effect on the management of craniomaxillofacial (CMF) bone defects. In this study, a GBR membrane consisting of a microporous layer and a struvite-nanowire-doped fibrous layer is constructed via non-solvent induced phase separation, followed by an electrospinning procedure to treat critical-sized calvarial defects. The microporous layer shows selective permeability for excluding the rapid-growing non-osteogenic tissues and potential wound stabilization. The nanowire-like struvite is synthesized as the deliverable therapeutic agent within the fibrous layer to facilitate bone regeneration. Such a membrane displays a well-developed heterogeneous architecture, satisfactory mechanical performance, and long-lasting characteristics. The in vitro biological evaluation reveals that apart from being a strong barrier, the bilayer struvite-laden membrane can actively promote cellular adhesion, proliferation, and osteogenic differentiation. Consequently, the multifunctional struvite-doped membranes are applied to treat 5 mm-sized bilateral calvarial defects in rats, resulting in overall improved healing outcomes compared with the untreated or the struvite-free membrane-treated group, which is characterized by enhanced osteogenesis and significantly increased new bone formation. The encouraging preclinical results reveal the great potential of the bilayer struvite-doped membrane as a clinical GBR device for augmenting large-area CMF bone reconstruction.

3D printing of inorganic-biopolymer composites for bone regeneration

In most cases, bone injuries heal without complications, however, there is an increasing number of instances where bone healing needs major clinical intervention. Available treatment options have severe drawbacks, such as donor site morbidity and limited availability for autografting. Bone graft substitutes containing growth factors would be a viable alternative, however they have been associated with dose-related safety concerns and lack control over spatial architecture to anatomically match bone defect sites. 3D printing offers a solution to produce patient specific bone graft substitutes that are customized to the patient bone defect with temporal control over the incorporated therapeutics to maximize their efficacy. Inspired by the natural constitution of bone tissue, composites made of inorganic phases, such as nanosilicate particles, calcium phosphate, and bioactive glasses, combined with biopolymer matrices have been investigated as building blocks for the biofabrication of bone constructs. Besides capturing elements of the bone physiological structure, these inorganic/organic composites can be designed for specific cohesivity, rheological and mechanical properties, while both inorganic and organic constituents contribute to the composite bioactivity. This review provides an overview of 3D printed composite biomaterial-inks for bone tissue engineering. Furthermore, key aspects in biomaterial-ink design, 3D printing techniques, and the building blocks for composite biomaterial-inks are summarized.

Synthesis of nano hydroxyapatite from Hypopthalmichthys molitrix (silver carp) bone waste by two different methods: a comparative biophysical and in vitro evaluation on osteoblast MG63 cell lines

More than a thousand tonnes of fish bone wastes can be transformed into biomedical products annually. Alkaline hydrolysis and thermal calcification were used to create nanosized hydroxyapatite (HAp) crystals from Silver carp bone wastes. Biophysical tests were used to determine the nano size and chemical composition of synthesised hydroxyapatite. Alkaline hydrolysis hydroxyapatite (AH-HAp) was 58.3 nm, while Thermal calcination hydroxyapatite (TC-HAp) was 64.3 nm in size, confirmed by Atomic Force Microscopy. Energy Dispersive X-ray Analysis studies showed Ca/P (Calcium phosphate) ratio of AH-HAp to be 1.65, whereas TC-HAp as 1.45, confirming AH-HAp to be organically rich along with a similar Ca/P ratio as natural HAp. Fourier Transform Infrared Spectroscopy spectra indicated HAp formation from both procedures, however AH-HAp had superior crystallinity than TC-HAp confirmed from X-Ray Diffraction spectra. MG63 osteoblast cell lines showed 91% cell viability in cytotoxicity studies and 70.1% proliferation efficiency in Alkaline Phosphatase assay, which was higher than TC-HAp. The present study shows that HAp produced via alkaline hydrolysis has better biocompatibility which enhances its applicability as a biomaterial, than HAp synthesized through thermal calcination, which tends to incinerate organic moieties.

Rapid Synthesis of Multifunctional Apatite via the Laser-Induced Hydrothermal Process

Synthetic biomaterials are used to overcome the limited quantity of human-derived biomaterials and to impart additional biofunctionality. Although numerous synthetic processes have been developed using various phases and methods, currently commonly used processes have some issues, such as a long process time and difficulties with extensive size control and high-concentration metal ion substitution to achieve additional functionality. Herein, we introduce a rapid synthesis method using a laser-induced hydrothermal process. Based on the thermal interaction between the laser pulses and titanium, which was used as a thermal reservoir, hydroxyapatite particles ranging from nanometer to micrometer scale could be synthesized in seconds. Further, this method enabled selective metal ion substitution into the apatite matrix with a controllable concentration. We calculated the maximum temperature achieved by laser irradiation at the surface of the thermal reservoir based on the validation of three simplification assumptions. Subsequent linear regression analysis showed that laser-induced hydrothermal synthesis follows an Arrhenius chemical reaction. Hydroxyapatite and Mg²⁺-, Sr²⁺-, and Zn²⁺-substituted apatite powders promoted bone cell attachment and proliferation ability due to ion release from the hydroxyapatite and the selective ion-substituted apatite powders, which had a low crystallinity and relatively high solubility. Laser-induced hydrothermal synthesis is expected to become a powerful ceramic material synthesis technology.

Osteoimmunomodulation role of exosomes derived from immune cells on osseointegration

Despite the high success rate of biomedical implants adopted clinically, implant failures caused by aseptic loosening still raise the risk of secondary surgery and a substantial economic burden to patients. Improving the stable combination between the implant and the host bone tissue, achieving fast and high-quality osseointegration can effectively reduce the probability of aseptic loosening. Accumulating studies have shown that the osteoimmunomodulation mediated by immune cells mainly dominated by macrophages plays a pivotal role in osseointegration by releasing active factors to improve the inflammatory microenvironment. However, the mechanism by which osteoimmunomodulation mediates osseointegration remains unclear. Recent studies have revealed that exosomes released by macrophages play a central role in mediating osteoimmunomodulation. The exosomes can be internalized by various cells participating in de novo bone formation, such as endothelial cells and osteoblasts, to intervene in the osseointegration robustly. Therefore, macrophage-derived exosomes with multifunctionality are expected to significantly improve the osseointegration microenvironment, which is promising in reducing the occurrence of aseptic loosening. Based on this, this review summarizes recent studies on the effects of exosomes derived from the immune cells on osseointegration, aiming to provide a theoretical foundation for improving the clinical success rate of biomedical implants and achieving high-quality and high-efficiency osseointegration.

A study of bioactive glass-ceramic's mechanical properties, apatite formation, and medical applications

Apparently, bioactive glass-ceramics are made by doing a number of steps, such as creating a microstructure from dispersed crystals within the residual glass, which provides high bending strength, and apatite crystallizes on surfaces of glass-ceramics when calcium ions are present in the blood. Apatite crystals grow on the glass and ceramic surfaces due to the hydrated silica. These materials are biocompatible with living bone in a matter of weeks, don't weaken mechanically or histologically, and exhibit good osteointegration as well as mechanical properties that are therapeutically relevant, such as fracture toughness and flexural strength. As part of this study, we examined mechanical properties, process mechanisms involved in apatite formation, and potential applications for bioactive glass-ceramic in orthopedic surgery, including load-bearing devices.

Dual photothermal nanocomposites for drug-resistant infectious wound management

Management of antibiotic-resistant bacteria-induced skin infections for rapid healing remains a critical clinical challenge. Photothermal therapy, which uses mediated hyperthermia to combat such problems, has recently been recognised as a promising approach to take. In this study, bacterial cellulose-based photothermal membranes were designed and developed to combat bacterial infections and promote rapid wound healing. Polydopamine was incorporated into gold nanoparticles to produce superior dual-photothermal behaviour. The in vitro antibacterial efficacy of the prepared composite membranes against S. aureus, E. coli and methicillin-resistant Staphylococcus aureus (MRSA) could reach 99% under near-infrared (NIR) irradiation. In addition, the synthesised nanocomposite exhibited good biocompatibility in vitro as demonstrated by a cell survival ratio of >85%. The effectiveness of the composite membranes on wound healing was further investigated in a murine model of MRSA-infected wounds, focusing on the effect of photothermal temperature. According to the detailed therapeutic mechanism study undertaken, the composite membranes cause bacterial killing initially and promote the transition from the inflammatory phase to proliferation by suppressing pro-inflammatory cytokine production, promoting collagen deposition, and stimulating angiogenesis. Considering their remarkable effectiveness and facile fabrication process, it is expected that these novel materials could serve as competitive multifunctional dressings in the management of infectious wounds and accelerate the regeneration of damaged tissues related to abnormal immune responses.

A Preliminary Study about the Role of Reactive Oxygen Species and Inflammatory Process after COVID-19 Vaccination and COVID-19 Disease

During the last couple of critical years, worldwide, there have been more than 550 million confirmed cases of COVID-19, including more than 6 million deaths (reported by the WHO); with respect to these cases, several vaccines, mainly mRNA vaccines, seem to prevent and protect from SARS-CoV-2 infection. We hypothesize that oxidative stress is one of the key factors playing an important role in both the generation and development of various kinds of disease, as well as antibody generation, as many biological paths can generate reactive oxygen species (ROS), and cellular activities can be modulated when ROS/antioxidant balance is interrupted. A pilot study was conducted in two stages during the COVID-19 pandemic in 2021 involving 222 participants between the ages of 26 and 66 years. ROS levels were measured before an after vaccination in the blood samples of 20 individuals who were vaccinated with two doses of mRNA vaccine, and an increase in ROS levels was observed after the first dose, with no modifications observed until the day before the second vaccination dose. A statistically significant difference (p < 0.001) was observed between time points 3 and 4 (before and after second dose), when participants were vaccinated for the second time, and ROS levels decreased from 21,758 to 17,580 a.u. In the second stage, blood was collected from 28 participants 45 days after COVID-19 infection (Group A), from 131 participants 45 days after receiving two doses of mRNA vaccine against COVID-19 (Group B), and from 13 healthy individuals as a control group (Group C). Additionally, antibodies levels were measured in all groups to investigate a possible correlation with ROS levels. A strong negative correlation was found between free radicals and disease antibodies in Group A (r = −0.45, p = 0.001), especially in the male subgroup (r = −0.88, p = 0.001), as well as in the female subgroup (r = −0.24, p < 0.001). Furthermore, no significant correlation (only a negative trend) was found with antibodies derived from vaccination in Group B (r = −0.01), and a negative trend was observed in the female subgroup, whereas a positive trend was observed in the male subgroup.

Tailoring Cu2+-loaded electrospun membranes with antibacterial ability for guided bone regeneration

Copper (Cu)-loaded electrospun membranes were tailored for guided bone regeneration (GBR), targeting the stimulation of innate cells active in bone growth and the prevention of bacterial infections. Functional GBR membranes were produced via an electrospinning set-up using a silk-based solution associated with polyethylene oxide (Silk/PEO - control). Experimental groups were loaded with copper oxide using varying weight percentages (0.05 % to 1 % of CuO). The morphological, structural, chemical, and mechanical properties of membranes were evaluated. Direct and indirect in vitro cytocompatibility experiments were performed with primary human bone mesenchymal stem cells and primary human umbilical vein endothelial cells. The antibacterial potential of membranes was tested with Staphylococcus aureus and Fusobacterium nucleatum biofilm. CuO was successfully incorporated into membranes as clusters without compromising their mechanical properties for clinical applicability. Increased Cu concentrations generated membranes with thinner nanofibers, greater pore areas, and stronger antimicrobial effect (p < 0.01). Cu²⁺ ion was released from the nanofiber membranes during 1 week, showing higher release in acidic conditions. CuO 0.1 % and CuO 0.05 % membranes were able to support and stimulate cell adhesion and proliferation (p < 0.05), and favor angiogenic responses of vascular cells. In addition, detailed quantitative and qualitative analysis determined that amount of the attached biofilm was reduced on the tailored functional Cu²⁺-loaded GBR membrane. Importantly, these qualities represent a valuable strategy to improve the bone regeneration process and diminish the risk of bacterial infections.

Advances in nanoenabled 3D matrices for cartilage repair

Cartilage repair strategies are evolving at a fast pace with technology development. Matrices that offer multifaceted functions and a full adaption to the cartilage defect are of pivotal interest. Current cartilage repair strategies face numerous challenges, mostly related to the development of highly biomimetic materials, non-invasive injectable solutions, and adequate degradation rates. These strategies often fail due to feeble mechanical properties, the inability to sustain cell adhesion, growth, and differentiation or by underestimating other players of cartilage degeneration, such as the installed pro-inflammatory microenvironment. The integration of nanomaterials (NMs) into 3D scaffolds, hydrogels and bioinks hold great potential in the improvement of key features of materials that are currently applied in cartilage tissue engineering strategies. NMs offer a high surface to volume ratio and their multiple applications can be explored to enhance cartilage mechanical properties, biocompatibility, cell differentiation, inflammation modulation, infection prevention and even to function as diagnostic tools or as stimuli-responsive cues in these 3D structures. In this review, we have critically reviewed the latest advances in the development of nanoenabled 3D matrices - enhanced by means of NMs - in the context of cartilage regeneration. We have provided a wide perspective of the synergistic effect of combining 3D strategies with NMs, with emphasis on the benefits brought by NMs in achieving functional and enhanced therapeutic outcomes. STATEMENT OF SIGNIFICANCE: Cartilage is one of the most challenging tissues to treat owing to its limited self-regeneration potential. Novel strategies using nanoenabled 3D matrices have emerged from the need to design more efficient solutions for cartilage repair, that take into consideration its unique mechanical properties and can direct specific cell behaviours. Here we aim to provide a comprehensive review on the synergistic effects of 3D matrices nanoenrichment in the context of cartilage regeneration, with emphasis on the heightening brought by nanomaterials in achieving functional and enhanced therapeutic outcomes. We anticipate this review to provide a wide perspective on the past years' research on the field, demonstrating the great potential of these approaches in the treatment and diagnosis of cartilage-related disorders.

Powder 3D Printing of Bone Scaffolds with Uniform and Gradient Pore Sizes Using Cuttlebone-Derived Calcium Phosphate and Glass-Ceramic

The pore geometry of bone scaffolds has a major impact on their cellular response; for this reason, 3D printing is an attractive technology for bone tissue engineering, as it allows for the full control and design of the porosity. Calcium phosphate materials synthesized from natural sources have recently attracted a certain interest because of their similarity to natural bone, and they were found to show better bioactivity than synthetic compounds. Nevertheless, these materials are very challenging to be processed by 3D printing due to technological issues related to their nanometric size. In this work, bone scaffolds with different pore geometries, with a uniform size or with a size gradient, were fabricated by binder jetting 3D printing using a biphasic calcium phosphate (BCP) nanopowder derived from cuttlebones. To do so, the nanopowder was mixed with a glass-ceramic powder with a larger particle size (45–100 µm) in 1:10 weight proportions. Pure AP40mod scaffolds were also printed. The sintered scaffolds were shown to be composed mainly by hydroxyapatite (HA) and wollastonite, with the amount of HA being larger when the nanopowder was added because BCP transforms into HA during sintering at 1150 °C. The addition of bio-derived powder increases the porosity from 60% to 70%, with this indicating that the nanoparticles slow down the glass-ceramic densification. Human mesenchymal stem cells were seeded on the scaffolds to test the bioactivity in vitro. The cells’ number and metabolic activity were analyzed after 3, 5 and 10 days of culturing. The cellular behavior was found to be very similar for samples with different pore geometries and compositions. However, while the cell number was constantly increasing, the metabolic activity on the scaffolds with gradient pores and cuttlebone-derived powder decreased over time, which might be a sign of cell differentiation. Generally, all scaffolds promoted fast cell adhesion and proliferation, which were found to penetrate and colonize the 3D porous structure.

Experimental borosilicate bioactive glasses: pulp cells cytocompatibility and mechanical characterisation

AIM

To assess in vitro the effect of two novel phase separated borosilicate glasses (PSBS) in the system SiO₂ -B₂ O₃ -K₂ O-CaO-Al₂ O₃ on dental pulp cells; and to compare their bioactivity and mechanical properties to a conventional fluoroaluminosilicate glass namely FUJI IX.

METHODOLOGY

The cytocompatibility assessment of the two novel borosilicate glasses, one without alumina (PSBS8) and one containing alumina (PSBS16), was performed on cultured primary human pulp cells (hDPCs). Alamar blue assay was used to assess cell metabolic activity and cell morphology was evaluated by confocal imaging. The bioactivity in Stimulated Body Fluid was also evaluated after 1 and 3 weeks of immersion using SEM-EDX analysis. Vickers microhardness and flexural strength were assessed after incorporating the glass particles into a commercial glass ionomer cement liquid containing both polyacrylic and polybasic carboxylic acid.

RESULTS

The data revealed that the two borosilicate glasses enhanced cell viability ratios at all-time points in both direct and indirect contact assays. After 3 days of contact, PSBS8 without alumina showed higher viability rate (152%) compared to the PSBS16 containing alumina (145%) and the conventional glass ionomer particles (117%). EDX analysis confirmed an initial Ca/P ratio of 2.1 for 45S5K and 2.08 for PSBS8 without alumina after 3 weeks of immersion. The cement prepared using PSBS8 showed significantly higher Vickers hardness values (p=0.001) than that prepared using PSBS16 (46.6 vs 36.7 MPa). After 24 hours of maturation, PSBS8 (without alumina) exhibited a flexural strength of 12.9 MPa compared to a value of 16.4 MPa for the commercial control. PSBS8 without alumina had a higher strength than PSBS16 with alumina, after 1 and 7 days of maturation (p=0.001).

CONCLUSIONS

The present in vitro results demonstrated that the borosilicate bioactive glass without alumina enhanced pulp cell viability, spreading and acellular bioactivity better than the conventional glass ionomer cement and the experimental borosilicate glass containing alumina.

Zn-Mn-Doped Mesoporous Bioactive Glass Nanoparticle-Loaded Zein Coatings for Bioactive and Antibacterial Orthopedic Implants

In recent years, natural polymers have replaced synthetic polymers for antibacterial orthopedic applications owing to their excellent biocompatibility and biodegradability. Zein is a biopolymer found in corn. The lacking mechanical stability of zein is overcome by incorporating bioceramics, e.g., mesoporous bioactive glass nanoparticles (MBGNs). In the present study, pure zein and zein/Zn–Mn MBGN composite coatings were deposited via electrophoretic deposition (EPD) on 316L stainless steel (SS). Zn and Mn were co-doped in MBGNs in order to make use of their antibacterial and osteogenic potential, respectively. A Taguchi design of experiment (DoE) study was established to evaluate the effect of various working parameters on the morphology of the coatings. It was observed that coatings deposited at 20 V for 5 min with 4 g/L concentration (conc.) of Zn–Mn MBGNs showed the highest deposition yield. Uniform coatings with highly dispersed MBGNs were obtained adopting these optimized parameters. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) were employed to investigate the morphology and elemental composition of zein/Zn–Mn MBGN composite coatings. Surface properties, i.e., coating roughness and wettability analysis, concluded that composite coatings were appropriate for cell attachment and proliferation. For adhesion strength, various techniques, including a tape test, bend test, pencil hardness test, and tensile test, were performed. Wear and corrosion analysis highlighted the mechanical and chemical stability of the coatings. The colony forming unit (CFU) test showed that the zein/Zn–Mn MBGN composite coating was highly effective against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) due to the presence of Zn. The formation of a hydroxyapatite (HA)-like structure upon immersion in the simulated body fluid (SBF) validated the in vitro bioactivity of the coating. Moreover, a WST-8 assay depicted that the MG-63 cells proliferate on the composite coating. It was concluded that the zein/Zn–Mn MBGN coating synthesized in this work can be used for bioactive and antibacterial orthopedic applications.

Borate Bioactive Glasses (BBG): Bone Regeneration, Wound Healing Applications, and Future Directions

Since the early 2000s, borate bioactive glasses (BBGs) have been extensively investigated for biomedical applications. The research so far indicates that BBGs frequently exhibit superior bioactivity and bone healing capacity compared to silicate glasses. They are also suitable candidates as drug delivery devices for infection or disease treatment such as osteoporosis. Additionally, BBGs are also an excellent option for wound healing applications, which includes the availability of commercial (FDA approved) microfibrous BBG dressings to treat chronic wounds. By addition of modifying ions, the bone or wound healing capacity of BBGs can be enhanced. For instance, addition of copper ions into BBGs was shown to drastically increase blood vessel formation for wound healing applications. Moreover, addition of ions such as magnesium, strontium, and cobalt improves bone healing. Other recent research interest related to BBGs is focused on nerve and muscle regeneration applications, while cartilage regeneration is also suggested as a potential application field for BBGs. BBGs are commonly produced by melt-quenching; however, sol-gel processing of BBGs is emerging and appears to be a promising alternative. In this review paper, the physical and biological characteristics of BBGs are analyzed based on the available literature, the applications of BBGs are discussed, and future research directions are suggested.

Synthesis, Processing and the Effect of Thermal Treatment on the Solubility, Antioxidant Potential and Cytocompatibility of Y2O3 and CeO2 doped SiO2-SrO-Na2O Glass-Ceramics

Thermal treatment of a 0.52SiO₂-0.24SrO-0.24-xNa₂O-xMO glass-ceramic series (where x = 0.08 and MO = Y₂O₃ or CeO₂) was conducted in order to synthesize yttrium (Y³⁺) and cerium (Ce³⁺) crystalline species that may act as radical oxygen specie (ROS) scavengers. The prominent phase for the Control is a sodium-strontium-silicate while the experimental glass-ceramics (HY, YCe, and HCe) present sodium-Y/Ce-silicate and oxide phases. Disk shrinkage during thermal processing ranges from 1-7% for Control, HY, YCe, and HCe in both diameter and thickness. Solubility studies determined that the release of Si⁴⁺ and Na⁺ are greatest from the Control disks which peaks at 1550 µg/mL. Release from the Y³⁺ and Ce³⁺ glass-ceramics reached 320 µg/mL for Si⁴⁺ and 630 µg/mL for Na⁺. The range of antioxidant capacity (ABTS assay) for all samples was 0.31-3.9 mMTE. No significant reduction in MC 3T3 Osteoblast cell viability was observed for any composition tested.

A Review on the Recent Advancements on Therapeutic Effects of Ions in the Physiological Environments

This review focuses on the therapeutic effects of ions when released in physiological environments. Recent studies have shown that metallic ions like Ag+, Sr2+, Mg2+, Mn2+, Cu2+, Ca2+, P+5, etc., have shown promising results in drug delivery systems and regenerative medicine. These metallic ions can be loaded in nanoparticles, mesoporous bioactive glass nanoparticles (MBGNs), hydroxyapatite (HA), calcium phosphates, polymeric coatings, and salt solutions. The metallic ions can exhibit different functions in the physiological environment such as antibacterial, antiviral, anticancer, bioactive, biocompatible, and angiogenic effects. Furthermore, the metals/metalloid ions can be loaded into scaffolds to improve osteoblast proliferation, differentiation, bone development, fibroblast growth, and improved wound healing efficacy. Moreover, different ions possess different therapeutic limits. Therefore, further mechanisms need to be developed for the highly controlled and sustained release of these ions. This review paper summarizes the recent progress in the use of metallic/metalloid ions in regenerative medicine and encourages further study of ions as a solution to cure diseases.

Magnetic bioactive glass nano-heterostructures: a deeper insight into magnetic hyperthermia properties in the scope of bone cancer treatment

Primary bone cancers commonly involve surgery to remove the malignant tumor, complemented with a postoperative treatment to prevent cancer resurgence. Studies on magnetic hyperthermia, used as a single treatment or in synergy with chemo- or radiotherapy, have shown remarkable success in the past few decades. Multifunctional biomaterials with bone healing ability coupled with hyperthermia property could thus be of great interest to repair critical bone defects resulting from tumor resection. For this purpose, we designed superparamagnetic and bioactive nanoparticles (NPs) based on iron oxide cores (γ-Fe₂O₃) encapsulated in a bioactive glass (SiO₂-CaO) shell. Nanometric heterostructures (122 ± 12 nm) were obtained through a two-step process: co-precipitation of 16 nm sized iron oxide NPs, followed by the growth of a bioactive glass shell via a modified Stöber method. Their bioactivity was confirmed by hydroxyapatite growth in simulated body fluid, and cytotoxicity assays showed they induced no significant death of human mesenchymal stem cells after 7 days. Calorimetric measurements were carried out under a wide range of alternating magnetic field amplitudes and frequencies, considering clinically relevant parameters, and some were made in viscous medium (agar) to mimic the implantation conditions. The experimental specific loss power was predictable with respect to the Linear Response Theory, and showed a maximal value of 767 ± 77 W g_Fe^-1 (769 kHz, 23.9 kA m^-1 in water). An interesting value of 166 ± 24 W g_Fe^-1 was obtained under clinically relevant conditions (157 kHz, 23.9 kA m^-1) for the heterostructures immobilized in agar. The good biocompatibility, bioactivity and heating ability suggest that these γ-Fe₂O₃@SiO₂-CaO NPs are a promising biomaterial to be used as it is or included in a scaffold to heal bone defects resulting from bone tumor resection.

Strontium doped bioglass incorporated hydrogel-based scaffold for amplified bone tissue regeneration

Repairing of large bone injuries is an important problem in bone regeneration field. Thus, developing new therapeutic approaches such as tissue engineering using 3D scaffolds is necessary. Incorporation of some bioactive materials and trace elements can improve scaffold properties. We made chitosan/alginate/strontium-doped bioglass composite scaffolds with optimized properties for bone tissue engineering. Bioglass (BG) and Sr-doped bioglasses (Sr-BG) were synthesized using Sol–Gel method. Alginate-Chitosan (Alg/Cs) scaffold and scaffolds containing different ratio (10%, 20% and 30%) of BG (Alg/Cs/BG10, 20, 30) or Sr-BG (Alg/Cs/Sr-BG10, 20, 30) were fabricated using freeze drying method. Characterization of bioglasses/scaffolds was done using zeta sizer, FTIR, XRD, (FE) SEM and EDS. Also, mechanical strength, antibacterial effect degradation and swelling profile of scaffolds were evaluated. Bone differentiation efficiency and viability of MSCs on scaffolds were determined by Alizarin Red, ALP and MTT methods. Cell toxicity and antibacterial effect of bioglasses were determined using MTT, MIC and MBC methods. Incorporation of BG into Alg/Cs scaffolds amplified biomineralization and mechanical properties along with improved swelling ratio, degradation profile and cell differentiation. Mechanical strength and cell differentiation efficiency of Alg/Cs/BG20 scaffold was considerably higher than scaffolds with lower or higher BG concentrations. Alg/Cs/Sr-BG scaffolds had higher mechanical stability and more differentiation efficiency in comparison with Alg/Cs and Alg/Cs/BG scaffolds. Also, Mechanical strength and cell differentiation efficiency of Alg/Cs/Sr-BG20 scaffold was considerably higher than scaffolds with various Sr-BG concentrations. Biomineralization of Alg/Cs/BG scaffolds slightly was higher than Alg/Cs/Sr-BG scaffolds. Overall, we concluded that Alg/Cs/Sr-BG20 scaffolds are more suitable for repairing bone major injuries.

Electrospun fibers of poly (lactic acid) containing bioactive glass and magnesium oxide nanoparticles for bone tissue regeneration

Electrospun fibers of poly (lactic acid) (PLA) containing 10 and 20 wt% of bioactive glass (n-BG) and magnesium oxide (n-MgO) nanoparticles of ca. 27 and 23 nm respectively, were prepared toward to application in bone tissue engineering. The addition of both nanoparticles into the PLA will produce a synergic effect increasing its bioactivity and antimicrobial behavior. Neat PLA scaffold and the composites with MgO showed an average fiber diameter of 1.7 ± 0.6 μm, PLA/n-BG and PLA/n-BG/n-MgO fibers presented a significant diameter increase reaching values of ca. 3.1 ± 0.8 μm. Young's modulus of the electrospun scaffolds was affected by the direct presence of the particle and scaffold morphologies. All the composites having n-BG presented bioactivity through the precipitation of hydroxyapatite structures on the surface. Although n-MgO did not add bioactivity to the PLA fibers, they were able to render antimicrobial characteristics reducing the S. aureus viability around 30%, although an effect on E. coli strain was not observed. PLA/n-BG nanocomposites did not display any significant antimicrobial behavior. The different composites increased the alkaline phosphatase (ALP) expression as compared with pure PLA barely affecting the cell viability, meaning a good osteoblastic phenotype expression capacity, with PLA/n-BG presenting the highest osteoblastic expression.

Tunable Behavior in Solution of Amorphous Calcium Ortho/Pyrophosphate Materials: An Acellular In Vitro Study

Amorphous calcium phosphate-based materials are of major interest in the field of bone substitution. Very recently, the low-temperature synthesis of a new family of amorphous calcium phosphate containing both orthophosphate and pyrophosphate ions in controlled proportions has been reported. Despite their interest, especially due to the biochemical role and the hydrolysis of pyrophosphate occurring in vivo, the behavior of such materials when interacting with aqueous media has never been described. Consequently, we herein report the in vitro acellular evolution of three compositions of mixed calcium ortho- and pyrophosphate amorphous materials including a different orthophosphate proportion. As a first step to assess the physicochemical reactivity of these amorphous materials, they were tested in two different media at 37 °C, acidified water and simulated body fluid solution, from 1 h up to 15 days. The results demonstrated that they were quite stable and that they progressively released part of their constitutive ions, highlighting their potential for controlled delivery of bioactive ions (calcium, orthophosphate, and pyrophosphate ions). In addition to these properties, we showed that the material with the highest ortho/(ortho + pyro) phosphate ratio started to crystallize into nanocrystalline apatite analogous to bone mineral within 2 days or 2 weeks depending on the medium. For the other material compositions, no layer of apatite was detected at their surface with SBF testing despite the favorable supersaturation indexes, crystallization being probably inhibited by pyrophosphate ions released in the medium. This varying apatite-forming ability emphasizes the key role of the ortho/(ortho + pyro) phosphate ratio of these materials in their in vitro reactivity and bioactivity, which paves the way for the development of this promising family of amorphous calcium phosphate materials with tunable physicochemical and biological properties.

Porcine liver injury model to assess tantalum-containing bioactive glass powders for hemostasis

This study evaluates compositions of tantalum-containing mesoporous bioactive glass (Ta-MBG) powders using a porcine fatal liver injury model. The powders based on (80-x)SiO₂-15CaO-5P₂O₅-xTa₂O₅ compositions with x = 0 (0Ta/Ta-free), 1 (1Ta), and 5 (5Ta) mol% were made using a sol-gel process. A class IV hemorrhage condition was simulated on the animals; hemodynamic data and biochemical analysis confirmed the life-threatening condition. Ta-MBGs were able to stop the bleeding within 10 min of their application while the bleeds in the absence of any intervention or in the presence of a commercial agent, Arista^TM (Bard Davol Inc., Rhode Island, USA) continued for up to 45 min. Scanning electron microscopy (SEM) imaging of the blood clots showed that the presence of Ta-MBGs did not affect clot morphology. Rather, the connections seen between fibrin fibers of the blood clot and Ta-MBG powders point towards the powders' surfaces embracing fibrin. Histopathological analysis of the liver tissue showed 5Ta as the only composition reducing parenchymal hemorrhage and necrosis extent of the tissue after their application. Additionally, 5Ta was also able to form an adherent clot in worst-case scenario bleeding where no adherent clot was seen before the powder was applied. In vivo results from the present study agree with in vitro results of the previous study that 5Ta was the best Ta-MBG composition for hemostatic purposes. Graphical abstract.

Sustained local ionic homeostatic imbalance caused by calcification modulates inflammation to trigger heterotopic ossification

Heterotopic ossification (HO) is a condition triggered by an injury leading to the formation of mature lamellar bone in extraskeletal soft tissues. Despite being a frequent complication of orthopedic and trauma surgery, brain and spinal injury, the etiology of HO is poorly understood. The aim of this study is to evaluate the hypothesis that a sustained local ionic homeostatic imbalance (SLIHI) created by mineral formation during tissue calcification modulates inflammation to trigger HO. This evaluation also considers the role SLIHI could play for the design of cell-free, drug-free osteoinductive bone graft substitutes. The evaluation contains five main sections. The first section defines relevant concepts in the context of HO and provides a summary of proposed causes of HO. The second section starts with a detailed analysis of the occurrence and involvement of calcification in HO. It is followed by an explanation of the causes of calcification and its consequences. This allows to speculate on the potential chemical modulators of inflammation and triggers of HO. The end of this second section is devoted to in vitro mineralization tests used to predict the ectopic potential of materials. The third section reviews the biological cascade of events occurring during pathological and material-induced HO, and attempts to propose a quantitative timeline of HO formation. The fourth section looks at potential ways to control HO formation, either acting on SLIHI or on inflammation. Chemical, physical, and drug-based approaches are considered. Finally, the evaluation finishes with a critical assessment of the definition of osteoinduction. STATEMENT OF SIGNIFICANCE: The ability to regenerate bone in a spatially controlled and reproducible manner is an essential prerequisite for the treatment of large bone defects. As such, understanding the mechanism leading to heterotopic ossification (HO), a condition triggered by an injury leading to the formation of mature lamellar bone in extraskeletal soft tissues, would be very useful. Unfortunately, the mechanism(s) behind HO is(are) poorly understood. The present study reviews the literature on HO and based on it, proposes that HO can be caused by a combination of inflammation and calcification. This mechanism helps to better understand current strategies to prevent and treat HO. It also shows new opportunities to improve the treatment of bone defects in orthopedic and dental procedures.

Experimental data on the characterization of hydroxyapatite produced from a novel mixture of biowastes

The purpose of this data narrative is to report the morphological structures, functional groups, elemental composition, pH adaptability and mechanical properties of hydroxyapatite (HAp) biomaterials synthesized from a novel mixture of biowastes (bovine and catfish bones) by a simple sol-gel method assisted with sintering at 900 °C. The produced powders were homogenously mixed by the sol-gel approach at different weights (depicted by sample nomenclature) and characterized using scanning electron microscopy (SEM) equipped with electron dispersive X-ray analysis (EDX), X-ray fluorescence (XRF), Fourier Transform Infrared Spectroscopy (FT-IR), immersion in phosphate buffer saline (PBS), and mechanical measurements (hardness and fracture toughness). The SEM micrographs revealed pore interconnections in all samples. The EDX analysis revealed that the as-sintered HAp samples had Ca/P weight ratios of 2.38, 2.51, 2.86, 2.89, and 3.10 for C100, BC 75/25, BC 50/50, BC 25/75, and B100 samples, respectively. The FT-IR spectra was typical of the bands associated with hydroxyapatite (i.e., those associated with the PO₄³⁻ , CO₃^2- groups and absorbed water). The prepared biomaterials showed pH adaptability and good mechanical strength.

Application of non-metal nanoparticles, as a novel approach, for improving the stability of blood products: 2011-2021

Despite the importance of the proper quality of blood products for safe transfusion, conventional methods for preparation and their preservation, they lack significant stability. Non-metal nanoparticles with particular features may overcome these challenges. This review study for the first time provided a comprehensive vision of the interaction of non-metal nanoparticles with each blood product (red blood cells, platelets and plasma proteins). The findings of this review on the most effective nanoparticle for improving the stability of RBCs indicate that graphene quantum dots and nanodiamonds show compatibility with RBCs. For increasing the stability of platelet products, silica nanoparticles exhibited a suppressive impact on platelet aggregation. Pristine graphene also shows compatibility with platelets. For better stability of plasma products, graphene oxide was indicated to preserve free human serum albumin from thermal shocks at low ionic strength. For increased stability of Factor VIII, mesoporous silica nanoparticles with large pores exhibit the superb quality of recovered proteins. Furthermore, 3.2 nm quantum dots exhibited anticoagulant effects. As the best promising nanoparticles for immunoglobulin stability, graphene quantum dots showed compatibility with γ-globulins. Overall, this review recommends further research on the mentioned nanoparticles as the most potential candidates for enhancing the stability and storage of blood components.