Borate-based glasses are attractive for bone regeneration due to their rapid dissolution and their ability to promote the formation of an apatite-like layer in physiological environments. However, a challenge associated with borate glasses is controlling boron ion (B) release, which is critical for maintaining biocompatibility and structural stability. In this study, a borate glass series based on 47B2O3-XSrO-17ZnO-11Ag2O-(25-X)CaO (wt%, X = 0, 1, 3, and 5) glasses were synthesized to investigate the influence of strontium oxide (SrO) on glass structure, thermal behaviour, and B release. X-ray diffraction (XRD) confirmed that all compositions were fully amorphous, and 11B magic angle spinning nuclear magnetic resonance (MAS-NMR) revealed no significant changes in B speciation with SrO incorporation. Differential scanning calorimetry (DSC) showed a progressive decrease in melting temperature with increasing SrO content, suggesting that SrO modifies the melt behavior of the borate glass system. However, the relatively constant Tg and Tc values across compositions indicate that overall thermal stability and network rigidity were not substantially altered. Immersion in phosphate-buffered saline for up to 60 days demonstrated that B release increased with immersion time, while only the highest SrO substitution (5 wt%) showed a statistically significant difference compared with the Sr-free control. These findings suggest that, within alkali-free borate glass systems, SrO acts as a secondary network modifier that modestly influences long-term B dissolution without substantially altering early-stage degradation behavior.

Bone defects caused by trauma, infection, or tumor resection remain difficult to treat because successful repair requires both structural restoration and control of the local pathological microenvironment. Osteolysis, defined as pathological bone resorption, is central to many of these conditions and is commonly driven by excessive osteoclast activity. Clinically translated injectable products such as NovaBone® Putty demonstrate the value of moldable bioactiveglass grafts for defect filling; however, conventional silicate bioactive glasses are permanent and provide limited therapeutic ion release. This limitation has motivated the development of injectable borate bioactive glass (B-BGs) and injectable borosilicate bioactive glass (BS-BG) systems as more degradable, ion-releasing platforms for hard-tissue regeneration. Early borate/chitosan cements showed injectability, apatite formation, and bone-regenerative potential, but rapid boron release raised concerns regarding biological safety. SrO incorporations was therefore introduced to moderate dissolution while enhancing osteogenesis. Because vascularization is also essential for defect repair, subsequent systems targeted vascular endothelial growth factor (VEGF) signaling either through direct VEGF delivery or indirect Cu-mediated VEGF upregulation. For osteomyelitis, where bacterial infection accelerates bone destruction, B-BG/BS-BG cements have been loaded with vancomycin or gentamicin to provide localized antibiotic release after debridement. Magnetothermal systems further expand this approach by incorporating magnetic nanoparticles that generate heat under an alternating magnetic field to disrupt bacteria or ablate tumor cells. In osteosarcoma, B-BG/BS-BG platforms offer combined bone regeneration and local therapy through magnetic hyperthermia, metal-containing adhesives, and dual hyperthermia/chemotherapy systems incorporating doxorubicin. Overall, these systems show promise but require stricter release control, safety validation, and mechanical durability assessment.

Comminuted fractures, characterized by multiple bone fragments, present significant challenges in orthopedic surgery. Effective treatment often requires augmentation techniques to enhance fixation stability and promote bone regeneration. This review explores the application of bone void filler materials, including autografts, allografts, polymethyl methacrylate (PMMA), and synthetic bone substitutes such as calcium phosphate ceramics and bioactive glass, in managing comminuted fractures. Autografts are the gold standard due to their superior osteogenic potential but are limited by donor site morbidity and availability. Allografts mitigate these issues but face concerns regarding immunogenicity and reduced biological activity. PMMA, widely used for structural augmentation, provides immediate stability but suffers from thermal necrosis, polymer shrinkage, and cytotoxic risks. Synthetic bone substitutes, including calcium phosphate cement and bioactive glass, offer promising alternatives by promoting bone integration while reducing complications associated with traditional grafts. However, their mechanical limitations and their artificial nature leave room for improvement. The review highlights recent advancements in biomaterial modifications to improve degradation rates, osteointegration, and mechanical resilience, such as composite materials and ion-doped bio ceramics. Despite these innovations, a gap remains in developing an ideal augmentation material that combines structural integrity with bioactivity. Future research should focus on integrating bioactive elements with load-bearing capabilities to optimize patient outcomes in comminuted fracture management.

Metastatic bone lesions are often osteolytic, which causes advanced-stage cancer sufferers to experience severe pain and an increased risk of developing a pathological fracture. Gallium (Ga) ion possesses antineoplastic and anti-bone resorption properties, suggesting the potential for its local administration to impede the growth of metastatic bone lesions. This study investigated the chemotherapeutic potential, cytotoxicity, and osteogenic effects of a Ga-doped glass polyalkenoate cement (GPC) (C-TA2) compared to its non-gallium (C-TA0) counterpart. Ion release profiles revealed a biphasic pattern characterized by an initial burst followed by a gradually declining release of ions. C-TA2 continued to release Ga steadily throughout the experimentation period (7 d) and exhibited prolonged zinc (Zn) release compared to C-TA0. Interestingly, the Zn release from both GPCs appeared to cause a chemotherapeutic effect against H1092 lung cancer cellsin vitro, with the prolonged Zn release from C-TA2 extending this effect. Unfortunately, both GPCs enhanced the viability of HCC2218 breast cancer cells, suggesting that the chemotherapeutic effects of Zn could be tied to cellular differences in preferred Zn concentrations. The utilization of SAOS-2 and MC3T3 cell lines as bone cell models yielded conflicting results, with the substantial decline in MC3T3 viability closely associated with silicon (Si) release, indicating cellular variations in Si toxicity. Despite this ambiguity, both GPCs exhibited harmful effects on the osteogenesis of primary rat osteoblasts, raising concerns about excessive burst Zn release. While Ga/Zn-doped GPCs hold promise for treating metastatic bone lesions caused by lung cancers, further optimization is required to mitigate cytotoxicity on healthy bone.

Haemorrhage is the leading cause of battlefield deaths and second most common cause for civilian mortality worldwide. Biomaterials-based haemostatic agents are used to aid in bleeding stoppage; mesoporous bioactive glasses (MBGs) are candidates for haemostasis. Previously made Tantalum-containing MBG (Ta-MBG) powders' compositions were fabricated as electrospun fibres for haemostatic applications in the present study. The fibres were fabricated to address the challenges associated with the powder form: difficult to compress without gauze, getting washed away in profuse bleeding, generating dust in the surgical environment, and forming thick callus-difficult to remove for surgeons and painful for patients. Ta-MBGs were based on (80-x)SiO2-15CaO-5P2O5-xTa2O5 mol% compositions with x = 0 (0Ta), 0.5 (0.5Ta), 1 (1Ta), and 5 (5Ta) mol%. The present study details the fibres' in vitro analyses, elucidating their cytotoxic effects, and haemostatic capabilities and relating these observations to fibre chemistry and previously fabricated powders of the same glasses. As expected, when Ta addition is increased at the expense of silica, a new FTIR peak (non-bridging oxygen-silicon, Si-NBO) develops and Si-O-Si peaks become wider. Compared to 0Ta and 1Ta fibres, 0.5Ta show Si-O peaks with reduced intensity. The fibres had a weaker intensity of Si-NBO peaks and release fewer ions than powders. A reduced ion profile provides fibres with a stable matrix for clot formation. The ion release profile for 1Ta and 5Ta fibres was significantly lower than 0Ta and 0.5Ta fibres. Ta-MBGs were not found to be cytotoxic to primary rat fibroblasts using a methyl thiazolyl tetrazolium (MTT) assay. Furthermore, a modified activated partial thromboplastin time assay analysing the fibrin absorbance showed that the absorption increases from physiological clotting < 0Ta < 0.5Ta < 5Ta < commercial haemostat, Surgical SNoWTM, Ethicon, USA < 1Ta. Higher absorption signifies a stronger clot. It is concluded that Ta-MBG fibres can provide stable matrix for clot formation and 1Ta can potentially enhance clotting best among other Ta-MBGs.

Adhesive-augmented sternal fixation (AASF) has been investigated as an alternative to the clinical standard of cerclage wires; however, previous studies have focused on a full adhesive layer across the sternal midline, which acts as a barrier to bone healing. This study used a human cadaveric model to investigate if partial coverage AASF used in combination with wired fixation could provide adequate stability. Median sternotomies were performed on fifteen human cadaveric sterna. Three groups (n = 5) with varying adhesive coverage (50 %, 62.5 %, 75 %) of the sternal midline and traditional wiring were investigated. Cyclic lateral distraction loading of 10 N to 100 N was applied at 50 N/s. Every 30 cycles, the maximum load was increased by 100 N to a maximum of 500 N. Displacement was measured using transducers spanning the transection line at the manubrium, body, and xiphoid. Mean maximum total displacement (MMTD) for all groups was significantly below 2 mm (p < 0.001) with 1.49 mm ± 0.82 mm, 0.97 mm ± 0. 55 mm, and 0.67 mm ± 0.65 mm in the 50 %, 62.5 %, and 75 % groups respectively. MMTD in the 50 % group was significantly greater than MMTD in the 62.5 % and 75 % groups. AASF improved stability as coverage of the sternal surface with adhesive increased. Partial coverage of the sternal midline with adhesive may provide similar rigidity to a full layer while enabling earlier sternal ossification at the transection line compared to wiring alone.

Lidocaine hydrochloride is used as an anesthetic for clinical applications. This study considers the effects of the substitution of 2% lidocaine hydrochloride for deionized (DI) water on the rheological, mechanical, ion release, pH and injectable properties of two formulations of aluminum-free glass polyalkenoate cements (GPCs) using two distinct poly(acrylic) acids (PAA), E9 and E11, which have different molecular weights (Mw). The substitution of 2% lidocaine hydrochloride demonstrated increased injectability, but did not affect mechanical properties. The mechanical properties increased with time, as expected, and, in general, E9-based GPCs displayed significantly higher strengths over E11-based GPCs. With respect to ion release, which includes calcium (Ca), strontium (Sr), zinc (Zn) and silicon (Si); all ions displayed a steady and consistent increased release over time. Ca and Sr showed similar ion release patterns, whereby the GPC made with E11 PAA and lidocaine hydrochloride released significantly more ions than all other compositions likely due to similar chemical kinetics. However, Zn is also divalent in nature, but displayed only one significant difference across the GPC series at all time points, which was attributed to its higher electronegativity allowing for increased participation in the setting reaction. Finally, an analysis of the pH confirmed an increase in pH with time, suggesting that H+ ions were attacking the glass structure to allow for ion release. After 1 and 7 days, water-based GPCs environments achieved a higher pH than lidocaine hydrochloride-based GPCs, indicating that the lidocaine hydrochloride may be releasing additional protons upon bond formation with PAA.

Median sternotomy provides access to the heart and surrounding valves for cardiothoracic surgery. However, complications arise such as micro-motion and separation between the two sternal halves. To prevent these complications, the use of a bone adhesive has been proposed to augment the mechanical union of the two sternal halves when combined with wire cerclage. Our group has developed a bone adhesive for sternal fixation, utilizing a glass polyalkenoate cement (GPC) based on a zinc silicate ionomeric glass (mole fraction: SiO2:0.48, ZnO:0.36, CaO:0.12, SrO:0.04). Here we present the first soft-tissue biological safety assessment of this novel Sr/Zn-GPC, where we implanted the material subcutaneously in rats for 6 and 12 weeks. Polymethyl-methacrylate (PMMA) bone cement was used as a baseline control with respect to inflammation and biocompatibility. Histological assessment revealed no adverse tissue reaction nor ectopic bone formation in response to the novel material. Additionally, relative expression of pro-inflammatory and osteogenic genes (Col1a1, SOX9, Runx2, IL-1, IL-6, and TNF-alpha) was assessed in the tissue surrounding implants and revealed no significant differences in expression between the Sr/Zn-GPC and PMMA implants.

Glass Polyalkenoate Cements (GPCs) are composed of ionomeric glass having setting reaction with aqueous poly (acrylic) acid (PAA). The mechanical properties of GPCs are normally affected by various factors such as the concentration of the acid solution, the molar mass of the polyacid, and the powder:liquid ratio. A previous study using fracture testing of double cantilever beam specimens made with a GPC (GPC A) adhered to bovine bone showed that the mode I energy release rate decreased significantly when the specimens were prepared in a flooded liquid environment, simulating a worst-case surgical sternal closure application. The present study used pull-out and butt strength tests to determine the extent to which the adhesion to bovine bone could be improved in wet environments by using a more viscous adhesive (GPC B). The pull-out samples were prepared in both dry and flooded liquid environments and incubated in both humid and flooded liquid environments at 37 degrees C for two time periods: one and seven days. Overall, the pull-out strength of GPC B was found to be between 56% and 808% higher than GPC A, indicating that the more viscous formulation could mitigate the effects of the wet environment. The GPC B samples prepared and incubated in a flooded liquid environment (L-LI) had a significantly lower pull-out strength than all three other conditions: (1) when prepared in a dry environment and incubated in either a liquid (D-LI) or (2) humid environment (D-H), and (3) when prepared in a liquid environment and incubated in a humid one (L-H), which were all of similar strength. No significant difference in pullout strength between the samples tested after 1 and 7 days of incubation was found indicating that robust adhesion strength was obtained rapidly. To further assess the adhesive strength for augmenting sternal closure, GPC B and bovine bone were used to create butt joints which were tested at strain rates typical of breathing and coughing. The tests revealed that GPC B's viscoelastic properties resulted in a higher butt joint strength for coughing loads compared to breathing. Overall, the results of the present study show that when the adhesives are expected to be subjected to a flooded liquid environment while they set, significant gains in adhesive strength can be obtained by using more viscous GPC adhesives.

Bisphosphonate-based pharmacological therapy of osteoporosis reduces risk of fracture, but modulation of bone mineral density does not solely explain this. Additional bone quality aspects affecting fragility need to be better understood, alongside methods to monitor them. Systemic factors that influence bone collagen remodelling also remodel keratin in parallel processes. In this study, human fingernail clippings from subjects with and without bone active pharmaceutical intervention are compared. A discriminant model was able to distinguish between the nails from patients that were treatment-naive and treated with an area under the curve of 71% in the test set. A time series of changes relative to baseline revealed that after 1 year, the scores of the treated group (95 confidence interval 37% to 377% change) differed from both the 12 week measurements (-198% to 34%) and scores from untreated subjects (-92% to -674%). Analysis of the spectral differences and model coefficients revealed features that were inverse to those observed in three previous osteoporosis models, indicating that treatment was reverting damaged protein structure. This study provides preliminary evidence that bone active medication systemically influences keratin structure in humans and provides some discussion on the underlying mechanism. The study demonstrates that bisphosphonates have a direct influence on protein structure, warranting further investigation of these effects. Bone active medication systemically influences keratin structure in humans. Model based on Raman spectra of human fingernails can discriminate between treated and untreated individuals. Model is correlated with previous models of osteoporosis. Over time, untreated individuals show a trend suggestive of increasing osteoporosis risk, whereas treated individuals show a reversal suggesting lowering of risk.image

Understanding the failure modes and the fracture resistance is critical in evaluating the performance of an adhesive for sternal fixation. In this paper, a fracture mechanics testing methodology was used to assess the adhesion of a bioactive glass-based adhesive to bovine bone in terms of a measured mode I critical strain energy release rate (GIC). Reinforced double cantilever beam (DCB) samples were observed to produce repeatable values of GIC. The measured GIC was found to increase significantly from 5.41 to 12.60 J/m2 with an increase in adhesive thickness from 390 to 990 μm because of the constraint from the two adherends regulating the plastic zone size ahead of the crack. The specimens failed cohesively in all cases demonstrating that there was good adhesion to bone, a condition necessary to restrict micromotion and thus provide rigid sternal fixation when used along with sternal wires. It was also found that when the bone was flooded with liquid during adhesive application a much lower GIC of between 0.69 and 1.15 J/m2 was measured. Overall, the results demonstrate that the fracture mechanics approach can be used to provide a quantitative measure of the adhesion of the bioactive glass-based adhesive to the bone and that the adhesive should only be applied to clean bone in a dry environment.

The most common complication of median sternotomy surgery is sternum re-separation after sternal fixation, which leads to high rates of morbidity and mortality. The adhered sternal fixation technique comprises the wiring fixation technique and the use of bio-adhesives. Adhered sternal fixation techniques have not been extensively studied using finite element analysis, so mechanical testing studies and finite element analysis of sternal fixation will be presented in this review to find the optimum techniques for simulating sternal fixation with adhesives. The optimal wiring technique should enhance bone stability and limit sternal displacement. Bio-adhesives have been proposed to support sternal fixation, as wiring is prone to failure in cases of post-operative problems. The aim of this paper is to review and present the existing numerical and biomechanical sternal fixation studies by reviewing common sternal closure techniques, adhesives for sternal closure, biomechanical modeling of sternal fixation, and finite element modeling of sternal fixation systems. Investigating the physical behavior of 3D sternal fixation models by finite element analysis (FEA) will lower the expense of conducting clinical trials. This indicates that FEA studies of sternal fixation with adhesives are needed to analyze the efficiency of this sternal closure technique virtually.

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, AristaTM (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.

BACKGROUND Glass polyalkenoate cements (GPCs) are bio-adhesives which consist of ionomeric glass particles embedded in a poly-salt matrix. These materials have been used in dentistry and orthodontics extensively but are presently being optimized as bone putties for orthopedic applications. OBJECTIVE This study utilized a patented ionomeric glass (mole fraction: SiO2:0.48, ZnO:0.36, CaO:0.12, SrO:0.04) to formulate two GPCs: GPC A (<45 μm particle size glass) and GPC B (45 μm-63 μm). These formulations were previously assessed for their effect on osteoblast viability and osteogenic function. However, the immunomodulatory effects of GPC A and B have not previously been investigated. METHOD Non-toxic concentrations of (a) GPC dissolution products and (b) fragmented GPC particles were tested for their ability to affect the secretion of cytokines (TNF-α, IL-1β, IL-6 and IL-10) by rat peripheral blood mononuclear cells (PBMCs), in the presence or absence of the stimulant liposaccharide (LPS). Additionally, the ionic concentrations of Sr, Zn, Ca, and Si were measured in GPC ionic extracts, and the size, shape and concentration of fragmented GPC particles in deionized water were characterized using an optical microscope-based particle analyzer. RESULTS The results showed that GPC A ionic products reduced the concentration of TNF-α secreted by stimulated cells compared with cells stimulated in the absence of GPC products. Interestingly, the particles released from GPC A significantly increased the secretion of both TNF-α and IL-6 from unstimulated cells, compared to control cells. CONCLUSION Neither GPC B ionic products nor released particles were found to be biologically active with respect to PBMC cytokine secretion.

The primary treatment for patients suffering from bone cancers is resection of the tumour followed by reconstruction of the damaged bone. Despite the administration of post-operative chemotherapy, tumour recurrence continues to present itself as a severe complication leading to re-operation. Attempts to incorporate chemotherapeutic drugs into bone cements elicits local toxic effects on healthy bone, which could compromise implant fixation. Alternatively, the local administration of gallium (Ga) may prove to be more effective. This report considers the development of a Ga ionomeric glass series (0.48SiO 2 -0.355ZnO-0.06CaO-0.08SrO-0.02P 2 O 5 -0.005Ta 2 O 5 , with 0.01–0.05 mol% substitution for ZnO). X-ray Diffraction (XRD) confirmed the amorphous glass structure and Energy Dispersive x-ray Fluorescence (EDXRF) verified the successful addition of Ga into the glass series at the expense of Zinc (Zn). A Ga-GPC series was then formulated by mixing the glass particles with aqueous poly(acrylic) acid (PAA) and trisodium citrate (TSC). Fourier transform infrared (FTIR) spectroscopy demonstrated no structural changes to the GPC matrix with the incorporation of Ga. Measurements of the rheological properties demonstrated an exponential increase in setting time with increasing Ga content. Furthermore, the addition of ≥ 3 mol% Ga demonstrated deleterious effects on the GPC’s mechanical properties and an analysis of pH confirmed that it decreased with increasing Ga content, suggesting a reduction in glass reactivity and PAA cross-linking. Finally, inductively coupled plasma—optical emission spectrometry (ICP-OES) demonstrated the controlled release of Ga across the GPC series, which will prove beneficial to future in vitro studies.

Poly(methyl methacrylate) (PMMA) is used to manage bone loss in revision total knee arthroplasty (rTKA). However, the application of PMMA has been associated with complications such as volumetric shrinkage, necrosis, wear debris, and loosening. Glass polyalkenoate cements (GPCs) have potential bone cementation applications. Unlike PMMA, GPC does not undergo volumetric shrinkage, adheres chemically to bone, and does not undergo an exothermic setting reaction. In this study, two different compositions of GPCs (GPCA and GPCB), based on the patented glass system SiO2-CaO-SrO-P2O5-Ta2O5, were investigated. Working and setting times, pH, ion release, compressive strength, and cytotoxicity of each composition were assessed, and based on the results of these tests, three sets of samples from GPCA were implanted into the distal femur and proximal tibia of three sheep (alongside PMMA as control). Clinical CT scans and micro-CT images obtained at 0, 6, and 12 weeks revealed the varied radiological responses of sheep bone to GPCA. One GPCA sample (implanted in the sheep for 12 weeks) was characterized with no bone resorption. Furthermore, a continuous bone–cement interface was observed in the CT images of this sample. The other implanted GPCA showed a thin radiolucent border at six weeks, indicating some bone resorption occurred. The third sample showed extensive bone resorption at both six and 12 weeks. Possible speculative factors that might be involved in the varied response can be: excessive Zn2+ ion release, low pH, mixing variability, and difficulty in inserting the samples into different parts of the sheep bone.

Metastatic bone lesions are common among patients with advanced cancers. While chemotherapy and radiotherapy may be prescribed immediately after diagnosis, the majority of severe metastatic bone lesions are treated by reconstructive surgery, which, in some cases, is followed by postoperative radiotherapy or chemotherapy. However, despite recent advancements in orthopedic surgery, patients undergoing reconstruction still have the risk of developing severe complications such as tumor recurrence and reconstruction failure. This has led to the introduction and evaluation of poly (methyl methacrylate) and inorganic bone cements as local carriers for chemotherapeutic drugs (usually, antineoplastic drugs (ANPDs)). The present work is a critical review of the literature on the potential use of these cements in orthopedic oncology. While several studies have demonstrated the benefits of providing high local drug concentrations while minimizing systemic side effects, only six studies have been conducted to assess the local toxic effect of these drug-loaded cements and they all reported negative effects on healthy bone structure. These findings do not close the door on chemotherapeutic bone cements; rather, they should assist in materials selection when designing future materials for the treatment of metastatic bone disease.

Novel tantalum-containing meso-porous bioactive glass (Ta-MBG) powders, developed via the sol-gel process, have demonstrable hemostatic properties. However, powders can create dust in the operating environment and may be washed away if profuse bleeding occurs. Powders may not adequately compress wound tissue, and in certain circumstances, a thick callus can form, which is challenging to remove. Fibrous forms of MBGs offer advantages over powders for hemostatic applications, yet they appear comparatively under-researched. In this study, Ta-MBG compositions were successfully designed and fabricated into fibrous mats using electrospinning. State-of-the-art imaging techniques were used to investigate the mats. The individual fibres were ∼300 nm in diameter and contained porosity (1−50 nm). There was also micrometre-sized -porosity (1−2 μm) – this constituted the pore space between the matted fibres, unlike the Ta-MBG powders, which comprised of uni-modal channels (pore size: 4 nm) within the particles themselves. Hierarchical micro-nano porosity is known to enhance the activation of coagulation proteins. The surface area and pore volume of the fibrous mats were a maximum of 61 m2 g−1, 0.23 cm3 g−1 compared to 374 m2 g−1, 0.27 cm3 g−1 for powders. The surface area is an important property facilitating blood fluid sorption and enhancing clotting. The measured zeta potential of the fibres was more highly-negative than that of powder; a highly-negative zeta potential can provide a stable matrix for hemostasis. Overall, the texture of the fibrous mats, the easily-accessible micron-sized pores, the presence of tantalum, the hierarchical porosity, the favourable zeta potential, and the naturally biomimetic architecture are important attributes which make the fibrous mats developed here an attractive alternative for hemostatic applications.

This study evaluates the hemostatic properties of tantalum-containing mesoporous bioactive glasses (Ta-MBGs) through a suite of in-vitro methods: hemolysis percentage, zeta potential, blood coagulation assays (Activated Partial Thromboplastin Time – APTT and Prothrombin Time - PT) and cytotoxicity tests. Five compositions of Ta-MBG, with x mol% Ta 2 O 5 added to the glass series (80- x)SiO 2 -15CaO-5P 2 O 5 - xTa 2 O 5 where x=0 (0Ta), x=0.5 (0.5Ta), x=1 (1Ta), x=5 (5Ta), and x=10 (10Ta) mol%, were synthesised. The hemostatic potential of all the Ta-MBGs was confirmed by their negative zeta potential (–23 to –31 mV), which enhances the intrinsic pathway of blood coagulation. The hemolysis percentages of all Ta-MBGs except 10Ta showed statistically significant reductions compared to the same experiments carried out both in the absence of a sample (‘no treatment’ group) and in the presence of 10Ta. These observations validate the consideration of Ta-MBGs as hemostatic agents as they do not cause significant lysis of red blood cells. Cytotoxicity analysis revealed that Ta-MBGs had no effect on bovine fibroblast viability. Furthermore, a reduction in both APTT (a test to evaluate the intrinsic pathway of coagulation) and PT (a test to evaluate the extrinsic pathway) signified enhancement of hemostasis: 5Ta caused a significant reduction in APTT compared to ‘no treatment’, 1Ta and 10Ta and a significant reduction in PT compared to 0Ta. Therefore, we conclude that 5mol% of Ta optimised the hemostatic properties of these mesoporous bioactive glasses.

Glass polyalkenoate cements (GPCs) are under investigation as potential bone adhesives, as they may provide an alternative to polymethylmethacrylate-based cements. GPCs containing strontium (Sr) and zinc (Zn) in place of aluminium (Al) are of particular interest because these ions are known stimulators of osteoprogenitor differentiation. GPCs have been manufactured from a novel bioactive glass (SiO2:0.48, ZnO:0.36, CaO:0.12, SrO:0.04) in the past, but, while such materials have been assessed for their influence on viability, their influence on osteogenic function has not been investigated until now. For this study, two GPCs were formulated from the same glass precursor evaluated in previous studies. These GPCs were named GPC A and GPC B, and they differed in glass particle size, polyacrylic acid molecular weight, and their powder: liquid ratios. The effect of these two GPCs on osteogenic differentiation of primary rat osteoblasts were evaluated using three culture systems: culture with dissolution extracts, indirect contact with transwell-inserts and direct contact. Additionally, the degradation characteristics of GPCs were assessed, including their interfacial pH and surrounding pH. The experimental outcomes revealed that collagen deposition, alkaline phosphatase expression, and mineralization were largely dependent on GPC composition as well as the mode of interaction with cells. These markers were found to be significantly elevated in response to GPC A's dissolution products. However, osteogenic differentiation was inhibited when osteoblasts were cultured indirectly and directly with GPCs, with, overall, GPC B significantly outperforming GPC A. These results suggest that GPC degradation products effect osteogenic differentiation in a dose-dependent manner.