Bioactive Glass Surface Research Articles

Integrative treatment of anti-tumor/bone repair by combination of MoS2 nanosheets with 3D printed bioactive borosilicate glass scaffolds

Malignant bone tumors have caused great obstacles and serious illnesses for tumor recurrence and difficulty in reconstructing and repairing large defects after tumorectomy. Additionally, long-term efficacy, satisfactory biocompatibility and excellent properties for anti-tumor agents are necessary in the biomedical field. To solve these problems, a novel idea has been proposed on building an integrative anti-tumor/bone repairing scaffold by covering photothermal therapy (PTT) composite MoS2-PLGA film on the surface of borosilicate bioactive glass (BG). In our study, the MoS2-integrated composite BG (BGM) scaffolds can rapidly and effectively elevate temperature, and they exhibited excellent photothermal stability, under 808 nm laser irradiation. Notably, the BGM scaffolds can effectively reduce the viability of osteosarcoma cells (MNNG/HOS) in vitro as well as inhibit the tumor growth in nude mice. Furthermore, the prepared BGM scaffolds can stimulate the proliferation and differentiation of rat bone mesenchymal stem cells (rBMSCs), upregulate the expression of osteogenesis-related genes (Runx-2, OCN and Col-I) in vitro and promote in vivo bone repair in critical-sized rat calvarial defects. Therefore, the novel MoS2-integrated composite BG scaffolds are highly promising for the treatment of tumor-related bone defects, offering ideas for the manufacture of new materials in the tissue engineering field.

Fine analysis of interaction mechanism of bioactive glass surface after soaking in SBF solution: AFM and ICP-OES investigations

Bioactive glasses have the physical characteristics enabling them to be used in bone tissue engineering applications. However, the exact mechanism of the interactions between the glass surface and environment leading to the transition from the vitreous phase to the crystalline phase remains a subject of study. This work focuses on the growth of a calcium phosphate layer on the surface of the glass after immersion in a mineral solution, which mimics the mineral phase of human blood. The investigations use the Inductively Coupled Plasma and the Atomic Force Microscopy to establish the kinetic of crystallization, the kinetic of chemical reactivity and the surface transformations such as structure, texture and morphology of the bioactive glass. Obtained results show the progressive formation of a hydroxyapatite layer within 2 weeks. This crystal which is that of the bone belongs to the crystallographic structure within space group of P63/m. In addition, results show a decrease of the gradient of thickness which varies according to the immersion time from 7.5 µm to 2.8 µm and an increase of the homogeneity of the surface visible by the lowering of the gradient in the phase measurement from 60 Å to 15 Å.

Resorption of the calcium phosphate layer on S53P4 bioactive glass by osteoclasts

Clinically, S53P4 bioactive glass (BAG) has shown very promising results in bone infection treatment, but it is also known to degrade very slowly in vivo. To evaluate which mechanisms (cellular or dissolution) can play a role in the degradation of S53P4 BAG and S53P4 BAG putty, in vitro degradation experiments at different pH (7.4 and 4.6) were performed. Micro computed tomography showed a rapid dissolution of the synthetic binder in the putty formulation, within 12 h is simulated body fluid (pH = 7.4), leaving behind only loose granules. Therefore the degradation of the loose granules was investigated further. Significant weight loss was observed and ion chromatography showed that Ca2+, Na+ and PO43− ions were released from S54P4 BAG granules in the two fluids. It was observed that the weight loss and ion release were increased when the pH of the fluid was decreased to 4.6. Osteoclasts are known to create such a low pH when resorbing bone and therefore their capacity to degrade S53P4 surfaces were studied as well. Scanning electron microscopy and energy-dispersive X-ray spectroscopy confirmed that osteoclasts were able to create resorption pits in the calcium phosphate layer on S53P4 BAG surfaces. The silica of the BAG, located underneath the calcium phosphate, seemed to hinder further osteclastic resorption of the material. To our knowledge we were the first to observe actively resorbing osteoclasts on S53P4 bioactive glass surfaces, in vitro. Future research is needed to define the specific role osteoclasts play in the degradation of BAG in vivo.

In situ chemical and physical reduction of copper on bioactive glass surface

In this work silica-based bioactive glass powders were doped with Cu++ ions by means of ion-exchange process and subsequently they were exposed to different chemical (tannic acid, ascorbic acid and NaOH) and physical processes (UV irradiation, thermal treatment in air or argon atmosphere) to promote the in situ reduction of Cu++ ions to Cu+ or Cu0. The obtained glasses were investigated by means of structural (X-Ray diffraction – XRD), morphological and compositional analyses (scanning-transmission electron microscopy equipped with energy dispersive spectroscopy (FESEM/STEM-EDS); moreover, glasses were subjected to in vitro bioactivity test in simulated body fluid up to 14 days to investigate the influence of the performed chemical and physical treatments on glass bioactivity. At the end of incubation time glasses were analyzed by means of FESEM-EDS and Fourier transformation infrared spectroscopy (FT-IR). The obtained results evidenced that, in general, the chemical treatments are useful to induce the formation of Cu0, while thermal treatment induce the nucleation of CuO (in air) or Cu2O (in argon). All samples maintained a bioactive behavior. At least, preliminary antibacterial effect evaluation by inhibition halo test evidenced that samples containing free Cu++ ions or Cu0 nanoparticles possess the best antibacterial effect.

Effect of selenium incorporation on the structure and in vitro bioactivity of 45S5 bioglass

In vitro bioactivity, biodegradation, and biocompatibility behavior of a new bioactive glass systems were investigated with the incorporation of selenium oxide, for the replacement of sodium oxide in the traditional 45S5 bioglass composition. The apatite-forming ability of melt-derived bioactive glasses was evaluated by immersion studies in simulated body fluid while monitoring the concentration of silicon, calcium, phosphorus, sodium, and selenium in the medium. The weight loss of bioactive glasses and pH change in the tris-(hydroxymethyl)-amino methane buffer solution was determined to observe the biodegradation behavior of glass samples. The glasses were characterized by a Fourier transform infrared spectroscopy, scanning electron microscopy, inductively coupled plasma, and Vickers hardness measurements. The biocompatibility evaluation of the glasses was determined through in vitro osteogenesis assays by cell viability, alkaline phosphatase activity, and mineralized matrix formation. The incorporation of selenium enhanced the hydroxyapatite formation on the bioactive glass surface and microhardness of glasses. The hardness of glasses was found to decrease with immersion duration. The results indicate that selenium incorporated bioactive glasses can be used as bioactive material in bone tissue engineering applications.

Formation of hydroxyapatite on surface of SiO2– P2O5–CaO–SrO–ZnO bioactive glass synthesized through sol-gel route

Abstract The bioactive glass (BG) system of 60SiO2–4P2O5–31CaO-xSrO-(5-x) ZnO (0 ≤ x ≤ 5 %mol) was synthesized by sol-gel route. The role of zinc contents and strontium on the in-vitro formation of hydroxyapatite (HA), antibacterial properties, and cell viability of BGs were investigated. XRD (X-ray diffraction analysis), SEM (Scanning electron microscopy) and FTIR (Fourier transform infrared spectroscopy) were utilized to study the HA morphology, its functional groups and obtained phases, respectively. The results established the formation of HA on the surface of strontium and zinc-containing BGs. The 3-(4,5 dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay after one day immersion in SBF, implied that the viability of samples containing 4 %mol Sr and 1 %mol Zn (S4-Z1) and 3 %mol Sr and 2 %mol Zn (S3-Z2) increases by increasing immersion time, while the sample containing 1 %mol Sr and 4 %mol Zn (S1-Z4) showed a statistically significant increase in osteoblast G292 proliferation. Furthermore, the antibacterial tests showed that all Zn containing BGs created clear inhabitation zones. The zone of clearance around the bioactive glasses demonstrated that sufficient Zn ion was released to create an antibacterial activity around the bioactive glasses.

Surface properties of Ce-TZP/Al2O3 composite ceramics by coating mesoporous bioactive glass

The Ce-TZP/Al2O3 composite ceramic substrate coated mesoporous bioactive glass was obtained by the sol-gel dip-coating method. As a comparative investigation, the traditional bioactive glass (BG) coatings were prepared. The results displayed that BG coatings surface could found many cracks, while MBG coatings were crack-free and intact. Hydroxyapatite (HAp) formation was confirmed by XRD and SEM after the vitro SBF soaking. Cells experiments were carried to analyze cell viability, cell proliferation and cell attachment upon BG and MBG coatings surface. Compared to BG coatings, crack-free MBG coatings can greatly improve the bioactivity of Ce-TZP/Al2O3 composite ceramic substrate. The present results suggest that the composite material of Ce-TZP/Al2O3 coated MBG has excellent bioactivity and is expected to be the potential bone replacement materials.

Contrasting In Vitro Apatite Growth from Bioactive Glass Surfaces with that of Spontaneous Precipitation.

Body-fluid-exposed bioactive glasses (BGs) integrate with living tissues due to the formation of a biomimetic surface layer of calcium hydroxy-carbonate apatite (HCA) with a close composition to bone mineral. Vast efforts have been spent to understand the mechanisms underlying in vitro apatite mineralization, as either formed by direct precipitation from supersaturated solutions, or from BG substrates in a simulated body fluid (SBF). Formally, these two scenarios are distinct and have hitherto been discussed as such. Herein, we contrast them and identify several shared features. We monitored the formation of amorphous calcium phosphate (ACP) and its crystallization into HCA from a NaO–CaO–SiO–PO glass exposed to SBF for variable periods out to 28 days. The HCA growth was assessed semi-quantitatively by Fourier transform infrared spectroscopy and powder X-ray diffraction, with the evolution of the relative apatite content for increasing SBF-exposure periods evaluated against trends in Ca and P concentrations in the accompanying solutions. This revealed a sigmoidal apatite growth behavior, well-known to apply to spontaneously precipitated apatite. The results are discussed in relation to the prevailing mechanism proposed for in vitro HCA formation from silicate-based BGs, where we highlight largely simultaneous growth processes of ACP and HCA.

The response of pre-osteoblasts and osteoclasts to gallium containing mesoporous bioactive glasses

Mesoporous bioactive glasses (MBGs) in the system SiO2-CaO-P2O5-Ga2O3 have been synthesized by the evaporation induced self-assembly method and subsequent impregnation with Ga cations. Two different compositions have been prepared and the local environment of Ga(III) has been characterized using 29Si, 71Ga and 31P NMR analysis, demonstrating that Ga(III) is efficiently incorporated as both, network former (GaO4 units) and network modifier (GaO6 units). In vitro bioactivity tests evidenced that Ga-containing MBGs retain their capability for nucleation and growth of an apatite-like layer in contact with a simulated body fluid with ion concentrations nearly equal to those of human blood plasma. Finally, in vitro cell culture tests evidenced that Ga incorporation results in a selective effect on osteoblasts and osteoclasts. Indeed, the presence of this element enhances the early differentiation towards osteoblast phenotype while disturbing osteoclastogenesis. Considering these results, Ga-doped MBGs might be proposed as bone substitutes, especially in osteoporosis scenarios. Statement of SignifcanceOsteoporosis is the most prevalent bone disease affecting millions of patients every year. However, there is a lack of bone grafts specifically designed for the treatment of bone defects occurred because of osteoporotic fractures. The consequence is that osteoporotic bone defects are commonly treated with the same biomaterials intended for high quality bone tissue. In this work we have prepared mesoporous bioactive glasses doped with gallium, demonstrating osteoinductive capability by promoting the differentiation of pre-osteoblast toward osteoblasts and partial inhibition of osteoclastogenesis. Through a deep study of the local environment of gallium within the mesoporous matrix, this work shows that gallium release is not required to produce this effect on osteoblasts and osteoclasts. In this sense, the presence of this element at the surface of the mesoporous bioactive glasses would be enough to locally promote bone formation while reducing bone resorption.

Collagen as Coating Material for 45S5 Bioactive Glass-Based Scaffolds for Bone Tissue Engineering.

Highly porous 45S5 bioactive glass-based scaffolds were fabricated by the foam replica technique and coated with collagen by a novel method. After an initial cleaning step of the bioactive glass surface to expose reactive –OH groups, samples were surface functionalized by (3-aminopropyl)triethoxysilane (APTS). Functionalized scaffolds were immersed in a collagen solution, left for gelling at 37 °C, and dried at room temperature. The collagen coating was further stabilized by crosslinking with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and N-hydroxysuccinimide (NHS). Applying this coating method, a layer thickness of a few micrometers was obtained without affecting the overall scaffold macroporosity. In addition, values of compressive strength were enhanced by a factor of five, increasing from 0.04 ± 0.02 MPa for uncoated scaffolds to 0.18 ± 0.03 MPa for crosslinked collagen-coated scaffolds. The composite material developed in this study exhibited positive cell (MG-63) viability as well as suitable cell attachment and proliferation on the surface. The combination of bioactivity, mechanical competence, and cellular response makes this novel scaffold system attractive for bone tissue engineering.

Periodic microstructures on bioactive glass surfaces enhance osteogenic differentiation of human mesenchymal stromal cells and promote osteoclastogenesis in vitro.

Bioactive glasses (BG) are known for their ability to bond to hard and soft tissues. We hypothesized that the stimulation of bone remodeling, including cellular bone forming and bone resorbing processes, can be increased by applying periodic microstructures on the glass surfaces in vitro. To test our hypothesis, two different BG (45S5 and 13-93) were microstructured in a groove-and-ridge pattern of different sizes by a novel casting process and tested in cell culture experiments using human mesenchymal stromal cells (hMSCs) and RAW 264.7 cells. The microstructures induced contact guidance of hMSCs and increased osteogenic marker gene expression of the stem cells, compared to non-structured glass surfaces as verified by ELISA and quantitative real-time PCR (qPCR) analyses. Furthermore, the structures stimulated the differentiation of RAW cells to osteoclast-like cells confirmed by TRAP gene expression and their resorption activity causing visible resorption lacunae. Our results demonstrate that periodically microstructured BG (especially 45S5) might improve the osteogenic differentiation of hMSCs and influence the activity of material resorbing cells in vitro. Hence, microstructuring of BG could enhance the remodeling process of bone substitutes critical for the formation of new bone tissue in vivo and thus be used to trigger bone remodeling kinetics in vivo. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1965-1978, 2018.

Finite Element Modeling of the Flexural Mechanical Response of Polymer-Coated Bioactive Glass Scaffolds Composed of Thermally-Bonded Unidirectional Fibers

AbstractBioactive glasses have attractive characteristics as a scaffold material for healing bone defects but their brittle mechanical response, particularly in bending, is a concern. Recent studies have shown that coating the external surface of strong porous bioactive glass (13-93) scaffolds with an adherent biodegradable polymer layer can significantly improve their load-bearing capacity andwork of fracture, resulting in a non-brittle mechanical response. In the present study, finite element modeling (FEM) was used to analyze the mechanical response in four-point bending of composites composed of a porous glass scaffold and an adherent polymer surface layer. The glass scaffold with a cylindrical geometry (diameter = 4.2 mm; porosity = 20%) was composed of randomly arranged unidirectional fibers (diameter 200-700 μm) thatwere bonded at their contact points. The thickness of the polymer layer was 500 μm. By analyzing the stresses in the individual glass fibers, the simulations can account for the main trends in the observed mechanical response of practical composites with a similar architecture composed of a bioactive glass (13-93) scaffold and an adherent polylactic acid surface layer. These FEM simulations could play a useful role in designing bioactive glass composites with improved mechanical properties.

Melt-derived bioactive glass based on SiO2-CaO-Na2O-P2O5 system fabricated at lower melting temperature

This work addresses the development and fabrication of new bioactive glass composition based on SiO2-CaO-Na2O-P2O5 system that can be melted at lower melting temperature (1377 °C and 1348 °C) than 1400 °C through melt-derived route. All BG compositions did not show significant differences on their particle size while retaining their amorphous structure. Formation of Si-O-Si (tetrahedral) functional group indicated that silicate based glass structure was established as discovered by Fourier transform infrared spectroscope (FTIR). Apatite formation was observed on bioactive glass surface though being fabricated at lower melting temperature upon soaking in Tris-buffer solution. Feature of carbonate (C-O) and P-O functional group was discovered from FTIR for all glass composition. Present of crystalline peaks was detected in X-ray diffraction (XRD) though fewer peaks were observed for glass fabricated at lower melting temperature. Morphology of apatite in crystal cluster form on the glass surface was identified through scanning electron microscope (SEM).

Early clinical and radiographic outcomes of trabecular metal total ankle using transfibular approach

Musculoskeletal conditions are the most commonly occurring medical conditions, and they have a considerable influence on the quality of health and living standard of the millions of people across the world. Annually, around the globe, approximately 2.3 million bone-tissue graft transplants are performed. The bone fracture, osteoporosis, osteoarthritis, and various neoplastic disorders are the common clinical problems related with bone and skeletal system. The common approaches to these bone problems are autografts or allografts. These protocols have certain limitations such as resorption, donor site morbidity, compromised supply, rejection rate up to 50% at some sites, and the risk of inducing transmissible diseases. Consequently, considerable attention has been directed toward the use of bioactive materials as synthetic grafts for bone regeneration. These include hydroxyapatite (HAP), tricalcium phosphate, bioactive glass, and glass ceramics. More significantly, calcium phosphates are the major constituent of bone mineral. The most extensively used synthetic calcium phosphate ceramic for bone replacement is HAP with a chemical formula of Ca10(PO4)6(OH)2. It has Ca:P molar ratio of 1.667 and is regarded as the most stable composition compared to other calcium phosphate ceramic within a pH range of 4.2–8.0. Calcium phosphate cement is one of the most important types of bioceramic material. In combination with various calcium phosphates, an injectable paste can be formed, which is cured over a period of time, in which resultant product is a carbonate apatite. The cements cure in situ and are gradually resorbed and replaced by a newly formed bone. The concept of a bioactive glass was pioneered by Hench and colleagues. The composition of Bioglass is a series of special designed glasses, consisting of a Na2O–CaO–SiO2 glass with the addition of P2O5, B2O3, and CaF2. A biologically active hydroxycarbonate apatite layer is formed on the surface of bioactive glasses in vitro and in vivo. The chemical properties could be controlled in bioactive glasses and eventually its bonding to tissue. Certain specialized compositions of Bioglass (e.g., 45S5) can bond to soft tissue as well as bone, in either bulk or particulate form. Moreover, apatite-wollastonite glass-ceramic, with an assembly of small apatite particles effectively reinforced by β-wollastonite exhibit not only bioactivity, but also a fairly high mechanical strength. Mechanical properties like the bending strength, toughness against fracture, and Young’s modulus of A-W glass-ceramic are the highest among bioactive glasses and glass-ceramics enabling it to be used in some compression load-bearing applications. Overall, the advantages of bioactive glasses are the magnitude of their surface reactivity and the ability to change the chemical composition, thus facilitating bonding with variety of tissues. Mechanical properties are the drawback as these materials have relatively low bending strength in comparison to other ceramic materials. The bioactive calcium phosphate ceramics, bioglasses, and glass-ceramics form a mechanically strong interfacial bond with bone. The strength of the bond is normally equivalent to or greater than the strength of the host bone, depending on test conditions. Therefore, all of these materials have excellent bioactivity. Nevertheless, bioactive ceramics have a flexural strength, strain-to-failure, and fracture toughness, which is less than the bone and the elastic modulus is greater than the bone. In other words, most bioactive materials have a less-than-optimal biomechanical compatibility when used in load-bearing applications. An approach to mitigate this problem involves designing and structural tailoring of bioactive composites. The concept of matching the mechanical behavior of an implant, with the tissue to be replaced in order to solve the problem of stress shielding of conventional biomaterials, was proposed by Bonfield et al. Thus, the composite approach can significantly meet the challenge of a long life, as a demand for the new-generation implant materials. Calcium phosphate ceramics, bioglasses, and glass ceramics are generally considered to be bone bioactive ceramics. These materials generally get bonded to the surrounding osseous tissue and enhance further bone-tissue formation. The direct bone bonding to bioactive glasses was first observed and reported by Hench et al., since then considerable progress has been made in understanding the basic mechanism of the formation of bone and biomaterial bond and its effect on bone formation.

Hydroxyapatite and bioactive glass surfaces for fiber reinforced composite implants via surface ablation by Excimer laser.

In skeletal reconstructions, composites, such as bisphenol-A-glycidyldimethacrylate resin reinforced with glass fibers, are potentially useful alternatives to metallic implants. Recently, we reported a novel method to prepare bioactive surfaces for these composites. Surface etching by Excimer laser was used to expose bioactive glass granules embedded in the resin. The purpose of this study was to analyze two types of bioactive surfaces created by this technique. The surfaces contained bioactive glass and hydroxyapatite granules. The selected processing parameters were adequate for the creation of the surfaces. However, the use of porous hydroxyapatite prevented the complete exposure the granules. In cell culture, for bioactive glass coatings, the pattern of proliferation of MG63 cells was comparable to that in the positive control group (Ti6Al4V) while inferior cell proliferation was observed on the surfaces containing hydroxyapatite granules. Scanning electron microscopy revealed osteointegration of implants with both types of surfaces. The technique is suitable for the exposure of solid bioactive glass granules. However, the long-term performance of the surfaces needs further assessment.

Apatite formation on melt-derived bioactive glass powder based on SiO2-CaO-Na2O-P2O5 system

Abstract The higher melting temperature and longer soaking time during conventional glass melting route promoted the search for alternative in developing new bioactive glass (BG) composition with improved in fabrication temperature and melting time. The current project involved fabrication of new BG compositions based on SiO 2 -CaO-Na 2 O-P 2 O 5 system via melt derived route. It was confirmed that all bioactive glass composition can be melted at temperature lower than 1400 °C. Formation of Si-O-Si (tetrahedral) functional group highlighted that silicate based glass was established as detected by Fourier transform infrared spectroscope (FTIR). BG bioactivity was performed by incubating the BG powder in Tris-buffer solution (pH 8) for 7, 14 and 21 days. In vitro test confirmed the apatite formation on the bioactive glass surface upon soaking in Tris-buffer solution with characteristic of carbonate group (C-O) and P-O band noticed from FTIR and present of crystalline peak observed in X-ray diffraction (XRD). Morphology of apatite formation on BG surface was observed using scanning electron microscope (SEM).

Mimicking physiological flow conditions to study alterations of bioactive glass surfaces in vitro.

Bioactive glasses form a strong bond with surrounding tissue and slowly degrade when implanted in vivo, stimulating the host bone to regenerate itself. We investigated the behaviour of microstructured bioactive glass surfaces (13-93) in an SBF reactor, which mimics physiological flow conditions. The structures were developed to potentially influence cell-biological long term processes such as osteogenic differentiation. It is therefore important that the structures withstand a certain time in SBF or body fluids. The experiments revealed that these structures were preserved up to 30 days. Although macroscopically stable, mass loss under flowing conditions was 2-2.5%, in contrast to <1% under static conditions. Polished samples in flowing medium lost 2.7% up to day 7 and then regained mass, resulting in overall 0.5% mass loss after 30 days. Thicker calcium phosphate rich layers for the samples in flowing medium were detected, demonstrating better bone bonding capacity than predicted conventionally. The hydroxyapatite conversion in the reactor was comparable to published in vivo data. We conclude that surface alterations that occur in vivo can be better mimicked by using the proposed flow bioreactor than by the established SBF method in static medium. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 228-236, 2018.

Tough and strong porous bioactive glass-PLA composites for structural bone repair.

Bioactive glass scaffolds have been used to heal small contained bone defects but their application to repairing structural bone is limited by concerns about their mechanical reliability. In the present study, the addition of an adherent polymer layer to the external surface of strong porous bioactive glass (13-93) scaffolds was investigated to improve their toughness. Finite element modeling (FEM) of the flexural mechanical response of beams composed of a porous glass and an adherent polymer layer predicted a reduction in the tensile stress in the glass with increasing thickness and elastic modulus of the polymer layer. Mechanical testing of composites with structures similar to the models, formed from 13-93 glass and polylactic acid (PLA), showed trends predicted by the FEM simulations but the observed effects were considerably more dramatic. A PLA layer of thickness -400 µm, equal to -12.5% of the scaffold thickness, increased the load-bearing capacity of the scaffold in four-point bending by ~50%. The work of fracture increased by more than 10,000%, resulting in a non-brittle mechanical response. These bioactive glass-PLA composites, combining bioactivity, high strength, high work of fracture and an internal architecture shown to be conducive to bone infiltration, could provide optimal implants for healing structural bone defects.

The effect of fibrin sealant on bioactive glass S53P4 particles – pH impact and dissolution characteristics in vitro

Fibrin glue, a two-component tissue adhesive, has a range of clinical indications. Bioactive glass (BG) S53P4 has been approved for clinical use in several craniomaxillofacial and orthopedic applications. Although sometimes used simultaneously, there is no data available regarding the possible interaction of these two biocompatible substances. In this in vitro study, using a BG particle concentration of 4 mg/ml, a 0.4 unit pH increment (p < 0.001) was observed in simulated body fluid (SBF) after a 7-day incubation period. The addition of fibrin glue (0.13 g, SD 0.04; or 3.7 mg/ml) on top of the BG particles raised further the pH by 0.5 units (p < 0.001). The difference between these groups was statistically significant (p = 0.008). With a BG concentration of 25 mg/ml and a fibrin glue concentration of 18 mg/ml during a 14-day incubation period, a pH increment of 0.6 units and SBF ion concentration change of Ca, K, Mg, Na, P and Si ions was seen. Moreover, a penetration depth between 4 and 6 mm was observed when fibrin glue was applied on top of a bed of BG particles. Conclusions: Fibrin glue is not likely to have a distracting effect on BG-induced pH increase of the SBF although it might delay early BG surface reactions based on ion concentration measurements. Fibrin glue penetrated to the interparticle space to some extent, binding the particles together for easy clinical use of BG.

Characteristics and Effects on Dental Pulp Cells of a Polycaprolactone/Submicron Bioactive Glass Composite Scaffold

IntroductionThis study aimed to evaluate the potential applications of polycaprolactone (PCL)/submicron bioactive glass (smBG) hybrid composites for pulp and dentin tissue regeneration. MethodsPCL/smBG hybrid composites were made with novel monodispersive bioactive glass submicrospheres, and pure PCL and bioactive glass samples were used as controls. Surface characteristics were assessed by scanning electron microscopy. Crystalline apatite deposition in vitro was examined after incubation in simulated body fluid. Inductively coupled plasma spectroscopy was used to further analyze the concentration of Si ions released by the scaffolds. Cell adhesion and morphology of human dental pulp cells were observed by immunofluorescence staining. The proliferation and expression of odontogenic-related markers were subsequently investigated using the Cell Counting Kit-8 assay (Beyotime Institute of Biotechnology, Jiangsu, China), Western blotting, and real-time reverse-transcription polymerase chain reaction. Mineralization activity was assessed by alizarin red staining. ResultsCrystalline apatites were precipitated on the PCL/smBG hybrid and pure bioactive glass surfaces after incubation in vitro, and pure PCL did not exhibit precipitation. Surface deposition on PCL/smBG hybrids presented different topographies and was thicker than on pure bioactive glass scaffolds at a later stage. Human dental pulp cells had a significantly higher proliferation rate on the PCL/smBG hybrid than on the bioactive glass and PCL scaffolds. Furthermore, the integration of smBG into the hybrid scaffold significantly promoted the expression of markers for odontogenic differentiation. More mineralized nodules were generated in the PCL/smBG group than in the other 2 groups. ConclusionsPCL/smBG hybrid composites may serve as potential material for pulp repair and dentin regeneration. The physical and chemical properties of the bioactive glass component affect the bioactivity of hybrid composites.