Bioactive Glass Scaffolds Research Articles

Fabrication of Micro-Nano Bioactive Glass Scaffold Incorporated with Siglec-15 for Bone Repair and Postoperative Treatment of Osteosarcoma

This study aimed to fabricate micro-nano bioactive glass (MNBG) scaffolds loaded with chemotherapeutics and siglec-15 monoclonal antibody with bone repair capability and high-active drug loading capability for postoperative treatment of osteosarcoma. Bioactive glass (BG) particles were incorporated with siglec-15 mAb and gemcitabine through mesopores and calcium ions on the surface. Dendritic cells (DCs) were treated with siglec-loaded BGs and gemcitabine. RT-qPCR analysis was conducted to detect DJ-1 and PTEN mRNA levels, CCK-8 technology to detect cell activity, and flow cytometry to detect cell apoptosis. Rats were administrated with siglec-15-MNBG composite scaffolds with/without gemcitabine. 3D printing was used to determine adhesion strength of each group. Administration of MNBG scaffold decreased the expression of PTEN and up-regulated expression of DJ-1 when inducing cell apoptosis. Combined treatment with gemcitabine augmented adhesion of material and enhanced phosphorylation activity of p-AKT, mitigating the inhibitory effect of scaffold loaded with siglec-15 on p-AKT protein expression. Collectively, MNBG scaffold loaded with siglec-15 might promote bone regeneration and incorporate with chemotherapeutic drugs to suppress tumor development and promote apoptosis through PTEN/PI3 K pathway. These findings provide a novel insight into postoperative treatment of osteosarcoma and help development of tumor immunotherapy/bone repair integrated materials.

Production of Porous Bioactive Glass (13-93)/Poly Ethylene Glycol Composite Scaffold for Bone Tissue Defects

Using the sol-gel process, glass powder was made. After the preparation method of the glass powder, x-ray analytical (XRD), particle size analysis and Fourier Transform Infrared (FTIR) were performed. The particle size analysis of manufactured glass (13-93) is found to be about 2.978 μm. (XRD) mode analysis suggested that the resulting porous scaffolds were amorphous. Using the process of salt leaching to create bioactive glass scaffolds (13-93) with structural and physical properties suitable for the human trabecular bone. XRD spectroscopy, scanning electron microscopy (SEM) and FTIR after sintering at temperature 750 °C were used to investigate the microstructure and chemical bonding of the porous scaffolds. The synthesized scaffold was soaked in medium of the simulated body fluid (SBF) and examined by SEM and XRD analysis in order to evaluate bioactivity. From the SEM morphology analysis results, it was noticed that the scaffolds comprised open and interconnected pores with a porosity range of 75-78%. High bioactivity of pours scaffolds was reported to have been observed after soaking 7days in SBF media because of the formation of apatite layer on its surfaces. Keywords: bioactive glass (13-93), scaffold, salt leaching method, SBF, sol-gel.

Antibacterial and antioxidant activity of cinnamon essential oil-laden 45S5 bioactive glass/soy protein composite scaffolds for the treatment of bone infections and oxidative stress

This study aimed to fabricate cinnamon essential oil (CO)-laden 45S5 bioactive glass (BG)/soy protein (SP) scaffolds exhibiting antioxidant and antibacterial activity. In this regard, 45S5 BG-based scaffolds were produced by the foam replica method, and subsequently the scaffolds were coated with various concentrations of CO (2.5, 5 and 7 (v/v) %) incorporated SP solution. Scanning electron microscopy images revealed that the CO-laden SP effectively attached to the 45S5 BG scaffold struts. The presence of 45S5 BG, SP and CO was confirmed using Fourier transform infrared spectroscopy. Compressive strength results indicated that SP based coatings improved the scaffolds' mechanical properties compared to uncoated BG scaffolds. The loading efficiency and releasing behaviour of the different CO concentrations were tested by gas chromatography-mass spectroscopy and UV–Vis spectroscopy. The results showed that CO incorporated scaffolds have controlled releasing behaviour over seven days. Furthermore, the coating on the scaffold surfaces slightly retarded, but it did not inhibit, the in vitro bioactivity of the scaffolds. Moreover, the antioxidant and antibacterial activity of CO was studied. The free radical scavenging activity measured by DPPH was 5 ± 1, 41 ± 3, 44 ± 1 and 43 ± 1 % for BGSP, CO2.5, CO5 and CO7, respectively. The antioxidant activity was thus enhanced by incorporating CO. Agar diffusion and colony counting results indicated that the incorporation of CO increased the antibacterial activity of scaffolds against S. aureus and E. coli. In addition, cytotoxicity of the scaffolds was investigated using MG-63 osteoblast-like cells. The results showed that the BG-SP scaffold was non-toxic under the investigated conditions, whereas dose-dependent toxicity was observed in CO-laden scaffolds. Considered together, the developed phytotherapeutic agent laden 45S5 BG-based scaffolds are promising for bone tissue engineering exhibiting capability to combat bone infections and to protect against oxidative stress damage.

Engineering Single-Atomic Iron-Catalyst-Integrated 3D-Printed Bioscaffolds for Osteosarcoma Destruction with Antibacterial and Bone Defect Regeneration Bioactivity.

Effective antitumor therapeutics with distinctive bactericidal and osteogenic properties are in high demand for comprehensive osteosarcoma treatment. Here, a "scaffold engineering" strategy that integrates highly active single-atomic iron catalysts (FeSAC) into a 3D printed bioactive glass (BG) scaffold is reported. Based on the atomically dispersed iron species within the catalysts, the engineered FeSAC displays prominent Fenton catalytic activity to generate toxic hydroxyl radicals (•OH) in response to the microenvironment specific to osteosarcoma. In addition, the constructed FeSAC-BG scaffold can serve as a sophisticated biomaterial platform for efficient osteosarcoma ablation, with concomitant bacterial sterilization via localized hyperthermia-reinforced nanocatalytic therapeutics. The destruction of the osteosarcoma, as well as the bacterial foci, can be achieved, further preventing susceptible chronic osteomyelitis during osteogenesis. In particular, the engineered FeSAC-BG scaffold is identified with advances in accelerated osteoconduction and osteoinduction, ultimately contributing to the sophisticated therapeutics and management of osteosarcoma. This work broadens the biomedical potential of single-atom catalysts and offers a comprehensive clinically feasible strategy for overall osteosarcoma therapeutics, bacterial inhibition, and tissue regeneration.

Polymer-Coated and Nanofiber-Reinforced Functionally Graded Bioactive Glass Scaffolds Fabricated Using Additive Manufacturing.

In this study, carbon nanotube (CNT) reinforced functionally graded bioactive glass scaffolds have been fabricated using additive manufacturing technique. Sol-gel method was used for the synthesis of the bioactive glass. For ink preparation, Pluronic F-127 was used as an ink carrier. The CNT-reinforced scaffolds were coated with the polymer polycaprolactone (PCL) using dip-coating method to improve their properties further by sealing the micro-cracks. The CNT- reinforcement and polymer coating resulted in an improvement in the compressive strength of the additively manufactured scaffolds by 98% in comparison to pure bioactive glass scaffolds. Further, the morphological analysis revealed interconnected pores and their size appropriate for osteogenesis and angiogenesis. Evaluation of the in vitro bioactivity of the scaffolds after immersion in simulated body fluid (SBF) confirmed the formation of hydroxyapatite (HA). Further, the cellular studies showed good cell viability and initiation of osteogensis. These results demonstrate the potential of these scaffolds for bone tissue engineering applications.

Foam Replica Method in the Manufacturing of Bioactive Glass Scaffolds: Out-of-Date Technology or Still Underexploited Potential?

Since 2006, the foam replica method has been commonly recognized as a valuable technology for the production of highly porous bioactive glass scaffolds showing three-dimensional, open-cell structures closely mimicking that of natural trabecular bone. Despite this, there are important drawbacks making the usage of foam-replicated glass scaffolds a difficult achievement in clinical practice; among these, certainly the high operator-dependency of the overall manufacturing process is one of the most crucial, limiting the scalability to industrial production and, thus, the spread of foam-replicated synthetic bone substitutes for effective use in routine management of bone defect. The present review opens a window on the versatile world of the foam replica technique, focusing the dissertation on scaffold properties analyzed in relation to various processing parameters, in order to better understand which are the real issues behind the bottleneck that still puts this technology on the Olympus of the most used techniques in laboratory practice, without moving, unfortunately, to a more concrete application. Specifically, scaffold morphology, mechanical and mass transport properties will be reviewed in detail, considering the various templates proposed till now by several research groups all over the world. In the end, a comprehensive overview of in vivo studies on bioactive glass foams will be provided, in order to put an emphasis on scaffold performances in a complex three-dimensional environment.

Influence of the replacement of silica by boron trioxide on the properties of bioactive glass scaffolds

AbstractThe dissolution properties and bioactivity of bioactive glasses (BGs) are mainly determined by their composition and glass network structure. Silicate BGs are arguable the most popular representatives of BGs. However, borate BGs have gained increasing interest due to their faster degradation rate. By adding boron trioxide in the silicate network, borosilicate BGs can be fabricated with controlled degradation rates. Since the kind and amount of network former determines the resulting BG properties, the aim of this study was to examine the glass structure of silicate, borosilicate and borate BGs. Also, the effect of changing the network former on the ability to fabricate BG scaffolds by the foam replica method was investigated. The resulting silicate, borosilicate, and borate scaffolds were further examined on their chemical, morphological, mechanical, and bioactive properties. Structural analyses showed that the introduction of boron trioxide into silicate BGs leads to the depolymerization of the silicate network. Accordingly, the ion release profile and the ability to form hydroxyapatite of the different scaffolds were affected. Thus, this study shows that tailored BG compositions with case‐specific properties can be designed and used to fabricate 3D scaffolds for potential use in bone tissue engineering.

Optimized BMSC-derived osteoinductive exosomes immobilized in hierarchical scaffold via lyophilization for bone repair through Bmpr2/Acvr2b competitive receptor-activated Smad pathway

Mesenchymal stem cell-derived exosomes (MSC-exos), with its inherent capacity to modulate cellular behavior, are emerging as a novel cell-free therapy for bone regeneration. Herein, focusing on practical applying problems, the osteoinductivity of MSC-exos produced by different stem cell sources (rBMSCs/rASCs) and culture conditions (osteoinductive/common) were systematically compared to screen out an optimized osteogenic exosome (BMSC-OI-exo). Via bioinformatic analyses by miRNA microarray and in vitro pathway verification by gene silencing and miRNA transfection, we first revealed that the osteoinductivity of BMSC-OI-exo was attributed to multi-component exosomal miRNAs (let-7a-5p, let-7c-5p, miR-328a-5p and miR-31a-5p). These miRNAs targeted Acvr2b/Acvr1 and regulated the competitive balance of Bmpr2/Acvr2b toward Bmpr-elicited Smad1/5/9 phosphorylation. On these bases, lyophilized delivery of BMSC-OI-exo on hierarchical mesoporous bioactive glass (MBG) scaffold was developed to realize bioactivity maintenance and sustained release by entrapment in the surface microporosity of the scaffold. In a rat cranial defect model, the loading of BMSC-OI-exo efficiently enhanced the bone forming capacity of the scaffold and induced rapid initiation of bone regeneration. This paper could provide empirical bases of MSC-exo-based therapy for bone regeneration and theoretical bases of MSC-exo-induced osteogenesis mechanism. The BMSC-OI-exo-loaded MBG scaffold developed here represented a promising bone repairing strategy for future clinical application.

Preparation of a PLGA-coated porous bioactive glass scaffold with improved mechanical properties for bone tissue engineering approaches

The study aimed to improve the mechanical properties of a sol-gel-derived bioactive glass (BG) foam scaffold by poly-lactic co-glycolic acid (PLGA) coating as a potential scaffold for bone tissue regeneration. Polyurethane (PU) foam as the initial frame was submerged into a sol-gel-derived BG solution. The heat treatment process was carried out at 450°C to remove the PU foam and 860°C to consolidate the glass and remove the nitrate groups. The prepared BG scaffolds then were submerged into 10 and 15 wt% of PLGA solution. The uncoated BG scaffold was characterized by DTA/TGA, XRD, SEM, and TEM. The PLGA-coated scaffolds were characterized using SEM, and the mean compressive strength of the samples was measured. The DTA/TGA and XRD pattern indicated the removal of all nitrate groups at the temperatures above 700°C and also crystallization of BG after 800°C. The mean compressive strength of 10% and 15% PLGA-coated scaffolds were obtained 1.36±0.39 and 1.95±0.70 MPa, respectively, while the uncoated samples were crushed before the test. The SEM images exhibited that in the coated samples, the BG struts were covered with a PLGA layer and the coated layer was thicker in 15% PLGA samples. The SEM images also revealed that the PLGA coating maintained the structure of the broken struts and prevented them from coming apart. Thus, based on the obtained results, the PLGA coating was successfully toughened the BG scaffold and improved its elasticity. The study aimed to improve the mechanical properties of a sol-gel derived bioactive glass (BG) foam scaffold by Poly-lactic co-glycolic acid (PLGA) coating as a potential scaffold for bone tissue regeneration. Based on the results of this study, the PLGA coating can improve the elasticity and relieve the brittleness of sol-gel derived BG scaffold by supporting the fractured struts and prevent the scaffold from coming apart during a compressive strength test. Consequently, based on the obtained results a 15% PLGA-coated sol-gel derived BG scaffold can be considered as a potential scaffold for bone tissue regeneration.

S53P4 bioactive glass scaffolds induce BMP expression and integrative bone formation in a critical-sized diaphysis defect treated with a single-staged induced membrane technique

Critical-sized diaphysis defects are complicated by inherent sub-optimal healing conditions. The two-staged induced membrane technique has been used to treat these challenging defects since the 1980’s. It involves temporary implantation of a membrane-inducing spacer and subsequent bone graft defect filling. A single-staged, graft-independent technique would reduce both socio-economic costs and patient morbidity. Our aim was to enable such single-staged approach through development of a strong bioactive glass scaffold that could replace both the spacer and the graft filling. We constructed amorphous porous scaffolds of the clinically used bioactive glass S53P4 and evaluated them in vivo using a critical-sized defect model in the weight-bearing femur diaphysis of New Zealand White rabbits. S53P4 scaffolds and standard polymethylmethacrylate spacers were implanted for 2, 4, and 8 weeks. Induced membranes were confirmed histologically, and their osteostimulative activity was evaluated through RT-qPCR of bone morphogenic protein 2, 4, and 7 (BMPs). Bone formation and osseointegration were examined using histology, scanning electron microscopy, energy-dispersive X-ray analysis, and micro-computed tomography imaging. Scaffold integration, defect union and osteosynthesis were assessed manually and with X-ray projections. We demonstrated that S53P4 scaffolds induce osteostimulative membranes and produce osseointegrative new bone formation throughout the scaffolds. We also demonstrated successful stable scaffold integration with early defect union at 8 weeks postoperative in critical-sized segmental diaphyseal defects with implanted sintered amorphous S53P4 scaffolds. This study presents important considerations for future research and the potential of the S53P4 bioactive glass as a bone substitute in large diaphyseal defects. Statement of significanceSurgical management of critical-sized diaphyseal defects involves multiple challenges, and up to 10% result in delayed or non-union. The two-staged induced membrane technique is successfully used to treat these defects, but it is limited by the need of several procedures and bone graft. Repeated procedures increase costs and morbidity, while grafts are subject to donor-site complications and scarce availability. To transform this two-staged technique into one graft-independent procedure, we developed amorphous porous scaffolds sintered from the clinically used bioactive glass S53P4. This work constitutes the first evaluation of such scaffolds in vivo in a critical-sized diaphyseal defect in the weight-bearing rabbit femur. We provide important knowledge and prospects for future development of sintered S53P4 scaffolds as a bone substitute.

Nanostructure of bioactive glass affects bone cell attachment via protein restructuring upon adsorption

The nanostructure of engineered bioscaffolds has a profound impact on cell response, yet its understanding remains incomplete as cells interact with a highly complex interfacial layer rather than the material itself. For bioactive glass scaffolds, this layer comprises of silica gel, hydroxyapatite (HA)/carbonated hydroxyapatite (CHA), and absorbed proteins—all in varying micro/nano structure, composition, and concentration. Here, we examined the response of MC3T3-E1 pre-osteoblast cells to 30 mol% CaO–70 mol% SiO2 porous bioactive glass monoliths that differed only in nanopore size (6–44 nm) yet resulted in the formation of HA/CHA layers with significantly different microstructures. We report that cell response, as quantified by cell attachment and morphology, does not correlate with nanopore size, nor HA/CHO layer micro/nano morphology, or absorbed protein amount (bovine serum albumin, BSA), but with BSA’s secondary conformation as indicated by its β-sheet/α-helix ratio. Our results suggest that the β-sheet structure in BSA interacts electrostatically with the HA/CHA interfacial layer and activates the RGD sequence of absorbed adhesion proteins, such as fibronectin and vitronectin, thus significantly enhancing the attachment of cells. These findings provide new insight into the interaction of cells with the scaffolds’ interfacial layer, which is vital for the continued development of engineered tissue scaffolds.

13-93B3 Bioactive glasses containing Ce3+, Ga3+ and V5+: dose rate and gamma radiation characteristic for medical purposes

In this study, dose rates and radiation attenuation features of a group of fabricated bioactive glasses were investigated. The borate-based 13-93B3 bioactive glass powders (B3) containing cerium (III), gallium (III) or vanadium (IV) were prepared by melting a homogenized mixture of reagent-grade CaCO3, Na2CO3, MgCO3, K2CO3, H3BO3, CaHPO4.2H2O, Ga2O3, V2O5 or Ce(CH3CO2)3, and disc-shaped scaffolds were prepared by die pressing. Bioactive glasses were modelled by using MCNPX (version 2.7.0) general-purpose Monte Carlo code. A gamma-ray transmission set-up was utilized for determination of mass attenuation coefficients. The obtained coefficients were used for determination of other essential attenuation properties. Finally, exposure (EBF) and energy absorption (EABF) build-up factors were determined. Although the chemical structure of the additive material in bioactive glasses is identical, it can be inferred that the chemical structure of the additive is closely linked to the radiation attenuation characteristics of the bioactive glasses. Results also revealed that, although the bulk densities of the disc-shaped bioactive glass samples were lower than the measured true density values of the melt-derived glass powders due to porosity concerns, they exhibited radiation shielding effect. Findings of the study may be useful in understanding the radiation shielding characteristics of the bioactive glass scaffolds fabricated by powder processing. It can be concluded that outcomes of recent investigation can be useful during the evaluation of potential interactions between the bioactive glasses and medical radiation in the body.

Influence of random and designed porosities on 3D printed tricalcium phosphate-bioactive glass scaffolds.

Calcium phosphate (CaP)-based ceramics are a popular choice for bone-graft applications due to their compositional similarities with bone. Similarly, Bioactive glass (BG) is also common for bone tissue engineering applications due to its excellent biocompatibility and bone binding ability. We report tricalcium phosphate (TCP)-BG (45S5 BG) composite scaffolds using conventional processing and binder jetting-based 3D printing (3DP) technique. We hypothesize that BG's addition in TCP will enhance densification via liquid phase sintering and improve mechanical properties. Further, BG addition to TCP should modulate the dissolution kinetics in vitro. This work's scientific objective is to understand the influence of random vs. designed porosity in TCP-BG ceramics towards variations in compressive strength and in vitro biocompatibility. Our findings indicate that a 5 wt % BG in TCP composite shows a compressive strength of 26.7 ± 2.7 MPa for random porosity structures having a total porosity of ~47.9%. The same composition in a designed porosity structure shows a compressive strength of 21.3 ± 2.9 MPa, having a total porosity of ~54.1%. Scaffolds are also tested for their dissolution kinetics and in vitro bone cell materials interaction, where TCP-BG compositions show favorable bone cell materials interactions. The addition of BG enhances a flaky hydroxycarbonate apatite (HCA) layer in 8 weeks in vitro. Our research shows that the porous TCP- BG scaffolds, fabricated via binder jetting method with enhanced mechanical properties and dissolution properties can be utilized in bone graft applications.

Synthesis and Characterisation of Bioactive Glass 13-93 Scaffolds for Bone Tissue Regeneration

A modified sol-gel method was used in the current work to prepare a 13-93 bioactive glass powder, which was selected for the therapeutic actions of its constituent parts. In particular bioactive glass 13-93 can chemically bond with host tissue and induce osteogenesis. The produced gel was calcined at a temperature of 600 °C, while particle size analysis and x-ray diffraction were performed after the preparation of the glass powder. Porous bioactive glass 13-93 scaffolds were synthesised using the polymer foam replication technique that uses polyurethane sponges as a template. Sintering at 700 °C was then performed for one hour to the produce the required structures. After sintering, the microstructure was examined by scanning electron microscope (SEM) and Fourier transform infrared analysis (FTIR). The x-ray diffraction (XRD) results were also examined. The average particle size of bioactive glass 13-93 thus produced was about 2.978 μm, and XRD pattern analysis showed that the porous scaffolds were amorphous. The microstructure of the 13 – 93 glass scaffolds contained interconnected cellular pores and a dense network of bioactive glass, allowing scaffolds with porosity between 80 and 83% to be obtained. An in vitro bioactivity test was performed on the scaffolds by soaking them in a solution of simulated body fluid (SBF). The subsequent SEM images confirmed the bioactivity of the prepared scaffolds based on the formation of obvious and dense hydroxyapatite particles on the surface after 7 days of immersion in SBF. It was thus concluded that bioactive glass scaffold prepared in this work via the polymer foam replication technique has the potential to be used in several future applications.

Manuka Honey and Zein Coatings Impart Bioactive Glass Bone Tissue Scaffolds Antibacterial Properties and Superior Mechanical Properties

The combination of traditional herbal medicine (phytotherapeutic agents) with bioactive glasses is a promising strategy to generate advanced scaffolds for bone tissue engineering (BTE). An old remedy used for wound care since ancient times is honey. The antioxidant, antimicrobial and antibacterial properties of Manuka honey, in particular, make it an attractive substance for application in BTE scaffolds to prevent infections and biofilm formation. In this study 45S5 bioactive glass-based scaffolds produced via the foam replica technique were coated with corn protein zein and Manuka honey with two purposes: to improve the mechanical properties of the brittle scaffolds and to impart antibacterial properties. The morphology and chemical composition of the coated scaffolds were characterized with scanning electron microscopy and Fourier transform infrared spectroscopy, respectively, demonstrating the presence of Manuka honey in the coating. The release of the honey was quantified via ultraviolet-visible spectrophotometry; moreover, the antibacterial activity against Staphylococcus aureus was evaluated via colony-forming units counting, reduction of Alamar blue and turbidity measurements. Our findings suggest the effective combination of Manuka honey and bioactive glass, adding one more system to the novel family of bioactive glass scaffolds functionalized with phytotherapeutic agents.

Sintered S53P4 bioactive glass scaffolds have anti-inflammatory properties and stimulate osteogenesis in vitro

Bioactive glasses (BAG) are used as bone-graft substitutes in orthopaedic surgery. A specific BAG scaffold was developed by sintering BAG-S53P4 granules. It is hypothesised that this scaffold can be used as a bone substitute to fill bone defects and induce a bioactive membrane (IM) around the defect site. Beyond providing the scaffold increased mechanical strength, that the initial inflammatory reaction and subsequent IM formation can be enhanced by coating the scaffolds with poly(DL-lactide-co-glycolide) (PLGA) is also hypothesised. To study the immunomodulatory effects, BAG-S53P4 (± PLGA) scaffolds were placed on monolayers of primary human macrophage cultures and the production of various pro- and anti-inflammatory cytokines was assessed using reverse transcriptase quantitative polymerase chain reaction (RT-qPCR) and ELISA. To study the osteogenic effects, BAG-S53P4 (± PLGA) scaffolds were cultured with rabbit mesenchymal stem cells and osteogenic differentiation was evaluated by RT-qPCR and matrix mineralisation assays. The scaffold ion release was quantified and the BAG surface reactivity visualised. Furthermore, the pH of culture media was measured. BAG-S53P4 scaffolds had both anti-inflammatory and osteogenic properties that were likely attributable to alkalinisation of the media and ion release from the scaffold. pH change, ion release, and immunomodulatory properties of the scaffold could be modulated by the PLGA coating. Contrary to the hypothesis, the coating functioned by attenuating the BAG surface reactions and subsequent anti-inflammatory properties, rather than inducing an elevated inflammatory response compared to BAG-S53P4 alone. These results further validated the use of BAG-S53P4 (± PLGA) scaffolds as bone substitutes and indicate that scaffold properties can be tailored to a specific clinical need.

Evaluation of bioactive glass scaffolds incorporating SrO or ZnO for bone repair: In vitro bioactivity and antibacterial activity.

A series of bioactive glass scaffolds doped with SrO or ZnO (0, 5, and 10 mol%) were synthesized by the foam replica and melting method. The thermodynamic evolution, phase composition, microstructure, ion release, in vitro bioactivity, and oxygen density of the scaffolds were characterized. The proliferation of murine long bone osteocyte Y4 cells was studied by cell culture. The survival rate of the BGs evaluated the antibacterial activity and Escherichia coli strains in co-culture. The results indicated that the process window decreases with the increase of dopants. All the samples have a pore structure size of 200-400 μm. When the scaffolds were immersed in simulated body fluid for 28 days, hydroxyapatite formation was not affected, but the degradation process was retarded. The glass network packing and ionic radii variations of the substitution ions control surface degradation, glass dissolution, and ion release. MTT results revealed that 5Sr-BG had a significant effect on promoting cell proliferation and none of the BGs were cytotoxicity. Sr-BGs and Zn-BGs exhibited significantly inhibited growth against E. coli bacterial strains. Generally, these results showed the 5Sr-BG scaffold with high vitro bioactivity, cell proliferation, and antibacterial property is an important candidate material for bone tissue regeneration and repair.

Three-dimensionally printed polycaprolactone/multicomponent bioactive glass scaffolds for potential application in bone tissue engineering

AbstractOver the last years, three-dimensional (3D) printing has been successfully applied to produce suitable substitutes for treating bone defects. In this work, 3D printed composite scaffolds of polycaprolactone (PCL) and strontium (Sr)- and cobalt (Co)-doped multi-component melt-derived bioactive glasses (BGs) were prepared for bone tissue engineering strategies. For this purpose, 30% of as-prepared BG particles (size <38 μm) were incorporated into PCL, and then the obtained composite mix was introduced into a 3D printing machine to fabricate layer-by-layer porous structures with the size of 12 × 12 × 2 mm3.The scaffolds were fully characterized through a series of physico-chemical and biological assays. Adding the BGs to PCL led to an improvement in the compressive strength of the fabricated scaffolds and increased their hydrophilicity. Furthermore, the PCL/BG scaffolds showed apatite-forming ability (i.e., bioactivity behavior) after being immersed in simulated body fluid (SBF). The in vitro cellular examinations revealed the cytocompatibility of the scaffolds and confirmed them as suitable substrates for the adhesion and proliferation of MG-63 osteosarcoma cells. In conclusion, 3D printed composite scaffolds made of PCL and Sr- and Co-doped BGs might be potentially-beneficial bone replacements, and the achieved results motivate further research on these materials.

Design and evaluation of a novel sub-scaffold dental implant system based on the osteoinduction of micro-nano bioactive glass.

ABSTRACTAlveolar ridge atrophy brings great challenges for endosteal implantation due to the lack of adequate vertical bone mass to hold the implants. To overcome this limitation, we developed a novel dental implant design: sub-scaffold dental implant system (SDIS), which is composed of a metal implant and a micro-nano bioactive glass scaffold. This implant system can be directly implanted under mucous membranes without adding any biomolecules or destroying the alveolar ridge. To evaluate the performance of the novel implant system in vivo, SDISs were implanted into the sub-epicranial aponeurosis space of Sprague-Dawley rats. After 6 weeks, the SDIS and surrounding tissues were collected and analysed by micro-CT, scanning electron microscopy and histology. Our results showed that SDISs implanted into the sub-epicranial aponeurosis had integrated with the skull without any mobility and could stably support a denture. Moreover, this design achieved alveolar ridge augmentation, as active osteogenesis could be observed outside the cortical bone. Considering that the microenvironment of the sub-epicranial aponeurosis space is similar to that of the alveolar ridge, SDISs have great potential for clinical applications in the treatment of atrophic alveolar ridges. The study was approved by the Animal Care Committee of Guangdong Pharmaceutical University (approval No. 2017370).

On the role of alginate coating on the mechanical and biological properties of 58S bioactive glass scaffolds

In this study, novel 3D porous alginate-coated 58S bioactive glass scaffolds were fabricated through a foam replication method using a combination of amorphous 58S bioactive glass structure and sodium alginate. The formation of the alginate coating on the surface of the struts of BG scaffolds was confirmed. The effect of alginate coating on the microstructure, mechanical properties, biodegradability, biomineralization, adhesion, viability, and differentiation of human bone marrow-derived mesenchymal stem cells (hMSCs) on the 58S BG scaffolds were evaluated. A 45.2% increase in hMSC's viability and a 3.4-fold increase in ALP activity of the 1AlBG scaffold in the absence of an osteogenic differentiation media compared to an uncoated BG scaffold were observed. Notably, gene expression analysis exhibited that the 1AlBG scaffold resulted in accelerated osteogenic differentiation of hMSCs, as expression of COL-1, RUNX2, and OCN increased after 14 days. Results revealed a significant increase of antibacterial inhibition in the 1AlBG scaffold in comparison to the BG scaffold. Based on the microstructural, mechanical, and biological investigations, the 1AlBG scaffold exhibited enhanced mechanical and biological properties, making it a promising candidate for bone regeneration. Overall, our findings have highlighted the potential of alginate-coated BG scaffolds to stimulate bone regeneration through stem cell osteoinduction.