Distributed Fibre Optic Sensing (DFOS) for Deformation Assessment of Composite Collectors and Pipelines.

Due to the low costs of distributed optical fibre sensors (DFOS) and the possibility of their direct integration within layered composite members, DFOS technology has considerable potential in structural health monitoring of linear underground infrastructures. Often, it is challenging to truly simulate the actual ground conditions at all construction stages. Thus, reliable measurements are required to adjust the model and verify theoretical calculations. The article presents a new approach to monitor displacements and strains in Glass Fiber Reinforced Polymer (GFRP) collectors and pipelines using DFOS. The research verifies the effectiveness of the proposed monitoring solution for health monitoring of composite pipelines. Optical fibres were installed over the circumference of a composite tubular pipe, both on the internal and external surfaces, while loaded externally. Analysis of strain profiles allowed for calculating the actual displacements (shape) of the pipe within its cross-section plane using the Trapezoidal method. The accuracy of proposed approach was positively verified both with reference spot displacement transducer as well as numerical simulations using finite element method (FEM). DFOS could obtain a comprehensive view of structural deformations, including both strains and displacements under externally applied load. The knowledge gained during research will be ultimately used for renovating existing collectors.

Strategies for Enhancing Polyester-Based Materials for Bone Fixation Applications.

Polyester-based materials are established options, regarding the manufacturing of bone fixation devices and devices in routine clinical use. This paper reviews the approaches researchers have taken to develop these materials to improve their mechanical and biological performances. Polymer blending, copolymerisation, and the use of particulates and fibre bioceramic materials to make composite materials and surface modifications have all been studied. Polymer blending, copolymerisation, and particulate composite approaches have been adopted commercially, with the primary focus on influencing the in vivo degradation rate. There are emerging opportunities in novel polymer blends and nanoscale particulate systems, to tune bulk properties, and, in terms of surface functionalisation, to optimise the initial interaction of devices with the implanted environment, offering the potential to improve the clinical performances of fracture fixation devices.

Evaluation of flexural strength of resin interim restorations impregnated with various types of silane treated and untreated glass fibres.

BACKGROUND: Flexural strength is an important mechanical property that determines the long-term prognosis of interim restorations. Studies are lacking regarding the effect of silanation of the various types of glass fibre impregnation on the flexural strength of resin interim restorations. METHODS: A customized metal die was milled to simulate the prepared abutments of a three-unit fixed dental prosthesis. A total of seventy five samples of interim fixed dental prostheses were prepared using autopolymerizing tooth colour acrylic resin. Unidirectional and woven forms of glass fibres (Stick and Stick Net), which were silane treated and untreated were used to reinforce the resin matrix. Fifteen samples were prepared for each group along with unreinforced group serving as control. The flexural strength was evaluated with universal testing machine. RESULTS: The means and standard deviations of flexural strength for different groups were 13.90 ± 2.96 (control), 61.58 ± 5.26 (unidirectional fibres), 30.89 ± 3.60 (woven fibres), 112.05 ± 5.51 (silane treated unidirectional fibres) and 73.85 ± 4.10 (silane treated woven fibres) respectively. The mean flexural strength of silane treated unidirectional fibres (112.05 MPa) was highest and statistically highly significant (P < 0.0001) compared to all other groups. CONCLUSIONS: Within the limitations of the current study, flexural strength of the reinforced PMMA interim fixed dental prosthesis was significantly higher (P < 0.0001) when compared to the unreinforced PMMA interim fixed dental prosthesis. The use of silane treated unidirectional glass fibres is an effective method of reinforcing interim fixed restorations made of PMMA resins.

Slovakian glass fibre factory genotoxicity biomonitoring study - unsupported adverse outcome pathway (AOP) from the toxicology and human epidemiological experience of synthetic vitreous fibres (SVFs).

The article by Ceppi and colleagues, Genotoxic Effects of Occupational Exposure to, Glass Fibres - A Human Biomonitoring Study, published in Mutation Research -Genetic Toxicology and Environmental Mutagenesis in 2023 was reviewed with great interest. The authors undertook a novel approach to conducting a biomonitoring study of genotoxicity markers among a population of glass fibre manufacturing workers in Slovakia. On the surface, the Ceppi et al. (2023) study provides an interesting application of genotoxicity markers among a human population of workers to explore potential markers of effect (DNA strand breaks) and potential risk of susceptibility (e.g., genetic damage, disease, death). However, limited data for exposure reconstruction, uncertain influences from smoking history, and lack of consideration of decades of human epidemiology research showing no increased risk of malignant or non-malignant respiratory disease and mortality among glass fibre manufacturing workers, reveals that the conclusions of the authors are overreaching and inconsistent with the existing science. The limitations of this study preclude the ability to draw causal inferences or conclusions about DNA strand breaks as a marker of exposure, effect, or susceptibility within this population of Slovakian glass fibre workers. Further longitudinal research is required (e.g., more robust temporal assessment of occupational exposures - fibres and other compounds - and smoking history) to support the study conclusions.

Mechanical Properties and Ion Release from Fibre-Reinforced Glass Ionomer Cement.

The aim of this study was to compare the mechanical properties and ion release from a commercially available resin-modified glass ionomer cement to a formulation reinforced by the addition of short glass fibres at various percentages. Methods: Three experimental groups were prepared by adding a mass ratio of 10%, 15% and 20% of short glass fibres to the powder portion of the cement from a capsule (GC Fuji II LC), while the control group contained no fibres. Microhardness (n = 12), fracture toughness, and flexural, compressive and diametral tensile strength (n = 8) were evaluated. To study ion release, readings were obtained utilising fluoro-selective and calcium-selective electrodes after 24 h, 7 days and 30 days (n = 12). The spatial distribution of fibres within the material was evaluated through scanning electron microscopy. The data were analysed using one-way ANOVA with a Bonferroni adjustment. Results: The findings suggest that elevating fibre weight ratios to 20 wt% results in improved mechanical properties (p < 0.05) in microhardness, flexural strength, diametral tensile strength and fracture toughness. In terms of ion release, a statistically significant difference (p < 0.001) was observed between the groups at the conclusion of 24 h and 7 days, when the fluoride release was much higher in the control group. However, after 30 days, no significant distinction among the groups was identified (p > 0.05). Regarding calcium release, no statistically significant differences were observed among the groups at any of the evaluated time points (p > 0.05). SEM showed the fibres were homogeneously incorporated into the cement in all experimental groups. Conclusions: Resin-modified glass ionomer enhanced with short glass fibres at a weight loading of 20% showcased the most favourable mechanical properties while concurrently maintaining the ability to release fluoride and calcium after a 30-day period.

Flexural Creep Behaviour of Pultruded GFRP Composites Cross-Arm: A Comparative Study on the Effects of Stacking Sequence.

Pultruded glass fibre reinforced polymer (pGFRP) composites provide outstanding properties for composite polymer cross arms in power transmission line applications. This study has investigated the effects of various stacking sequences of fibres directions of pGFRP on flexural strength and creep behaviour. The use of static four-point bending flexural tests revealed that Stacking Sequence 2 (±45/0/90/0/90/0) had a significant flexural strength of 399.9 MPa while Stacking Sequence 1 (±45/90/0/±45) had a flexural strength of 242.5 MPa. Furthermore, the four-point bending creep experiments were performed at three distinct stress levels, notably 12%, 24%, and 37% of the ultimate flexural strength, to characterise the creep behaviour of distinct stacking sequences. Moreover, Findley's power law equation for bending creep behaviour has revealed that the time-dependent reduction factor of Stacking Sequence 1 and Stacking Sequence 2 estimates a drop in flexural modulus of 23% and 10% respectively.

Influence of Natural Weather Conditions in the Long-Term Fracture Energy of Glass Fibre Reinforced Cement (GRC) Modified with Chemical Additions.

The use of glass fibre-reinforced cement (GRC) in structural elements has been limited due to the reduction in the mechanical properties of the material with aging. Chemical additions have been used to modify the cement mortar formulation in order to minimise such loss, but no conclusive results have been obtained yet. Moreover, the application of accelerated aging methods in such modified GRC formulations still poses several uncertainties. An experimental campaign seeking to assess the reduction in the fracture energy of two GRCs manufactured with modified matrixes after five years of exposure to natural environment was performed. Furthermore, a comparison with results from the literature that used accelerated aging methods was performed. The results show that the use of the chemical additives might be capable of maintaining to a notable extent the mechanical properties of GRC after five years of natural aging. Regarding the accelerated aging method by means of immersion in hot water tanks, it seemed that the equivalences applied in previous research accurately match the degradation of the material after natural exposure to weather. Additionally, a digital image correlation analysis showed that aged GRCs seemed to distribute damage in a smaller area than young GRCs.

Evaluation of depth-wise post-gel polymerisation shrinkage behaviour of flowable dental composites.

Short fibre reinforced flowable dental composites are gaining acceptance over particulate filled composites due to their competence to impart improved physio-mechanical properties and capability to prevent crack propagation. However, limited research exists to assess their overall post-gel shrinkage behaviour, which is an important factor to determine marginal seal around restoration and hence its longevity. In this paper, depth-wise post-gel shrinkage strain and the resulting factors such as degree of conversion and rheological behaviour of flowable fibre reinforced composite (FRC) containing 5% weight fraction of 5 µm diameter, 350 µm length S-Glass fibres in UDMA/TEGDMA mixture along with 50% strontium filler particles were investigated. Post-gel shrinkage strain was measured using an array of optical fibre Bragg grating sensors (FBGs) of diameter 250 µm and length 1 mm each embedded at three different depths (depth 0 mm, depth 2.5 mm and depth 5 mm from curing light tip) within the flowable dental composite samples. The rheological behaviour during the polymerisation process was carried out using dynamic oscillatory tests. To evaluate the conversion of CC during polymerisation, degree of conversion tests were conducted by using FTIR spectroscopy. The results obtained for FRC samples were further compared with that of particulate filled composite (PFC) samples, with 55% strontium filler particles only within the same resin system. The relationship between post-gel shrinkage strain at different depths, rheological behaviour and degree of conversion was also explored. The experimental results from the sensor embedded materials suggested that the post-gel shrinkage strain was higher at the top surface (depth 0 mm) and was 50% more than at the bottom surface (depth of 5 mm) for dental FRC as well as PFC samples. Further, similar flow behaviour and not significant different (p<0.05) degree of conversion (DC), post-gel shrinkage strain for dental PFC and FRC composites was observed, establishing a convincing positive relationship between all the key factors and further implying that replacement of fibres with fillers did not affect the overall post-gel polymerisation shrinkage behaviour in dental composites. This investigation has also demonstrated that fibre optic sensors-based shrinkage measurements can be an ideal technique to evaluate post-gel shrinkage performance of dental resins with PFCs or FRCs.

Mechanical Performance of Granite Fine Fly Dust-Filled Basalt/Glass Polyurethane Polymer Hybrid Composites.

The granite processing industry generates large amounts of bottom granite dust waste every day. After the drying and heating process of concrete mixture production, the granite dust is blown and collected in the filtering nozzle. This very fine particle granite dry fly dust, with a particle size maximum distribution of 500 µm, can easily be blown away by wind and cause serious environmental impacts. The use of this waste material would be an effective way to reduce such impacts. Therefore, this paper presents an experimental study on the potential of granite dust as a filler in enhancing the mechanical performance of a hybrid basalt/glass (WB/GCSM) composite. The unhole and open hole tensile (UHT and OHT) properties, low velocity impact (LVI) properties, quasi-static indentations (QSI) properties, flexural properties, interlaminar shear stress (ILSS) properties, and morphology of the developed WB/GCSM composites were evaluated. To meet the objective of this study, composite specimens were produced using 1.5-60 µm granite fly dust at three (3) different loadings (1, 3 and 5 wt%). This granite fly dust was incorporated into polyurethane resin using a mechanical stirring technique. The production of FRP laminates then completed using a hand lay-up and vacuum bagging technique. Four types of the WB/GCSM composites systems, i.e., [WB/GCSM], [WB/GCSM/1GD], [WB/GCSM/3GD] and [WB/GCSM/5GD] were fabricated and compared. The analysis results for the mechanical tests revealed that the incorporation of granite dust of up to 3 wt% had increased the UHT, OHT, LVI, QSI, flexural and ILSS properties of all WB/GCSM composites systems. Higher levels of damage tolerance in UHT and OHT tests, and increased ductility index in the LVI test were obtained when granite dust was added up to 5 wt%. However, a remarkable improvement in all mechanical properties was noticed for [WB/GCSM/1GD], which recorded the highest mechanical performance among all WB/GCSM composite systems.

Effect of fibre-reinforced composite as a post-obturation restorative material on fracture resistance of endodontically treated teeth: A systematic review.

BACKGROUND: Fracture resistance of endodontically treated tooth is affected due to large cavity designs and access cavities and an appropriate material capable to resist fracture plays an important role. This review aims to evaluate the effect of fibre-reinforced composite (FRC) as a post-obturation material on fracture resistance of endodontically treated teeth. OBJECTIVES: To systematically gather and evaluate the fracture resistance of fibre-reinforced composite as a post-obturation restorative material in endodontically treated teeth. DATA SOURCES: A systematic search was conducted using PubMed, Ebsco Host, Scopus, Google Scholar, Hinari and manual search library resources from 1st Jan 2000 to 30th November 2019 to identify appropriate studies. RESULT: A total of 157 articles were examined out of which 55 articles were selected after reading the title. After removing the duplicates, 27 articles were screened for abstract and 1 article was eliminated as it did not meet the eligibility criteria. A thorough reading of the full text of the remaining 26 selected articles was assessed for eligibility. Amongst these, 1 article was then excluded from the study as the full text was not accessible. Lastly, 25 articles were included in the study. CONCLUSION: FRC as a core material increases fracture resistance of endodontically treated teeth but they do not have the fracture resistance similar to the intact tooth. Both polyethylene and short fibre-reinforced composites showed greater fracture resistance when compared to glass FRC and restoration without reinforcement. Also, the fracture resistance increases if restored with FRC along with retention slots and are placed on the occlusal third surfaces of cavities. Also, favourable fractures were most commonly seen and it usually occurred at the level of enamel and dentin and adhesive fractures were seen.

Resizing Approach to Increase the Viability of Recycled Fibre-Reinforced Composites.

Most recycling methods remove the essential sizing from reinforcing fibres, and many studies indicate the importance of applying sizing on recycled fibres, a process we will denote here as resizing. Recycled fibres are not continuous, which dissociates their sizing and composite lay-up processes from virgin fibres. In this study, commercial polypropylene and polyurethane-based sizing formulations with an aminosilane coupling agent were used to resize recycled glass and carbon fibres. The impact of sizing concentration and batch process variables on the tensile properties of fibre-reinforced polypropylene and polyamide composites were investigated. Resized fibres were characterized with thermal analysis, infrared spectroscopy and electron microscopy, and the tensile properties of the composites were analysed to confirm the achievable level of performance. For glass fibres, an optimal mass fraction of sizing on the fibres was found, as an excess amount of film former has a plasticising effect. For recycled carbon fibres, the sizing had little effect on the mechanical properties but led to significant improvement of handling and post-processing properties. A comparison between experimental results and theoretical prediction using the Halpin-Tsai model showed up to 81% reinforcing efficiency for glass fibres and up to 74% for carbon fibres.

Effect of MWCNT Surface Functionalisation and Distribution on Compressive Properties of Kenaf and Hybrid Kenaf/Glass Fibres Reinforced Polymer Composites.

The aim of this study is to evaluate the effect of surface treated multi wall carbon nanotubes (MWCNTs) on compressive properties of the unidirectional (UD) kenaf and hybrid woven glass/UD kenaf fibre reinforced polymer composites. The MWCNTs were first treated using concentrated acid (a mix of H2SO4 and HNO3) and silane (three-aminoprophyltriethoxysilane) in order to improve the dispersion within the epoxy matrix using a high shear roll milling technique. In this study, nanomodified epoxies were prepared using 0.5, 0.75 and 1.0 wt % of pristine MWCNT (PCNT), acid treated MWCNT (ACNT) and silane treated MWCNT (SCNT). These nanomodified epoxies were then used for the fabrication of kenaf and hybrid composites using combination of filament winding and resin impregnation. The uniaxial compression test was conducted using a universal testing machine according to the ASTM D3410 standard. The morphology of fractured samples was observed and analysed using scanning electron microscopy (SEM) in order to evaluate the failure behaviour and mechanisms involved during compression. It was found that the addition of treated MWCNT (ACNT and SCNT) improved the compressive properties of kenaf and hybrid composites as compared to those of untreated-MWCNT (PCNT). The addition of 1.0 wt % of SCNT exhibited good compressive properties in both kenaf and hybrid composite systems. The compressive modulus and strength increased by 73.25% and 20.15%, respectively, for composites made of 1.0 wt % SCNT and Kenaf (1.0SCNT/K). For the hybrid composites, the compressive modulus and strength increased by 21.18% and 7.73% for composites made of 1.0 wt % SCNT filled G/K composites (1.0SCNT/G/K).

Comparison of Analytical Approaches Predicting the Compressive Strength of Fibre Reinforced Polymers.

Common analytical models to predict the unidirectional compressive strength of fibre reinforced polymers are analysed in terms of their accuracy. Several tests were performed to determine parameters for the models and the compressive strength of carbon fibre reinforced polymer (CFRP) and glass fibre reinforced polymer (GFRP). The analytical models are validated for composites with glass and carbon fibres by using the same epoxy matrix system in order to examine whether different fibre types are taken into account. The variation in fibre diameter is smaller for CFRP. The experimental results show that CFRP has about 50% higher compressive strength than GFRP. The models exhibit significantly different results. In general, the analytical models are more precise for CFRP. Only one fibre kinking model's prediction is in good agreement with the experimental results. This is in contrast to previous findings, where a combined modes model achieves the best prediction accuracy. However, in the original form, the combined modes model is not able to predict the compressive strength for GFRP and was adapted to address this issue. The fibre volume fraction is found to determine the dominating failure mechanisms under compression and thus has a high influence on the prediction accuracy of the various models.

Effect of Denture Base Reinforcement Using Light Cured E- Glass Fibers on the Level of Salivary Immunoglobulin A.

BACKGROUND: A gap still exists between in vitro and clinical studies concerning the biocompatibility of the material in the oral environment and their potential to cause immunological undesirable side effects. The uses of glass fibres to improve the mechanical properties of acrylic resin denture base polymers are well documented in vitro. AIM: The present study aimed to evaluate the effect of denture base reinforcement using light-cured E- glass fibres mesh on the level of salivary immunoglobulin A (S-IgA) in patients wearing complete dentures. MATERIAL AND METHODS: Fourteen completely edentulous patients, in need of complete dentures, participated in the study. The patients were divided into two groups (n = 7) according to the treatment protocol. In the first group, patients received conventional heat-cured acrylic resin dentures. In the second group, the mandibular dentures were reinforced using light cured resin impregnated E glass fibres mesh. In both groups, salivary samples were collected using passive drool technique. The level IgA was assessed by enzyme-linked immunosorbent assay (ELISA) technique at different time intervals. Statistical analysis was carried out using one-way ANOVA followed by Tukey`s post-hoc test and independent t-test. The significant level was set at P ≤ 0.05. RESULTS: Acrylic resin dentures and reinforced ones demonstrated an increase in the mean values of IgA level at the end of the follow-up intervals. And this increase was statistically significant (P ≤ 0.05). Although, the reinforced dentures revealed higher mean values, there was no statistically significant difference between the two groups (P > 0.05). CONCLUSIONS: Within the limitations of the present study, the following could be concluded: (1) the insertion of complete dentures induced changes in the level of IgA; and (2) denture base reinforcement using light cured resin impregnated E-glass fibres mesh had a similar effect to that of heat cured acrylic resin on the level of IgA.

Broad-spectrum bactericidal activity of a new bioactive grafting material (F18) against clinically important bacterial strains.

Infection is the most relevant surgical complication in implant or grafting procedures. Osteomyelitis and other chronic conditions pose a constant challenge in current medical practice. In this context, a grafting biomaterial that possesses antibacterial properties combined with bioactivity could have great clinical impact. Researchers at the Vitreous Materials Laboratory (LaMaV-UFSCar) recently developed a glass composition, named F18, that presents an improved workability range combined with high bioactivity. With F18, one can easily manufacture complex shapes, such as scaffolds, continuous fibres and coat implants. This biomaterial has proven to be a viable alternative for bone and skin regeneration in in vivo tests, however its antimicrobial properties have not been explored. Hence, the purpose of this study was to systematically investigate the antibacterial activity of F18 in powder and fibre forms according to the JIS Z 2801:2010 standard. Whether incorporation of silver into F18 glass could impact its antimicrobial activity was also evaluated. Four clinically relevant Gram-positive and Gram-negative pathogenic bacterial strains (Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli and Pseudomonas aeruginosa) were used in this study. In both powder and fibre forms, F18 presented extremely efficient bactericidal activity against all strains tested, eliminating virtually 100% of the bacterial cells after 24 h. Kinetic tests showed that silver doping further increased the bactericidal activity, leading to S. aureus eradication in only 30 min after incubation. Both doped and non-doped glasses demonstrated very high bactericidal activity, making F18 a promising infection-preventing alternative for bone and wound regeneration in clinical practice.

Cytocompatibility, mechanical and dissolution properties of high strength boron and iron oxide phosphate glass fibre reinforced bioresorbable composites.

In this study, Polylactic acid (PLA)/phosphate glass fibres (PGF) composites were prepared by compression moulding. Fibres produced from phosphate based glasses P2O5-CaO-MgO-Na2O (P45B0), P2O5-CaO-MgO-Na2O-B2O3 (P45B5), P2O5-CaO-MgO-Na2O-Fe2O3 (P45Fe3) and P2O5-CaO-MgO-Na2O-B2O3-Fe2O3 (P45B5Fe3) were used to reinforce the bioresorbable polymer PLA. Fibre mechanical properties and degradation rate were investigated, along with the mechanical properties, degradation and cytocompatibility of the composites. Retention of the mechanical properties of the composites was evaluated during degradation in PBS at 37°C for four weeks. The fibre volume fraction in the composite varied from 19 to 23%. The flexural strength values (ranging from 131 to 184MPa) and modulus values (ranging from 9.95 to 12.29GPa) obtained for the composites matched those of cortical bone. The highest flexural strength (184MPa) and modulus (12.29GPa) were observed for the P45B5Fe3 composite. After 28 days of immersion in PBS at 37°C, ~35% of the strength profile was maintained for P45B0 and P45B5 composites, while for P45Fe3 and P45B5Fe3 composites ~40% of the initial strength was maintained. However, the overall wet mass change of P45Fe3 and P45B5Fe3 remained significantly lower than that of the P45B0 and P45B5 composites. The pH profile also revealed that the P45B0 and P45B5 composites degraded quicker, correlating well with the degradation profile. From SEM analysis, it could be seen that after 28 days of degradation, the fibres in the fractured surface of P45B5Fe3 composites remain fairly intact as compared to the other formulations. The in vitro cell culture studies using MG63 cell lines revealed both P45Fe3 and P45B5Fe3 composites maintained and showed higher cell viability as compared to the P45B0 and P45B5 composites. This was attributed to the slower degradation rate of the fibres in P45Fe3 and P45B5Fe3 composites as compared with the fibres in P45B0 and P45B5 composites.

In-situ polymerisation of fully bioresorbable polycaprolactone/phosphate glass fibre composites: In vitro degradation and mechanical properties.

Fully bioresorbable composites have been investigated in order to replace metal implant plates used for hard tissue repair. Retention of the composite mechanical properties within a physiological environment has been shown to be significantly affected due to loss of the integrity of the fibre/matrix interface. This study investigated phosphate based glass fibre (PGF) reinforced polycaprolactone (PCL) composites with 20%, 35% and 50% fibre volume fractions (Vf) manufactured via an in-situ polymerisation (ISP) process and a conventional laminate stacking (LS) followed by compression moulding. Reinforcing efficiency between the LS and ISP manufacturing process was compared, and the ISP composites revealed significant improvements in mechanical properties when compared to LS composites. The degradation profiles and mechanical properties were monitored in phosphate buffered saline (PBS) at 37°C for 28 days. ISP composites revealed significantly less media uptake and mass loss (p<0.001) throughout the degradation period. The initial flexural properties of ISP composites were substantially higher (p<0.0001) than those of the LS composites, which showed that the ISP manufacturing process provided a significantly enhanced reinforcement effect than the LS process. During the degradation study, statistically higher flexural property retention profiles were also seen for the ISP composites compared to LS composites. SEM micrographs of fracture surfaces for the LS composites revealed dry fibre bundles and poor fibre dispersion with polymer rich zones, which indicated poor interfacial bonding, distribution and adhesion. In contrast, evenly distributed fibres without dry fibre bundles or polymer rich zones, were clearly observed for the ISP composite samples, which showed that a superior fibre/matrix interface was achieved with highly improved adhesion.

Phosphate glass fibre scaffolds: Tailoring of the properties and enhancement of the bioactivity through mesoporous glass particles.

Novel bone glass fibre scaffolds were developed by thermally bonding phosphate glass fibres belonging to the P2O5-CaO-Na2O-SiO2-MgO-K2O-TiO2 system (TiPS2.5 glass). Scaffolds with fibres of 85 or 110µm diameter were fabricated, showing compressive strength in the range of 2-3.5MPa, comparable to that of the trabecular bone. The effect of different thermal treatments and fibre diameters and length on the final scaffold structure was investigated by means of micro-CT analysis. The change of the sintering time from 30 to 60min led to a decrease in the scaffold overall porosity from 58 to 21vol.% for the 85µm fibre scaffold and from 50 to 40vol.% when increasing the sintering temperature from 490 to 500°C for the 110µm fibre scaffold. The 85µm fibres resulted in an increase of the scaffold overall porosity, increased pore size and lower trabecular thickness; the use of different fibre diameters allowed the fabrication of a scaffold showing a porosity gradient. In order to impart bioactive properties to the scaffold, for the first time in the literature the introduction in these fibre scaffolds of a bioactive phase, a melt-derived bioactive glass (CEL2) powder or spray-dried mesoporous bioactive glass particles (SD-MBG) was investigated. The scaffold bioactivity was assessed through soaking in simulated body fluid. CEL2/glass fibre scaffold did not show promising results due to particle detachment from the fibres during soaking in simulated body fluid. Instead the use of mesoporous bioactive powders showed to be an effective way to impart bioactivity to the scaffold and could be further exploited in the future through the ability of mesoporous particles to act as systems for the controlled release of drugs.

Development of a novel smart scaffold for human skeletal muscle regeneration.

Skeletal muscle defects are notoriously difficult to manage and the current methods used are associated with many limitations. Engineered skeletal muscle tissue has the potential to provide a solution that circumvents these disadvantages. Our previous work has identified a novel three-dimensionally aligned degradable phosphate glass fibre scaffold that can support myoblast differentiation and maturation. This current study has further developed the scaffold by encasing the fibres within a collagen gel to produce a smart composite scaffold that provides key biomimetic cues and supports the formation of a tissue that may be implanted in vivo. The constructs formed were approximately 30 mm long and microscopic examination confirmed favourable unidirectional cell alignment. There was good cell survival, and gene expression studies demonstrated upregulation of the myogenic regulatory factors and developmental and adult myosin heavy chain isoforms indicating myofibre formation and maturation respectively. Compared with the three-dimensional glass fibre scaffolds, the composite scaffolds had later gene upregulation, however, the use of collagen gels reinforced with degradable aligned glass fibres offers the opportunity to create a tissue analogue that can be easily manipulated. Furthermore, the glass fibre ends could support tendon/bone formation, and the channels formed as the fibres degrade could allow for vascular ingrowth.