Scale-up manufacture and characterisation of resorbable phosphate based glass fibre for textile production

Bioresorbable phosphate-based glasses (PBG) have been investigated for varying tissue engineering applications such as fibrous reinforcement for fully resorbable PLA composite for fracture fixation. The mechanical properties of these composites are determined by the mechanical properties of phosphate glass fibre (PGF) which can be tailored by varying the chemical composition of glass. However, current phosphate glass fibre production is in lab-scale quantities and in single filament form which limits the use of these fibres as they can only be produced as non-woven random or unidirectional fibre mats. The main aim of this project was to scale-up manufacture of phosphate glass fibres and textile product for reinforcement of PLA composite. The detail objectives included novel phosphate glass formulation development, design and manufacture of multifilament PGF drawing system, multifilament PGF fabrication, textile weaving and textile reinforced PLA composite characterisation. In this study, PBGs of the system P2O5-B2O3-CaO-MgO-Na2O-Fe2O3 were investigated. In order to determine the effects of replacing P2O5 with B2O3 on the glass structure, thermal properties, density, degradation properties and cytocompatibility studies were carried out. The investigation revealed that the thermal properties and chemical durability of the glass were decreased when phosphate was replaced by boron, due to the increase of BO3 units which, could increase crystallisation tendency and easily be attacked by solution. During phosphate glass fibre fabrication, single filament fibre fabrication was achieved successfully using all glass codes of glass system (48-x)P2O5-(12+x)B2O3-14CaO-20MgO-1Na2O-5Fe2O3. In order to produce phosphate glass fibre, all phosphate based glasses in this study were taken into account during single filament fibre drawing trials. To assess the performance of the single filament fibres, the PGF were subjected to mechanical and degradation testing. The performance of PGF was assessed by measuring three different post-processing methods including: annealed, size (water-soluble epoxy size) coated, and size coated and heat-treated. It was found that size coating and annealing treatment of the fibre improved the chemical durability of fibres significantly, whilst heat treatment damaged the coatings on the fibre and eliminated the protection on fibre surface. Based on the success from the single filament fibre manufacture, the glasses with excellent fibre drawing performance were then used in multifilament fibre fabrication. A novel furnace design was then used as a multifilament fibre drawing system. The final multifilament fibres were produced successfully and coated with water-soluble epoxy size for fibre combination and surface protection. Final strands of multifilament fibre were rewound and combined to be fibre products such as roving (without twist) and yarns (with twist). The PLA composite reinforced by unidirectional (UD) roving or yarns were produced and investigated in vitro in terms of degradation profiles and mechanical property retention in order to evaluate the effect of fibre volume fraction and twist on the performance of composites. The flexural properties of UD composites were found to rapidly reduce in aqueous medium, and the high level of twist was also seen to reduce the flexural properties of composite. With the design and manufacture of a small inkle-type loom for hand weaving, yarns were used successfully in the small Inkle-type loom to produce narrow, plain weave textiles which, to the authors knowledge is the first time textile products of phosphate glass fibre has been produced in the world. The cytocompatibility of this textile was investigated via MG63 cell seeding on the textile surface and characterisation of cell metabolic activity. For further study, the textile reinforced PLA composite was produced and compared with a 0°/90° unidirectional lay-up composite as a pseudo-zero crimp textile. Due to the limitation of the hand weaving technique, a higher density of yarns laying along the longitudinal direction (load direction) demonstrated greater mechanical properties when compared to 0°/90° composite. Retention of mechanical properties for both composites was also investigated during a degradation study and ~20% flexural strength was maintained for both textile reinforced composite and 0º/90º lay-up composite. Generally, this novel composite could be a good preliminary study to investigate feasibility of industrial scale production of phosphate glass fibre reinforced composites. However, fast degradation behaviour resulted in significant reduction of mechanical properties of composite. As such, the development of novel glass formulations with better degradation behaviours and good fibre drawing performance should be taken into account in future research

The mechanical property, degradation and cytocompatibility analysis of novel phosphate glass fiber textiles

© The Author(s) 2018. Phosphate glass fibers have been widely considered as potential biomedical materials for orthopedical application due to their full degradability and excellent cytocompatibility. In this study, phosphate-based glass fibers were drawn from the glass system 48P2O5-12B2O3-14CaO-20MgO-1Na2O-5Fe2O3, via a melt-drawn spinning process and then woven into textile fabric using a small lab-scale inkle-loom. The annealing treatment was applied to both fibers and textiles with 1-hour heat treatment at 540℃, which was 10℃ above the glass transition temperature. An increase in Young's modulus was observed for the single filament fibers and a decrease in tensile strength with annealing treatment. During the degradation period, the tensile strength of non-annealed fibers presented a decrease by day 28, whilst annealed fibers had increased by day 7, then decreased by day 28, which was suggested to be due to the peeling effect observed on the surface of the fibers. The cytocompatibility of the textile fabric with annealing treatment (A-textile) and the non-annealed fabric (N-textile) was characterized via seeding of MG63 cells. Higher metabolic activity and DNA concentration were obtained for the A-textile samples when compared to the N-textile, which was suggested to be due to the lower dissolution rate of the A-textile resulting in fewer ions leaching into the solution. The phosphate glass fiber textiles investigated in this study have shown potential application as bioresorbable composites reinforcement for orthopedic treatment

Production and characterisation of novel phosphate glass fibre yarns, textiles, and textile composites for biomedical applications

This work presents manufacturing, processing and characterisation of the phosphate glass fibre (PGF) products for biomedical applications, including multifilament PGF strands, yarns and textiles, and PGF textile composites. The multifilament production of PGF strands was achieved using a 50-nozzle bushing. PGF yarns, with a linear density of 87 tex, a twist angle of 14° and a tensile strength of 0.29 N/tex, were produced by combining 8 fibre strands using the ring-spinning method. PGF textiles, with a width of 15 mm and a thickness of 0.36 mm, were prepared using an inkle loom. The maximum flexural strength and modulus of unidirectional (UD) composites with a fibre volume fraction of ~17% were 262 ± 11 MPa and 10.4 ± 0.2 GPa, respectively. PGF textile composites with a fibre volume fraction of ~21% exhibited mechanical properties of 176 ± 13 MPa for flexural strength and 8.6 ± 0.6 GPa for flexural modulus. Despite the UD and textile composites having almost an equivalent amount of fibres in the 0 direction, the crimp of the yarns was found to contribute to the significantly lower flexural properties of the textile composites in comparison with the unidirectional (UD) composites. Additionally, the processing conditions such as processing temperature and time were found to have a strong effect on the mechanical properties of the resultant composite products. The number-average molecular weight of PLA was also found to reduce by 13% and 19% after the production of PLA films and PLA plates, respectively, in comparison with the as-received PLA pellets

Investigation of fire protection performance and mechanical properties of thin-ply bio-epoxy composites

Hybrid composites composed of bio-based thin-ply carbon fibre prepreg and flameretardant mats (E20MI) have been produced to investigate the effects of laminate design on their fire protection performance and mechanical properties. These flame-retardant mats rely primarily on expandable graphite, mineral wool and glass fibre to generate a thermal barrier that releases incombustible gasses and protects the underlying material. A flame retardant (FR) mat is incorporated into the carbon fibre bio-based polymeric laminate and the relationship between the fire protection properties and mechanical properties is investigated. Hybrid composite laminates containing FR mats either at the exterior surfaces or embedded 2-plies deep have been tested by the limited oxygen index (LOI), vertical burning test and cone calorimetry. The addition of the surface or embedded E20MI flame retardant mats resulted in an improvement from a base line of 33.1% to 47.5% and 45.8%, respectively. All laminates passed the vertical burning test standard of FAR 25.853. Cone calorimeter data revealed an increase in the time to ignition (TTI) for the hybrid composites containing the FR mat, while the peak of heat release rate (PHRR) and total heat release (TTR) were greatly reduced. Furthermore, the maximum average rate of heat emission (MARHE) values indicated that both composites with flame retardant mats had achieved the requirements of EN 45545-2. However, the tensile strengths of laminates with surface or embedded flame-retardant mats were reduced from 1215.94 MPa to 885.92 MPa and 975.48 MPa, respectively. Similarly, the bending strength was reduced from 836.41 MPa to 767.03 MPa and 811.36 MPa, respectively

Interaction Mechanisms Between the NOX4/ROS and RhoA/ROCK1 Signaling Pathways as New Anti- fibrosis Targets of Ursolic Acid in Hepatic Stellate Cells

BackgroundStudies have shown that both NOX4 and RhoA play essential roles in fibrosis and that they regulate each other. In lung fibrosis, NOX4/ROS is located upstream of the RhoA/ROCK1 signaling pathway, and the two molecules are oppositely located in renal fibrosis. Currently, no reports have indicated whether the above mechanisms or other regulatory mechanisms exist in liver fibrosis.ObjectivesTo investigate the effects of the NOX4/ROS and RhoA/ROCK1 signaling pathways on hepatic stellate cell (HSC)-T6 cells, the interaction mechanisms of the two pathways, and the impact of UA on the two pathways to elucidate the role of UA in the reduction of hepatic fibrosis and potential mechanisms of HSC-T6 cell proliferation, migration, and activation.MethodsStable cell lines were constructed using the lentiviral transduction technique. Cell proliferation, apoptosis, migration, and invasion were examined using the MTS, TdT-mediated dUTP nick-end labeling, cell scratch, and Transwell invasion assays, respectively. The DCFH-DA method was used to investigate the ROS levels in each group. RT-qPCR and western blotting techniques were utilized to assess the mRNA and protein expression in each group. CoIP and the Biacore protein interaction analysis systems were used to evaluate protein interactions.ResultsThe NOX4/ROS and RhoA/ROCK1 signaling pathways promoted the proliferation, migration, and activation of HSCs. UA inhibited cell proliferation, migration, and activation by inhibiting the activation of the two signaling pathways, but the mechanism of apoptosis was independent of these two pathways. The NOX4/ROS pathway was upstream of and positively regulated the RhoA/ROCK1 pathway in HSCs. No direct interaction between the NOX4 and RhoA proteins was detected.ConclusionThe NOX4/ROS and RhoA/ROCK1 signaling pathways are two critical signaling pathways in a series of behavioral processes in HSCs, and NOX4/ROS regulates RhoA/ROCK1 through an indirect pathway to control the activation of HSCs. Additionally, NOX4/ROS and RhoA/ROCK1 constitute a new target for UA antifibrosis treatment

Novel bioresorbable textile composites for medical applications

Currently, phosphate glass fibre (PGF) reinforced composites are a potential solution for bone repairing due to sufficient mechanical properties and full bioresorbability. In this study, a small inkle-type loom for hand weaving facilitated the production of PGF in textile form. These PGF textiles, along with unidirectional (UD) fibre mats made from the same batch of yarns, were utilised to manufacture fully resorbable textile composites (T-C) and 0°/90° lay-up UD fibre reinforced composites (0/90-C). Retention of flexural properties and weight loss of the composites were evaluated during degradation in phosphate buffered saline (PBS) at 37°C for 28 days. The initial flexural strength values that were observed for the T-C and 0/90-C composites were ∼;176 MPa and ∼;137 MPa, whilst the modulus values were 8.6 GPa and 6.9 GPa, respectively. The higher flexural strength and modulus values for the T-C when compared to those of 0/90-C were attributed to the textile weaving manually, resulting in a biased fabric with a higher density of fibres in the warp direction. ∼;20% flexural strength and ∼;25% flexural modulus were maintained for all composites at the 28 day interval. For this study, the textile achievement will be the significant milestone on the research of bioresorbable PGFs reinforced composite in medical application, and important step on the industrial direction of bioresorbable medical device. © 2017 International Committee on Composite Materials. All rights reserved

The effect of intumescent mat on post-fire performance of carbon fibre reinforced composites

This study investigated the effect of intumescent mats (M1 and M2) with different compositions on the post-fire performance of carbon fibre reinforced composites. The sandwich structure was designed for composites where M1 (carbon fibre reinforced composite-M1) or M2 (carbon fibre reinforced composite-M2) mats were covered on the composite surface. A significant reduction in the peak heat release rate and total heat release was observed from the cone calorimetric data, and carbon fibre reinforced composite-M1 showed the lowest value of 148 kW/m2 and 29 MJ/m2 for peak heat release rate and total heat release, respectively. In addition, a minor influence on mechanical properties was observed due to the variation of composite thickness and resin volume in the composite. The post-fire properties of composite were characterised, and the M1 mat presented better retention of flexural strength and modulus. The feasibility of two-layer model was confirmed to predict the post-fire performance of composites and reduce the reliance on the large amounts of empirical data. © The Author(s) 2019

Structural, thermal, in vitro degradation and cytocompatibility properties of P2O5-B2O3-CaO-MgO-Na2O-Fe2O3 glasses

Borophosphate glasses with compositions of (48 − x)P2O5-(12 + x)B2O3-14CaO-20MgO-1Na2O-5Fe2O3 (where x = 0, 3, 8 mol%) were prepared via a melt-quenching process. The effects of replacing P2O5 with B2O3 on the structural, thermal, degradation properties and cytocompatibility were investigated. Fourier transform infrared (FTIR) spectroscopy analysis confirmed the existence of BO3 triangular units and BO4 tetrahedral units within all the glasses with an increase of B/P ratio from 0.25 to 0.5. The BO4 units within the glass structure were observed to cause an increase in density (ρ) as well as glass transition (Tg) temperature and to decrease the crystallisation temperature (Tc). A decrease in thermal stability which indicated by process window was also observed in the case of substitution of P2O5 with B2O3. Degradation analysis of the glasses indicated that the dissolution rate increased with the addition of B2O3. The decrease in the thermal stability and chemical durability were attributed to the increase of BO3 units, which could increase crystallisation tendency and be easily hydrolysed by solution. The effect of boron addition on the cytocompatibility of the glasses was analysed using Alamar Blue and alkaline phosphatase (ALP) assays and DNA quantification. MG63 osteosarcoma cells cultured in direct contact with the glass samples surface for 14 days showed better cytocompatibility, compared to the tissue culture plastic (TCP) control group. In summary, the glass formulation with 12 mol% B2O3 presented the best cytocompatibility and thermal stability, thus could be considered for continuous fibre fabrication in future research and downstream activities

Structural, thermal and dissolution properties of MgO- and CaO-containing borophosphate glasses: effect of Fe2O3 addition

This paper investigated manufacture of high-durability phosphate glass fibres for biomedical applications. Five different borophosphate glass formulations in the systems of 45P2O5–5B2O3–5Na2O–(29 − x)CaO–16MgO–(x)Fe2O3 and 45P2O5–5B2O3–5Na2O–24CaO–(21 − x)MgO–(x)Fe2O3 where x = 5, 8 and 11 mol% were produced via melt quenching. The compositions and amorphous nature of the glasses were confirmed by ICP-MS and XRD, respectively. FTIR results indicated depolymerisation of the phosphate chains with a decrease in Q2 units with increasing Fe2O3 content. DSC analyses showed an increase in Tg by ~5 °C with an increment of 3 mol% in Fe2O3 content. The thermal properties were also used to calculate processing window (i.e. Tc,ons—Tg) and another parameter, Kgl, to determine the suitability for fibre drawing directly from melt, which equals (Tc,ons—Tg)/(Tl—Tc,ons). The degradation study conducted in PBS solution at 37 °C showed a decrease of 25–47% in degradation rate with increasing Fe2O3 content. This confirmed that the chemical durability of the glasses had increased, which was suggested to be due to Fe2O3 addition. Furthermore, the density measured via Archimedes method revealed a linear increase with increasing Fe2O3 content

Adolescent transport and unintentional injuries: a systematic analysis using the Global Burden of Disease Study 2019

Background: Globally, transport and unintentional injuries persist as leading preventable causes of mortality and morbidity for adolescents. We sought to report comprehensive trends in injury-related mortality and morbidity for adolescents aged 10–24 years during the past three decades. Methods: Using the Global Burden of Disease, Injuries, and Risk Factors 2019 Study, we analysed mortality and disability-adjusted life-years (DALYs) attributed to transport and unintentional injuries for adolescents in 204 countries. Burden is reported in absolute numbers and age-standardised rates per 100 000 population by sex, age group (10–14, 15–19, and 20–24 years), and sociodemographic index (SDI) with 95% uncertainty intervals (UIs). We report percentage changes in deaths and DALYs between 1990 and 2019. Findings: In 2019, 369 061 deaths (of which 214 337 [58%] were transport related) and 31·1 million DALYs (of which 16·2 million [52%] were transport related) among adolescents aged 10–24 years were caused by transport and unintentional injuries combined. If compared with other causes, transport and unintentional injuries combined accounted for 25% of deaths and 14% of DALYs in 2019, and showed little improvement from 1990 when such injuries accounted for 26% of adolescent deaths and 17% of adolescent DALYs. Throughout adolescence, transport and unintentional injury fatality rates increased by age group. The unintentional injury burden was higher among males than females for all injury types, except for injuries related to fire, heat, and hot substances, or to adverse effects of medical treatment. From 1990 to 2019, global mortality rates declined by 34·4% (from 17·5 to 11·5 per 100 000) for transport injuries, and by 47·7% (from 15·9 to 8·3 per 100 000) for unintentional injuries. However, in low-SDI nations the absolute number of deaths increased (by 80·5% to 42 774 for transport injuries and by 39·4% to 31 961 for unintentional injuries). In the high-SDI quintile in 2010–19, the rate per 100 000 of transport injury DALYs was reduced by 16·7%, from 838 in 2010 to 699 in 2019. This was a substantially slower pace of reduction compared with the 48·5% reduction between 1990 and 2010, from 1626 per 100 000 in 1990 to 838 per 100 000 in 2010. Between 2010 and 2019, the rate of unintentional injury DALYs per 100 000 also remained largely unchanged in high-SDI countries (555 in 2010 vs 554 in 2019; 0·2% reduction). The number and rate of adolescent deaths and DALYs owing to environmental heat and cold exposure increased for the high-SDI quintile during 2010–19. Interpretation: As other causes of mortality are addressed, inadequate progress in reducing transport and unintentional injury mortality as a proportion of adolescent deaths becomes apparent. The relative shift in the burden of injury from high-SDI countries to low and low–middle-SDI countries necessitates focused action, including global donor, government, and industry investment in injury prevention. The persisting burden of DALYs related to transport and unintentional injuries indicates a need to prioritise innovative measures for the primary prevention of adolescent injury. Funding: Bill & Melinda Gates Foundation