We synthesized Fe foams using water suspensions of micrometric Fe2O3 powder by reducing and sintering the sublimated Fe oxide green body to Fe under 5% H2/Ar gas. The resultant Fe foam showed aligned lamellar macropores replicating the ice dendrites. The compressive behavior and deformation mechanism of the synthesized Fe foam were studied using an acoustic emission (AE) method, with which we detected sudden localized structural changes in the Fe foam material. The evolution of the deformation mechanism was elucidated using the adaptive sequential k-means (ASK) algorithm; specifically, the plastic deformation of the cell struts was followed by localized cell collapse, which eventually led to fracturing of the cell walls. For potential biomedical applications, the corrosion and biocompatibility characteristics of the two synthesized Fe foams with different porosities (50% vs. 44%) were examined and compared. Despite its larger porosity, the superior corrosion behavior of the Fe foam with 50% porosity can be attributed to its larger pore size and smaller microscopic surface area. Based on the cytotoxicity tests for the extracts of the foams, the Fe foam with 44% porosity showed better cytocompatibility than that with 50% porosity.
- MeSH
- akustika * MeSH
- biokompatibilní materiály chemie toxicita MeSH
- buněčné linie MeSH
- difrakce rentgenového záření MeSH
- elektrochemie metody MeSH
- fibroblasty MeSH
- koroze MeSH
- myši MeSH
- pevnost v tlaku MeSH
- poréznost MeSH
- testování materiálů MeSH
- viskoelastické látky chemie MeSH
- železité sloučeniny chemie MeSH
- železo chemie toxicita MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Volumetric compressibility and Poisson's ratios of fibrous soft tissues are analyzed in this paper on the basis of constitutive models and experimental data. The paper extends the previous work of Skacel and Bursa (J Mech Behav Biomed Mater, 54, pp. 316-327, 2016), dealing with incompressible behaviour of constitutive models, to the area of compressibility. Both recent approaches to structure-based constitutive modelling of anisotropic fibrous biomaterials (based on either generalized structure tensor or angular integration) are analyzed, including their compressibility-related aspects. New experimental data related to compressibility of porcine arterial layer are presented and compared with the theoretical predictions of analyzed constitutive models. The paper points out the drawbacks of recent models with distributed fibres orientation since none of the analyzed constitutive models seems to be capable to predict the experimentally observed Poisson's ratios and volume change satisfactory.
- MeSH
- arterie * MeSH
- biologické modely * MeSH
- biomechanika MeSH
- mechanický stres MeSH
- pevnost v tlaku * MeSH
- prasata MeSH
- testování materiálů * MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Meniscus is a semilunar fibrocartilaginous tissue, serving important roles in load buffering, stability, lubrication, proprioception, and nutrition of the knee joint. The degeneration and damage of meniscus has been proved to be a risk factor of knee osteoarthritis. Mechanical stimulus is a critical factor of the development, maintenance and repair of the meniscus fibrochondrocytes. However, the mechanism of the mechano-transduction process remains elusive. Here we reported that cyclic hydrostatic compress force (CHCF) treatment promotes proliferation and inhibits apoptosis of the isolated primary meniscus fibrochondrocytes (PMFs), via upregulating the expression level of integrin ?5ß1. Consequently, increased phosphorylated-ERK1/2 and phosphorylated-PI3K, and decreased caspase-3 were detected. These effects of CHCF treatment can be abolished by integrin ?5ß1 inhibitor or specific siRNA transfection. These data indicate that CHCF regulates apoptosis of PMFs via integrin ?5ß1-FAK-PI3K/ERK pathway, which may be an important candidate approach during meniscus degeneration.
- MeSH
- apoptóza fyziologie účinky léků MeSH
- buněčný převod mechanických signálů fyziologie MeSH
- chondrocyty metabolismus účinky léků MeSH
- fibroblasty metabolismus účinky léků MeSH
- hydrostatický tlak MeSH
- integrin alfa5beta1 antagonisté a inhibitory metabolismus MeSH
- krysa rodu rattus MeSH
- kultivované buňky MeSH
- malá interferující RNA aplikace a dávkování MeSH
- meniskus cytologie metabolismus MeSH
- pevnost v tlaku fyziologie MeSH
- potkani Sprague-Dawley MeSH
- proliferace buněk fyziologie MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
The structure degradation and strength changes of calcium phosphate scaffolds after long-term exposure to an acidic environment simulating the osteoclastic activity were determined and compared. Sintered calcium phosphate scaffolds with different phase structures were prepared with a similar cellular pore structure and an open porosity of over 80%. Due to microstructural features the biphasic calcium phosphate (BCP) scaffolds had a higher compressive strength of 1.7 MPa compared with the hydroxyapatite (HA) and β-tricalcium phosphate (TCP) scaffolds, which exhibited a similar strength of 1.2 MPa. After exposure to an acidic buffer solution of pH = 5.5, the strength of the HA scaffolds did not change over 14 days. On the other hand, the strength of the TCP scaffolds decreased steeply in the first 2 days and reached a negligible value of 0.09 MPa after 14 days. The strength of the BCP scaffolds showed a steady decrease with a reasonable value of 0.5 MPa after 14 days. The mass loss, phase composition and microstructural changes of the scaffolds during degradation in the acidic environment were investigated and a mechanism of scaffold degradation was proposed. The BCP scaffold showed the best cell response in the in vitro tests. The BCP scaffold structure with the highly soluble phase (α-TCP) embedded in a less soluble matrix (β-TCP/HA) exhibited a controllable degradation with a suitable strength stability and with beneficial biological behavior it represented the preferred calcium phosphate structure for a resorbable bone scaffold.
- MeSH
- buněčná adheze MeSH
- DNA metabolismus MeSH
- fosforečnany vápenaté chemie MeSH
- keramika chemie MeSH
- koncentrace vodíkových iontů MeSH
- kosti a kostní tkáň fyziologie MeSH
- lidé MeSH
- mezenchymální kmenové buňky cytologie MeSH
- pevnost v tlaku MeSH
- poréznost MeSH
- tkáňové podpůrné struktury chemie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
Articular cartilage is a complex, anisotropic, stratified tissue with remarkable resilience and mechanical properties. It has been subject to extensive modelling as a multiphase medium, with many recent studies examining the impact of increasing detail in the representation of this tissue's fine scale structure. However, further investigation of simple models with minimal constitutive relations can nonetheless inform our understanding at the foundations of soft tissue simulation. Here, we focus on the impact of heterogeneity with regard to the volume fractions of solid and fluid within the cartilage. Once swelling pressure due to cartilage fixed charge is also present, we demonstrate that the multiphase modelling framework is substantially more complicated, and thus investigate this complexity, especially in the simple setting of a confined compression experiment. Our findings highlight the importance of locally, and thus heterogeneously, approaching pore compaction for load bearing in cartilage models, while emphasising that such effects can be represented by simple constitutive relations. In addition, simulation predictions are observed for the sensitivity of stress and displacement in the cartilage to variations in the initial state of the cartilage and thus the details of experimental protocol, once the tissue is heterogeneous. These findings are for the simplest models given only heterogeneity in volume fractions and swelling pressure, further emphasising that the complex behaviours associated with the interaction of volume fraction heterogeneity and swelling pressure are likely to persist for simulations of cartilage representations with more fine-grained structural detail of the tissue.
OBJECTIVES: To explore fatigue limits of ceramic endocrowns for premolars. METHODS: Forty-eight devitalized premolars were cut at the CEJ. They were restored with standardized CAD-CAM lithium disilicate reinforced ceramic restorations (IPS e.max CAD, Ivoclar-Vivadent) and divided into four Groups (n=12): overlays (Group A, no endo-core, negative control), endocrowns with an endo-core of 2mm (Group B), 4mm (GroupC) and crowns with post and core (Group D, positive control). All specimens were first submitted to thermo-mechanical cyclic loading (TCML)(1.7Hz, 49N, 600000 cycles, 1500 thermo-cycles). Margins were analysed before and after the loading. Survived specimens were then submitted to cyclic isometric stepwise loading (5Hz, 200N to 1200N) until completion of 105000 cycles or failure. In case of fracture, fragments were analysed using SEM and failure mode was determined. Results of stepwise loading were statistically analysed by Kaplan-Meier life survival analysis and log rank test (p=0.05). RESULTS: All the specimens survived the TCML test except four specimens of Group A (early restorations' debonding). No difference in percentages of closed margins was found between endocrowns (Groups B, C) and crowns (Group D). After the stepwise test, differences in survival within the groups were not statistically significant. Most of restorations experienced non-reparable fracture. CONCLUSIONS: Endocrowns with both 2-mm and 4-mm long endo-cores displayed outcomes after fatigue equivalent to classical crowns. Results of this study discourage the use of flat overlays with only adhesive retention. CLINICAL SIGNIFICANCE: When restoring extremely destroyed devitalized premolars, adhesive strategies should be coupled to a macro-mechanical retention in the root.
- MeSH
- analýza přežití MeSH
- analýza zatížení zubů MeSH
- cementování MeSH
- design s pomocí počítače * MeSH
- keramika MeSH
- lidé MeSH
- mechanický stres MeSH
- pevnost v tlaku MeSH
- premolár * MeSH
- testování materiálů MeSH
- trvalá zubní náhrada MeSH
- výsledek terapie MeSH
- zubní korunky * MeSH
- zubní krček MeSH
- zubní marginální adaptace MeSH
- zubní materiály * MeSH
- zubní porcelán chemie MeSH
- zubní protéza - design * MeSH
- zuby neživé * MeSH
- zuby-sanace - selhání MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Direct ink writing (DIW) techniques open up new possibilities for the fabrication of patient-specific bone grafts. Self-setting calcium phosphate inks, which harden at low temperature, allow obtaining nanostructured scaffolds with biomimetic properties and enhanced bioactivity. However, the slow hardening kinetics hampers the translation to the clinics. Different hydrothermal treatments for the consolidation of DIW scaffolds fabricated with an α-tricalcium phosphate /pluronic F127 ink were explored, comparing them with a biomimetic treatment. Three different scaffold architectures were analysed. The hardening process, associated to the conversion of α-tricalcium phosphate to hydroxyapatite was drastically accelerated by the hydrothermal treatments, reducing the time for complete reaction from 7 days to 30 minutes, while preserving the scaffold architectural integrity and retaining the nanostructured features. β-tricalcium phosphate was formed as a secondary phase, and a change of morphology from plate-like to needle-like crystals in the hydroxyapatite phase was observed. The binder was largely released during the treatment. The hydrothermal treatment resulted in a 30% reduction of the compressive strength, associated to the residual presence of β-tricalcium phosphate. Biomimetic and hydrothermally treated scaffolds supported the adhesion and proliferation of rat mesenchymal stem cells, indicating a good suitability for bone tissue engineering applications. STATEMENT OF SIGNIFICANCE: 3D plotting has opened up new perspectives in the bone regeneration field allowing the customisation of synthetic bone grafts able to fit patient-specific bone defects. Moreover, this technique allows the control of the scaffolds' architecture and porosity. The present work introduces a new method to harden biomimetic hydroxyapatite 3D-plotted scaffolds which avoids high-temperature sintering. It has two main advantages: i) it is fast and simple, reducing the whole fabrication process from the several days required for the biomimetic processing to a few hours; and ii) it retains the nanostructured character of biomimetic hydroxyapatite and allows controlling the porosity from the nano- to the macroscale. Moreover, the good in vitro cytocompatibility results support its suitability for cell-based bone regeneration therapies.
- MeSH
- buněčná adheze MeSH
- fosforečnany vápenaté chemie MeSH
- inkoust * MeSH
- krysa rodu rattus MeSH
- mezenchymální kmenové buňky cytologie metabolismus MeSH
- nanostruktury chemie MeSH
- pevnost v tlaku MeSH
- polyethyleny chemie MeSH
- polypropyleny chemie MeSH
- potkani inbrední LEW MeSH
- tkáňové podpůrné struktury chemie MeSH
- vysoká teplota MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
As coprocessed excipients (CPE) gain a lot of focus recently, this article compares three commercially available CPE of Avicel brand, namely, CE 15, DG, and HFE 102. Comparison is based on measured physical properties of coprocessed mixtures, respectively, flow properties, pycnometric density, mean particle size, specific surface area, moisture content, hygroscopicity, solubility, pH leaching, electrostatic charge, SEM images, and DSC. Tablets were made employing three pressure sets. Viscoelastic properties and ejection force were assessed during compression, as well as pycnometric density, mass uniformity, height, tensile strength, friability, disintegration, and wetting times. Avicel CE 15 is of mid-range flow properties, contains mid-size and nonspherical particles, and has high hygroscopicity, growing negative charge, best lubricity, lowest tensile strength, and mid-long disintegration times. Avicel DG possesses the worst flow properties, small asymmetrical particles, lowest hygroscopicity, stable charge, intermediate lubricity, and tensile strength and exhibits fast disintegration of tablets. Finally, Avicel HFE 102 has the best flow properties, large symmetrical particles, and middle hygroscopicity and its charge fluctuates throughout blending. It also exhibits inferior lubricity, the highest tensile strength, and slow disintegration of tablets. Generally, it is impossible to select the best CPE, as their different properties fit versatile needs of countless manufacturers and final products.
- MeSH
- časové faktory MeSH
- celulosa chemie MeSH
- diferenciální skenovací kalorimetrie MeSH
- fyzikální absorpce MeSH
- koncentrace vodíkových iontů MeSH
- pevnost v tahu MeSH
- pevnost v tlaku MeSH
- pomocné látky chemie MeSH
- poréznost MeSH
- prášky, zásypy, pudry MeSH
- reologie MeSH
- rozpustnost MeSH
- smáčivost MeSH
- statická elektřina MeSH
- tablety MeSH
- tlak MeSH
- velikost částic MeSH
- vlhkost MeSH
- voda chemie MeSH
- vysoušení * MeSH
- Publikační typ
- časopisecké články MeSH
- srovnávací studie MeSH
Heat-treated polyacrylonitrile (HT-PAN), also referred to as black orlon (BO), is a promising carbon-based material used for applications in tissue engineering and regenerative medicine. To the best of our knowledge, no such complex bone morphology-mimicking three-dimensional (3D) BO structure has been reported to date. We report that BO can be easily made into 3D cryogel scaffolds with porous structures, using succinonitrile as a porogen. The cryogels possess a porous morphology, similar to bone tissue. The prepared scaffolds showed strong osteoconductive activity, providing excellent support for the adhesion, proliferation, and mitochondrial activity of human bone-derived cells. This effect was more apparent in scaffolds prepared from a matrix with a higher content of PAN (i.e., 10% rather than 5%). The scaffolds with 10% of PAN also showed enhanced mechanical properties, as revealed by higher compressive modulus and higher compressive strength. Therefore, these scaffolds have a robust potential for use in bone tissue engineering.
- MeSH
- akrylové pryskyřice chemie MeSH
- kosti a kostní tkáň MeSH
- lidé MeSH
- pevnost v tlaku MeSH
- poréznost MeSH
- tkáňové inženýrství MeSH
- tkáňové podpůrné struktury MeSH
- vysoká teplota MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
Collagen composite scaffolds have been used for a number of studies in tissue engineering. The hydration of such highly porous and hydrophilic structures may influence mechanical behaviour and porosity due to swelling. The differences in physical properties following hydration would represent a significant limiting factor for the seeding, growth and differentiation of cells in vitro and the overall applicability of such hydrophilic materials in vivo. Scaffolds based on collagen matrix, poly(DL-lactide) nanofibers, calcium phosphate particles and sodium hyaluronate with 8 different material compositions were characterised in the dry and hydrated states using X-ray microcomputed tomography, compression tests, hydraulic permeability measurement, degradation tests and infrared spectrometry. Hydration, simulating the conditions of cell seeding and cultivation up to 48 h and 576 h, was found to exert a minor effect on the morphological parameters and permeability. Conversely, hydration had a major statistically significant effect on the mechanical behaviour of all the tested scaffolds. The elastic modulus and compressive strength of all the scaffolds decreased by ~95%. The quantitative results provided confirm the importance of analysing scaffolds in the hydrated rather than the dry state since the former more precisely simulates the real environment for which such materials are designed.
- MeSH
- biokompatibilní materiály chemie MeSH
- fosforečnany vápenaté chemie MeSH
- kolagen chemie MeSH
- kyselina hyaluronová chemie MeSH
- mechanické jevy MeSH
- modul pružnosti MeSH
- pevnost v tlaku MeSH
- polyestery chemie MeSH
- poréznost MeSH
- rentgenová mikrotomografie MeSH
- testování materiálů MeSH
- tkáňové inženýrství metody MeSH
- tkáňové podpůrné struktury chemie MeSH
- voda chemie MeSH
- vysoušení * MeSH
- Publikační typ
- časopisecké články MeSH
