3D-printing of Urethane-based Photoelastomers for Vascular Tissue Regeneration

2009 ◽  
Vol 1239 ◽  
Author(s):  
Stefan Baudis ◽  
Thomas Pulka ◽  
Bernhard Steyrer ◽  
Harald Wilhelm ◽  
Guenter Weigel ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Blood Vessels ◽  
Vascular Tissue ◽  
Mechanical Performance ◽  
In Vitro Tests ◽  
Layer By Layer ◽  
Digital Light Processing ◽  
Tissue Replacement ◽  
Tear Resistance

AbstractThe mechanical properties of materials designated for vascular tissue replacement are of crucial importance. The elastic modulus, the tensile strength as well as the suture tear resistance have to be adjusted. Our approach is to use photopolymers for artificial vascular grafts. Via the layer-by-layer photopolymerization of suitable resin formulations as performed in additive manufacturing (AM) very complex structures are realizable. Hence AM offer the possibility to create cellular structures within the artificial grafts that might favor the ingrowth of new tissue. Commercially available urethane acrylates (UA) were chosen as base monomers since urethane groups are known to have good cell-adhesion behavior and poly-UAs show adequate mechanical performance. The mechanical properties of the photoelastomers can be tailored by addition of reactive diluents (e.g. 2-hydroxyethyl acrylate, HEA) and thiols (e.g. 3,6 dioxa-1,8-octane-dithiol) as chain transfer agents to comply with the mechanical properties of natural blood vessels. To examine the suture tear resistance a new testing method has been developed. Finally, a formulation containing 30 wt% UA and 70 wt% HEA complies with the mechanical properties of natural blood vessels, shows good biocompatibility in in-vitro tests and was successfully 3D-printed with digital light processing AM.

scholarly journals Elastomeric Electrospun Scaffolds of a Biodegradable Aliphatic Copolyester Containing PEG-Like Sequences for Dynamic Culture of Human Endothelial Cells

Biomolecules ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1620
Author(s):  
Luca Fusaro ◽  
Chiara Gualandi ◽  
Diego Antonioli ◽  
Michelina Soccio ◽  
Anna Liguori ◽  
...  
Keyword(s):  
Blood Vessels ◽  
Vascular Tissue ◽  
Mechanical Performance ◽  
Thrombus Formation ◽  
Cell Activity ◽  
Mechanical Tests ◽  
Cyclic Stretch ◽  
Biological Characterization ◽  
The Right

In the field of artificial prostheses for damaged vessel replacement, polymeric scaffolds showing the right combination of mechanical performance, biocompatibility, and biodegradability are still demanded. In the present work, poly(butylene-co-triethylene trans-1,4-cyclohexanedicarboxylate), a biodegradable random aliphatic copolyester, has been synthesized and electrospun in form of aligned and random fibers properly designed for vascular applications. The obtained materials were analyzed through tensile and dynamic-mechanical tests, the latter performed under conditions simulating the mechanical contraction of vascular tissue. Furthermore, the in vitro biological characterization, in terms of hemocompatibility and cytocompatibility in static and dynamic conditions, was also carried out. The mechanical properties of the investigated scaffolds fit within the range of physiological properties for medium- and small-caliber blood vessels, and the aligned scaffolds displayed a strain-stiffening behavior typical of the blood vessels. Furthermore, all the produced scaffolds showed constant storage and loss moduli in the investigated timeframe (24 h), demonstrating the stability of the scaffolds under the applied conditions of mechanical deformation. The biological characterization highlighted that the mats showed high hemocompatibility and low probability of thrombus formation; finally, the cytocompatibility tests demonstrated that cyclic stretch of electrospun fibers increased endothelial cell activity and proliferation, in particular on aligned scaffolds.

Investigation of 3-D mechanical properties of blood vessels using a new in vitro tests system: results on sheep common carotid arteries

2001 ◽  
Vol 48 (4) ◽  
pp. 442-451 ◽  
Author(s):  
W.C.P.M. Blondel ◽  
J. Didelon ◽  
G. Maurice ◽  
J.-P. Carteaux ◽  
Xiong Wang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Blood Vessels ◽  
Carotid Arteries ◽  
In Vitro Tests ◽  
Common Carotid Arteries

scholarly journals Goldmann Tonometry and Corneal Biomechanics

2021 ◽  
Vol 11 (9) ◽  
pp. 4025
Author(s):  
Dario Messenio ◽  
Marco Ferroni ◽  
Federica Boschetti
Keyword(s):  
Mechanical Properties ◽  
Anterior Chamber ◽  
Pressure Transducer ◽  
Pearson Correlation ◽  
Corneal Thickness ◽  
Applanation Tonometry ◽  
In Vitro Tests ◽  
Goldmann Tonometry ◽  
The Difference

Glaucoma is the second cause of irreversible blindness in the world. Intraocular pressure (IOP) is a recognized major risk factor for the development and progression of glaucomatous damage. Goldmann applanation tonometry (GAT) is internationally accepted as the gold standard for the measurement of IOP. The purpose of this study was to search for correlations between Goldmann tonometry and corneal mechanical properties and thickness by means of in vitro tests. IOP was measured by the Goldmann applanation tonometer (GIOP), and by a pressure transducer inserted in the anterior chamber of the eye (TIOP), at increasing pressure levels by addition of saline solution in the anterior chamber of enucleated pig eyes (n = 49). Mechanical properties were also determined by inflation tests. The GAT underestimated the real measurements made by the pressure transducer, with most common differences in the range 15–28 mmHg. The difference between the two instruments, highlighted by the Bland–Altman test, was confirmed by ANOVA, normality tests, and Mann–Whitney’s tests, both on the data arranged for infusions and for the data organized by pressure ranges. Pearson correlation tests revealed a negative correlation between (TIOP-GIOP) and both corneal stiffness and corneal thickness. In conclusion, data obtained showed a discrepancy between GIOP and TIOP more evident for softer and thinner corneas, that is very important for glaucoma detection.

Scaffolds in tissue engineering of blood vessels

2010 ◽  
Vol 88 (9) ◽  
pp. 855-873 ◽  
Author(s):  
Divya Pankajakshan ◽  
Devendra K. Agrawal
Keyword(s):  
Tissue Engineering ◽  
Extracellular Matrix ◽  
Blood Vessels ◽  
Vascular Tissue ◽  
Small Diameter ◽  
Biological Scaffolds ◽  
Hemodynamic Forces ◽  
Biodegradable Scaffolds

Tissue engineering of small diameter (<5 mm) blood vessels is a promising approach for developing viable alternatives to autologous vascular grafts. It involves in vitro seeding of cells onto a scaffold on which the cells attach, proliferate, and differentiate while secreting the components of extracellular matrix that are required for creating the tissue. The scaffold should provide the initial requisite mechanical strength to withstand in vivo hemodynamic forces until vascular smooth muscle cells and fibroblasts reinforce the extracellular matrix of the vessel wall. Hence, the choice of scaffold is crucial for providing guidance cues to the cells to behave in the required manner to produce tissues and organs of the desired shape and size. Several types of scaffolds have been used for the reconstruction of blood vessels. They can be broadly classified as biological scaffolds, decellularized matrices, and polymeric biodegradable scaffolds. This review focuses on the different types of scaffolds that have been designed, developed, and tested for tissue engineering of blood vessels, including use of stem cells in vascular tissue engineering.

scholarly journals Electron Beam Melting of Ti-6Al-4V Lattice Structures; Correlation between Post Heat Treatment and Mechanical Properties

2021 ◽  
Author(s):  
Giuseppe Del Guercio ◽  
Manuela Galati ◽  
Abdollah Saboori
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Computer Aided Design ◽  
Mechanical Performance ◽  
Industrial Applications ◽  
Heat Treatments ◽  
Layer By Layer ◽  
Lattice Structures ◽  
Heat Treated ◽  
Aided Design

Abstract Additive Manufacturing processes are considered advanced manufacturing methods. It would be possible to produce complex shape components from a Computer-Aided Design model in a layer-by-layer manner. Lattice structures as one of the complex geometries could attract lots of attention for both medical and industrial applications. In these structures, besides cell size and cell type, the microstructure of lattice structures can play a key role in these structures' mechanical performance. On the other hand, heat treatment has a significant influence on the mechanical properties of the material. Therefore, in this work, the effect of the heat treatments on the microstructure and mechanical behaviour of Ti-6Al-4V lattice structures manufactured by EBM was analyzed. The main mechanical properties were compared with the Ashby and Gibson model. It is very interesting to notice that a more homogeneous failure mode was found for the heat-treated samples. The structures' relative density was the main factor influencing their mechanical performance of the heat-treated samples. It is also found that the heat treatments were able to preserve the stiffness and the compressive strength of the lattice structures. Besides, an increment of both the elongation at failure and the absorbed energy was obtained after the heat treatments. Microstructure analysis of the heat-treated samples confirms the increment of ductility of the heat-treated samples with respect to the as-built one.

Biphasic Calcium Phosphate/Poly-(DL-Lactide-Co-Glycolide) Biocomposite as Filler and Blocks for Reparation of Bone Tissue

2005 ◽  
Vol 494 ◽  
pp. 519-524 ◽  
Author(s):  
N. Ignjatović ◽  
P. Ninkov ◽  
Z. Ajduković ◽  
V. Konstantinović ◽  
Dragan P. Uskokovic
Keyword(s):  
Bone Tissue ◽  
Vascular Tissue ◽  
Average Diameter ◽  
In Vitro Tests ◽  
Scanning Calorimetry ◽  
Tissue Reconstruction ◽  
High Level ◽  
Osseous Regeneration

Composite biomaterials, like calciumphosphate/bioresorbable polymer, offer excellent potential for reconstruction and reparation of bone tissue defects induced by different sources. In this paper synthesis of calciumphosphate/poly-DL-lactide-co-glycolide (BCP/DLPLG) composite biomaterial formed as filler and blocks was studied. BCP/DLPLG composite biomaterial was produced in the form of spherical granules of BCP covered by a DLPLG layer, average diameter of 150-250 µm. By cold and hot pressing of granules at up to 10000 kg/cm2, blocks with fine distribution of phases and porosity up to 3% were obtained. Characterization was performed by wide-angle X-ray structural analysis (WAXS), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), infrared spectroscopy (IR), and mechanical properties by defining the compressive strength. In vitro citotoxicity research was carried out on cellular cultures of fibroblasts of human (MRC5) and mouse (L929). In vivo research was performed in two steps. Reparatory ability of BCP/DLPLG in mice was examined in the first step, and then bone tissue reconstruction possibilities on 10 patients in the next step. In vitro tests showed very good fibroblast adhesion and non-citotoxicity of the composite. A material is considered non-cytotoxic if the cell survival is above 50 %, and in our case it was 90%. In vivo research on mice indicated high level of reparatory ability of this composite with formation of new bone and vascular tissue six weeks after reparation. Application of this composite for healing infrabone defects of patients showed a high level of osseous regeneration.

Role of pH on stability and mechanical properties of gelatin films

2012 ◽  
Vol 27 (1) ◽  
pp. 67-77 ◽  
Author(s):  
Michela Gioffrè ◽  
Paola Torricelli ◽  
Silvia Panzavolta ◽  
Katia Rubini ◽  
Adriana Bigi
Keyword(s):  
Mechanical Properties ◽  
Young’S Modulus ◽  
Triple Helix ◽  
Young's Modulus ◽  
In Vitro Tests ◽  
Diffraction Reflection ◽  
X Ray Diffraction ◽  
Solution Ph ◽  
Gelatin Films

The effect of the film-forming solution pH on the triple-helix content, thermal stability, and mechanical properties of gelatin films was investigated. The films were prepared from solutions at different pHs of type A pigskin gelatin, and their mechanical characteristics were determined. At pHs higher than 9 and lower than 5, Young’s modulus, E, and the stress at break, σb, of the films decreased significantly. Cross-linking with genipin reduced deformation at break, ϵb, and increased Young’s modulus. The intensity of the 1.1-nm X-ray diffraction reflection and the denaturation enthalpy decreased at these pHs, indicating that the triple helix reduced. Preliminary in vitro tests on the cross-linked samples indicated good cell proliferation and viability.

scholarly journals Erratum to “Detergent-Enzymatic Decellularization of Swine Blood Vessels: Insight on Mechanical Properties for Vascular Tissue Engineering”

2014 ◽  
Vol 2014 ◽  
pp. 1-2 ◽  
Author(s):  
Alessandro F. Pellegata ◽  
M. Adelaide Asnaghi ◽  
Ilaria Stefani ◽  
Anna Maestroni ◽  
Silvia Maestroni ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tissue Engineering ◽  
Blood Vessels ◽  
Vascular Tissue ◽  
Vascular Tissue Engineering

scholarly journals Electrospun polyester-urethane scaffold preserves mechanical properties and exhibits strain stiffening during in situ tissue ingrowth and degradation

2019 ◽  
Author(s):  
Hugo Krynauw ◽  
Rodaina Omar ◽  
Josepha Koehne ◽  
Georges Limbert ◽  
Neil H Davies ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Mechanical Performance ◽  
Hydrolytic Degradation ◽  
Material Strength ◽  
Fibre Direction ◽  
Tissue Ingrowth ◽  
Polyester Urethane

AbstractConsistent mechanical performance from implantation through healing and scaffold degradation is highly desired for tissue-regenerative scaffolds, e.g. when used for vascular grafts. The aim of this study was the paired in vivo mechanical assessment of biostable and fast degrading electrospun polyester-urethane scaffolds to isolate the effects of material degradation and tissue formation after implantation. Biostable and degradable polyester-urethane scaffolds with substantial fibre alignment were manufactured by electrospinning. Scaffold samples were implanted paired in subcutaneous position in rats for 7, 14 and 28 days. Morphology, mechanical properties and tissue ingrowth of the scaffolds were assessed before implantation and after retrieval. Tissue ingrowth after 28 days was 83 ± 10% in the biostable scaffold and 77 ± 4% in the degradable scaffold. For the biostable scaffold, the elastic modulus at 12% strain increased significantly between 7 and 14 days and decreased significantly thereafter in fibre but not in cross-fibre direction. The degradable scaffold exhibited a significant increase in the elastic modulus at 12% strain from 7 to 14 days after which it did not decrease but remained at the same magnitude, both in fibre and in cross-fibre direction. Considering that the degradable scaffold loses its material strength predominantly during the first 14 days of hydrolytic degradation (as observed in our previous in vitro study), the consistency of the elastic modulus of the degradable scaffold after 14 days is an indication that the regenerated tissue construct retains it mechanical properties.

scholarly journals Enhancement the Osseo Integration Properties of Polymer for Human Body Implants

2020 ◽  
Vol 23 (4) ◽  
pp. 331-337
Author(s):  
Dhurgham Majid Rasheed ◽  
Dunya Abdulsahib Hamdi
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Scanning Electron Microscopy ◽  
Grain Boundaries ◽  
Mechanical Performance ◽  
Wear Test ◽  
High Energy ◽  
In Vitro Test ◽  
Scanning Electron

In this research, polymer polymethyl methacrylate PMMA composite with nano ceramic Zr and HAp material were used to manufacture one part of the implant system (femoral ball head of hip implant). Three set of hybrid materials were fabricated and tested for this study; the first mixtures which contains 100% (PMMA), the second mixtures which contains (90% (PMMA) + 8% (Zr) + 2% (HAp)), and the third mixtures which contains (80% (PMMA) + 18% (Zr) + 2% (HAp)) were investigated. The mechanical properties for these mixtures increased with the increasing of nano ceramic concentration (Zr and HAp) composite material in the polymer compared to pure polymer PMMA sample. However, an increase in the concentration of Zr from 8% to 18% content cause a considerable decrease of the hardness where a drop of homogeneity in Zr- matrix PMMA contact occurred, V Hardness value are (68 ,80 and 70) Kg.mm for three mixture respectively. The wear test was in agreement with results of the hardness test. The weight loss of the above samples of the wear test were (0.041, 0.035 and 0.037) respectively. According to mechanical properties, the best sample contains (90% (PMMA) + 8% (Zr) + 2% (HAp)). The Scanning electron microscopy resolute showed the particles forming semi-continuous network along grain boundaries polymer for second sample mixtures containing (90% (PMMA) + 8% (Zr) + 2% (HAp)), provides a low atomic packing and high energy. This will make the grain boundaries more reactive and strengthen mechanical performance. The Optical microscopy, Scanning electron microscopy and Xray spectroscopy analysis for In vitro test using SBF shows the growth of HAp layer with an increase in concentration of Ca and P elements formed on the surface of the second sample. This display of good results is a proof of the biocompatibility of the polymer sample.

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