scholarly journals Characterization of Polycaprolactone Nanohydroxyapatite Composites with Tunable Degradability Suitable for Indirect Printing

Polymers ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 295
Author(s):  
Stephanie E. Doyle ◽  
Lauren Henry ◽  
Ellen McGennisken ◽  
Carmine Onofrillo ◽  
Claudia Di Bella ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Large Scale ◽  
Three Dimensional ◽  
Cell Number ◽  
Compressive Modulus ◽  
Degradation Rates ◽  
Scaffold Materials ◽  
Natural Tissue ◽  
Complete Regeneration

Degradable bone implants are designed to foster the complete regeneration of natural tissue after large-scale loss trauma. Polycaprolactone (PCL) and hydroxyapatite (HA) composites are promising scaffold materials with superior mechanical and osteoinductive properties compared to the single materials. However, producing three-dimensional (3D) structures with high HA content as well as tuneable degradability remains a challenge. To address this issue and create homogeneously distributed PCL-nanoHA (nHA) scaffolds with tuneable degradation rates through both PCL molecular weight and nHA concentration, we conducted a detailed characterisation and comparison of a range of PCL-nHA composites across three molecular weight PCLs (14, 45, and 80 kDa) and with nHA content up to 30% w/w. In general, the addition of nHA results in an increase of viscosity for the PCL-nHA composites but has little effect on their compressive modulus. Importantly, we observe that the addition of nHA increases the rate of degradation compared to PCL alone. We show that the 45 and 80 kDa PCL-nHA groups can be fabricated via indirect 3D printing and have homogenously distributed nHA even after fabrication. Finally, the cytocompatibility of the composite materials is evaluated for the 45 and 80 kDa groups, with the results showing no significant change in cell number compared to the control. In conclusion, our analyses unveil several features that are crucial for processing the composite material into a tissue engineered implant.

scholarly journals Hydrogel: Preparation, Characterization and Applications

2020 ◽  
Vol 3 (01) ◽  
Author(s):  
Ujjwal Nautiyal ◽  
Nandini Sahu ◽  
Diksha Gupta
Keyword(s):  
Drug Delivery ◽  
Molecular Weight ◽  
Biological Tissue ◽  
Biological Fluids ◽  
Three Dimensional ◽  
Review Article ◽  
Advantages And Disadvantages ◽  
Concise Review ◽  
Large Molecular Weight

This review article is intended to provide an overview of hydrogel as novel vesicular drug delivery system.For the treatment of many diseases large molecular weight proteins are required. These can be available with the availability of Hydrogels. Hydrogels are hydrophilic, three-dimensional networks, which are able to imbibe large amounts of water or biological fluids, and thus resemble, to a large extent, a biological tissue. They are insoluble due to the presence of chemical (tie-points, junctions) and/or physical crosslinks such as entanglements and crystallites. It has focused on to present a concise review on the applications of hydrogels in the pharmaceutical field, hydrogel properties, method of preparation of hydrogel, advantages and disadvantages of hydrogel, characterization of hydrogel.

scholarly journals MicroCT analysis of connectivity in porous structures: optimizing data acquisition and analytical methods in the context of tissue engineering

2020 ◽  
Vol 17 (165) ◽  
pp. 20190833
Author(s):  
Malavika Nair ◽  
Jennifer H. Shepherd ◽  
Serena M. Best ◽  
Ruth E. Cameron
Keyword(s):  
Tissue Engineering ◽  
Analytical Methods ◽  
Large Scale ◽  
Structural Parameters ◽  
Three Dimensional ◽  
Data Capture ◽  
Pixel Size ◽  
Scale Invariant ◽  
Structural Anisotropy

Micro-computed X-ray tomography (MicroCT) is one of the most powerful techniques available for the three-dimensional characterization of complex multi-phase or porous microarchitectures. The imaging and analysis of porous networks are of particular interest in tissue engineering due to the ability to predict various large-scale cellular phenomena through the micro-scale characterization of the structure. However, optimizing the parameters for MicroCT data capture and analyses requires a careful balance of feature resolution and computational constraints while ensuring that a structurally representative section is imaged and analysed. In this work, artificial datasets were used to evaluate the validity of current analytical methods by considering the effect of noise and pixel size arising from the data capture, and intrinsic structural anisotropy and heterogeneity. A novel ‘segmented percolation method’ was developed to exclude the effect of anomalous, non-representative features within the datasets, allowing for scale-invariant structural parameters to be obtained consistently and without manual intervention for the first time. Finally, an in-depth assessment of the imaging and analytical procedures are presented by considering percolation events such as micro-particle filtration and cell sieving within the context of tissue engineering. Along with the novel guidelines established for general pixel size selection for MicroCT, we also report our determination of 3 μm as the definitive pixel size for use in analysing connectivity for tissue engineering applications.

Molecular and cytological characterization of genomic variability in hexaploid wheat 'Lindström'

Genome ◽  
2005 ◽  
Vol 48 (5) ◽  
pp. 895-904
Author(s):  
Pedro Costa-Nunes ◽  
Teresa Ribeiro ◽  
Margarida Delgado ◽  
Leonor Morais-Cecílio ◽  
Neil Jones ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Large Scale ◽  
Expression Patterns ◽  
5S Rdna ◽  
Rdna Locus ◽  
B Chromosomes ◽  
Addition Line ◽  
Rdna Loci

'Lindström' wheat (AABBDD + rye B chromosomes) was used to study the effects of alien chromatin introgressed into a wheat genetic background, subjecting the wheat genome to a new and transient allopolyploidisation episode. Using this experimental material, we have previously demonstrated that no large-scale chromosomal translocations occurred as a result of the genomic constitution of the addition line. However, we have shown that the presence of a number of rye B chromosomes is associated with changes in the interphase organization and expression patterns of wheat rDNA loci. We have now extended our studies to focus on a further characterization of 'Lindström' 5S rDNA loci and also on high molecular weight glutenin subunit (HMW-GS) patterns. In the process, we have uncovered an unusually large variant of the 5S rDNA locus on wheat chromosome 1B (not to be confused with rye B chromosomes) and 2 novel HMW glutenin y-type alleles. These changes are not directly related to variation in rye B chromosome number in the present material, but the fact that a new, and still segregating, 1Dy HMW-GS gene was identified indicates a recent timescale for its origin. Strikingly, the 'Lindström' 5S rDNA 1B locus integrates a unit sharing 94% homology with a rye 5S rDNA sequence, suggesting the possibility that the wheat locus was colonized by highly homologous rye sequences during the breeding of 'Lindström', when the rye and wheat genomes were together, albeit briefly, in the same nucleus.Key words: Triticum aestivum 'Lindström', allopolyploidisation, 5S rDNA, NTS, high molecular weight glutenin (HMW-GS).

scholarly journals Structural geology and geophysics as a support to build a hydrogeologic model of granite rock

Solid Earth ◽  
2016 ◽  
Vol 7 (3) ◽  
pp. 881-895 ◽  
Author(s):  
Lurdes Martinez-Landa ◽  
Jesús Carrera ◽  
Andrés Pérez-Estaún ◽  
Paloma Gómez ◽  
Carmen Bajos
Keyword(s):  
Structural Geology ◽  
Large Scale ◽  
Preferential Flow ◽  
Three Dimensional ◽  
Pumping Test ◽  
Discrete Elements ◽  
Flow Paths ◽  
Preferential Flow Paths

Abstract. A method developed for low-permeability fractured media was applied to understand the hydrogeology of a mine excavated in a granitic pluton. This method includes (1) identifying the main groundwater-conducting features of the medium, such as the mine, dykes, and large fractures, (2) implementing this factors as discrete elements into a three-dimensional numerical model, and (3) calibrating these factors against hydraulic data . A key question is how to identify preferential flow paths in the first step. Here, we propose a combination of several techniques. Structural geology, together with borehole sampling, geophysics, hydrogeochemistry, and local hydraulic tests aided in locating all structures. Integration of these data yielded a conceptual model of the site. A preliminary calibration of the model was performed against short-term (< 1 day) pumping tests, which facilitated the characterization of some of the fractures. The hydraulic properties were then used for other fractures that, according to geophysics and structural geology, belonged to the same families. Model validity was tested by blind prediction of a long-term (4 months) large-scale (1 km) pumping test from the mine, which yielded excellent agreement with the observations. Model results confirmed the sparsely fractured nature of the pluton, which has not been subjected to glacial loading–unloading cycles and whose waters are of Na-HCO3 type.

scholarly journals Chemically Responsive Hydrogel Deformation Mechanics: A Review

Molecules ◽  
2019 ◽  
Vol 24 (19) ◽  
pp. 3521 ◽  
Author(s):  
Eanna Fennell ◽  
Jacques M. Huyghe
Keyword(s):  
Numerical Models ◽  
Three Dimensional ◽  
Soft Materials ◽  
Dimensional Network ◽  
Health Products ◽  
Deformation Mechanics ◽  
Natural Tissue ◽  
Responsive Hydrogels ◽  
Geometric Surface

A hydrogel is a polymeric three-dimensional network structure. The applications of this material type are diversified over a broad range of fields. Their soft nature and similarity to natural tissue allows for their use in tissue engineering, medical devices, agriculture, and industrial health products. However, as the demand for such materials increases, the need to understand the material mechanics is paramount across all fields. As a result, many attempts to numerically model the swelling and drying of chemically responsive hydrogels have been published. Material characterization of the mechanical properties of a gel bead under osmotic loading is difficult. As a result, much of the literature has implemented variants of swelling theories. Therefore, this article focuses on reviewing the current literature and outlining the numerical models of swelling hydrogels as a result of exposure to chemical stimuli. Furthermore, the experimental techniques attempting to quantify bulk gel mechanics are summarized. Finally, an overview on the mechanisms governing the formation of geometric surface instabilities during transient swelling of soft materials is provided.

Rapid Three-Dimensional Thermal Characterization of Large-Scale Computing Facilities

2008 ◽  
Vol 31 (2) ◽  
pp. 444-448 ◽  
Author(s):  
H.F. Hamann ◽  
J.A. Lacey ◽  
M. O'Boyle ◽  
R.R. Schmidt ◽  
M. Iyengar
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Thermal Characterization ◽  
Large Scale Computing

Physical Properties of Fractions of GR-S and Their Vulcanizates

1949 ◽  
Vol 22 (2) ◽  
pp. 494-517 ◽  
Author(s):  
John A. Yanko
Keyword(s):  
Molecular Weight ◽  
Intrinsic Viscosity ◽  
Large Scale ◽  
Average Molecular Weight ◽  
Three Dimensional ◽  
Reduced Pressure ◽  
Molecular Weights ◽  
Styrene Copolymers ◽  
Straight Line ◽  
The Relationship

Abstract A large-scale precise fractionation of GR-S (X-55) was carried out at 25° C, using a fractional precipitation technique. Nine fractions, each weighing approximately 150 grams and comprising about 11 per cent by weight of the original unfractionated sample, were obtained, with number-average molecular weights varying from 4000 to 1,650,000. High molecular fractions undergo gelation rapidly, even when dried in the absence of light at reduced pressure, and the higher the molecular weight of the fraction, the greater the amount of gel formed. Compared to unfractionated butadiene-styrene copolymers of similar gel contents, the gel portions of the higher molecular fractions had unusually high swelling indices, indicating qualitatively that the average molecular weights between points of effective cross-linking in the three-dimensional gel structure were higher than those found in the past in unfractionated samples of similar gel contents. Through the concentration range studied, the intrinsic viscosity values varied as a straight-line function of the concentration terms for all the fractions. However, the negative slopes of these lines increased as the molecular weight of the fraction increased, demonstrating the greater dependence of the intrinsic viscosity values of the higher molecular fractions on the concentration variable. The relationship between number-average molecular weight, as determined by osmometric measurements, and limiting intrinsic viscosity of the GR-S fractions is given by the equation: [η]0=5.4×10−4 M0.66, which is similar to that obtained by French and Ewart. The μi values calculated from the equation of Huggins were essentially the same (0.35) through the molecular range 12,400 to 723,000.

scholarly journals Pengaruh Jumlah Inokulum Sel Inang Bakteri E.coli BL21 (DE3) pLysS dan Waktu Overekspresi pada Produksi Protein Rekombinan Fim-C Salmonella typhi

2018 ◽  
Vol 4 (2) ◽  
pp. 98-106
Author(s):  
Muktiningsih - Nurjayadi ◽  
Izzatul Ilma Chairinnisa ◽  
Geta Putri Mentari ◽  
Dudi Hardianto ◽  
Asri Sulfianti ◽  
...  
Keyword(s):  
Recombinant Protein ◽  
Large Scale ◽  
Salmonella Typhi ◽  
Cell Number ◽  
Bacterial Cells ◽  
Typhoid Vaccine ◽  
Over Expression ◽  
Bacterial Cultures ◽  
Sds Page

Recombinant protein Fim-C S.typhi is a potential protein that can be used as an alternative typhoid vaccine and produced on a large scale. However, before entering into a large-scale stage, laboratory optimum data on the factors that affect the production process of Fim-C Salmonella typhi proteins are required. This study aims to obtain information regarding the effect of host cell number E.coli BL21 (DE3) pLysS and overexpression time on production of recombinant protein Fim-C Salmonella typhi as the basis for developing candidate of typhoid vaccine. The optimization process of overexpression was done by adding 0.5 mM IPTG (Isopropyl-β-D-thiogalactopyranoside) inducer into bacterial cultures of 2%, 4%, and 6% with 4, 5, and 6 hours over expression. The measurement of the concentration of Fim-C recombinant protein extracted samples were done by a spectrophotometric method used BCA Kit Assay Thermo ScientificTM with wavelength 590nm. The characterization of those protein extracts was performed using SDS-PAGE method. The results from the study concluded that the number of 4% E.coli bacterial cells and four-hour overexpression time are the optimum condition of Fim- C Salmonella typhi characterized by the presence of high-intensity bands at ± 31 kDa.  

scholarly journals Hypoxia Onset in Mesenchymal Stem Cell Spheroids: Monitoring With Hypoxia Reporter Cells

2021 ◽  
Vol 9 ◽  
Author(s):  
Carola Schmitz ◽  
Ekaterina Potekhina ◽  
Vsevolod V. Belousov ◽  
Antonina Lavrentieva
Keyword(s):  
Critical Role ◽  
Three Dimensional ◽  
Human Adipose Tissue ◽  
Medical Application ◽  
Cell Number ◽  
Dependent Manner ◽  
Differentiation Potential ◽  
Stems Cells ◽  
Scaffold Materials

The therapeutic and differentiation potential of human mesenchymal stems cells (hMSCs) makes these cells a promising candidate for cellular therapies and tissue engineering. On the path of a successful medical application of hMSC, the cultivation of cells in a three-dimensional (3D) environment was a landmark for the transition from simple two-dimensional (2D) testing platforms to complex systems that mimic physiological in vivo conditions and can improve hMSC curative potential as well as survival after implantation. A 3D arrangement of cells can be mediated by scaffold materials where cells get entrapped in pores, or by the fabrication of spheroids, scaffold-free self-organized cell aggregates that express their own extracellular matrix. Independently from the cultivation method, cells expanded in 3D experience an inhomogeneous microenvironment. Many gradients in nutrient supply, oxygen supply, and waste disposal from one hand mimic in vivo microenvironment, but also put every cell in the 3D construct in a different context. Since oxygen concentration in spheroids is compromised in a size-dependent manner, it is crucial to have a closer insight on the thresholds of hypoxic response in such systems. In this work, we want to improve our understanding of oxygen availability and consequensing hypoxia onset in hMSC spheroids. Therefore, we utilized human adipose tissue-derived MSCs (hAD-MSCs) modified with a genetical sensor construct to reveal (I) the influence of spheroid production methods and (II) hMSCs cell number per spheroid to detect the onset of hypoxia in aggregates. We could demonstrate that not only higher cell numbers of MSCs, but also spheroid formation method plays a critical role in onset of hypoxia.

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