Physicochemical and Biochemical Properties of Trypsin-like Enzyme from Two Sturgeon Species

This work aimed to determine the physicochemical and biochemical properties of trypsin from beluga Huso huso and sevruga Acipenser stellatus, two highly valuable sturgeon species. According to the results obtained from the methods of casein-zymogram and inhibitory activity staining, the molecular weight of trypsin for sevruga and beluga was 27.5 and 29.5 kDa, respectively. Optimum pH and temperature values for both trypsins were recorded at 8.5 and 55 °C by BAPNA (a specific substrate), respectively. The stability of both trypsins was well-preserved at pH values from 6.0 to 11.0 and temperatures up to 50 °C. TLCK and SBTI, two specific trypsin inhibitors, showed a significant inhibitory effect on the enzymatic activity of both trypsins (p 0.05). The results of our study show that the properties of trypsin from beluga and sevruga are in agreement with data reported in bony fish and can contribute to the clear understanding of trypsin activity in these primitive species.info:eu-repo/semantics/publishedVersio

Personalized Development of Human Organs using 3D Printing Technology

3D printing is a technique of fabricating physical models from a 3D volumetric digital image. The image is sliced and printed using a specific material into thin layers, and successive layering of the material produces a 3D model. It has already been used for printing surgical models for preoperative planning and in constructing personalized prostheses for patients. The ultimate goal is to achieve the development of functional human organs and tissues, to overcome limitations of organ transplantation created by the lack of organ donors and life-long immunosuppression. We hypothesized a precision medicine approach to human organ fabrication using 3D printed technology, in which the digital volumetric data would be collected by imaging of a patient, i.e. CT or MRI images followed by mathematical modeling to create a digital 3D image. Then a suitable biocompatible material, with an optimal resolution for cells seeding and maintenance of cell viability during the printing process, would be printed with a compatible printer type and finally implanted into the patient. Life-saving operations with 3D printed implants were already performed in patients. However, several issues need to be addressed before translational application of 3D printing into clinical medicine. These are vascularization, innervation, and financial cost of 3D printing and safety of biomaterials used for the construct

Mechanical guidelines on the properties of human healthy arteries in the design and fabrication of vascular grafts: experimental tests and quasi-linear viscoelastic model

Knowledge of mechanical behavior of healthy human arteries as the guidelines to target properties of vascular grafts deserves special attention. There is a lack of mathematical model to characterize mechanical behavior of biomaterial while many mathematical models to reflect mechanics of human arteries have been proposed. The objective of this paper was set to measure mechanical properties of healthy human arteries including Common Carotid Artery (CCA), Abdominal Aorta Artery (AAA), Subclavian Artery (SA), Common Iliac Artery (CIA) and Right and Left Iliac Artery (RIA and LIA) and compare them to those of commercial ePTFE and Dacron®. Methods: Series of stress relaxation and strain to failure tests vere performed on all samples. The experimental data was utilized to develop quasi-linear viscoelastic (QLV) model of both natural and artificial arteries. Results: ePTFE is the stiffest sample, while the CCA is the most compliant one among all. RIA and CIA are more viscous than the other natural arteries, while AA and CCA are less viscous. The proposed model demonstrated an accurate fit to the experimental results, a proof of its ability to model both nonlinear elasticity and viscoelasticity of the human arteries and commercial ones. Conclusions: ePTFE and Dacron® are much stiffer than human arteries that may lead to the disruption of blood hemodynamic and may not be biomechanically feasible as a replacement

Regeneration of musculoskeletal injuries using mesenchymal stem cells loaded scaffolds: review article

An increase in the average age of the population and physical activities where the musculoskeletal system is involved as well as large number of people suffering from skeletal injuries which impose high costs on the society. Bone grafting is currently a standard clinical approach to treat or replace lost tissues. Autografts are the most common grafts, but they can lead to complications such as pain, infection, scarring and donor site morbidity. The alternative is allografts, but they also carry the risk of carrying infectious agents or immune rejection. Therefore, surgeons and researchers are looking for new therapeutic methods to improve bone tissue repair. The field of tissue engineering and the use of stem cells as an ideal cell source have emerged as a promising approach in recent years. Three main components in the field of tissue engineering include proper scaffolds, cells and growth factors that their combination leads to formation of tissue-engineered constructs, resulting in tissue repair and regeneration. The use of scaffolds with suitable properties could effectively improve the tissue function or even regenerate the damaged tissue. The main idea of tissue engineering is to design and fabricate an appropriate scaffold which can support cell attachment, proliferation, migration and differentiation to relevant tissue. Scaffold gives the tissue its structural and mechanical properties, for instance flexibility and stiffness that is related with the tissue functions. Biomaterials used to fabricate scaffolds can be categorized into natural or synthetic biodegradable or non-biodegradable materials. Polymers are the most widely used materials in tissue engineering. Growth factors are a group of proteins that cause cell proliferation and differentiation. Two main cell sources are specialized cells of desired tissue and stem cells. However, according to the low proliferation and limited accessibility to the cells of desired tissue, stem cells are better suggestion. Combination of mesenchymal stem cells harvested from bone marrow, adipose tissue and cord blood with proper scaffolds and growth factors could be a useful method in treatment of skeletal injuries. In this review paper, we focus on the application of mesenchymal stem cells in the repair of damaged bone, cartilage, meniscus, ligaments, tendons and spine tissue

An Injectable Enzymatically Crosslinked and Mechanically Tunable Silk Fibroin/Chondroitin Sulfate Chondro‐Inductive Hydrogel

Abstract An injectable hybrid hydrogel is synthesized, comprising silk fibroin (SF) and chondroitin sulfate (CS) through di‐tyrosine formation bond of SF chains. CS and SF are reported with excellent biocompatibility as tissue engineering scaffolds. Nonetheless, the rapid degradation rate of pure CS scaffolds presents a challenge to effectively recreate articular cartilage. As CS is one of the cartilage extracellular matrix (ECM) components, it has the potential to enhance the biological activity of SF‐based hydrogel in terms of cartilage repair. Therefore, altering the CS concentrations (i.e., 0 wt%, 0.25 wt%, 0.5 wt%, 1 wt%, and 2 wt%), which are interpenetrated between SF β‐sheets and chains, can potentially adjust the physical, chemical, and mechanical features of these hybrid hydrogels. The formation of β‐sheets by 30 days of immersion in de‐ionized (DI) water can improve the compression strength of the SF/CS hybrid hydrogels in comparison with the same SF/CS hybrid hydrogels in the dried state. Biological investigation and observation depicts proper cell attachment, proliferation and cell viability for C28/I2 cells. Gene expression of sex‐determining region YBox 9 (SOX9), Collagen II α1, and Aggrecan (AGG) exhibits positive C3H10T1/2 growth and expression of cartilage‐specific genes in the 0.25 wt% and 0.5 wt% SF/CS hydrogels

Mussel-inspired polydopamine-coated silk fibroin as a promising biomaterial

Silk fibroin (SF) is one of the natural biomaterials with promising and growing potential in different clinical applications such as corneal transplantation, donor site skin substitute and tympanic membrane. Some of the SFs which are extracted from mulberry silkworm do not have the Arginyl-glycyl-aspartic acid (RGD) sequence to properly support cell adhesion and proliferation. Therefore, in the current study, polydopamine (PDA) coated SF are prepared to provide RGD sequence and the effect of PDA coating on different properties of SF is investigated. The results are also compared with amniotic membrane (AM) that is a commercially available natural biomaterial for mentioned applications. Raman spectra depicted characteristic peaks at 1581 and 1370 cm−1 that demonstrated the formation of the coating layer on the surface of the films. The results showed that coating led to a little decrease in membrane transparency but still transparent enough to provide vivid vision through membrane, no significant difference in surface hydrophilicity, smoother surface and improved cell attachment and distribution

Novel experimental strategy towards temperature inhomogeneity during spark plasma sintering of metallic glasses

Despite the importance of temperature distribution in spark plasma sintering of metallic glasses, its quantification has been experimentally laborious. This work proposes an experimental strategy to determine the sintering temperature by establishing a quantitative relationship between the temperature-thermal signal. We reproduced the thermal profiles of spark plasma sintering by isothermal annealing and found a correlation between annealing temperature and isothermal crystallization time. This strong correlation indicates the temperature-dependent structural evolution of glassy powders. Using isothermal crystallization time as the measuring gauge, we correlated the annealing temperature to the sintering temperature and obtained the sample temperature map. The sample temperature is at least 19 ​°C higher than the nominal temperature of 425 ​°C measured by the thermocouple. Meanwhile, the sample temperature shows a hump-shaped pattern closely correlated with the current density. The maximum temperature of 453 ​°C occurs on the sample/punches contact surfaces. Temperature heterogeneity within the sample induces diverse microstructures and porous structures. We elucidate that the temperature inhomogeneity is intrinsic, given the presence of contact interfaces. Contact resistances affect the current distribution and heat transfer, resulting in a larger temperature gradient than the traditional powder metallurgy process

Polyurethane Coatings Derived from 1,2,3-Triazole-Functionalized Soybean Oil-Based Polyols: Studying their Physical, Mechanical, Thermal, and Biological Properties

Preparation of polyurethanes derived from novel 1,2,3-triazole-functionalized soybean oil-based polyols and assessment of their possible biocidal activities were considered. Epoxidized soybean oil was reacted with sodium azide to produce an azide-containing polyol. The product was subjected to the cycloaddition reaction with various alkynes. Alkylation of <i>tertiary</i> amine-containing polyol with methyl iodide was also performed to prepare a quaternary ammonium salt (QAS)-containing polyol. The polyols and their mixtures with PEG1000 were reacted with isophorone diisocyanate to prepare polyurethane coatings. The influence of embedded functional groups on physical, mechanical, thermal and biological properties of polyurethanes was studied. Incorporation of 1,2,3-triazole groups within the polyol backbone resulted in higher storage modulus at glassy state, glass transition temperature, thermal stability and hardness of corresponding polyurethanes, while it led to lower adhesion strength and hydrophilicity. Although QAS-containing polyurethanes displayed better physical and mechanical properties, but their thermal stability were reduced. Studying the interaction of fibroblast cells with polyurethanes derived merely from oil-based polyols revealed their good cells viability (60–110%). Moderate to high biocidal activity was detected for polyols and polyurethanes containing tertiary amine and QAS groups. Improving the hydrophilicity of polyurethanes via incorporation of PEG1000 improved their biocidal activity, while it reduced their cytocompatibility

Safely dissolvable and healable active packaging films based on alginate and pectin

Extensive usage of long-lasting petroleum based plastics for short-lived application such as packaging has raised concerns regarding their role in environmental pollution. In this research, we have developed active, healable, and safely dissolvable alginate-pectin based biocomposites that have potential applications in food packaging. The morphological study revealed the rough surface of these biocomposite films. Tensile properties indicated that the fabricated samples have mechanical properties in the range of commercially available packaging films while possessing excellent healing efficiency. Biocomposite films exhibited higher hydrophobicity properties compared to neat alginate films. Thermal analysis indicated that crosslinked biocomposite samples possess higher thermal stability in temperatures below 120 &deg;C, while antibacterial analysis against E. coli and S. aureus revealed the antibacterial properties of the prepared samples against different bacteria. The fabricated biodegradable multi-functional biocomposite films possess various imperative properties, making them ideal for utilization as packaging material