1,721,104 research outputs found
Designing Viscoelastic Gelatin-PEG Macroporous Hybrid Hydrogel with Anisotropic Morphology and Mechanical Properties for Tissue Engineering Application
No full textThe mechanical properties of scaffolds play a vital role in regulating key cellular processes in tissue development and regeneration in the field of tissue engineering. Recently, scaffolding material design strategies leverage viscoelasticity to guide stem cells toward specific tissue regeneration. Herein, we designed and developed a viscoelastic Gel-PEG hybrid hydrogel with anisotropic morphology and mechanical properties using a gelatin and functionalized PEG (as a crosslinker) under a benign condition for tissue engineering application. The chemical crosslinking/grafting reaction was mainly involved between epoxide groups of PEG and available functional groups of gelatin. FTIR spectra revealed the hybrid nature of Gel-PEG hydrogel. The hybrid hydrogel showed good swelling behavior (water content > 600%), high porosity and pore interconnectivity suitable for tissue engineering application. Simple unidirectional freezing followed by a freeze-drying technique allowed the creation of structurally stable 3D anisotropic macroporous architecture that showed tissue-like elasticity and was capable of withstanding high deformation (50% strain) without being damaged. The tensile and compressive modulus of Gel-PEG hybrid hydrogel were found to be 0.863 MPa and 0.330 MPa, respectively, which are within the range of normal human articular cartilage. In-depth mechanical characterizations showed that the Gel-PEG hybrid hydrogel possessed natural-tissue-like mechanics such as non-linear and J-shaped stress-strain curves, stress softening effect, high fatigue resistance and stress relaxation response. A month-long hydrolytic degradation test revealed that the hydrogel gradually degraded in a homogeneous manner over time but maintained its structural stability and anisotropic mechanics. Overall, all these interesting features provide a potential opportunity for Gel-PEG hybrid hydrogel as a scaffold in a wide range of tissue engineering applications
3D printing of gelatin/chitosan biodegradable hybrid hydrogel: Critical issues due to the crosslinking reaction, degradation phenomena and process parameters
No full textHydrogel materials are being investigated for application as scaffolds in tissue engineering owing to their many advantages, such as high water content, softness and flexibility similar to many soft tissues, tuneable physical, chemical, and biological properties, excellent biocompatibility and biodegradability, and extensive framework for cell proliferation and survival. During the past decade, because of the great versatility offered in terms of processing approach, material selection, and customization, 3D printing has become a leading technology used to fabricate hydrogel scaffolds. Furthermore, high reproducibility and unparalleled control over structural and compositional characteristics make additive manufacturing the preferred technology for the fabrication of biodegradable hydrogel scaffolds. However, the production time could become critical in relation to any crosslinking reactions and degradation that may occur in the hydrogel and make the printing process unstable. In this study an analysis of the critical issues due to the crosslinking reaction and degradation phenomena have been executed following a statistical approach. In particular, three different experimental campaign demonstrate how the printing process became instable due to the mentioned phenomena. Finally, a procedure was developed to print gelatine-based biocompatible hydrogels with chitosan and functionalized polyethylene glycol as a cross linker (G-PEG-CH). In order to reach the printing temperature, the hydrogel mixture was initially stored in the refrigerator at 4°C for 12 h, followed by a 10 min incubation in warm water at 40°C. Based on this procedure, a filament strand of 950 μm with a standard deviation in the range of 20% was obtained by imposing a printing pressure of 1 bar and a printing speed of 100 mm/s at a temperature of 28 °C
Preparation and Performance of Novel Biodegradable Polymeric Materials Based on Hydrolyzed Proteins for Agricultural Application
No full textAim of the research is the development of biodegradable
polymeric materials based on hydrolyzed proteins,
derived from waste products of the leather industry.
Particular attention has been devoted to evaluate the application
of such biobased materials in the agricultural practice
of mulching. Biobased mulching films were generated in situ
by low-pressure spraying of polymeric water dispersion on
the soil; the mulches were tested in an ornamental cultivation
carried out inside a greenhouse. The innovative spray films
based on biodegradable components lasted in the field up to
12 months, keeping their mulching effect, thus guarantying
weed suppression and preserving soil aggregates
Hydrostratigraphical modeling using a 3D geostatistical approach
No full textIn hydrogeology and environmental science, it can be important to assess the geological heterogeneity of the subsoil, and to predict or simulate different scenarios of the 3D architecture of the subsoil.
The most known methods which predict or simulate categorical data (lithologies) are the indicator based methods (Johnson and Driess, 1989 Trevisani and Fabbri, 2010). Here, the lithological spatial variability is modeled by variograms. Indicator methods consider the categorical nature of lithologies and incorporate the geometric context of geological facies. However, such methods have proven to be difficult in representing and modeling a classical indicator approach, especially when the lithological categories exceed two. In the 1997, Carle and Fogg introduced in geostatistics the transition probability/Markov chain approach (transiograms) where some important geological information are take into account to model spatial variability. The mean lengths of materials, their juxtapositional tendencies and the volumetric proportions are incorporated into the Markov chain model of the transiogram. The spMC package (Sartore, 2013) was developed in R environment with the purpose of analyzing categorical data observed in 3-D locations. Three algorithms to simulate spatial random fields were implemented in the spMC package, including the multinomial categorical simulation (MCS) proposed by Allard et al. (2011).
This research concerns an hydrogeological study in an experimental site of 1.5 ha, which is located inside the drinking water supply area of the Padua town (NE, Italy). More specifically, this area is localized inside a plain springs area, in a shallow part of the transition zone between the high and the middle Venetian plain. Here, the results of hydrostratigraphic predictions based on MCS are presented and compared with the classical hydrostratigraphic cross-sections made in this area
A direct assay for evaluation of polyethylene glycol in enzyme adducts used as drugs or biocatalysts.
No full textA specific and direct method for the evaluation of monomethoxypolyethylene glycol (MPEG) in enzyme adducts has been developed. The method is based on extensive modification by trinitrobenzensulfonic acid (TNBS) of the MPEG-enzyme, to form an acid-stable TNBS adduct with the available amino groups of lysine and alpha-amino acid. The MPEG-modified trinitrophenylated enzyme was hydrolyzed in 6N HCl and amino acid composition evaluated by a standard AA analyzer in comparison with the analysis of a MPEG enzyme sample. The number of bound MPEG polymers was calculated from the difference in amino acid composition of the two sample
Trattamento delle radiodermiti della spalla: tecniche tradizionali versus chirurgia rigenerativa
No full text
Multiblock copolymers based on segments of poly(D,L-lactic-glycolic acid) and poly(ethylene glycol) or poly(ε-caprolactone): A comparison of their thermal properties and degradation behavior
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