scholarly journals Comparative Study of Gelatin Hydrogels Modified by Various Cross-Linking Agents

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 396
Author(s):  
Joanna Skopinska-Wisniewska ◽  
Marta Tuszynska ◽  
Ewa Olewnik-Kruszkowska
Keyword(s):  
Thermal Analysis ◽  
Infrared Spectroscopy ◽  
Food Industry ◽  
Squaric Acid ◽  
Cross Linking ◽  
Dialdehyde Starch ◽  
Sem Images ◽  
Swelling Capacity ◽  
Strength Tests ◽  
Cross Linker

Gelatin is a natural biopolymer derived from collagen. Due to its many advantages, such as swelling capacity, biodegradability, biocompatibility, and commercial availability, gelatin is widely used in the field of pharmacy, medicine, and the food industry. Gelatin solutions easily form hydrogels during cooling, however, the materials are mechanically poor. To improve their properties, they are often chemically crosslinked. The cross-linking agents are divided into two groups: Zero-length and non-zero-length cross-linkers. In this study, gelatin was cross-linked by three different cross-linking agents: EDC-NHS, as a typically used cross-linker, and also squaric acid (SQ) and dialdehyde starch (DAS), as representatives of a second group of cross-linkers. For all prepared gelatin hydrogels, mechanical strength tests, thermal analysis, infrared spectroscopy, swelling ability, and SEM images were performed. The results indicate that the dialdehyde starch is a better cross-linking agent for gelatin than EDC-NHS. Meanwhile, the use of squaric acid does not give beneficial changes to the properties of the hydrogel.

scholarly journals Effect of the Cross-Linking Density on the Swelling and Rheological Behavior of Ester-Bridged β-Cyclodextrin Nanosponges

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 478
Author(s):  
Gjylije Hoti ◽  
Fabrizio Caldera ◽  
Claudio Cecone ◽  
Alberto Rubin Pedrazzo ◽  
Anastasia Anceschi ◽  
...  
Keyword(s):  
Scale Up ◽  
Future Application ◽  
Cross Linking ◽  
Synthesis Reaction ◽  
Dependent Behavior ◽  
Cyclodextrin Nanosponges ◽  
Potential Applications ◽  
Cross Linker ◽  
The Cross ◽  
Shed Light

The cross-linking density influences the physicochemical properties of cyclodextrin-based nanosponges (CD-NSs). Although the effect of the cross-linker type and content on the NSs performance has been investigated, a detailed study of the cross-linking density has never been performed. In this contribution, nine ester-bridged NSs based on β-cyclodextrin (β-CD) and different quantities of pyromellitic dianhydride (PMDA), used as a cross-linking agent in stoichiometric proportions of 2, 3, 4, 5, 6, 7, 8, 9, and 10 moles of PMDA for each mole of CD, were synthesized and characterized in terms of swelling and rheological properties. The results, from the swelling experiments, exploiting Flory–Rehner theory, and rheology, strongly showed a cross-linker content-dependent behavior. The study of cross-linking density allowed to shed light on the efficiency of the synthesis reaction methods. Overall, our study demonstrates that by varying the amount of cross-linking agent, the cross-linked structure of the NSs matrix can be controlled effectively. As PMDA βCD-NSs have emerged over the years as a highly versatile class of materials with potential applications in various fields, this study represents the first step towards a full understanding of the correlation between their structure and properties, which is a key requirement to effectively tune their synthesis reaction in view of any specific future application or industrial scale-up.

scholarly journals FLIm and Raman Spectroscopy for Investigating Biochemical Changes of Bovine Pericardium upon Genipin Cross-Linking

Molecules ◽  
2020 ◽  
Vol 25 (17) ◽  
pp. 3857
Author(s):  
Tanveer Ahmed Shaik ◽  
Alba Alfonso-Garcia ◽  
Martin Richter ◽  
Florian Korinth ◽  
Christoph Krafft ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Fluorescence Lifetime ◽  
Density Functional ◽  
Bovine Pericardium ◽  
Biochemical Changes ◽  
Blue Pigment ◽  
Cross Linking ◽  
Fluorescence Lifetime Imaging ◽  
Fluorescence Intensity Ratio ◽  
Cross Linker

Biomaterials used in tissue engineering and regenerative medicine applications benefit from longitudinal monitoring in a non-destructive manner. Label-free imaging based on fluorescence lifetime imaging (FLIm) and Raman spectroscopy were used to monitor the degree of genipin (GE) cross-linking of antigen-removed bovine pericardium (ARBP) at three incubation time points (0.5, 1.0, and 2.5 h). Fluorescence lifetime decreased and the emission spectrum redshifted compared to that of uncross-linked ARBP. The Raman signature of GE-ARBP was resonance-enhanced due to the GE cross-linker that generated new Raman bands at 1165, 1326, 1350, 1380, 1402, 1470, 1506, 1535, 1574, 1630, 1728, and 1741 cm−1. These were validated through density functional theory calculations as cross-linker-specific bands. A multivariate multiple regression model was developed to enhance the biochemical specificity of FLIm parameters fluorescence intensity ratio (R2 = 0.92) and lifetime (R2 = 0.94)) with Raman spectral results. FLIm and Raman spectroscopy detected biochemical changes occurring in the collagenous tissue during the cross-linking process that were characterized by the formation of a blue pigment which affected the tissue fluorescence and scattering properties. In conclusion, FLIm parameters and Raman spectroscopy were used to monitor the degree of cross-linking non-destructively.

Efficient substrate accessibility of cross-linked levanase aggregates using dialdehyde starch as a macromolecular cross-linker

2021 ◽  
pp. 118159
Author(s):  
Noor Hidayah Abd Rahman ◽  
Nardiah Rizwana Jaafar ◽  
Nur Arbainah Shamsul Annuar ◽  
Roshanida A. Rahman ◽  
Abdul Munir Abdul Murad ◽  
...  
Keyword(s):  
Dialdehyde Starch ◽  
Cross Linker

scholarly journals Effect of Cross-Linking Density on the Structures and Properties of Carbodiimide-Treated Gelatin Matrices as Limbal Stem Cell Niches

2018 ◽  
Vol 19 (11) ◽  
pp. 3294 ◽  
Author(s):  
Jui-Yang Lai ◽  
Li-Jyuan Luo ◽  
David Ma
Keyword(s):  
Surface Roughness ◽  
Stem Cell ◽  
Cross Linking ◽  
Epithelial Tissue ◽  
Human Amniotic Membrane ◽  
Limbal Stem Cells ◽  
Structures And Properties ◽  
Cross Linker ◽  
Limbal Stem Cell ◽  
Stem Cell Niches

Given that human amniotic membrane is a valuable biological material not readily available for corneal epithelial tissue engineering, gelatin is considered as a potential alternative to construct a cellular microenvironment. This study investigates, for the first time, the influence of cross-linking density of carbodiimide-treated gelatin matrices on the structures and properties of artificial limbal stem cell niches. Our results showed that an increase in the carbodiimide concentration from 1.5 to 15 mM leads to an upward trend in the structural and suture strength of biopolymers. Furthermore, increasing number of cross-linking bridges capable of linking protein molecules together may reduce their crystallinity. For the samples treated with 50 mM of cross-linker (i.e., the presence of excess N-substituted carbodiimide), abundant N-acylurea was detected, which was detrimental to the in vitro and in vivo ocular biocompatibility of gelatin matrices. Surface roughness and stiffness of biopolymer substrates were found to be positively correlated with carbodiimide-induced cross-link formation. Significant increases of integrin β1 expression, metabolic activity, and ABCG2 expression were noted as the cross-linker concentration increased, suggesting that the bulk crystalline structure and surface roughness/stiffness of niche attributed to the number of cross-linking bridges may have profound effects on a variety of limbal epithelial cell behaviors, including adhesion, proliferation, and stemness maintenance. In summary, taking the advantages of carbodiimide cross-linking-mediated development of gelatin matrices, new niches with tunable cross-linking densities can provide a significant boost to maintain the limbal stem cells during ex vivo expansion.

scholarly journals Thermal and structural characterization of the vitreous samples in the SiO2 - PbO - Na2O system

2006 ◽  
pp. 89-95 ◽  
Author(s):  
Catalina Mocioiu ◽  
Georgeta Jitianu ◽  
Maria Zaharescu
Keyword(s):  
Thermal Stability ◽  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Infrared Spectroscopy ◽  
Silicate Glasses ◽  
Lead Silicate ◽  
High Chemical ◽  
Nuclear Techniques ◽  
Infrared Data

Lead-containing glasses have been used from the ancient time. Recently, due to the possible application in optics, electronics, nuclear techniques, wastes inactivation. the interest in these types of glasses has been renewed. For lead waste inactivation, glasses with high amount of PbO in the composition are required, those exhibiting at the same time a high chemical and thermal stability. Thermal behavior of lead-silicate glasses was examined by differential thermal analysis (DTA). Infrared spectroscopy was used to investigate the structure of the glasses. The spectra were interpreted in terms of the structures of silicate group by comparison with the spectra of other silicate crystals. The DTA and infrared data were correlated with the chemical stability tests.

scholarly journals Hydrogel-Silver Nanoparticle Composites for Biomedical Applications

2020 ◽  
Vol 65 (5) ◽  
pp. 446
Author(s):  
O. Nadtoka ◽  
N. Kutsevol ◽  
T. Bezugla ◽  
P. Virych ◽  
A. Naumenko
Keyword(s):  
Silver Nanoparticle ◽  
Biomedical Applications ◽  
Polymer Network ◽  
Cross Linking ◽  
Polyacrylamide Hydrogels ◽  
Photochemical Generation ◽  
Vis Spectroscopy ◽  
Swelling Capacity ◽  
Swelling Studies ◽  
Nanoparticle Composites

Polyacrylamide and dextran-graft-polyacrylamide hydrogels are prepared and used as nanoreactors and networks for the synthesis of silver nanoparticles (AgNPs). Photochemical generation of AgNPs is carried out under UV-irradiation of Ag+ ions in swollen hydrogels of different cross-linking densities. The obtained hydrogels and hydrogel/AgNPs composites are characterized by TEM, FTIR, and UV–Vis spectroscopy. Swelling studies have shown a relationship between the structure of the hydrogels and their ability to swell. It is shown that the presence of AgNPs in the polymer network leads to a decrease of the swelling capacity. An increase in the cross-linking density leads to an expansion of the AgNPs size distribution for both types of hydrogels. All synthesized hydrogel-silver nanoparticle composites have shown a high activity in the growth retardation of Staphylococcus aureus microorganisms.

scholarly journals Migration and bidirectional phototaxis in Dictyostelium discoideum slugs lacking the actin cross-linking 120 kDa gelation factor.

1997 ◽  
Vol 200 (24) ◽  
pp. 3213-3220 ◽  
Author(s):  
E Wallraff ◽  
H G Wallraff
Keyword(s):  
Dictyostelium Discoideum ◽  
Incident Light ◽  
Actin Binding ◽  
Cross Linking ◽  
Alternative Possibility ◽  
Wild Type ◽  
Oblique Angle ◽  
Mutant Strains ◽  
Cross Linker ◽  
Actin Capping

Three mutant strains of Dictyostelium discoideum, lacking different actin-binding proteins, were tested for behavioural deficits in the multicellular pseudoplasmodium (slug) stage. Two strains, defective in the production of either -actinin (an actin cross-linker) or severin (an actin capping and severing protein), did not show changes in slug behaviour. Slugs of the mutant lacking another actin cross-linker, the 120 kDa gelation factor (ABP-120), however, migrated shorter distances in darkness as well as in horizontally directed light. More remarkably, they migrated at an angle of approximately 45 degrees to the left or right of the incident light, whereas wild-type slugs migrated on fairly straight paths towards the light. We discuss the hypothesis that this bidirectional oblique-angle phototaxis is due to changes in the optical properties of the pseudoplasmodia. Normally, in wild-type slugs, a lens effect causes stronger stimulation on the side distal to the incident light. We propose that in the mutant the lens quality is reduced, so that at small angles between the slug axis and the rays of light the proximal side is stimulated more intensely. As a result, the intended symmetrical stimulation is achieved at a certain angle to the left or right of the incident light. We assume that the absence of ABP-120 alters the shape of the lens and/or enhances internal light scattering via degradation of intercellular coherence; however, intracellular attenuation of light remains an additional or alternative possibility.

scholarly journals Thermal stability and thermal decomposition of sucralose

2018 ◽  
Vol 39 (4) ◽  
pp. 21
Author(s):  
Gilbert Bannach ◽  
Rafael R. Almeida ◽  
Luis G. Lacerda ◽  
Egon Schnitzler ◽  
Massao Ionashiro
Keyword(s):  
Thermal Stability ◽  
Thermal Analysis ◽  
Differential Scanning Calorimetry ◽  
Thermal Decomposition ◽  
Differential Thermal Analysis ◽  
Infrared Spectroscopy ◽  
Scanning Calorimetry ◽  
Thermoanalytical Techniques ◽  
Thermal Stability Of

Several papers have been described on the thermal stability of the sweetener, C12H19Cl3O8 (Sucralose). Nevertheless no study using thermoanalytical techniques was found in the literature. Simultaneous thermogravimetry and differential thermal analysis (TG-DTA), differential scanning calorimetry (DSC) and infrared spectroscopy, have been used to study the thermal stability and thermal decomposition of sweetener.

scholarly journals Fabrication and Properties of High-Content Keratin/Poly (Ethylene Oxide) Blend Nanofibers Using Two-Step Cross-Linking Process

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Yong Liu ◽  
Xia Yu ◽  
Jia Li ◽  
Jie Fan ◽  
Meng Wang ◽  
...  
Keyword(s):  
Ethylene Oxide ◽  
Average Diameter ◽  
Diglycidyl Ether ◽  
Cross Linking ◽  
Electrospun Fibers ◽  
Hydrophobic Property ◽  
Poly Ethylene Oxide ◽  
Cross Linker ◽  
Poly Ethylene ◽  
Nanofiber Mats

High-content keratin/poly (ethylene oxide) (PEO) (90/10) blend nanofibers were prepared by electrospinning combined with a two-step cross-linking process. The keratin/PEO aqueous solution was firstly mixed with ethylene glycol diglycidyl ether (EGDE) as cross-linker and then electrospun into nanofibers. The resulting nanofibrous mats were cross-linked with EGDE vapor to decrease the solubility of nanofibers in water. The morphologies and properties of electrospun fibers were investigated by SEM, FTIR, TG, XRD, and contact angle testing, respectively. The results showed that the morphologies of nanofibers were uniform at the fiber average diameter of 300 nm with negligible bead defects by adding EGDE to keratin/PEO solutions. The cross-linking results showed that EGDE vapor could improve the hydrophobic property of blended nanofibers. The crystallinity of the keratin/PEO blend nanofiber mat increased from 13.14% for the uncross-linked sample to 21.54% and 35.15% for the first cross-linked and second cross-linked samples, respectively. Free defect nanofiber mats with high keratin content producing from this two-step cross-linking process are particularly promising for tissue engineering and cell-seeded scaffold.

scholarly journals Cross-linking of histones with dimethyl 3,3′-dithiobispropionimidate. Interference by a one-end reaction modifying histones at lysine amino groups

1984 ◽  
Vol 224 (3) ◽  
pp. 1019-1022
Author(s):  
E Kotthaus ◽  
W H Strätling
Keyword(s):  
Insoluble Fraction ◽  
Cross Linking ◽  
Amino Groups ◽  
Large Excess ◽  
Histone Dimers ◽  
Acid Solubility ◽  
Cross Linker ◽  
The Cross ◽  
Linker Molecules

We have studied the HClO4-solubility of histones H1 and H5 in hen erythrocyte nuclei after treatment with the cross-linker dimethyl 3,3′-dithiobispropionimidate (DTPI). The amount of acid-soluble, non-cross-linked, H1 and H5 histones was drastically decreased, and that of acid-soluble H1/H5 histone dimers went through an optimum as the DTPI concentration was raised. Incubation of the HClO4-insoluble fraction with 2-mercaptoethanol regenerated the acid-solubility of H1/H5 histones in this fraction. When purified H1/H5 histones were treated with increasing concentrations of DTPI under non-cross-linking conditions, the amount of HClO4-soluble histones also greatly decreased, but to a much lesser extent if the DTPI treatment was followed by reduction with 2-mercaptoethanol. This decrease was inversely correlated to the proportion of amino groups modified. It is concluded that, when the cross-linker was used in large excess, the cross-linking reaction competed with a one-end reaction modifying the histones at lysine amino groups by cross-linker molecules, of which the imidoester groups that had not reacted were hydrolysed. It is suggested that this modification produced the changes in acid-solubility.

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