Showing papers on "Gelatin published in 2013"

Chemical tailoring of gelatin to adjust its chemical and physical properties for functional bioprinting

Abstract: Double chemical functionalization of gelatin by methacrylation and acetylation of free amino groups enables control over both the viscous behavior of its solutions and the mechanical properties of the resulting hydrogels after photochemical crosslinking. The degree of methacrylation is controlled by the molar excess of methacrylic anhydride applied. Tenfold molar excess leads to highly methacrylated gelatin (GM10), resulting in solutions with low viscosities within the inkjet-printable range (10 wt%: 3.3 ± 0.5 mPa s, 37 °C) and crosslinked hydrogels with high storage moduli G′ (10 wt%: 15.2 ± 6.4 kPa). Twofold excess of methacrylic anhydride leads to less methacrylated gelatin (GM2) proper for preparation of soft hydrogels (10 wt%: G′ = 9.8 ± 4.6 mPa s) but its solutions are highly viscous (10 wt%: 14.2 ± 1.1 mPa s, 37 °C) and thus prone to clogging printing nozzles. Here we show that additional introduction of acetyl functionalities into GM2 results in a significant decrease in solution viscosity (10 wt%: 2.9 ± 0.2 mPa s, 37 °C) and prevention of physical gel formation. In such a manner twofold functionalized gelatin can be inkjet-printed while the degree of chemical crosslinking remains low and the resulting gels are soft. Thus, by adjustable twofold modification of gelatin, i.e. inserting photochemically reactive and inert groups, a versatile bioink for inkjet bioprinting is created, which allows for addressing ECM based hydrogel matrices with a broad range of physical properties. Moreover, bioinks are proven to be cytocompatible and proper for inkjet printing of viable mammalian cells.

Mechanical, Physical, Antioxidant, and Antimicrobial Properties of Gelatin Films Incorporated with Thymol for Potential Use as Nano Wound Dressing

Abstract: UNLABELLED The aim of this study was to determine the properties of gelatin films incorporated with thymol. Gelatin films were prepared from gelatin solutions (10% w/v) containing thymol (1, 2, 4, and 8% w/w), glycerol (25% w/w) as plasticizer, and glutaraldehyde (2% w/w) as cross-linker. Cross-likened films showed higher tensile strength, higher elongation at break, lower Young's modulus, lower water solubility, lower swelling, lower water uptake, and lower water vapor permeability. Incorporation of thymol caused a significant decrease in tensile strength, increase in elongation at break, decrease in Young's modulus, increase in water solubility, decrease in swelling and water uptake, and increase in water vapor permeability slightly. The films incorporated with thymol exhibited excellent antioxidant and antibacterial properties. The antibacterial activity of the films containing thymol was greatest against Staphylucoccus aureus followed by Bacillus subtilis followed by Escherichia coli and then by Pseudomonas aeruginosa. Thus, gelatin films-containing thymol can be used as safe and effective source of natural antioxidant and antimicrobial agents with the purpose of evaluating their potential use as modern nano wound dressing. PRACTICAL APPLICATION This study clearly demonstrates the potential of gelatin films incorporated with thymol as natural antioxidant and antimicrobial nano film. Such antimicrobial films exhibited excellent mechanical, physical, and water activities and could be used as antibacterial nano wound dressing against wounds burn pathogens.

Composite electrospun gelatin fiber-alginate gel scaffolds for mechanically robust tissue engineered cornea

Abstract: A severe shortage of good quality donor cornea is now an international crisis in public health. Alternatives for donor tissue need to be urgently developed to meet the increasing demand for corneal transplantation. Hydrogels have been widely used as scaffolds for corneal tissue regeneration due to their large water content, similar to that of native tissue. However, these hydrogel scaffolds lack the fibrous structure that functions as a load-bearing component in the native tissue, resulting in poor mechanical performance. This work shows that mechanical properties of compliant hydrogels can be substantially enhanced with electrospun nanofiber reinforcement. Electrospun gelatin nanofibers were infiltrated with alginate hydrogels, yielding transparent fiber-reinforced hydrogels. Without prior crosslinking, electrospun gelatin nanofibers improved the tensile elastic modulus of the hydrogels from 78±19 kPa to 450±100 kPa. Stiffer hydrogels, with elastic modulus of 820±210 kPa, were obtained by crosslinking the gelatin fibers with carbodiimide hydrochloride in ethanol before the infiltration process, but at the expense of transparency. The developed fiber-reinforced hydrogels show great promise as mechanically robust scaffolds for corneal tissue engineering applications.

Review: gelatin, source, extraction and industrial applications

Abstract: Gelatin is an important functional biopolymer widely used in foods to improve elasticity, consistency, and stability. It can be obtained not only from the skin and bones of land animals, but also from fi sh and insects. In recent years gelatins from fi sh and edible insects provide an alternative source that is acceptable for halal (Muslim) and kosher (Jewish) products, gelatin extraction has been reported for different fi shes and insects. In gelatin manufacture, two methods are usually used: the acid and the alkaline processes, to produce type A and type B gelatins, respectively.

Physical properties of fish gelatin-based bio-nanocomposite films incorporated with ZnO nanorods.

Abstract: Well-dispersed fish gelatin-based nanocomposites were prepared by adding ZnO nanorods (NRs) as fillers to aqueous gelatin. The effects of ZnO NR fillers on the mechanical, optical, and electrical properties of fish gelatin bio-nanocomposite films were investigated. Results showed an increase in Young's modulus and tensile strength of 42% and 25% for nanocomposites incorporated with 5% ZnO NRs, respectively, compared with unfilled gelatin-based films. UV transmission decreased to zero with the addition of a small amount of ZnO NRs in the biopolymer matrix. X-ray diffraction showed an increase in the intensity of the crystal facets of (10ī1) and (0002) with the addition of ZnO NRs in the biocomposite matrix. The surface topography of the fish gelatin films indicated an increase in surface roughness with increasing ZnO NR concentrations. The conductivity of the films also significantly increased with the addition of ZnO NRs. These results indicated that bio-nanocomposites based on ZnO NRs had great potentials for applications in packaging technology, food preservation, and UV-shielding systems.

Properties of gelatin-based films with added ethanol–propolis extract

Abstract: Considering the possibility of using propolis as a natural bioactive compound, and the growing interest in active and biodegradable packaging materials, gelatin-based films plasticized with sorbitol and added of ethanol–propolis extract (EPE) were produced. Four different concentrations of EPE (0, 5, 40 or 200 g/100 g of gelatin) were analyzed. The effect of concentrations of EPE were evaluated on: mechanical properties, solubility, moisture content, water vapor permeability, scanning electron microscopy and infrared spectroscopy characteristics, stability of polyphenol concentrations, and antimicrobial activity against Staphylococcus aureus . EPE incorporation to the films promoted reduction in rupture tension and water vapor permeability, besides other microstructural changes, when compared with the control films (0 g of EPE/100 g of gelatin). Activity against S. aureus was observed in films with 40 and 200 g of EPE/100 g of gelatin. These films kept their antimicrobial activity and polyphenol concentration for 177 days of storage.

In situ forming gelatin-based tissue adhesives and their phenolic content-driven properties

Abstract: The present study describes enzymatically cross-linked gelatin-based hydrogels as in situ forming tissue adhesives. A series of gelatin derivatives with different phenolic contents were synthesized by conjugating hydroxyphenyl propionic acid and tyramine to gelatin backbones. Two gelatin derivatives, gelatin–hydroxyphenyl propionic acid (GH) and gelatin–hydroxyphenyl propionic acid–tyramine (GHT) with maximum obtainable phenolic contents (146.6 μmol g−1 GH and 395.7 μmol g−1 GHT), were used to prepare gelatin-based hydrogels via horseradish peroxidase (HRP)-mediated reactions in the presence of hydrogen peroxide (H2O2). By changing the HRP and H2O2 concentrations, the gelation time, mechanical strength, and degradation rate of the hydrogels were fairly well controlled, indicating a tunable rate and degree of cross-linking. In addition, we found that an increase in phenolic content led to increased mechanical strength of the hydrogels. Lap-shear test results clearly showed that the GH and GHT hydrogels exhibited 2–3 times greater tissue adhesiveness compared to fibrin glues. On the basis of these results, we conclude that in situ forming gelatin-based hydrogels, which are both injectable and sprayable, can be used as an alternative to conventional tissue adhesives.

Gelapin, a degradable genipin cross-linked gelatin hydrogel

Abstract: The synthesis of genipin cross-linked gelatin (Gelapin) hydrogel materials is presented. Gelapin hydrogels were comprehensively characterised through chemical, mechanical and physical analysis techniques. It was found that the hydrogels could be cross-linked to up to 90% using a genipin concentration of 24.4% (w/w). The hydrogels reach a stable swollen state and cease leaching of residual starting materials after 72 h in phosphate buffered saline solution at 37 °C. The proteolytic degradation of Gelapin by collagenase is tuneable through manipulation of the material composition with the rate of degradation ranging from 60 mg per day up to 500 mg per day. The mechanical characteristics (at 37 °C) are controllable through adjustment of the gelatin and genipin concentrations resulting in compressive stress-at-failure values ranging from 26 kPa to 300 kPa. Gelapin gels were found to become more elastic and ductile during proteolytic degradation up to 70% mass loss. The ability for vascularisation of these hydrogels was demonstrated using a chick embryo chorioallantoic membrane assay method.