Mechanical Properties Of Gelatin Research Articles

Engineering biodegradable controlled gelatin-zein bilayer film with improved mechanical strength and flexibility

Compiling hydrophobic and hydrophilic proteins to form mechanically reliable bilayer film with improved water barrier properties and hydrophobicity to replace petroleum-based standards is challenging because fabricating compatible surfaces and flexible film with interlinked interfaces is complex. The mechanical properties of gelatin and zein layers exhibited unique variations, and synergistic enhancement of bilayer properties reflected robust layer-by-layer (LBL) interactions. To overcome the problem of impaired integrated surface, viscously cross-linked zein film forming solution (FFS) by glyoxal (GX) introduced compact and closely entangled network formation with cross-linking of gelatin film. Zein surface compatibility and flexibility by GX and polyethylene glycol (PEG 400) synergized with the gelatin layer closed to compare flexible plastic materials such as PE and PP besides modulated color and transparency. Enhancing flexible formation was mechanized by acetic acid as solvent of zein solution after long-range repulsion during casting on well-manageable plasticized and cross-linked gelatin film with glutaraldehyde (GA) and PEG 400, respectively. Elongation (E%) was achieved by nearly 192% with modified tensile strength (TS) and Young's modulus (YM). Cross-linkers, especially GX, resulted in lower water solubility (WS), and joint layers resulted in controlled water vapor permeability (WVP) of bilayer films. Decreased surface roughness and WS increased water contact angle (WCA). FTIR spectroscopy, XRD analysis, DMTA, and SDS-PAGE analyzed cross-linking mode and intensity. Hence, gelatin-zein bilayer films showed significant potential for improving value-added functional properties.

Identification of the concentration‐dependent viscoelastic constitutive parameters of gelatin by combining computational mechanics and machine learning

AbstractSince the mechanical properties of gelatin are similar to those of soft biological tissues, gelatin is a commonly used surrogate for real tissues, for example in safety engineering or medical engineering. Additional advantages of gelatin over real tissues are lower costs and better reproducibility of experiments. Therefore, constitutive models of gelatin are of great interest. In particular, it is important to capture the concentration dependence of the mechanical properties since the gelatin mass concentration significantly affects the constitutive behavior. To this end, we propose a hybrid approach linking artificial neural networks (ANN) and classical constitutive modeling to relate the gelatin's concentration to its viscoelastic material properties using indentation data.

Antimicrobially active gelatin/[Mg-Al-CO3]-LDH composite films based on clove essential oil for skin wound healing

In this study, gelatin, a biocompatible, collagen-derived protein, was combined with clove essential oil (CEO) and hydrotalcite ([Mg-Al-CO3]-LDH) nanoplates (D ∼ 100 nm) as an attempt to develop new antimicrobial wound dressings. CEO-loaded gelatin films covering different hydrotalcite contents (0.5–5.0 wt.%) were obtained by solution casting and characterized by light microscopy, FTIR and UV–vis spectroscopies, tensile and optical tests, water contact angle (WCA) determinations, and disc diffusion assays. CEO formed emulsified morphologies with gelatin over the entire hydrotalcite content range. Hydrotalcite contents larger than 2.5 wt.% were key for retain CEO in the gelatin matrix, which ensured antimicrobial activity for the films against Staphylococcus aureus and Escherichia coli. The UV barrier and mechanical properties of gelatin were significantly increased by CEO and further sustained upon hydrotalcite addition. All the composite films were regarded as hydrophilic materials (WCA < 75°), which was a preliminary requirement for their in vivo biocompatibility. The films were nontoxic towards HeLa cells, with cell viabilities above 70 %, as determined by MTT assay. These outcomes point out a simple way of using hydrotalcite to produce functional, biocompatible composites based on gelatin and clove essential oil for cutaneous wound healing and other biomedical applications.

Effect of plasticizer type and essential oils on mechanical, physicochemical, and antimicrobial characteristics of gelatin, starch, and pectin‐based films

Plastic packaging has been widely criticized due to the environmental pollution it entails. Biopolymer-based films could provide an interesting eco-friendly alternative. This study aimed to investigate the effect of plasticizer type on the physicochemical and mechanical properties of gelatin, pectin, starch, gelatin/pectin, gelatin/starch, and starch/pectin-based films. Films were prepared using the casting method. Among the six types of films studied, gelatin/pectin-based film plasticized with sorbitol displayed the best functional properties. Tensile strength and elongation at break were 52.46 MPa and 19.80%; moisture content, water vapor permeability, and water resistance were 19.96%, 3.24 × 107 g s–1 m–1 Pa–1, and 19.96%, respectively. Mentha pulegium and Lavandula angustifolia essential oils were incorporated into the selected film and their effects on the film's characteristics were evaluated. The incorporation of essential oils resulted in films with enhanced antibacterial properties, lower water vapor permeability, and reduced mechanical properties. Practical applications Biopolymer-based films have attracted widespread attention as an alternative to plastic packaging. In this study, we have demonstrated that gelatin/pectin-based film plasticized with sorbitol at 30% displayed good mechanical and physicochemical properties. The incorporation of Mentha pulegium and Lavandula angustifolia essential oils into this matrix resulted in films with important antimicrobial activity and adequate mechanical and physicochemical characteristics. The selected combination could be used as bioactive packaging to preserve and prolong the shelf life of food.

Physicochemical properties of gelatin films containing tea polyphenol-loaded chitosan nanoparticles generated by electrospray

In this study, gelatin (GEL) extracted from grass carp and tea polyphenols (TP) were encapsulated in chitosan (CS) nanoparticles using an innovative electrospray based ionic gelation method. CS-TP nanoparticles were fully optimized in terms of encapsulation efficiency and polydispersity. The average diameter of the optimal CS-TP nanoparticles was 205 ± 14 nm, and encapsulation efficiency of 66.7% ± 9.9% was achieved. The effects of CS-TP nanoparticles on the physicochemical properties of the GEL/CS-TP composite films were studied. Our results showed that the combination of CS-TP and grass carp gelatin (GEL) can not only weaken the strong interaction between GEL and TP, but also improved the swelling and mechanical properties of GEL. Furthermore, GEL/CS-TP30% composite film showed strong barrier and good mechanical properties, low UV transmission, exhibited high free radical-scavenging ability and prolonged the stability of an easily oxidizable oil for over 14 days, making it a suitable film for use as an edible packaging material.

Effect of ageing on the calibration of ballistic gelatin

PurposeBallistic gelatin is commonly used as a validated surrogate for soft tissue during terminal ballistic testing. However, the effect of a delay between production and testing of a gelatin mould...

Comparison of starch and gelatin hydrogels for non-toxic supercapacitor electrolytes

Starch and gelatin are two of the most abundantly available natural polymers. Their non-toxicity, low cost, and compatibility with aqueous solvents make them ideal for use in ubiquitous, environmentally friendly electronics systems. This work presents the results of conductivity measurements through impedance spectroscopy for gelatin- and starch-based aqueous gel electrolytes. The NaCl-based gels were physically cross-linked. The conductivity values were 84.6 mS/cm at 1.5 mol L−1 and 71.5 mS/cm at 2 mol L−1 for gelatin and starch, respectively. The mechanical properties of gelatin were found preferable to those of starch, although they deteriorated significantly when the salt concentration exceeded 2 mol L−1. The ability of the gels to successfully act as a supercapacitor electrolyte was demonstrated with printed electrodes on plastic substrate. The devices were characterized through cyclic voltammetry measurements. The results imply that these polymer gel electrolytes are very promising for replacing the traditional aqueous liquid electrolytes in supercapacitors in applications where, for example, user and environmental safety is essential.

Variation of Hydroxyapatite Content in Soft Gelatin Affects Mesenchymal Stem Cell Differentiation

Gelatin is a common material used in tissue engineering and hydroxyapatite (HA) has a composition and structure similar to natural bone mineral. HA is also used to increase the adhesion ability of scaffolds. The physical and mechanical properties of gelatin, together with the chemical properties of HA, can affect cell differentiation. The main purpose of this study is to investigate the gene expression of human mesenchymal stem cells (HMSCs) upon culturing on gelatin composite with HA. Low amounts of HA were introduced into the gelatin in order to modulate properties of gelatin. Three types of hydrogel were fabricated by glutaraldehyde crosslinking before lyophilization to produce the porous 3D structure: (1) pure gelatin, (2) 0.5 mg/ml HA in gelatin, and (3) 1 mg/ml HA in gelatin. The fabricated hydrogels were used as scaffolds to cultivate HMSCs for two periods - 24 hours and 3 weeks. The results showed that all types of fabricated hydrogels could be used to cultivate HMSCs. Changes of gene expressions indicated that the HMSCs cultured on the 1 mg/ml HA in gelatin showed neuronal lineage-specific differentiation.

Effectiveness of Posterolateral Lumbar Fusion Varies with the Physical Properties of Demineralized Bone Matrix Strip.

Study DesignA randomized, controlled animal study.PurposeTo investigate the effectiveness of fusion and new bone formation induced by demineralized bone matrix (DBM) strips with jelly strengths.Overview of LiteratureThe form of the DBM can make a difference to the outcome. The effect of different jelly strengths on the ability of DBM to form new bone is not known.MethodsForty-eight rabbits were randomized into a control group and two experimental groups. In the control group (group 1), 1.4 g of autologous iliac crest bone was placed bilaterally. In the experimental groups, a high jelly strength DBM-hyaluronic acid (HA)-gelatin strip (group 2) and a low jelly strength DBM-HA-gelatin strip (group 3) were used. The fusion was assessed with manual manipulation and radiographs. The volume of the fusion mass was determined from computed tomographic images.ResultsThe fusion rates as determined by manual palpation were 37.5%, 93.8% and 50.0% in group 1, group 2, and group 3, respectively (p<0.05). By radiography, the fusion rate of High jelly strength DBM strip was statistically significantly greater than that of the other alternatives (p<0.05). The mean bone volume of the fusion mass as determined by computed tomography was 2,142.2±318.5 mm3, 3,132.9±632.1 mm3, and 2,741.5±380.4 mm3 in group 1, group 2, and group 3, respectively (p<0.05).ConclusionsThese results indicate that differences in the structural and mechanical properties of gelatin that are associated with jelly strength influenced cellular responses such as cell viability and bony tissue ingrowth, facilitating greater bone fusion around high jelly strength implants.

Preparation and validation of a skin model for the evaluation of intradermal powder injection devices

A very promising novel needle-free application method is epidermal powder immunisation, a method delivering particulate vaccines into the viable epidermis of human skin where a dense network of immunocompetent cells resides. These antigen-presenting cells (Langerhans cells) are able to recognise antigens, process them and present them to naïve T-cells and induce effective immune responses. Powder injection devices are being developed, and their evaluation is essential before applying them on live animals and individuals. An appropriate skin model will accelerate the development of such injection devices. Different films made from gelatin, silicon and agar were prepared and investigated as skin model candidates for the evaluation of powder injection devices. The mechanical properties of the skin model candidates were measured with an indentation method using a texture analyser, and the results were compared to the properties of human skin and pig skin. The indentation behaviour of the model films and the biological skin samples suggest that gelatin films plasticised with glycerol are very well suitable for a skin model. The mechanical properties of gelatin based films can be tailored by changing the glycerol content in the film making it even possible to simulate human skin with different mechanical properties as the mechanical properties depend on the individual, age, sex and site of injection. The stability of the gelatin films was also investigated under long-term storage. In addition, confocal laser scanning microscopy was used as a novel tool to determine the depths and size of fluorescently labelled particles in the gelatin model.

Effect of Gelatin Gelation Kinetics on Probe Diffusion Determined by FRAP and Rheology

The time-dependent diffusion and mechanical properties of gelatin in solution, in the gel state, and during the sol/gel transition were determined using fluorescence recovery after photobleaching (FRAP) and rheology. The parameters in the experimental design were 2% w/w and 5% w/w gelatin concentration; 15, 20, and 25 °C end quench temperatures; and Na(2)-fluorescein, 10 kDa FITC-dextran, and 500 kDa FITC-dextran as diffusion probes. The samples were monitored in solution at 60 °C, during quenching, for 75 min at end quench temperatures and after 1, 7, and 14 days of storage at the end quench temperature. The effect of temperature on the probe diffusion was normalized by determining the free diffusion of the probes in pure water for the different temperatures. The results gained by comparing FRAP and rheology showed that FRAP is able to capture structural changes in the gelatin before gelation occurs, which was interpreted as a formation of transient networks. This was clearly seen for 2% w/w gelatin and 20 and 25 °C end quench temperatures. The structural changes during sol/gel transition are detected only by the larger probes, giving information about the typical length scales in the gelatin structure. The normalized diffusion rate increased after 7 and 14 days of storage. This increase was most pronounced for fluorescein but was also seen for the larger probes.

SOLUBILIZATION AND BIODEGRADATION OF CROSS-LINKED GELATINS BY ALKALINE PROTEINASE

This investigation involves the chemical modification of gelatin, a biomaterial which has been widely studied because of its environmental friendliness, its ready availability from waste products, and its biodegradability. The focus was on cross-linking because it has been shown that the mechanical properties of gelatin can be improved by a sequence of processing steps involving cross-linking, swelling, orientation, and, finally, drying in the oriented state. Because cross-linking is required in this technique, the present study characterizes its possible effects on gelatin biodegradability, as gauged by the time required to solubilize the material. A series of cross-linking agents having various alkylene sequence lengths was used. The resulting cross-linked gelatins were relatively insoluble in phosphate buffer (pH = 8.2) at room temperature, but at higher temperatures, they became partially soluble. Full solubilization of cross-linked gelatins was successfully obtained, however, by the action of an alkaline proteinase, specifically subtilisin. Both the rate of the partial solubilization in buffer and the full solubilization with alkaline proteinase showed dependences on the type, concentration, and chain lengths of the cross-linking agent.

Effect of sodium poly(styrene sulfonate) on thermoreversible gelation of gelatin

The effect of an added polyanion, sodium poly(styrene sulfonate) (NaPSS), on the thermoreversible gelation and remelting of gelatin gels has been investigated by polarimetry and rheology. The presence of NaPSS can either enhance or reduce collagenlike helix formation, depending on the polymer concentration relative to that of gelatin and the gelation temperature. At temperatures < 20°C, the helical content is reduced by increasing the amount of added NaPSS, demonstrating the disruption of helical structure of gelatin by the polyanion. Synchronous measurements of optical rotation and modulus at 25°C, in both gelation and remelting, indicate that the optical rotation at the gel point for the pure gelatin is lowered on addition of NaPSS. At low frequency, the storage modulus of gelatin is increased by the addition of a small amount of NaPSS relative to that of gelatin, but decreased with excess NaPSS. The mechanical properties of gelatin with and without NaPSS will be discussed in light of the competition between network junction formation by strands of triple helices among gelatin chains and temporary ionic crosslinking between gelatin and the polyanion. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 2287–2295, 1999

Effect of sodium poly(styrene sulfonate) on thermoreversible gelation of gelatin

The effect of an added polyanion, sodium poly(styrene sulfonate) (NaPSS), on the thermoreversible gelation and remelting of gelatin gels has been investigated by polarimetry and rheology. The presence of NaPSS can either enhance or reduce collag- enlike helix formation, depending on the polymer concentration relative to that of gelatin and the gelation temperature. At temperatures , 20°C, the helical content is reduced by increasing the amount of added NaPSS, demonstrating the disruption of helical structure of gelatin by the polyanion. Synchronous measurements of optical rotation and modulus at 25°C, in both gelation and remelting, indicate that the optical rotation at the gel point for the pure gelatin is lowered on addition of NaPSS. At low frequency, the storage modulus of gelatin is increased by the addition of a small amount of NaPSS relative to that of gelatin, but decreased with excess NaPSS. The mechanical properties of gelatin with and without NaPSS will be discussed in light of the compe- tition between network junction formation by strands of triple helices among gelatin chains and temporary ionic crosslinking between gelatin and the polyanion. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 2287-2295, 1999

The effect of water on the physicochemical and mechanical properties of gelatin

Strips of gelatin have been prepared by extrusion at different water contents varying from 20 to 50% H2O (dry weight basis, d.w.b.). The processes of subsequent hydration or dehydration of these strips were followed by dynamic mechanical thermal analysis (DMTA), wide-angle X-ray diffraction and NMR relaxation measurements. A comparison of the calculated dependence of theT g of gelatin (T g anhydrous, 200‡C) on water content (using the Ten Brinke and Karasz equation) with experimental results derived from DMTA showed that freshly extruded material followed the theoretical plot below 25% H2O (d.w.b.), but at higher water contents, the7 g deviated positively, probably due in part to the effect of delayed re-equilibration of water content after thawing of separated ice crystals. The experimental results determined after storage for one week fell on a different line, with aT g of 145‡C for anhydrous gelatin Possibly, theT g is elevated by crystallization — a view supported by the WAXS spectra. The NMR relaxation results also showed a profound mobilization of the gelatin protons at water contents greater than 25% d.w.b.

Concentration Dependence of Mechanical Properties of Gelatin near the Sol-Gel Transition Point

The concentration dependence of mechanical properties for gelatin near the sol–gel transition point was analyzed by the scaling law derived from the percolation theory, and compared with the results previously obtained for polyacrylamide. The critical concentration at the sol–gel transition point, ϕg, was estimated from the concentration (ϕ) vs. the reciprocal of viscosity (η) plots by extrapolating 1/η to zero. The critical exponent for sol viscosity, s, was estimated from the slope of a log(ϕg–ϕ) vs. log η plot. The critical exponent s was about 1.1, being larger than the value predicted by the percolation theory assuming the superconductor model. The critical exponent for gel elasticity, t, was estimated from the slope of a log(ϕ–ϕg) vs. log G′ plot, where G′ is the dynamic shear modulus at a frequency of 2Hz. The critical exponent t was about 2, being similar to the value predicted by the percolation theory.