Solubility Of Gelatin Research Articles

Single-Chain Mechanical Properties of Gelatin: A Single-Molecule Study.

Gelatin is an important natural biological resource with a wide range of applications in the pharmaceutical, industrial and food industries. We investigated the single-chain behaviors of gelatin by atomic force microscopy (AFM)-based single-molecule force spectroscopy (SMFS), and found that gelatin exists as long chains by fitting with the M-FJC model. By comparing the single-chain elasticity in a nonpolar organic solvent (nonane) and DI water, it was surprising to find that there was almost no difference in the single-chain elasticity of gelatin in nonane and DI water. Considering the specificity of gelatin solubility and the solvent size effect of nonane molecules, when a single gelatin chain is pulled into loose nonane, dehydration does not occur due to strong binding water interactions. Gelatin chains can only interact with water molecules at high temperatures; therefore, no further interaction of single gelatin chains with water molecules occurred at the experimental temperature. This eventually led to almost no difference in the single-chain F–E curves under the two conditions. It is expected that our study will enable the deep exploration of the interaction between water molecules and gelatin and provide a theoretical basis and experimental foundation for the design of gelatin-based materials with more functionalities.

Zinc oxide nanoparticles and periodate oxidation in developing pH-sensitive packaging film based on modified gelatin

Response surface methodology was used to develop pH-sensitive gelatin-based films containing red cabbage extract and zinc oxide nanoparticles (ZnONPs). We also evaluated oxidized sucrose (OS), prepared via the periodate oxidation of sucrose, as a cross-linker to compensate for gelatin solubility. Solubility decreased in films containing higher OS levels. The minimum WVP of the cross-linked gelatin films was obtained at 12.8 % OS and high levels of ZnONPs. Antioxidant activity was reinforced by both ZnONPs and OS. Higher OS concentrations caused decreased opacity, while ZnONPs had the opposite effect. The optimum treatment included 0.043 % ZnONPs and 11.45 % OS. Together, ZnONPs and OS resulted in enhanced strength and decreased flexibility. Greater antimicrobial activity was witnessed against Staphylococcus aureus than Escherichia coli. The optimum film’s color changed from reddish-purple to blue-green between pH 3−12. In summary, we reinforced the gelatin film structure and achieved functional characteristics in a novel, intelligent, and active packaging material.

Preparation of gelatin beads treated with glucose and glycerol

Abstract Gelatin is employed in pharmaceutical applications because of its biodegradability, biocompatibility and low toxicity. However, it may be necessary to promote gelatin crosslinking in order to develop drug release systems and extend release times. SEC analyses are used here for the first time to monitor the evolution of molar mass distributions of gelatins during treatment with glycerol and glucose in dispersed media. Unambiguous experimental evidence of gelatin crosslinking in presence of sugars and glycerol has yet to be presented. SEC results indicate that average molar masses decrease during gelatin treatment, while FT-IR analyses indicate that gelatins are subject to structural modifications during processing, which can explain the decrease of gelatin solubility after treatment. The results presented here indicate the importance of using SEC techniques to monitor gelatin crosslinking, as they seemingly contradict previously published results that make use of indirect measures for this purpose.

Biofunctional gelatin-based films incorporated with food grade phycocyanin extracted from the Saharian cyanobacterium Arthrospira sp.

Biofunctional films based on bovine gelatin (G) incorporated with a food grade phycocyanin (PC) extract at various concentrations (1.25%, 2.5%, 6.25% and 12.5%; w/w) were developed. PC incorporation maintained the original solubility of gelatin (control) film, while, when added at 6.25% and 12.5% (w/w), PC decreased the L* and increased b*, ΔE and the opacity values of the films, which enhances their light-barrier feature. Further, the tensile strength (TS) and elongation at break (EAB) were reduced with the increase of PC content in G-based films, and were inversely correlated to films thickness with respective R2 values of 0.94 and 0.97. Regarding microstructure, PC eliminated cracks present in the control film matrix resulting in a more smooth structure. Moreover, PC addition contributed to the thermal stabilization of the gelatin chain, delaying the glass transition temperature by 20 °C and conferring a thermal stability up to 250 °C. Regarding the antioxidant activity, the incorporation of 12.5% of PC significantly increased by 4.09, 3.2, 13.6 and 1.47-folds the chelating, reducing, β-carotene bleaching inhibition and DPPH radical scavenging capacities, respectively. Likewise, G-PC films displayed antibacterial activity against several Gram (−) and Gram (+) bacteria. The present study suggested that G-PC films incorporated with 6.25% and 12.5% of PC extracted from Arthrospira sp. could be used as a promising colored external or inner (secondary) functional packaging for dehydrated food products as well as for hard or soft-shelled capsules containing powdered or oily active ingredients, although further analysis should be carried out.

Gelatin Solubility and Processing in Ionic Liquids: An Approach Towards Waste to Utilization

We have investigated the solubility behavior of protein gelatin, in neat protic ionic liquids (ILs) [alkyl ammonium nitrates, ([CnNH3][NO3], n= 2, 3, 4)] and their reciprocal binary mixtures with [C4mim][Cl](1-butyl-3-methyl imidazolium chloride). Very high dissolution of gelatin could be achieved in [C2NH3][NO3](Ethylammonium nitrate). High solvating ability of [C2NH3][NO3] towards gelatin was utilized to process solid pharmaceutical waste of gelatin capsules by dissolving in [C2NH3][NO3] for the recovery of pure gelatin. The recovered gelatin was further processed to prepare gelatin/Ag2O nano-composite in a mixed IL system, [C2NH3][NO3]+[C4mim][Cl]. The prepared nano-composite exhibited excellent antimicrobial activity on gram negative bacteria pseudomonas aeruginosa MTCC NO-1688 and Escherichia coli MTCC NO-42 and therefore, can be useful for potential biomedical applications. The developed process is a worthy alternative strategy for “waste to utilization” of gelatin pharmaceutical scrap.

Preparation of green and gelatin-free nanocrystalline cellulose capsules

The ambiguous source and uncontrolled solubility of gelatin make it crucial to develop gelatin capsule substitutes. Nanocrystalline cellulose (NCC) of excellent mechanical performance, good biocompatibility and green origin has drawn many attentions as a new class of biomaterials. In this work, NCC capsule was prepared by dipping method with PEG and glycerol as plasticizer. The effect of PEG and glycerol on the rheological property of NCC gel and the surface morphology of NCC capsule was evaluated. The disintegration time of NCC capsule meet the criteria in United States Pharmacopoeia (USP32-701).There is no significant difference in the release of sulfuric acid between gelatin capsule and NCC capsule. NCC capsule thus has the potential as a green platform for biomedical applications in drug delivery.

Fabrication of gelatin–laponite composite films: Effect of the concentration of laponite on physical properties and the freshness of meat during storage

The biodegradable and biocompatible gelatin–laponite composite films were developed in this study. The effect of the concentration of laponite on the physicochemical properties of the gelatin–laponite film was investigated. The results suggested that the gel strength, mechanical properties, water vapor permeability and water solubility of gelatin–laponite composite films are significantly improved with the increase of the concentration of laponite. In addition, the microstructures of gelatin–laponite films were also characterized by scanning electron microscope (SEM) micrographs. The results of fourier transform infrared spectroscopy (FTIR) indicated that laponite facilitated the conformational changes of proteins films. Furthermore, gelatin–laponite films exhibited substantial enhancement of the quality of meat during storage, which was improved with the concentration of laponite. Hence, gelatin–laponite composite films could be potentially utilized in the development of the novel packaging material in food industries.

Influence of bloom number and plastifiers on gelatin matrices produced for enzyme immobilization

In this study the immobilization of lipase in matrices produced with gelatin with different Bloom values and with the addition of plastifiers was investigated to evaluate the influence of the Bloom value, as well as the capacity of the plastifiers to maintain the enzyme immobilized and the immobilization yield. The results indicated the need for crosslinking of the matrices with glutaraldehyde due to the high solubility in water, explained by the amino acid profile, which confirms the solubility of gelatin. Mannitol showed greater efficiency in the lipase immobilization, since it led to more porous structures and more uniform pores. These structures were also influenced by the gelatin concentration; greater concentrations associated with intermediate concentrations of plastifier led to matrices with a greater immobilization yield (87.92%). The X-ray diffraction analysis revealed that the structure of the immobilization matrices was partially crystalline.

Evaluation of isophorone diisocyanate crosslinked gelatin as a carrier for controlled delivery of drugs

The high solubility of gelatin in neutral, basic, and acidic biofluids may not promote a controlled drug delivery as a drug carrier. The present study reports the modification of the solubility and swellability of gelatin by crosslinking with hitherto uninvestigated isophorone diisocyanate to achieve controlled drug release characteristics. The crosslinked gelatin was insoluble and swellable in biofluids and analyzed by FT-IR and proton NMR, thermal analysis, swellability and biodegradability in simulated biofluids, X-ray diffraction, biocompatibility, and in vitro drug release kinetics and mechanism with 5-Fluorouracil as model drug. Crosslinking decreased the biodegradability and solubility, and enhanced the amorphous character of gelatin. The mild decrease in thermal stability of crosslinked gelatin was attributed to the urea linkage introduced. Drug release predominately occurred via anomalous transport mechanism with mild degradative diffusion. The observed results demonstrated that crosslinked gelatin can be used as a potential carrier to achieve controlled drug release.

Synthesis, Characterization, and Drying of Absorbable Gelatin Foam

This research article pertains to a process for the preparation of lyophilized absorbable gelatin sponge. The Kenics static mixer was used for gelatin foam preparation and subsequently lyophilized in a freeze dryer. The lyophilized sponge was characterized for its pore size, bulk density, degree of cross-linking, mechanical stability, water absorption capacity, water intake rate, and thermal stability. The extent of cross-linking was evaluated by gelatin solubility test method. With increasing concentration of formaldehyde, Young's modulus and the stress at break increases and the strain at break decreases. Simultaneously, cross-linking provokes a significant reduction of swelling in water and it enhances the thermal stability of the sample as indicated by the differential scanning calorimetry (DSC) investigations. The pore size and bulk density of the dried sponge was found to increase from 100 to 500 µm and decrease from 26.7 to 22.4 kg/m3, respectively, with an increase in freezing temperature from −70 to −20°C. The drying study at different temperatures reveals that the effective diffusivity of moisture in foam increases from 7.5396 × 10−8 to 9.8285 × 10−8 m2/s with an increase in drying temperature from 40 to 60°C during the desorption stage. The sponge prepared from gelatin can be utilized as a promising matrix for wound healing and other surgical applications.

Analysis of aged gelatin by AFlFFF-MALS: Identification of high molar mass components and their influence on solubility

Gelatin is an important product for several industries and its solubility dramatically influences its functional properties. In order to be able to predict the gelatin behaviour, a new technique for its analysis has been developed with an Asymmetrical Flow Field-Flow Fractionation coupled to a multi-angle light scattering. The AFlFFF-MALS analysis showed the gelatin molar mass ranging from 5 × 10 4 to 2 × 10 7 g mol −1. This technique also permitted to follow aggregation of gelatin samples after process in an oven at 75 °C. Between 0 and 4 days, some huge aggregates appeared. Their size and density increased without changing gelatin solubility. From 8 to 30 days, the molar mass and density of these aggregates increased leading to partial gelatin insolubilisation in water. This phenomenon is supposed to be due to cross-linking of the gelatin macromolecules.

Dissolution and Enzymatic Degradation Studies Before and After Artificial Ageing of Silk‐ or Linen‐Reinforced Gelatin Laminates, 2

AbstractBiodegradable laminates based on gelatin and on gelatin/starch blend reinforced with fabrics (silk or linen) were prepared by melt pressing. Due to crosslinking during the thermal treatment and in some cases, to additional crosslinking with methylenedi(p‐phenyl) diisocyanate, the fresh and artificially aged samples demonstrated improved mechanical properties, as reported previously. In Part 1 of this study on the environmental behavior of these new laminated composites, the simple dissolution in a buffer solution or water of fresh and artificially aged samples was considered. During this treatment soluble, i.e., uncrosslinked molecules were removed leaving a product resulting from addition reactions and consequent crosslinking. These processes take place during the melt pressing at 180 °C and cause a decreased solubility of gelatin. The present Part 2 deals with the enzymatic treatment of the same samples. We have implicitly shown that the gelatin moiety of the laminates undergoes proteolysis and that this process depends on the laminate composition. At the end of the treatment the enzymatic buffer solution contains only peptides and virtually no high‐molecular gelatin. The degrees of degradation vs. time dependencies differ for water and enzymatic treatment of the samples, indicating different processes in either treatment. The time‐course curves of the enzymatic treatment of different laminates and the kinetic parameters derived therefrom were analyzed. Thereby the effect of many factors on the accessibility of the gelatin moiety to proteolysis was shown. These factors are: temperature treatment, artificial ageing, the nature of the reinforcing fabrics, the “additional” crosslinking with methylenedi(p‐phenyl) diisocyanate, etc. The gelatin‐linen laminate is the most sensitive to crosslinking. There is a tendency that the crosslinking smears the differences in the time‐course of the absorption behavior curves of the different samples.Degree of degradation, β′, (related to only the gelatin) vs. time, t, for laminates: (a) uncrosslinked gelatin‐linen; (b) crosslinked gelatin‐linen; (c) uncrosslinked gelatin‐silk; (d) crosslinked gelatin‐silk.magnified imageDegree of degradation, β′, (related to only the gelatin) vs. time, t, for laminates: (a) uncrosslinked gelatin‐linen; (b) crosslinked gelatin‐linen; (c) uncrosslinked gelatin‐silk; (d) crosslinked gelatin‐silk.

Solubility of drugs in the presence of gelatin: effect of drug lipophilicity and degree of ionization

The solubility of seven drugs (nitrofurantoin, chlorothiazide, phenobarbital, prednisolone, griseofulvin, diazepam and piroxicam) in the absence and presence of gelatin was measured, at three different pH values (3.7, 5.0 and 7.0) at 37°C. Drugs studied had different physicochemical properties (log P, p K a, aqueous solubility) and their solubility in presence of 0.1 and 0.5% (w/v) hydrolyzed (and in some cases common) gelatin was estimated. Results show that the solubility of all drugs is significantly enhanced, especially in the presence of 0.5% gelatin. This gelatin-induced enhancement in drug solubility is higher in the pH in which acidic drugs are less ionized, especially for the less lipophilic acidic drugs (nitrofurantoin, chlorothiazide). In all cases, drug solubility in presence of gelatin is correlated with their aqueous solubility. Therefore, the established relationships between aqueous and gelatin solubility can be employed to derive an estimate of the drug solubility in presence of gelatin once its aqueous solubility is known. With the exception of piroxicam which is highly ionized and phenobarbital which is relatively soluble, there seems to be a tendency for larger gelatin-induced increases in solubility as drug lipophilicity increases or aqueous solubility decreases.

Examination of Self-Crosslinked Gelatin as a Hydrogel for Controlled Release

A gelatin matrix crosslinked by extensive dehydration was examined for use in controlled drug delivery in this preliminary investigation. Crosslinking is necessary to prevent gelatin dissolution and immediate drug release at body temperature. Treatment at 105°C and reduced pressure induced crosslinking in discs prepared from Type B gelatin. Crosslinking was evaluated by determining changes in gelatin solubility at 37 °C in a USP paddle dissolution apparatus. The crosslinking treatment was reproducible and resulted in 90% of the original gelatin mass remaining after 12 h in water and in phosphate buffer solutions of pH 3 and 6.4. The treated gelatin discs remained intact for >24 h at pH 6.4. Chlorpromazine • HCI (CPZ) was incorporated as a model drug by soaking the treated gelatin discs in an aqueous solution of the drug. Release of CPZ at 37 °C in the dissolution apparatus was fitted to an empirical equation. A coefficient of this equation was used as the initial release rate for comparison between different release profiles. The roles of drug solubility, matrix swelling and erosion, and potential drug-matrix interactions were examined by conducting release studies at pH values of 3, 4, 6.4, and 7.4. The insoluble, un-ionized form of the drug had the slowest release rate. The soluble, ionized form under conditions of maximum swelling and a possible drug-matrix repulsive interaction had the fastest release rate. General electrostatic drug-matrix interactions were noted which could influence the drug release rate depending on conditions of the study. The times for 50% release of CPZ ranged from 1.8 to 11.3 h.

Interpenetrating hydrogel networks: 3. Properties of the gelatin-sodium carboxymethylcellulose system

The aqueous solubility of gelatin and the sodium salt of carboxymethylcellulose (CMC) together with the sol aigel transition of gelation and its crosslinking reaction with glutaraldehyde is exploited to synthesize interpenetrating complexes of these two macromolecules. This material exhibits swelling properties, typical of ionic hydrogels, which vary as a function of CMC content. Several compositions were cast into films. The protein component contributed more towards the mechanical properties of these films. The gels responded to an electric stimulus by a change in dimensions. The striking compositional resemblance of this system to cartilage tissues is discussed.

Chemical modification of gelatin with vaporized hexanal.

Changes in chemical and functional properties of gelatin were investigated on reaction with vaporized hexanal to reveal the reaction mechanism between oxidized lipids and proteins. Among the amino acid residues of gelatin, only lysine and hydroxylysine residues decreased on the reaction. The analysis of UV spectrum suggested that almost all of thee-amino groups in the decreased amino acid residues were modifed to alkyl-substituted pyridinium rings, i. e, , 1-(5-carboxy-5-aminopentyl)-2-pentyl-3, 5-dibutylpyridinium betaine.Gelatin was not assumed to polymerize on the reaction with hexanal. These results suggested that the hexanal-induced polymerization of proteins did not always require the cross-linking involving lysine residues. The solubility of gelatin decreased as the modified lysine and hydroxylysine residues increased. When the extent of such modifcation reached to 57%, a remarkable decrease in solubility occurred. On the other hand, the emulsifying activity of the modified gelatin increased as compared with that of the unmodified gelatin when the extent of the modification was 4 or 27%, but decreased at a 57 or 71% modification.

Oxidation Effects in a Freeze‐Dried Gelatin‐Methyl Linoleate System

SUMMARY– We studied oxidation of a freeze‐dried model system consisting of methyl linoleate and gelatin by incubating the model system in air at 50°C for up to 10 days in the dry state or at controlled relative humidities. Incubation for 5‐10 days caused a drop in the viscosity of gelatin solutions, an increase in the solubility of gelatin in ethanol‐rich solvent mixtures, an increase in the retention time of gelatin on a Sephadex G‐150 column, and a reduction in the melting point of a standard gelatin gel. There were no such changes in the viscosity and solubility properties of gelatin when incubation was at a relative humidity of approximately 60%. In some instances, incubation at high relative humidity led to partial insolubilization of gelatin in water or in acetate buffer. The oxidation effects in the dry state were consistent with the hypothesis that gelatin undergoes oxidative degradation. The effects of oxidation showed similarities to effects of ionizing radiations.

A New Oral Gelatinized Sustained-Release Dosage Form

A new sustained-release micropellet was prepared which takes advantage of the relationship of gelatin solubility to the hardness of the gelatin caused by formalin treatment. This new gelatin micropellet could be produced more easily than the coated micropellet employed in the usual sustained-release dosage forms.

STABILITY OF SUSPENSIONS OF SOLID PARTICLES OF PROTEINS AND PROTECTIVE ACTION OF COLLOIDS

1. It is shown that the concentrations of different salts required to precipitate suspensions of gelatin-coated collodion particles in water are practically identical with the concentrations of the same salts required for the "salting out" of gelatin from aqueous solutions. Neither effect shows any relation to the electrical double layers surrounding the particles. 2. It is shown that at the isoelectric point of gelatin, suspensions of gelatin-coated collodion particles are not stable and it had been shown previously that gelatin is least soluble at the isoelectric point. The addition of salt increases both the solubility of gelatin in water as well as the stability of suspensions of gelatin-coated collodion particles in water, and both effects increase with the valency of one of the ions of the salt. 3. This latter effect is not due to any charges conferred on the gelatin particles by the salts, since the cataphoretic experiments show that salts like NaCl, Na(2)SO(4), or CaCl(2), which at the isoelectric point of gelatin increase the solubility of gelatin as well as the stability of suspensions of gelatin-coated collodion particles, leave the particles practically uncharged in the concentrations in which the salts are efficient. 4. It follows from all these facts that the stability of suspensions of gelatin-coated particles in water depends on the solubility of gelatin in water; e.g., on the chemical affinity of certain groups of the gelatin molecule for water. 5. Though crystalline egg albumin is highly soluble in water, the stability of collodion particles coated with crystalline egg albumin does not depend upon the affinity of the albumin molecule for water, but depends practically alone on the electrical double layer surrounding each particle. As soon as the P.D. of this double layer falls below 13 millivolts, the suspension is no longer stable. 6. The critical potential for the stability of suspensions of collodion particles coated with genuine egg albumin is the same as that for particles of boiled (denatured) white of egg. Since through the process of heating, egg albumin loses its solubility in water, it is inferred that egg albumin undergoes the same change when it forms a film around a solid particle like collodion. 7. The influence of electrolytes on the stability of suspensions of collodion particles coated with casein or edestin was similar to that of collodion particles coated with egg albumin. The experiments are, however, complicated by the fact that near the isoelectric point CaCl(2) and even NaCl cause a suspension again at concentrations of about M/2 or 1 M, while still higher concentrations may cause a precipitation again. These latter effects have no connection with double layers, but belong probably in the category of solubility phenomena. 8. These experiments permit us to define more definitely the conditions for a general protective action of colloids. Protective colloids must be capable of forming a durable film on the surface of the suspended particles and the molecules constituting the film must have a higher attraction for the molecules of the solvent than for each other; in other words, they must possess true solubility. Only in this case can they prevent the precipitating action of low concentrations of electrolytes on particles which are kept in suspension solely by the high potentials of an electrical double layer. Thus gelatin films, in which the attraction of the molecules for water is preserved, have a general protective action, while crystalline egg albumin, casein, and edestin, which seem to lose their attraction for water when forming a film, have a protective action only under limited conditions stated in the paper.

ION SERIES AND THE PHYSICAL PROPERTIES OF PROTEINS. II

1. Our results show clearly that the Hofmeister series is not the correct expression of the relative effect of ions on the swelling of gelatin, and that it is not true that chlorides, bromides, and nitrates have "hydrating," and acetates, tartrates, citrates, and phosphates "dehydrating," effects. If the pH of the gelatin is taken into considertion, it is found that for the same pH the effect on swelling is the same for gelatin chloride, nitrate, trichloracetate, tartrate, succinate, oxalate, citrate, and phosphate, while the swelling is considerably less for gelatin sulfate. This is exactly what we should expect on the basis of the combining ratios of the corresponding acids with gelatin since the weak dibasic and tribasic acids combine with gelatin in molecular proportions while the strong dibasic acid H(2)SO(4) combines with gelatin in equivalent proportions. In the case of the weak dibasic acids he anion in combination with gelatin is therefore monovalent and in the case of the strong H(2)SO(4) it is bivalent. Hence it is only the valency and not the nature of the ion in combination with gelatin which affects the degree of swelling. 2. This is corroborated in the experiments with alkalies which show that LiOH, NaOH, KOH, and NH(4)OH cause the same degree of swelling at the same pH of the gelatin solution and that this swelling is considerably higher than that caused by Ca(OH)(2) and Ba(OH)(2) for the same pH. This agrees with the results of the titration experiments which prove that Ca(OH)(2) and Ba(OH)(2) combine with gelatin in equivalent proportions and that hence the cation in combination with the gelatin salt with these two latter bases is bivalent. 3. The fact that proteins combine with acids and alkalies on the basis of the forces of primary valency is therefore not only in full agreement with the influence of ions on the physical properties of proteins but allows us to predict this influence qualitatively and quantitatively. 4. What has been stated in regard to the influence of ions on the swelling of the different gelatin salts is also true in regard to the influence of ions on the relative solubility of gelatin in alcohol-water mixtures. 5. Conductivity measurements of solutions of gelatin salts do not support the theory that the drop in the curves for swelling, osmotic pressure, or viscosity, which occurs at a pH 3.3 or a little less, is due to a drop in the concentration of ionized protein in the solution; nor do they suggest that the difference between the physical properties of gelatin sulfate and gelatin chloride is due to differences in the degree of ionization of these two salts.