Aqueous Gelatin Solution Research Articles

Dynamics of magnetic nanoparticles in viscoelastic media

We compare different models for the description of the complex susceptibility of magnetic nanoparticles in an aqueous gelatin solution representing a model system for a Voigt-Kelvin scheme. The analysis of susceptibility spectra with the numerical model by Raikher et al. [7] is compared with the analysis applying a phenomenological, modified Debye model. The fit of the models to the measured data allows one to extract the viscoelastic parameter dynamic viscosity η and shear modulus G. The experimental data were recorded on single-core thermally blocked CoFe2O4 nanoparticles in an aqueous solution with 2.5wt% gelatin. Whereas the dynamic viscosities obtained by fitting the model – extended by distributions of hydrodynamic diameters and viscosities – agree very well, the derived values for the shear modulus show the same temporal behavior during the gelation process, but vary approximately by a factor of two. To verify the values for viscosity and shear modulus obtained from nanorheology, macrorheological measurements are in progress.

Controlled Antibiotic Delivery by Gelatin Nanospheres: Optimization, Characterization and Antibacterial Evaluation

The present work focuses on preparation and characterization of erythromycin loaded gelatin nanoparticles through nanoprecipitation method. The procedure consists of the addition of the aqueous gelatin solution to the non-solvent phase containing Lutherol F127. Three different measures of cross-linker and polymer concentration were also examined, and the optimum concentration was found. The morphology of gelatin nanoparticles was characterized by field emission scanning electron microscope. It was shown that the optimal morphology can be achieved at the concentration of 1.25 wt % of gelatin in aqueous phase by addition of 20 mL of glutaraldehyde 5%, as the crosslinking agent. Nanoparticle wet size determination was carried out using a dynamic light scattering system and found to be approximately 100 nm. Furthermore, Erythromycin release studies proved the suitability of these particles as a drug delivery system, at least in the studied 72 hours interval. As suggested by related measurements, these nanoparticles are good candidates for antibacterial agent release in any possible related application.

I-Rheo: Measuring the materials' linear viscoelastic properties “in a step”!

We present a simple new analytical method for educing the materials' linear viscoelastic properties, over the widest range of experimentally accessible frequencies, from a simple step-strain measurement, without the need of preconceived models nor the idealization of real measurements. This is achieved by evaluating the Fourier transforms of raw experimental data describing both the time-dependent stress and strain functions. The novel method has been implemented into an open access executable “i-Rheo,” enabling its use to a broad scientific community. The effectiveness of the new rheological tool has been corroborated by direct comparison with conventional linear oscillatory measurements for a series of complex materials as diverse as a monodisperse linear polymer melt, a bimodal blend of linear polymer melts, an industrial styrene-butadiene rubber, an aqueous gelatin solution at the gel point and a highly concentrated suspension of colloidal particles. The broadband nature of the new method and its general validity open the route to a deeper understanding of the material's rheological behavior in a variety of systems.

Gelatin based films capable of modifying its color against environmental pH changes

The aim of this work was to develop biodegradable protein-based films capable of sense pH changes. These protein films were prepared by casting from aqueous solutions of bovine gelatin, glycerol and three acid-base indicators: methyl orange (MO), neutral red (NR) and bromocresol green (BCG), at pH 2, 6 and 11. All resulting protein films were homogeneous, thin and had different colors depending on pH and the indicator used. The response of these materials was evaluated simulating their contact with liquid and semisolid media, and with a container headspace at acid and alkaline pH. In all tests, developed protein films could modify their color after being in contact with media of different pH. The physicochemical properties of films were also affected differently by the presence of each acid-base indicator. While the addition of BCG did not significantly modify the properties of control gelatin films, except its color; the incorporation of MO and NR into film-forming solutions significantly improved mechanical properties and decreased the water solubility and moisture content of the resulting protein films without affecting their water vapor permeability.

Ultrasonic wave velocity in the restructuring of disperse media

The ultrasonic wave velocities in the restructuring of disperse media were measured using interference and pulsed techniques and the coefficient of reflection in suspensions of starch, Al2O3, and SiO2 particles, glass bulbs, their porous sediments, and composites of Fe3O4 particles in 10% gelatin aqueous solution at a frequency of 3 MHz. The experiments showed alternating variation in the concentration velocity coefficient during the transition of the dispersed phase concentration from the subpercolation to percolation region. The minimum ultrasonic wave velocity in the region of discrete clusters correlates with the ratio between the particle and matrix densities. The results obtained are explained using the Isakovich, Chaban, Rytov, Biot, Hausdorff, and other theories.

Preparation and Properties of Gelatin Fibers Fabricated by Dry Spinning

Gelatin fibers have been prepared by dry spinning based on the sol-gel transition phenomena of aqueous gelatin solutions. This method is simple and environmentally friendly because only water is used for the spinning, thereby avoiding the use of any toxic organic solvents. A sol-state aqueous solution of gelatin at 50 °C was extruded into air through a thin nozzle at room temperature followed by high-speed stretching in air. As a result, a stretched and shiny gelatin fiber was produced. To improve the mechanical and water-resistant properties of the fibers, a crosslinking treatment by the addition of sugars, denacol, and glutaraldehyde vapor was used. Despite their smooth surfaces, the gelatin fibers exhibited a multi-porous phase on the inside, probably owing to the retention of water during the spinning process. The mean diameters of the obtained fibers with all crosslinking agents were approximately 50–60 μm. Furthermore, the mean tensile strength was increased by all crosslinking agents. In particular, the use of N-acetyl-d-glucosamine and glutaraldehyde as the crosslinkers resulted in a remarkable increase in tensile strength and water resistance. Moreover, their properties were further improved after heat treatment. These fibers also exhibited good water resistance and maintained their morphologies for more than 90 days.

Eco-friendly synthesis of gelatin-capped bimetallic Au-Ag nanoparticles for chemiluminescence detection of anticancer raloxifene hydrochloride.

This study described the utility of green analytical chemistry in the synthesis of gelatin-capped silver, gold and bimetallic gold-silver nanoparticles (NPs). The preparation of nanoparticles was based on the reaction of silver nitrate or chlorauric acid with a 1.0wt% aqueous gelatin solution at 50°C. The gelatin-capped silver, gold and bimetallic NPs were characterized using transmission electron microscopy, UV-vis, X-ray diffraction and Fourier transform infrared spectroscopy, and were used to enhance a sensitive sequential injection chemiluminescence luminol-potassium ferricyanide system for determination of the anticancer drug raloxifene hydrochloride. The developed method is eco-friendly and sensitive for chemiluminescence detection of the selected drug in its bulk powder, pharmaceutical injections and biosamples. After optimizing the conditions, a linear relationship in the range of 1.0×10(-9) to 1.0×10(-1) mol/L was obtained with a limit of detection of 5.0×10(-10) mol/L and a limit of quantification of 1.0×10(-9) mol/L. Statistical treatment and method validation were performed based on ICH guidelines. Copyright © 2016 John Wiley & Sons, Ltd.

Preparation and Properties of Nanocolloidal Solution based on Rhenium Sulfide for Lymphoscintigraphy Methods of Micrometastases Investigation

A method for producing a nanocolloidal solution of rhenium sulfide has been suggested. It includes the following stages: interaction of ammonium perrhenate and sodium thiosulfate in aqueous solution of gelatin in an acidic medium by heating up to 70-80°C; pH neutralization up to 7.0; dialysis against saline; desalination and concentrating by ultrafiltration. The obtained colloidal solution contains 85% particles with the optimal size 80-100 nm and can be used as a diagnostic tool in lymphoscintigraphy of “sentinel” lymph nodes in patients with cancer and other diseases.

放射性物質吸着除去を目的としたゼオライト／HA 複合体の作製と吸着特性評価

Zeolite/HA composite porous medium was prepared by the Gelation Freezing Method. Montmorillonite was used as a bonding material. Composite porous medium was prepared by freeze-drying a slurry which was added to aqueous gelatin solution to powder mixture of zeolite, HA and montmorillonite. Prepared the complex was heated at 500 ℃ and 800 ℃. The crystallinity was evaluated using X-ray diffractometer (XRD). The surface was observed with a scanning electron microscope (SEM). Flexural strength was calculated by destructive testing. In SEM analysis, it was observed that there is a pore in the all samples. The lower freezing temperature, the smaller pore size becomes.

Multi-responsive polyethylene-polyamine/gelatin hydrogel induced by non-covalent interactions

By simply introducing a gelatin aqueous solution, the polyethylene-polyamine (PPA)/gelatin hydrogel with multi-stimuli-responsive properties was obtained.

A convenient process to fabricate gelatin modified porous PLLA materials with high hydrophilicity and strength.

PLLA porous materials with high porosity were prepared by a gradual precipitation method and further modified by using different concentrations of gelatin aqueous solutions. Therefore, porous materials with different contents of gelatin coating were obtained. The micro morphology, crystallization, thermal performance, hydrophilicity and mechanical properties of the materials were evaluated by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), X-ray diffraction (XRD), thermogravimetric analysis (TGA), water uptake ability tests and compression tests. It was found that the modified materials were formed by the stacking of nanosheets. The materials can maintain more than 80% porosity, high water uptake abilities and fast water uptake rates after modification. The compressive moduli of the materials were significantly improved from the initial sample with a value of 0.57 MPa to 46.41 MPa with gelatin modification. Due to the high porosity of materials, interconnected pore structures, and good surface hydrophilicity, the materials were expected to be widely used in the field of tissue engineering scaffolds, especially for bone substitutes, mainly due to their tunable and excellent mechanical properties.

Effect of gelatin on the water dispersion and centrifugal purification of single-walled carbon nanotubes

We report a convenient and effective procedure for the water dispersion and purification of single-walled carbon nanotubes (SWNTs). The purification procedure involves a combination of dispersion and centrifugation, in which gelatin; an environmentally friendly material is used as a dispersing agent. It has been found that an aqueous solution of gelatin effectively disperses SWNTs for more than a month. Another advantage of using gelatin as a dispersing agent is that it can be easily removed by washing with water and filtration. The centrifugation procedure employs a centrifugal force of about 2500 times the gravitational force to separate the particles. Although carbonaceous and metallic impurities usually have higher density than SWNTs in arc-produced carbon soot, the centrifugation can easily remove impurities leaving undamaged SWNTs in solution when appropriate centrifugal force and a centrifugation time are used. Centrifugation is carried out for three times to sufficiently remove impurities. Finally, the SWNTs are separated from the gelatin by heating in water and filtering.

Synthesis of gelatin nano/submicron particles by binary nonsolvent aided coacervation (BNAC) method

A newly developed modified coacervation method is utilized to synthesize gelatin nano/submicron particles (GN/SPs) as a drug carrier. Binary nonsolvent aided coacervation (BNAC) method is a modified single step coacervation method, which has yielded approximately a threefold lower particle size and higher average yield in terms of weight percentage of around 94% in comparison to the conventional phase separation methods. In this study 0.5% (w/v) gelatin aqueous solution with a binary nonsolvent system of acetone and ethanol was used. Nanoparticle synthesis was optimized with respect to nonsolvent system type and pH. pH7 has resulted a minimum particle size of 55.67 (±43.74) nm in anhydrous medium along with a swollen particle size of 776nm (±38.57) in aqueous medium with a zeta potential of (−16.3±3.51) mV in aqueous medium. Swelling ratio of 13.95 confirms the crosslinked hydrogel nature of the particles. Furthermore, drug loading efficiency of the gelatin particles prepared at 7pH was observed with nitrofurazone as the model drug. Results of drug release study indicate the potential use of GN/SPs as drug loading matrix for wound management such as burn wound management.

Multi-scale patterns formed by sodium sulphate in a drying droplet of gelatin

We present a study of patterns, formed in drying drops of aqueous gelatin solution containing sodium sulphate. The patterns are highly complex, consisting of a hierarchical sequence of rings which form concentric bands as well as dendritic crystalline aggregates. When the preparation of the complex fluid is done by mixing an aqueous solution of the salt with an aqueous solution of gelatin prepared separately, another feature is observed in the pattern on the dried out drop. This is a viscous fingering pattern, superposed on the series of rings. We try to explain the origin of these two features from a simple physical approach.

Studies on electronic structure of interfaces between Ag and gelatin for stabilization of Ag nanoparticles

Extremely high stability of Ag nanoparticles in photographic materials has forced us to study the electronic structures of the interfaces between thin layers of Ag, Au, and Pt and their surface membranes in ambient atmosphere by photoelectron yield spectroscopy in air and Kelvin probe method. Owing to the Fermi level equalization between a metal layer and a membrane coming from air, the electron transfer took place from the membrane to Pt and Au layers and from an Ag layer to the membrane, giving the reason for poor stability of Ag nanoparticles in air. The control of the Fermi level of an Ag layer with respect to that of a gelatin membrane in air could be widely made according to Nernst’s equation by changing the pH and pAg values of an aqueous gelatin solution used to form the membrane, and thus available to stabilize Ag nanoparticles in a gelatin matrix.

Color Polymer Dispersed Liquid Crystal Device with Colored Core-Shell Structure

Due to the fact the conventional polymer dispersed liquid crystal (PDLC) device operates between the transparent state and the scattering sate, color realization is limited. In this paper, we propose the color PDLC device with colored core-shell structure. By the complex coacervation microencapsulation process, liquid crystal droplets are encapsulated by the aqueous solution of gelatin, arabic gum, and color pigments. The size of the color droplet can be controlled by the pore size of the membrane filter. The average diameter of the fabricated color droplets is approximately 10 μm.

Effect of salt and urea on complexation behavior of pharmaceutical excipient gelatin with phenothiazine drug promazine hydrochloride

An evaluation of the interactions of cationic phenothiazine drug promazine hydrochloride (PMZ) with gelatin in aqueous solution as well as in the presence of 50mM NaCl and 100mM urea, investigated through different physicochemical measurements is presented in the present study using conductometric method. PMZ is used for the control of mania and schizophrenia. The drug interacts with gelatin similar to the interaction of surfactants and polymers. The plots of specific conductivity versus concentration of the drug were nonlinear with three different linear regions with two clear breaks. The first break point, i.e., critical aggregation concentration (cac), appeared well below the typical critical micelle concentration (cmc). The second break point is considered as polymer saturation point (psp) that is akin to cmc. The cac value decreases on increasing the gelatin concentration, whereas the psp value increases for all fixed concentrations (%w/v) of gelatin which is a clear signal of the interaction of the drug with gelatin. As inorganic salts increase the ionic strength, the solubility of amphiphile (drug) is lowered by ionic screening effects, ensuing in a greater tendency to aggregates at lower concentration. As a result, both the cac and psp/cmc values decrease. By the addition of urea an increase in the surface charge of the micelles was observed followed by halt of the aggregation of the drug hence both the cac and psp/cmc values increase. Free energies of aggregation (ΔGagg), micellization (ΔGmic), polymer saturation (∆Gpsp) and transfer (ΔGt) were also evaluated.

Scaling up the Aqueous Synthesis of Visible Light Emitting Multinary AgInS2/ZnS Core/Shell Quantum Dots

Approximately 3 g of water-soluble AgInS2/ZnS core/shell quantum dots (AIS/ZnS QDs) with a maximum photoluminescence quantum yield of up to 39.1% was synthesized in an aqueous solution of gelatin and thioglycolic acid (TGA). The composition of the AIS QDs could be readily adjusted by controlling the molar ratio of the starting Ag/In precursors in the reaction solution, which leads to a tunable emission ranging from 535 to 607 nm. The as-prepared core/shell QDs exhibit excellent photostability and water/buffer stability. More importantly, these cadmium-free hydrophilic AIS/ZnS core/shell QDs are biocompatible and can be directly utilized in cancer cell imaging.

Fabrication of micro-spinbars with controllable aspect ratios using a simple fluidic device for fluid mixing

Micro-spinbars with uniform aspect ratios were fabricated from gelatin using a simple fluidic device based on water-in-oil emulsion for fluid mixing. Aqueous gelatin solution containing magnetic nanoparticles and toluene solution were used as the discontinuous and continuous phases, respectively. The gelatin droplets with uniform aspect ratios formed within the glass capillary tube of the fluidic device and flew into the cold collection phase (toluene). Due to the feature of sol–gel transition of the gelatin solution with respect to temperature, the gelatin droplets maintained their original shape in the cold collection phase during water evaporation. The aspect ratios of the micro-spinbars were finely controlled from 1 to 5 by simply changing the flow rate of the continuous phase. Their potential applications for active fluid mixing were demonstrated in a glass slide and Y-shaped small device.

Drying dissipative structures of gelatin solution

Macroscopic and microscopic drying patterns formed from aqueous gelatin solutions on a cover glass were studied as a function of gelatin concentration and temperature. Specific drying patterns were observed within the circular dried film resulting from a droplet of the solution (0.1 ml) placed on the cover glass surface when the droplet evaporated. Two broad rings formed at the outside edge of the dried film and the inner area. df/di values of the inner broad rings decreased sharply with increasing gel concentration, where df is the final size of the broad ring in the dried film and di is the size of initial liquid in diameter. Thickness profiles of the dried film changed sharply from the broad ring to the round hill at the center as gelatin concentration increased. The sharpness parameter S (or S′) were evaluated from the ratio of the film size (diameter) against the full widths at half maximum (or the full widths at the bottom layer) in the thickness profiles of the broad ring and/or the round hill. The S (or S′) values changed transitionally at the critical concentration and temperature of gelation. The gelation of gelatin collagen was resulted in the disturbed convectional diffusion of solutes during dryness. The round hill-like thickness profile at the high polymer concentration and at low temperature also supports the gelation. These observations support that gelation process of collagen molecules is followed from decrease in S (or S′) values in the macroscopic patterns. Dendritic, hedrite, and/or spherulite microscopic drying patterns were observed especially in the central area and at low temperatures.