罗望子胶的生产工艺研究

罗望子胶是一种多糖类天然食品增稠剂、稳定剂和胶凝剂。本文研究了从豆科罗望子属植物罗望子种子中提取罗望子胶的生产工艺,并就罗望子胶生产工艺中原料的处理,不同有机酸对罗望子种仁粉的水解,蛋白质沉降,胶的色泽和收率进行了比较试验,提出了简便、易于生产和提高罗望子胶纯度的方法     

Development of Bigels Based on Stearic Acid–Rice Bran Oil Oleogels and Tamarind Gum Hydrogels for Controlled Delivery Applications

In the last few decades, different types of gels have been widely studied as potential drug delivery carriers. In this paper, we propose the synthesis of an oleogel, a tamarind gum hydrogel, and bigels for applications as drug delivery matrices. The oleogel was prepared by mixing stearic acid and rice bran oil, whereas the hydrogel was prepared by mixing tamarind gum with a hydroethanolic solution. Hydrogel‐in‐oleogel and oleogel‐in‐hydrogel bigels were prepared by mixing the hydrogel and the oleogel. The suitability of the formulations for controlled drug release applications was thoroughly examined using microscopy, Fourier transform infrared (FTIR) spectroscopy, as well as mechanical, electrical, thermal, drug release, and antimicrobial studies. An alteration in the microarchitecture of the bigels is observed when the oleogel and the hydrogel are mixed in varying proportions. The associative interactions within the formulations increase with the increase in the hydrogel content. The bigels exhibit the presence of stearic acid melting endotherm (associated with the oleogel) and water evaporation endotherm (associated with the hydrogel). This study suggests that the hydrogel has lowest bulk resistance compared to the other formulations. The structural breakdown of the bigels is composition‐dependent, and the bulk electrical resistance is mainly governed by the oleogel phase. An increase in the diffusion of the moxifloxacin HCl from the formulations is observed with the increase of the hydrogel proportion, which in turn increases the rate of release of the drug. The proposed formulations also exhibit good antimicrobial efficacy. The analysis of these properties suggests that specific formulations can be tailored by need‐based applications of the drug release rate.     

Physico-Chemical Properties of the Egyptian Tamarind Seed Oil

The physico-chemical properties of the Egyptian Tamarind seed oil were investigated. The seeds were found to contain a fair amount of oil (16.25%). It was found that the oil has a high acid and iodine values in comparison with cotton seed oil. Arachidic, linoleic, oleic, stearic, palmitic, myristic, and lauric were fractionated by gas liquid chromatography from the tamarind seed oil. More than 50% of the total acids are unsaturated. The infrared spectroscopy showed the presence of 7 absorption bands at wave-number cm^?1 (730, 1150, 1380, 1480, 1750, 2900 and 2950) in the investigated oil. On the other hand chemical analysis of the cake showed a lower protein content and higher sugar content.     

Effect of Soya Protein Isolate as a Complementary Drying Aid of Maltodextrin on Spray Drying of Tamarind Pulp

The present study aimed to investigate the effect of adding soya protein isolate (SPI) as a complementary drying aid of maltodextrin (MD) on spray drying of tamarind pulp. Tamarind pulp powders were prepared by spray drying of tamarind pulp, adding 0, 5, 10, 15, and 20% of SPI together with maltodextrin as the drying aids. The results showed that the addition of SPI resulted in a significant increase in powder recovery from 9.35 to 70.04%, thereby reducing the requirement of higher levels of maltodextrin for the production of quality tamarind pulp powder. The powders were evaluated for moisture content, bulk density, particle size, morphological characteristics, cohesiveness, and glass transition temperature. With the addition of SPI in the feed material, the powder samples showed a significant variation in their properties. Addition of SPI decreased the cohesion index of the powders from 14.21 to 9.29 mm, thereby increasing the flowability of the powders. Surface morphology of the powders showed that the addition of SPI resulted in an indented and wrinkled particle surface, a characteristic feature of powders produced with protein as the drying aid.     

Preparation,Characterization and Assessment of the Novel Gelatin–tamarind Gum/Carboxymethyl Tamarind Gum-Based Phase-Separated Films for Skin Tissue Engineering Applications

The current study delineates the development of novel gelatin–tamarind gum/carboxymethyl tamarind gum-based phase-separated films for probable skin tissue engineering applications. Polyethylene glycol was used as plasticizer. The films were characterized thoroughly using mechanical tester and impedance analyzer. Cell proliferation ability and drug release properties of the films were investigated. Mechanical studies indicated composition-dependent stress relaxation properties. Polysaccharide containing films supported better proliferation of human keratinocytes as compared to control. Drug-loaded films showed good antimicrobial properties against Escherichia coli. Analysis of the results indicated that the prepared films may be tried as matrices for skin tissue engineering.     

Morphology and water affinity of superabsorbent hydrogels composed of methacrylated cashew gum and acrylamide with good mechanical properties

This paper comprises the characterization of superabsorbent hydrogels based on methacrylated cashew gum (CGMA) co-polymerized with acrylamide (AAm) by measuring of the water uptake, water retention capacity in dependence of time, morphological and mechanical properties. The morphological features of hydrogels were evidenced by SEM images. Stress measurements of hydrogels as a function of temperature were considered as being the necessary force for compressing the hydrogels at 1 mm deformation. Stress-strain modeling was used to obtain the compressive elastic modulus and apparent cross-linking density of superabsorbent hydrogels. Hydrolyzed CGMA-co-AAm hydrogels showed highly water absorbing. Another remarkably feature of these hydrogels is the efficiency in the water retaining that was caused by increasing in CGMA content. Higher temperature leads to an enhancement in the stress values of superabsorbent hydrogels because the large content of water that penetrates into superabsorbent hydrogels and expands their polymer network. The increase in the amount of CGMA and AAm were accompanied by an increasing on the apparent cross-linking density of hydrogels. This contributed to increase their elastic modulus, which is inherent to a more rigid structure.     

Preparation and properties of nanocomposite hydrogels containing silver nanoparticles by ex situ polymerization

A series of composite hydrogels containing silver nanoparticle used for bioadhesives were prepared from acrylic acid, poly(ethylene glycol) methyl ether acrylate, and silver nanoparticles through ex situ polymerization. Silver nanoparticles with a narrow size distribution were prepared by the reduction of a silver nitrate solution with ascorbic acid. The influence of the content of the silver nanoparticles in the hydrogels on the equilibrium swelling ratio, mechanical properties, electrical conductivity, and inactivation of Escherichia coli (E. coli) was investigated in this study. The results showed that the swelling ratios of the composite gels were reduced by silver nanoparticles in the gels but were not reduced with an increase in the content of silver nanoparticles. In addition, the crosslinking density and shear modulus of these hydrogels did not increase with an increase in the content of silver nanoparticles. The adhesive force of these hydrogels (the APECAg series) was not obviously changed. Finally, the initial rate of E. coli inactivation for the APECAg series hydrogels showed excellent antibacterial properties. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3653–3661, 2006     

Persulfate/ascorbic acid initiated synthesis of poly(acrylonitrile)‐grafted tamarind seed gum: A potential commercial gum

Acrylonitrile was grafted on to tamarind seed gum using persulfate/ascorbic acid redox initiator and a representative sample of the graft copolymer (Tm‐g‐PAN) was characterized using infrared spectroscopy (FTIR), X‐ray diffraction (XRD) and scanning electron microscopy (SEM). Grafting conditions were optimized where %G and %E were found to increase with the increase in the concentration of the monomer; initiator, and the reaction temperature, whereas increase in gum concentration decreased the %G in the concentration range of 4–12 g/L, The maximum % grafting (%G) and % efficiency (%E) achieved were 305 and 75%, respectively. Water/saline retention, gel forming ability, and the shelf life of the grafted gum solutions were also studied to explore the possibility of its commercial utilization. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Formulation and Evaluation of Buccal Bioadhesive Patches Employing Derivatized Tamarind Seed Polysaccharide

The present study was designed to formulate buccal bioadhesive patches of pentazocine hydrochloride employing aminated and sulfated derivatives of tamarind seed polysaccharide (TSP). The patches were evaluated for their physicomechanical characteristics, swelling index, in vitro release, and in vivo release profiles. The in vitro release of the drug was found to depend on the swelling index of the polymers. The sulfated TSP patches were releasing drug at a faster rate as compared to aminated TSP patches. The oral administration of aminated patches to rats was found to enhance the bioavailability of pentazocine hydrochloride 2.8 times as compared to oral solution.     

Development of gelatin/chitosan/PVA hydrogels: Thermal stability,water state,viscoelasticity, and cytotoxicity assays

Gelatin/chitosan/poly(vinyl alcohol) (PVA) hydrogels were fabricated with different polymer ratio using the freeze-drying process. The thermal stability, water state, rheological, and cytotoxic properties of the hydrogels were evaluated. Thermogravimetric/differential scanning calorimetry analyses showed a decomposition onset temperature below 242.7 ± 2.7 °C. The samples did not show statistical differences (p < 0.05) on the onset temperature values. Nonfreezing water reached a constant value around of 1 g water/g polymer. Freezing water increased linearly with the increase of the water content independently of the polymer ratio. The hydrogels showed an equilibrium water content from 9 to 13 times their mass. The hydrogels exhibited a solid-viscoelastic behavior. The elastic modulus was higher with the increase of chitosan concentration (G′ = 22 170 ± 85 Pa) independently of the temperature (5–55 °C). In vitro assay showed that hydrogels are nontoxic in the HT29-MTX-E12 cell line. These results indicate that the gelatin/chitosan/PVA hydrogels could be considered for biomedical applications. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47149.     

Effect of montmorillonite on the rheological properties of dually crosslinked guar gum‐based hydrogels

One strategy to create chemical and physical cross‐links simultaneously is to introduce into the chemical network hydrogen bonding with clay nanofillers. Understanding the relaxation mechanisms of these systems is crucially important and has drawn the extensive interest of many scientists. In this work, the influence of different amounts of montmorillonite on the structural and rheological properties of guar gum hydrogels was investigated. Depending on the clay content, different nanostructures were identified by X‐ray diffraction (XRD) and their effect on the rheological properties of the dual hydrogels was studied. From stress and frequency sweep tests it emerged that all the samples exhibit a weak gel behavior and showed a maximum for G″ that can be ascribed to the breaking and reforming of transient physical crosslinks. This relaxation mode is more pronounced for the hydrogel for which a minimum in the swelling degree was observed. On the basis of these results, a model structure was proposed according to which the clay sheets act as effective multifunctional cross‐linkers. The more homogeneously dispersed are the clay platelets, the higher is the density of physical crosslinks. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41373.     

Effect of montmorillonite on the swelling behavior and drug‐release behavior of nanocomposite hydrogels

A series of nanocomposite hydrogels were prepared from various ratios of N‐isopropylacrylamide (NIPAAm) and organic montmorillonite (MMT). The influence of the extent of MMT in the NIPAAm/MMT nanocomposite hydrogels on the physical properties and drug‐release behavior was the main purpose of this study. The microstructure and morphology were identified by X‐ray diffraction (XRD) and scanning electronic microscopy (SEM). The results showed that the swelling ratios for these nanocomposite hydrogels decreased with increase in the content of MMT. The gel strength and Young's modulus of the gels also increased with increase in the content of MMT. XRD results indicated that the exfoliation of MMT was achieved in the swollen state. Finally, the drug‐release behavior for the gels was also assessed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3652–3660, 2003     

Effect of storage time on the mechanical and microstructural properties of bigels based on xanthan gum and castor oil

As biphasic systems bigels are formed by hydrogels and organogels. Given their characteristics, they have been studied in food, pharmaceutical and cosmetic applications for bioactives delivery. The rheological characteristics and amount used of the individual structured systems influence the final properties; thus, the objective of this work was to evaluate the effect of the proportion of castor oil organogel, the concentration of organogelator, and the storage time in the mechanical and microstructural properties of bigeles. Bigels were prepared from structured castor oil organogels with monoacylglycerides at concentrations of 6% (MOG) and 6.5% (HOG) wt/wt, and hydrogels with 2% wt/wt xanthan gum (HG) at three organogel/hydrogel ratios 15 of 85, 30 of 70, and 45 of 55. Bigels were characterized by optical microscopy with polarized light filter, centrifugal stability, texture, and rheology for 60 days. The increase in the proportion of organogel favors the mechanical response (k, G₀, and firmness) of bigels. The high viscosity of castor oil slows down the structuring of organogel droplets, showing an improvement in its mechanical properties after 15 days of its preparation. The increase in the organogelator concentration is significant in the bigels with 30% and 45% proportions of organogel in the rheological tests. By using HOG in the formation of bigels, higher values for G₀ and k were obtained, as well as higher centrifugal stability compared with bigels formed from MOG. The rheological and microstructural behavior of bigels can be modified according to their application by varying the proportions of organogel/hydrogel and the concentration of the organogelator.     

Swelling and Thermal Characteristics of Genipin Crosslinked Chitosan and Poly(vinyl pyrrolidone) Hydrogels

Summary Chitosan / poly(vinyl pyrrolidone) (PVP) were used to prepare semi-interpenetrating polymeric networks. The hydrogels were crosslinked using genipin, a non-toxic cross-linking agent extracted from the fruits of Gardenia jasminoides Ellis. Swelling properties of these hydrogels were studied in media of different pHs and temperatures. States of water in the swollen hydrogels at 25°C and pH 7 were determined using Differential Scanning Calorimetry (DSC). The swelling behaviour of the hydrogels was found to be dependent on the temperature and the pH of the swelling medium. The total water content in the hydrogels was found to increase with increasing PVP content.     

Reinforcing biopolymer hydrogels with ionic‐covalent entanglement hydrogel microspheres

Microscopic hydrogel spheres can be used to improve the mechanical properties of conventional hydrogels. We prepared ionic‐covalent entanglement (ICE) hydrogel microspheres of calcium cross‐linked gellan gum and genipin cross‐linked gelatin using a water‐in‐oil emulsion‐based processing technique. The method was optimized to produce microspheres with number average diameter 4 ± 1 µm. These ICE microspheres were used to reinforce gelatin hydrogels and improve their compressive mechanical properties. The strongest microsphere reinforced hydrogels possessed a compressive mechanical stress at failure of 0.50 ± 0.1 MPa and a compressive secant modulus of 0.18 ± 0.02 MPa. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40557.     

Influence of MEOBiPA content on the properties of novel photoluminescent thermosensitive hydrogels

In order to establish a dual functional hydrogel, a special monomer, methacryloyloxy‐ethylene‐oxy‐carbonyl bis[4‐(phenyl‐isopropyl)phenyl]amine (MEOBiPA), was prepared from bis[4‐(phenyl‐isopropyl)phenyl]‐4‐cyanophenyl amine and 2‐hydroxyethyl methacrylate. Subsequently, a series of thermosensitive hydrogels was obtained through copolymerization of N‐isopropyl acrylamide (NIPAAm) with MEOBiPA by UV irradiation (named the NM series). The effect of MEOBiPA content on the swelling behavior, mechanical properties and drug release behavior of the hydrogels was further investigated. Results showed that the swelling ratios of the NM copolymeric hydrogels decreased from 4.73 to 1.74 g g^?1 when the MEOBiPA content in the hydrogel increased from 0.1 to 0.9 mol%. Both gel strength and crosslinking density of the NM hydrogels increased with increasing MEOBiPA. Conversely, the thermosensitive behavior of NM hydrogels significantly decreased upon increase of MEOBiPA content. Likewise, the caffeine release ratio also decreased from 70% to 25%. Notably, the intensity of photoluminescence increased with increasing MEOBiPA content in the hydrogels. Further, the corresponding copolymers of the hydrogels were prepared using free radical polymerization. The UV absorbance and photoluminescent behavior of the MEOBiPA, NIPAAm/MEOBiPA copolymeric hydrogels and their corresponding copolymers in different polar solvents were also investigated. © 2015 Society of Chemical Industry     

Ethanol organosolv lignin as a reactive filler for acrylamide‐based hydrogels

Hydrogels based on acrylamide (AM) and ethanol organosolv lignin (EOL) with high swelling and good mechanically elastic properties were synthesized in an alkaline solution. EOL was used as a reactive filler for the preparation of AM‐based hydrogels. The impact of EOL addition on the physicochemical properties of AM‐based hydrogels was investigated using Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy, and their mechanical properties were examined. The water swelling ratio of the prepared hydrogels increased with the increase of EOL content, and their maximum swelling ratio could reach up to 180. Mechanical measurements indicated that their tensile strength was highly dependent on the amount of EOL, and their elongation at break reached up to 1400%. The formation mechanism of EOL composite hydrogels was probably that most of AM was synthesized into the crosslinked poly(acrylic amide) network, and small quantities of AM was hydrolyzed to acrylic acid ions under alkaline condition. The chain transfer of free radicals from AM and/or AA to EOL molecules occurred in the polymerization process. With increasing EOL content in the hydrogels, an interpenetrating polymer network might be mainly formed by the hydrogen bonding between EOL and AA and/or AM molecules. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42638.     

Effect of intercalated hydrotalcite on swelling and mechanical behavior for poly(acrylic acid‐co‐N‐isopropylacrylamide)/hydrotalcite nanocomposite hydrogels

A series of nanocomposite hydrogels were prepared from acrylic acid (AA), N‐isopropylacrylamide (NIPAAm), and intercalated hydrotalcite (IHT) by photopolymerization. The influence of the intercalating content of 2‐acrylamido‐2‐methyl propane sulfonic acid (AMPS) in HT on the swelling and mechanical properties for poly(AA‐co‐NIPAAm)/IHT nanocomposite hydrogels was investigated. The results showed that the higher the content of the AMPS‐HT was, the higher the swelling ratio of the gels and the higher the content of the intercalating agent was, the lower swelling ratio. It was also demonstrated that the swelling ratio of the gel was not affected by the counterion in HT. The gel strength and crosslinking density were not enhanced by adding AMPS‐HT into the gel composition, but the maximum effective crosslink density and shear modulus of the nanocomposite hydrogels were increased with an increase of the content of the intercalating agent in HT. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1572–1580, 2005     

Physicochemical and morphological properties of poly(acrylamide) and methylcellulose hydrogels: Effects of monomer,crosslinker and polysaccharide compositions

This article describes the physicochemical (mechanical and swelling) and morphological characterization of poly(acrylamide) and methylcellulose (PAAm‐MC) hydrogels synthesized with different formulations by the free radical polymerization method. The structure‐property relationship of the PAAm‐MC hydrogels is very important for application of these materials in different fields. Results showed that the properties of the PAAm‐MC hydrogels can be controlled by varying the acrylamide (AAm) and N′,N‐methylene‐bis‐acrylamide (MBAAm) concentrations and methylcellulose (MC) content. Increase of AAm and MBAAm concentrations causes a pronounced decrease in swelling degree (SD) values and porosity, and an increase in mechanical properties. Increasing the MC concentration caused an increase in SD values and porosity, but decrease in maximum load and modulus of elasticity because of the increase in the hydrogel hydrophilicity due to incorporation of hydroxyl groups from MC chains. PAAm‐MC hydrogels are excellent candidates for several applications, such as matrices for cell transplantation, controlled release (agrochemicals and drugs), tissue repair and regeneration. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers     

Synthesis and swelling behavior of thermosensitive IPN hydrogels based on sodium acrylate and N‐isopropyl acrylamide by a two‐step method

A series of interpenetrating polymer network (IPN) hydrogels having higher swelling ratio (SR) and thermosensitivity were synthesized from sodium acrylate (SA) and N‐isopropyl acrylamide (NIPAAm) by a two‐step method. A series of the porous poly(sodium acrylate ‐co‐1‐vinyl–2‐pyrrolidone) [poly(SA‐co‐VP)], (SV), hydrogels were prepared from acrylic acid having 90% degree of neutralization and VP monomer in the first step. The second step is to immerse the SV dried gels into the NIPAAm solution containing initiator, accelerator, and crosslinker to absorb NIPAAm solution and then polymerized to form the poly(SA‐co‐VP)/poly(NIPAAm) IPN hydrogels (SVN). The effect of the different molar ratios of SA/VP and the content of NIPAAm on the swelling behavior and physical properties of the SVN hydrogels was investigated. Results showed that the SVN hydrogels displayed an obviously thermoreversible behavior when the temperature turns across the critical gel transition temperature (CGTT) of poly(NIPAAm) hydrogel. The pore diameter distributions inside the hydrogel also indicated that the pore sizes inside the SVN hydrogels were smaller than those inside the SV hydrogels. At the same time, the more proportion of SA was added into the hydrogel, the larger pore diameter of the SV hydrogel was formed. The results also showed that the SR decreased with an increase of the VP content in the SV hydrogel and more obviously decreased in the SVN hydrogels. The SVN networks also showed stronger shear moduli than SV hydrogels. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013