The Experts below are selected from a list of 234537 Experts worldwide ranked by ideXlab platform
Jie Pang - One of the best experts on this subject based on the ideXlab platform.
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the rheological and physicochemical properties of a novel thermosensitive Hydrogel based on konjac glucomannan gum tragacanth
Lwt - Food Science and Technology, 2019Co-Authors: Jingni Gong, Jiayu Wu, Ruojun Mu, Yu Du, Yi Yuan, Chunhua Wu, Lin Wang, Jie PangAbstract:Abstract Thermosensitive Hydrogels are known for their application potential in a wide range of fields. In this study, a novel thermosensitive Hydrogel was prepared under specific physical gelling conditions using konjac glucomannan (KGM) and gum tragacanth (GT). The rheology results showed that KGM/GT mixed hydrocolloids are a typical non-Newtonian pseudoplastic fluid. They have significant elastic properties: G′ was higher than G″ at all hydrocolloid ratios. Increasing the GT concentration resulted in decreased tan δ values, with the extreme values occurring at KGM:GT = 3:7. Moreover, the thermosensitive Hydrogels showed a sol-gel transformation temperature ranging from 40 to 35 °C. The physicochemical properties of KGM/GT Hydrogels were characterized by FTIR, TGA and SEM. The intermolecular interactions were mainly hydrogen bonding. Numerous connected porous structures were found in the Hydrogels microstructures. The results of this study indicate that KGM/GT thermosensitive Hydrogels might be a potential material for use in food and biomedical areas.
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The rheological and physicochemical properties of a novel thermosensitive Hydrogel based on konjac glucomannan/gum tragacanth
Lwt - Food Science and Technology, 2019Co-Authors: Jingni Gong, Jiayu Wu, Ruojun Mu, Yu Du, Yi Yuan, Chunhua Wu, Lin Wang, Jie PangAbstract:Abstract Thermosensitive Hydrogels are known for their application potential in a wide range of fields. In this study, a novel thermosensitive Hydrogel was prepared under specific physical gelling conditions using konjac glucomannan (KGM) and gum tragacanth (GT). The rheology results showed that KGM/GT mixed hydrocolloids are a typical non-Newtonian pseudoplastic fluid. They have significant elastic properties: G′ was higher than G″ at all hydrocolloid ratios. Increasing the GT concentration resulted in decreased tan δ values, with the extreme values occurring at KGM:GT = 3:7. Moreover, the thermosensitive Hydrogels showed a sol-gel transformation temperature ranging from 40 to 35 °C. The physicochemical properties of KGM/GT Hydrogels were characterized by FTIR, TGA and SEM. The intermolecular interactions were mainly hydrogen bonding. Numerous connected porous structures were found in the Hydrogels microstructures. The results of this study indicate that KGM/GT thermosensitive Hydrogels might be a potential material for use in food and biomedical areas.
Motoichi Kurisawa - One of the best experts on this subject based on the ideXlab platform.
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the role of stiffness of gelatin hydroxyphenylpropionic acid Hydrogels formed by enzyme mediated crosslinking on the differentiation of human mesenchymal stem cell
Biomaterials, 2010Co-Authors: Lishan Wang, Joo Eun Chung, Jerome Boulaire, Peggy P Y Chan, Motoichi KurisawaAbstract:Abstract We report the stimulation of neurogenesis and myogenesis of human mesenchymal stem cells (hMSCs) on the surfaces of biodegradable Hydrogels with different stiffness. The Hydrogels were composed of gelatin–hydroxyphenylpropionic acid (Gtn–HPA) conjugate were formed using the oxidative coupling of phenol moieties catalyzed by hydrogen peroxide (H2O2) and horseradish peroxidase (HRP). The storage modulus of the Hydrogels was readily tuned from 600 to 12800 Pa. It was found that the stiffness of the Hydrogel strongly affected the cell attachment, focal adhesion, migration and proliferation rate of hMSCs. The hMSCs on stiffer surfaces have a larger spreading area, more organized cytoskeletons, more stable focal adhesion, faster migration and a higher proliferation rate. The gene expression related to the extracellular matrix and adhesion molecules also differed when the cells were cultured on Hydrogels with different stiffness. The differentiation of hMSCs on the surface of the Hydrogel was closely linked to the Hydrogel stiffness. The cells on a softer Hydrogel (600 Pa) expressed more neurogenic protein markers, while cells on a stiffer Hydrogel (12000 Pa) showed a higher up-regulation of myogenic protein markers.
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an injectable hyaluronic acid tyramine Hydrogel system for protein delivery
Journal of Controlled Release, 2009Co-Authors: Joo Eun Chung, Motoichi KurisawaAbstract:Previously, we reported the independent tuning of mechanical strength (crosslinking density) and gelation rate of an injectable Hydrogel system composed of hyaluronic acid–tyramine (HA–Tyr) conjugates. The Hydrogels were formed through the oxidative coupling of tyramines which was catalyzed by hydrogen peroxide (H2O2) and horseradish peroxidase (HRP). Herein, we studied the encapsulation and release of model proteins using the HA–Tyr Hydrogel. It was shown that the rapid gelation achieved by an optimal concentration of HRP could effectively encapsulate the proteins within the Hydrogel network and thus prevented the undesired leakage of proteins into the surrounding tissues after injection. Hydrogels with different mechanical strengths were formed by changing the concentration of H2O2 while maintaining the rapid gelation rate. The mechanical strength of the Hydrogel controlled the release rate of proteins: stiff Hydrogels released proteins slower compared to weak Hydrogels. In phosphate buffer saline, α-amylase (negatively charged) was released sustainably from the Hydrogel. Conversely, the release of lysozyme (positively charged) discontinued after the fourth hour due to electrostatic interactions with HA. In the presence of hyaluronidase, lysozymes were released continuously and completely from the Hydrogel due to degradation of the Hydrogel network. The activities of the released proteins were mostly retained which suggested that the HA–Tyr Hydrogel is a suitable injectable and biodegradable system for the delivery of therapeutic proteins.
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an injectable enzymatically crosslinked hyaluronic acid tyramine Hydrogel system with independent tuning of mechanical strength and gelation rate
Soft Matter, 2008Co-Authors: Fan Lee, Joo Eun Chung, Motoichi KurisawaAbstract:In this study, we propose an enzymatically crosslinked hyaluronic acid (HA) Hydrogel with tunable mechanical strength and gelation rate as a novel injectable system. The Hydrogel composed of HA–tyramine conjugate (HA–Tyr) was formed using the oxidative coupling of tyramine moieties catalyzed by hydrogen peroxide (H2O2) and horseradish peroxidase (HRP). The mechanical strength of the HA–Tyr Hydrogel was tuned solely by the H2O2 amount without affecting the gelation rate. The Hydrogels formed more rapidly with increasing HRP concentration and the gelation time ranged from 1 s to 20 min. A faster gelling system yielded more localized gel formation than a slower gelling one at the site where it was administered through subcutaneous injection. Studies on the swelling ratio and scanning electron microscopy images of the Hydrogel structure further demonstrated that the crosslinking density was controlled by the concentration of H2O2 used. The mechanical strength of HA–Tyr Hydrogels strongly affected the degradation rate in the presence of hyaluronidase in vitro; Hydrogels degraded more slowly with increasing mechanical strength of the Hydrogel. The independently tunable mechanical strength and gelation rate achieved by this enzymatically formed HA–Tyr Hydrogel system will provide great advantages to a wide range of applications of injectable Hydrogels, such as drug delivery and tissue regeneration.
Yue Zhao - One of the best experts on this subject based on the ideXlab platform.
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Poly(vinyl alcohol)–Poly(ethylene glycol) Double-Network Hydrogel: A General Approach to Shape Memory and Self-Healing Functionalities
Langmuir, 2015Co-Authors: Guo Li, Daniel Fortin, Hongji Zhang, Yue ZhaoAbstract:A double-network polymer Hydrogel composed of chemically cross-linked poly(ethylene glycol) (PEG) and physically cross-linked poly(vinyl alcohol) (PVA) was prepared. When the Hydrogel (70 wt % of water) is subjected to freezing/thawing treatment under strain, the enhanced physical network as a result of crystallization of PVA chains can stabilize the Hydrogel deformation after removal of the external force at room temperature. Subsequent disruption of the physical network of PVA by heating allows for the recovery of the initial shape of the Hydrogel. Moreover, the double-network Hydrogel exhibits self-healing capability stemming from the physical network of PVA by virtue of the extensive interchain hydrogen bonding between the hydroxyl side groups. This study thus demonstrates a general approach to imparting both the shape memory and self-healing properties to chemically cross-linked Hydrogels that otherwise do not have such functionalities. Moreover, by making use of the fixed Hydrogel elongation, the ef...
Wenguang Liu - One of the best experts on this subject based on the ideXlab platform.
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T-shaped trifunctional crosslinker-toughening Hydrogels
Science China Technological Sciences, 2020Co-Authors: Dongfei Zhang, Jianhai Yang, Wenguang LiuAbstract:Currently, development of a single network Hydrogel with a high fracture toughness in swelling equilibrium remains challenging. In this work, a novel T-shaped trifunctional crosslinker (T-NAGAX) with dual vinyl on the backbone and dual amide group on the side chain is synthesized by Michael addition and acylation. The T-NAGAX is used to prepare chemically crosslinked Hydrogel by one-pot photo-initiated polymerization. The resulting single network Hydrogels of representative polyacrylamide (PAAm), poly(N-acryloyl 2-glycine) (PACG), and poly(N-isopropyl acrylamide) (PNIPAM) crosslinked with T-NAGAX with additional hydrogen-bonds exhibit much better fracture toughness than that of the corresponding Hydrogels crosslinked by N,N′ -methylene bisacrylamide, a conventional crosslinker; higher mechanical strengths are observed in the T-NAGAX crosslinked Hydrogels. These Hydrogels are promising to be exploited as load-bearing soft tissue substitutes. This T-NAGAX crosslinker can be expanded to toughen various types of Hydrogels.
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Methyl matters: An autonomic rapid self-healing supramolecular poly(N-methacryloyl glycinamide) Hydrogel
Polymer, 2017Co-Authors: Ren Yalei, Yinyu Zhang, Wenhui Sun, Fei Gao, Wenguang LiuAbstract:Abstract Poly( N -acryloyl glycinamide) (PNAGA) with a protein-like thermoresponsive gelation behavior in water has been developed as a high strength self-healable supramolecular polymer(SP) Hydrogels recently. However, harsh conditions, such as high temperature treatment and long waiting time, were required for achieving the complete healing due to strong dual amide hydrogen bonding interactions. In this study, to create an autonomic rapid self-healing SP Hydrogel, we deliberately introduced a methyl into the opposite side to dual amide to synthesize N -methacryloyl glycinamide (MNAGA) monomer. Rheological analysis, dynamic light scattering(DLS), Fourier transform infrared (FTIR) spectroscopy, and Gaussian calculation revealed that one substitution methyl caused a considerable perturbation to the hydrogen bonding interaction, thus leading to the increased starting gelling concentration and pronounced decrease in mechanical properties of PMNAGA Hydrogel compared to PNAGA Hydrogel. The PMNAGA Hydrogel was shown to exhibit rapid autonomic reparability without any external intervention, and dynamic swelling measurement indicated this PMNAGA Hydrogel could evolve from permanent to transient network due to the metastable hydrogen bonding crosslinkage, depending on its environmental temperature. This intriguing robust, autonomous healing and autolytic PMNAGA Hydrogel holds great potential as a short-term embolic agent for blocking blood vessel and artificial tears for moistening eyes.
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a mechanically strong highly stable thermoplastic and self healable supramolecular polymer Hydrogel
Advanced Materials, 2015Co-Authors: Xiyang Dai, Lina Gao, Yinyu Zhang, Yuanlu Cui, Tao Bai, Wenguang LiuAbstract:DOI: 10.1002/adma.201500534 the concomitant strengthening effect shown in condensed matters in polar media. [ 11 ] It is known that the secondary structure of proteins is held together by hydrogen bonding between the C O and N H groups, and hydrogen-bonded clusters contribute to their unique native structures. [ 12,13 ] As the smallest species of the 20 amino acids found in proteins, glycine is unique since it can fi t into hydrophilic or hydrophobic settings. Although O H···N hydrogen bonds can be formed, this interaction is unstable in water and therefore cannot be used to enhance mechanical strength. In the work reported by Tobias et al. on the stability of a model β-sheet in water, the binding free energies of two intermolecular hydrogen bonds and single amide hydrogen bond in the model β-sheet were calculated to be −5.5 and −0.34 kcal mol −1 , respectively, suggesting dual hydrogen bonds are quite stable while a simple amide hydrogen bond is only marginally stable. [ 14 ] Inspired by this theoretical basis and aiming to amplify the hydrogen bonding interaction of the simplest amino acid, glycine, we proposed to transform glycinamide (amidated glycine), which consists of two amides, into a polymerizable monomer, N -acryloyl glycinamide (NAGA, Scheme 1 A), by reacting glycinamide with acryloyl chloride using a reported method. [ 15,16 ] N -acryloyl glycinamide can be directly and conveniently initiated in water to form poly( N acryl oyl glycinamide) (PNAGA). From the molecular structure of PNAGA depicted in Scheme 1 A, we envisioned that a concentrated aqueous solution of poly( N -acryloyl glycinamide) could form a high-strength supramolecular polymer Hydrogel due to the strong physical crosslinking stemming from the highly stable hydrogen bonded interaction domains formed among dual amide motifs in the side chain. To verify our hypothesis, we prepared different concentrations of NAGA aqueous solutions, which were then photoinitiated at room temperature (Table S1). We found that at 1% and 2% NAGA, the polymer solutions were in the sol state, but gelation occurred when concentration was raised to 3%, as verifi ed with the inverted vial method (Figure S5, Supporting Information). The prepared Hydrogels were immersed in deionized and distilled water for 7 d, and equilibrium water contents (EWCs) were determined (Figure S6, Supporting Information). Unexpectedly, after reaching swelling equilibrium, the EWCs of the gels initially made with 10–25 wt% NAGA decrease by varied amounts compared with the water contents of the respective original Hydrogels. It is possible that the hydrogen bondings among dual amides may reorganize and intensify to result in an increased crosslinking density after the gels are re-immersed in water. PNAGA-30, made with 30% NAGA initially, showed only a slight increase in its EWC. In this case, the hydrogen-bonded supramolecular interactions started to achieve a saturated state. In spite of the increased water content after equilibrium Over the past decade, high strength Hydrogels have received growing interest due to their great potential for extended use in load-bearing applications. Many strategies have been explored to enhance the tensile strength, the compressive strength or toughness of Hydrogels, including double network, [ 1 ] topological sliding network, [ 2 ] composite reinforcement, [ 3 ] and covalent/ ionic crosslinking mechanisms. [ 4 ] Despite this, development of a Hydrogel with high comprehensive mechanical properties that are not weakened by soaking in aqueous media remains challenging. [ 5 ] Since chemical crosslinkers are generally essential for the construction of high-strength Hydrogels, the resultant gels tend not to be recyclable or reprocessable. Our group recently reported on Hydrogels strengthened by diaminotriazine-diaminotriazine (DAT-DAT) hydrogen bonding, which demonstrated both high tensile and compressive strengths and exceptional stability in aqueous solution due to the formation of stable DAT-DAT hydrogen bonding domains. [ 6 ] These H-bonding Hydrogels were typically synthesized from photoinitated copolymerization of 2-vinyl-4,6-diamino-1,3,5-triazine (VDT) and polyethylene glycol diacrylate in DMSO, which was required to solubilize VDT. These chemically crosslinked PVDT-based organogels were then soaked in water to replace DMSO, converting the organogels into Hydrogels and re-establishing cooperative DAT-DAT hydrogen bonding interaction which tremendously increased the mechanical strengths of the resultant fully swollen Hydrogel. Nonetheless, the organic solvent needed to make these gels is not environmentally benign. The hydrogen bonding is commonly a weak noncovalent bond, though their cooperative interaction can result in the strength of a covalent bond. [ 7 ] However, most hydrogen bonds only exhibit this strength in nonpolar organic solvents, with their strengthening effect severely discounted in polar solvents. [ 8,9 ] The remarkable reinforcement effect of DAT-DAT hydrogen bonding originates from the formation of stable hydrogen-bonded microdomain clusters. [ 6a , 10 ] This principle suggests that the formation of H-bonding microdomains is required for the stable existence of robust H-bonds, as well as
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Double hydrogen-bonding pH-sensitive Hydrogels retaining high-strengths over a wide pH range.
Macromolecular rapid communications, 2012Co-Authors: Han Gao, Ning Wang, Wenjing Nan, Yanjiao Han, Wenguang LiuAbstract:Traditional pH-sensitive Hydrogels inevitably suffer strength deterioration while the responsive weak acid or base groups are in the ionized state. In this study, we report on a facile approach to fabricate a novel pH-sensitive high-strength Hydrogel from copolymerization of two hydrogen-bonding motif-containing monomers, 3-acrylamidophenylboronic acid and 2-vinyl-4,6-diamino-1,3,5-triazine with a crosslinker N,N-methylenebisacrylamide through hydrophilic optimization of the comonomer oligo(ethylene glycol) methacrylate. The double hydrogen bonding Hydrogel exhibits both high tensile and compressive strengths over a broad pH range due to the unique ability to maintain at least one type of hydrogen-bonding crosslink over the whole course of pH change.
Jingni Gong - One of the best experts on this subject based on the ideXlab platform.
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the rheological and physicochemical properties of a novel thermosensitive Hydrogel based on konjac glucomannan gum tragacanth
Lwt - Food Science and Technology, 2019Co-Authors: Jingni Gong, Jiayu Wu, Ruojun Mu, Yu Du, Yi Yuan, Chunhua Wu, Lin Wang, Jie PangAbstract:Abstract Thermosensitive Hydrogels are known for their application potential in a wide range of fields. In this study, a novel thermosensitive Hydrogel was prepared under specific physical gelling conditions using konjac glucomannan (KGM) and gum tragacanth (GT). The rheology results showed that KGM/GT mixed hydrocolloids are a typical non-Newtonian pseudoplastic fluid. They have significant elastic properties: G′ was higher than G″ at all hydrocolloid ratios. Increasing the GT concentration resulted in decreased tan δ values, with the extreme values occurring at KGM:GT = 3:7. Moreover, the thermosensitive Hydrogels showed a sol-gel transformation temperature ranging from 40 to 35 °C. The physicochemical properties of KGM/GT Hydrogels were characterized by FTIR, TGA and SEM. The intermolecular interactions were mainly hydrogen bonding. Numerous connected porous structures were found in the Hydrogels microstructures. The results of this study indicate that KGM/GT thermosensitive Hydrogels might be a potential material for use in food and biomedical areas.
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The rheological and physicochemical properties of a novel thermosensitive Hydrogel based on konjac glucomannan/gum tragacanth
Lwt - Food Science and Technology, 2019Co-Authors: Jingni Gong, Jiayu Wu, Ruojun Mu, Yu Du, Yi Yuan, Chunhua Wu, Lin Wang, Jie PangAbstract:Abstract Thermosensitive Hydrogels are known for their application potential in a wide range of fields. In this study, a novel thermosensitive Hydrogel was prepared under specific physical gelling conditions using konjac glucomannan (KGM) and gum tragacanth (GT). The rheology results showed that KGM/GT mixed hydrocolloids are a typical non-Newtonian pseudoplastic fluid. They have significant elastic properties: G′ was higher than G″ at all hydrocolloid ratios. Increasing the GT concentration resulted in decreased tan δ values, with the extreme values occurring at KGM:GT = 3:7. Moreover, the thermosensitive Hydrogels showed a sol-gel transformation temperature ranging from 40 to 35 °C. The physicochemical properties of KGM/GT Hydrogels were characterized by FTIR, TGA and SEM. The intermolecular interactions were mainly hydrogen bonding. Numerous connected porous structures were found in the Hydrogels microstructures. The results of this study indicate that KGM/GT thermosensitive Hydrogels might be a potential material for use in food and biomedical areas.
