Journal articles: 'Hydrogele'

1

Bigall, Nadja C, Anne-Kristin Herrmann, Maria Vogel, Marcus Rose, Paul Simon, Wilder Carrillo-Cabrera, Dirk Dorfs, Stefan Kaskel, Nikolai Gaponik, and Alexander Eychmüller. "Hydrogele und Aerogele aus Edelmetallnanopartikeln." Angewandte Chemie 121, no. 51 (November 13, 2009): 9911–15. http://dx.doi.org/10.1002/ange.200902543.

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Nöll, Tanja, Sabine Wenderhold-Reeb, Holger Schönherr, and Gilbert Nöll. "DNA-Hydrogele aus Plasmid-DNA." Angewandte Chemie 129, no. 39 (August 17, 2017): 12167–71. http://dx.doi.org/10.1002/ange.201705001.

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Sano, Koki, Yasuhiro Ishida, and Takuzo Aida. "Anisotrope Hydrogele - Synthese und Anwendungen." Angewandte Chemie 130, no. 10 (January 10, 2018): 2558–70. http://dx.doi.org/10.1002/ange.201708196.

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Vigier-Carrière, Cécile, Fouzia Boulmedais, Pierre Schaaf, and Loïc Jierry. "Oberflächenunterstützte Selbstorganisationsstrategien für supramolekulare Hydrogele." Angewandte Chemie 130, no. 6 (January 4, 2018): 1462–71. http://dx.doi.org/10.1002/ange.201708629.

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Thiel, J., G. Maurer, and J. M. Prausnitz. "Hydrogele - Thermodynamische Eigenschaften und Einsatzmöglichkeiten." Chemie Ingenieur Technik 67, no. 9 (September 1995): 1121. http://dx.doi.org/10.1002/cite.330670957.

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Thiel, Joachim, Gerd Maurer, and John M. Prausnitz. "Hydrogele: Verwendungsmöglichkeiten und thermodynamische Eigenschaften." Chemie Ingenieur Technik 67, no. 12 (December 1995): 1567–83. http://dx.doi.org/10.1002/cite.330671203.

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Stannek, M., and H. J. Bart. "Adsorptionsverhalten in imprägnierte PVA/PAA-Hydrogele." Chemie Ingenieur Technik 81, no. 8 (August 2009): 1084. http://dx.doi.org/10.1002/cite.200950593.

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Jain, Mehak, and Bart Jan Ravoo. "Brennstoffbetriebene und enzymregulierte redoxresponsive supramolekulare Hydrogele." Angewandte Chemie 133, no. 38 (August 11, 2021): 21231–38. http://dx.doi.org/10.1002/ange.202107917.

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Schwarze-Benning, K., A. Nellesen, H. Wack, G. Deerberg, J. Antes, and S. Löbbecke. "Smarte Hydrogele für die reversible Immobilisierung von Enzymen." Chemie Ingenieur Technik 80, no. 9 (September 2008): 1395. http://dx.doi.org/10.1002/cite.200750701.

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Wack, H., and M. Ulbricht. "Polymere Hydrogele in der Abdichtungstechnik – Untersuchungen zum Quellungsdruck." Chemie Ingenieur Technik 79, no. 1-2 (February 2007): 147–52. http://dx.doi.org/10.1002/cite.200600080.

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Vázquez‐González, Margarita, and Itamar Willner. "Stimuliresponsive, auf Biomolekülen basierende Hydrogele und ihre Anwendungen." Angewandte Chemie 132, no. 36 (July 20, 2020): 15458–96. http://dx.doi.org/10.1002/ange.201907670.

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Blache, Ulrich, and Martin Ehrbar. "Synthetische Hydrogele als 3D-Matrix für definierte Gewebemodelle." BIOspektrum 26, no. 4 (June 2020): 398–401. http://dx.doi.org/10.1007/s12268-020-1409-z.

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Fänger, C. F., M. U. Ulbricht, G. D. Deerberg, J. B. Büchs, and M. A. S. Ansorge-Schumacher. "Intelligente Hydrogele: Ein neuer Weg zur reversiblen Immobilisierung von Enzymen." Chemie Ingenieur Technik 76, no. 9 (September 2004): 1254. http://dx.doi.org/10.1002/cite.200490105.

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König, Myriam, W. Vanscheidt, and Nicole Denig. "Wundauflagen in der Praxis." Phlebologie 28, no. 03 (1999): 100–104. http://dx.doi.org/10.1055/s-0037-1617056.

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ZusammenfassungChronische Wunden sind ein häufiges Problem in der medizinischen Praxis. Neben einer Therapie der Grunderkrankungen soll eine suffiziente Lokaltherapie zum Heilen dieser Wunden beitragen. Dieser Artikel bietet eine Übersicht über die große Gruppe der feuchten Wundauflagen, um dem Arzt die Auswahl des geeigneten Produktes zu erleichtern. Hydrokolloide, Hydrogele, Schaumstoffe, Folien, Alginate und Aktivkohleverbände kommen bei richtigem Einsatz den Anforderungen an einen optimalen Wundverband recht nahe.

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Sun, Shengtong, Li-Bo Mao, Zhouyue Lei, Shu-Hong Yu, and Helmut Cölfen. "Hydrogele aus amorphem Calciumcarbonat und Polyacrylsäure: bioinspirierte Materialien für “Mineral-Kunststoffe”." Angewandte Chemie 128, no. 39 (July 22, 2016): 11939–43. http://dx.doi.org/10.1002/ange.201602849.

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Kretschmann, Oliver, Soo Whan Choi, Masahiko Miyauchi, Itsuro Tomatsu, Akira Harada, and Helmut Ritter. "Schaltbare Hydrogele durch supramolekulare Vernetzung adamantylhaltiger LCST-Copolymere mit Cyclodextrin-Dimeren." Angewandte Chemie 118, no. 26 (June 26, 2006): 4468–72. http://dx.doi.org/10.1002/ange.200504539.

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17

Wack, H., and R. Kümmel. "Zincon-Natriumsalz- und 2,3-Dihydroxybenzoesäure-imprägnierte Hydrogele auf Basis von N-Isopropylacrylamid." Chemie Ingenieur Technik 75, no. 8 (August 25, 2003): 1157–58. http://dx.doi.org/10.1002/cite.200390437.

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18

Singh, Smriti, Fuat Topuz, Kathrin Hahn, Krystyna Albrecht, and Jürgen Groll. "Einbau aktiver Proteine und lebender Zellen in redoxsensitive Hydrogele und Nanogele durch enzymatische Vernetzung." Angewandte Chemie 125, no. 10 (February 5, 2013): 3074–77. http://dx.doi.org/10.1002/ange.201206266.

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Sun, Shengtong, Li-Bo Mao, Zhouyue Lei, Shu-Hong Yu, and Helmut Cölfen. "Rücktitelbild: Hydrogele aus amorphem Calciumcarbonat und Polyacrylsäure: bioinspirierte Materialien für “Mineral-Kunststoffe” (Angew. Chem. 39/2016)." Angewandte Chemie 128, no. 39 (July 21, 2016): 12290. http://dx.doi.org/10.1002/ange.201606536.

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20

Skopinska-Wisniewska, Joanna, Silvia De la Flor, and Justyna Kozlowska. "From Supramolecular Hydrogels to Multifunctional Carriers for Biologically Active Substances." International Journal of Molecular Sciences 22, no. 14 (July 9, 2021): 7402. http://dx.doi.org/10.3390/ijms22147402.

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Supramolecular hydrogels are 3D, elastic, water-swelled materials that are held together by reversible, non-covalent interactions, such as hydrogen bonds, hydrophobic, ionic, host–guest interactions, and metal–ligand coordination. These interactions determine the hydrogels’ unique properties: mechanical strength; stretchability; injectability; ability to self-heal; shear-thinning; and sensitivity to stimuli, e.g., pH, temperature, the presence of ions, and other chemical substances. For this reason, supramolecular hydrogels have attracted considerable attention as carriers for active substance delivery systems. In this paper, we focused on the various types of non-covalent interactions. The hydrogen bonds, hydrophobic, ionic, coordination, and host–guest interactions between hydrogel components have been described. We also provided an overview of the recent studies on supramolecular hydrogel applications, such as cancer therapy, anti-inflammatory gels, antimicrobial activity, controlled gene drug delivery, and tissue engineering.

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21

Zhang, Rui, Hongwei Peng, Tianxu Zhou, Min Li, Xuhong Guo, and Yuan Yao. "Selective Adsorption and Separation of Organic Dyes by Poly(acrylic acid) Hydrogels Formed with Spherical Polymer Brushes and Chitosan." Australian Journal of Chemistry 71, no. 11 (2018): 846. http://dx.doi.org/10.1071/ch18228.

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Direct discharge of industry organic dyes has caused serious environmental pollution. In this study, a series of double network poly(acrylic acid) (PAA) hydrogels were fabricated with spherical polymer brushes (SPBs) and chitosan (CS) as crosslinker. Neutral spherical polyelectrolyte brushes of polystyrene–poly-N-isopropylacrylamide (PNIPAM@PS) in which poly(N-isopropylacrylamide) (PNIPAM) arms were grafted on polystyrene (PS) nanospheres, were employed as macro-crosslinkers. The innumerable hydrogen bonds both between the highly entangled PAA chains and between PNIPAM and the PAA chains composed the first network of the hydrogels. The electrostatic interactions between CS and the PAA chains formed the second network of the hydrogels. These double network hydrogels, named PNIPAM@PS/CS/PAA, achieve good compressive performance and a low swell ratio because of their compact structure through plentiful hydrogen bonding and electrostatic interactions. The hydrogel could absorb cationic dyes from water with high separation efficiency and selectivity due to the electrostatic interaction between the carboxy groups and dye molecules. The adsorption process fitted a pseudo-second-order kinetic model and Langmuir isotherm model very well. Moreover, the hydrogel can separate cationic dyes from mixed dye solutions through electrostatic interactions. After being loaded with silver nanoparticles, the obtained silver@hydrogel exhibited a good capacity for the photocatalytic degradation towards different dyes. The hydrogels are promising for dye-containing wastewater treatment.

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22

Jiang, Zhiqiang, Ya Li, Yirui Shen, Jian Yang, Zongyong Zhang, Yujing You, Zhongda Lv, and Lihui Yao. "Robust Hydrogel Adhesive with Dual Hydrogen Bond Networks." Molecules 26, no. 9 (May 4, 2021): 2688. http://dx.doi.org/10.3390/molecules26092688.

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Hydrogel adhesives are attractive for applications in intelligent soft materials and tissue engineering, but conventional hydrogels usually have poor adhesion. In this study, we designed a strategy to synthesize a novel adhesive with a thin hydrogel adhesive layer integrated on a tough substrate hydrogel. The adhesive layer with positive charges of ammonium groups on the polymer backbones strongly bonds to a wide range of nonporous materials’ surfaces. The substrate layer with a dual hydrogen bond system consists of (i) weak hydrogen bonds between N,N-dimethyl acrylamide (DMAA) and acrylic acid (AAc) units and (ii) strong multiple hydrogen bonds between 2-ureido-4[1H]-pyrimidinone (UPy) units. The dual hydrogen-bond network endowed the hydrogel adhesives with unique mechanical properties, e.g., toughness, highly stretchability, and insensitivity to notches. The hydrogel adhesion to four types of materials like glass, 316L stainless steel, aluminum, Al2O3 ceramic, and two biological tissues including pig skin and pig kidney was investigated. The hydrogel bonds strongly to dry solid surfaces and wet tissue, which is promising for biomedical applications.

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23

Jiang, Yuchen, Guihua Li, Chenyu Yang, Fangong Kong, and Zaiwu Yuan. "Multiresponsive Cellulose Nanocrystal Cross-Linked Copolymer Hydrogels for the Controlled Release of Dyes and Drugs." Polymers 13, no. 8 (April 9, 2021): 1219. http://dx.doi.org/10.3390/polym13081219.

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Multiresponsive hydrogels have attracted tremendous interest due to their promising applications in tissue engineering, wearable devices, and flexible electronics. In this work, we report a multiresponsive upper critical solution temperature (UCST) composite hydrogel based on poly (acrylic acid-co-acrylamide), PAAc-co-PAAm, sequentially cross-linked by acid-hydrolysis cellulose nanocrystals (CNCs). Scanning electron microscopy (SEM) observations demonstrated that the hydrogels are formed by densely cross-linked porous structures. The PAAc/PAAm/CNC hybrid hydrogels exhibit swelling and shrinking properties that can be induced by multiple stimuli, including temperature, pH, and salt concentration. The driving force of the volume transition is the formation and dissociation of hydrogen bonds in the hydrogels. A certain content of CNCs can greatly enhance the shrinkage capability and mechanical strength of the hybrid hydrogels, but an excess addition may impair the contractility of the hydrogel. Furthermore, the hydrogels can be used as a matrix to adsorb dyes, such as methylene blue (MB), for water purification. MB may be partly discharged from hydrogels by saline solutions, especially by those with high ionic strength. Notably, through temperature-controlled hydrogel swelling and shrinking, doxorubicin hydrochloride (DOX-HCl) can be controllably adsorbed and released from the prepared hydrogels.

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Xing, Wenjin, Amin Jamshidi Ghahfarokhi, Chaoming Xie, Sanaz Naghibi, Jonathan A. Campbell, and Youhong Tang. "Mechanical Properties of a Supramolecular Nanocomposite Hydrogel Containing Hydroxyl Groups Enriched Hyper-Branched Polymers." Polymers 13, no. 5 (March 6, 2021): 805. http://dx.doi.org/10.3390/polym13050805.

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Owing to highly tunable topology and functional groups, hyper-branched polymers are a potential candidate for toughening agents, for achieving supramolecular interactions with hydrogel networks. However, their toughening effects and mechanisms are not well understood. Here, by means of tensile and pure shear testings, we characterise the mechanics of a nanoparticle–hydrogel hybrid system that incorporates a hyper-branched polymer (HBP) with abundant hydroxyl end groups into the matrix of the polyacrylic acid (PAA) hydrogel. We found that the third and fourth generations of HBP are more effective than the second one in terms of strengthening and toughening effects. At a HBP content of 14 wt%, compared to that of the pure PAA hydrogel, strengths of the hybrid hydrogels with the third and fourth HBPs are 2.3 and 2.5 times; toughnesses are increased by 525% and 820%. However, for the second generation, strength is little improved, and toughness is increased by 225%. It was found that the stiffness of the hybrid hydrogel is almost unchanged relative to that of the PAA hydrogel, evidencing the weak characteristic of hydrogen bonds in this system. In addition, an outstanding self-healing feature was observed, confirming the fast reforming nature of broken hydrogen bonds. For the hybrid hydrogel, the critical size of failure zone around the crack tip, where serious viscous dissipation occurs, is related to a fractocohesive length, being about 0.62 mm, one order of magnitude less than that of other tough double-network hydrogels. This study can promote the application of hyper-branched polymers in the rapid evolving field of hydrogels for improved performance.

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Jiang, Weihui, Peiyao Shen, and Ju Gu. "Nanocrystalline cellulose prepared by double oxidation as reinforcement in polyvinyl alcohol hydrogels." Journal of Polymer Engineering 40, no. 1 (December 18, 2019): 67–74. http://dx.doi.org/10.1515/polyeng-2019-0258.

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Abstract As a biopolymer with high mechanical strength, nanocellulose was increasingly studied to improve polymer properties. In this study, nanocrystalline cellulose (NCC) was efficiently isolated from eucalyptus pulp by double oxidation (ammonium persulfate oxidation and ultrasonic oxidation). The total yield of NCC (405.1 ± 180.5 nm long and 31.7 ± 9.5 nm wide) was 38.3%. A novel hybrid hydrogel was produced from polyvinyl alcohol (PVA) and NCC using the freeze-thaw technique. In this hybrid architecture, hydrogen bonds were formed between PVA and NCC. With the increasing proportion of NCC, the pore size of hydrogels shank gradually and the structure of the hybrid hydrogels became denser. The tensile strength of PVA/NCC hybrid hydrogels increased by 42.4% compared to the neat PVA hydrogel. The results showed that NCC can improve the swelling, thermal properties, and water evaporation rate of PVA hydrogels due to the hydrophilic hydroxyl groups of NCC and hydrogen bonds between PVA and NCC, indicating that PVA hydrogels would have a wider range of application due to the existence of NCC, a green hybrid filler. Most importantly, this novel double oxidation method for preparing nanocellulose will promote an efficient production of nanocellulose.

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Zitouni, Mohammed Amine, and Sofia Borsali Kara Slimane. "Preparation and Characterization of Hydrogels Based on Chitsoan/Polyvinyl Alcohol Blends." Advanced Materials Research 1105 (May 2015): 203–7. http://dx.doi.org/10.4028/www.scientific.net/amr.1105.203.

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In this study, a series of poly (vinyl alcohol) (PVA)/chitosan (CS) hydrogels with different weight ratio of PVA to CS were prepared by freezing-thawing (F-T) method. The structure, morphology, and crystallinity of hydrogels were investigated by Fourier Transform Infrared (FT-IR), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). FTIR demonstrated the presence of strong intermolecular hydrogen bonds between CS and PVA molecules. SEM images showed that the higher the chitosan, the greater the porous size of the hydrogel and DSC confirmed that crystallinity is higher when PVA is more in hydrogel. The mechanical properties of these hydrogels were studied by rheometry. The study of swelling ability demonstrated that the hydrogel developed with PVA and Cs was more swellable than that with PVA only because of its cross-linking interaction with PVA.

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Maikovych, O. V., I. A. Dron, N. M. Bukartyk, O. Yu Bordeniuk, and N. G. Nosova. "Іnvestigation of gel formation peculiarities and properties of hydrogels obtained by the structuring of acrylamide prepolymers." Chemistry, Technology and Application of Substances 4, no. 1 (June 1, 2021): 179–85. http://dx.doi.org/10.23939/ctas2021.01.179.

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The paper represents the results of the investigation of the formation of a polymeric matrix of hydrogel due to the structuring of polyacrylamide using its reactive polymeric derivative – poly-N- (hydroxymethyl) acrylamide. Research determined zones of optimum conditions of synthesis and characterized hydrogel depending on pH of media, the ratio between the concentration of prepolymers, and time of synthesis. The investigation of the reaction mixture showed that the hydrogen index of the synthesis of hydrogels is one of the important factors, which in the design of the polymer framework of hydrogels allows regulating their colloidal chemical properties in a wide range.

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Jumadilov, Talkybek, Zharylkasyn Abilov, Ruslan Kondaurov, Huangul Himersen, Gaukhar Yeskalieva, Moldir Akylbekova, and Auez Akimov. "Influence of Hydrogels Initial State on their Electrochemical and Volume-Gravimetric Properties in Intergel System Polyacrylic Acid Hydrogel and Poly-4-vinylpyridine Hydrogel." Chemistry & Chemical Technology 9, no. 4 (December 15, 2015): 459–62. http://dx.doi.org/10.23939/chcht09.04.459.

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Wu, Wen, and Dong Sheng Wang. "Green Synthesis of Semi-IPN Hydrogel-Silver Nanocomposites by a Biotemplate Redox Technique at Room Temperature." Advanced Materials Research 468-471 (February 2012): 1974–77. http://dx.doi.org/10.4028/www.scientific.net/amr.468-471.1974.

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Semi-IPN hydrogels in which silk sericin (SS) chains were physically dispersed throughout dextran (Dex) gel networks were synthesized. Highly stable distributed silver nanoparticles have been prepared using these semi-IPN hydrogels as a carrier via in situ reduction of silver nitrate without the addition of any reducing agent. The resultant semi-IPN hydrogel-silver nanocomposites were characterized by X-ray diffraction (XRD). And the swelling behavior of the hydrogles was also studied.

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Yue, Shuai, Hui He, Bin Li, and Tao Hou. "Hydrogel as a Biomaterial for Bone Tissue Engineering: A Review." Nanomaterials 10, no. 8 (July 31, 2020): 1511. http://dx.doi.org/10.3390/nano10081511.

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Severe bone damage from diseases, including extensive trauma, fractures, and bone tumors, cannot self-heal, while traditional surgical treatment may bring side effects such as infection, inflammation, and pain. As a new biomaterial with controllable mechanical properties and biocompatibility, hydrogel is widely used in bone tissue engineering (BTE) as a scaffold for growth factor transport and cell adhesion. In order to make hydrogel more suitable for the local treatment of bone diseases, hydrogel preparation methods should be combined with synthetic materials with excellent properties and advanced technologies in different fields to better control drug release in time and orientation. It is necessary to establish a complete method to evaluate the hydrogel’s properties and biocompatibility with the human body. Moreover, establishment of standard animal models of bone defects helps in studying the therapeutic effect of hydrogels on bone repair, as well as to evaluate the safety and suitability of hydrogels. Thus, this review aims to systematically summarize current studies of hydrogels in BTE, including the mechanisms for promoting bone synthesis, design, and preparation; characterization and evaluation methods; as well as to explore future applications of hydrogels in BTE.

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31

Jiang, Ping, Shaowei Chen, Linda Lv, Hongmin Ji, Gen Li, Zhechao Jiang, and Yiqiang Wu. "Effect of 2-(dimethylamino) Ethyl Methacrylate on Nanostructure and Properties of pH and Temperature Sensitive Cellulose-Based Hydrogels." Journal of Nanoscience and Nanotechnology 20, no. 3 (March 1, 2020): 1799–806. http://dx.doi.org/10.1166/jnn.2020.17341.

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The novel double responsive cellulose/poly 2-(dimethylamino) ethyl methacrylate (PDMAEMA) hydrogel was synthesized via in situ free radical polymerization. The results from light transmittance measurements, scanning electron microscopy (SEM), mechanical property testing as well as swelling experiments demonstrated that DMAEMA played a significant impact on in hydrogel’s nanostructure.With increasing DMAEMA concentration, the transparency of hydrogels dropped and texture became softer. The incorporation of relatively hard cellulose and increase in crosslink density significantly enhanced 3D network structure of hydrogel. The tensile strength, compression and bending capabilities of the composite responsive hydrogels were fine with the DMAEMA in a certain range. When the DMAEMA concentration increased to 6 g/g(cellulose), the mechanical strength decreased noticeably. An increase in DMAEMA concentration resulted in a faster initial swelling rate and higher equilibrium swelling ratio. Further, three-dimensional structure and increase of DMAEMA concentration can also improve pH and temperature response sensitivity of hydrogels. Thus, the mechanical, swelling and responsive properties of hydrogel could be adjusted by the DMAEMA and polymerization modes.

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Iresha, Harshani, and Takaomi Kobayashi. "In Situ Viscoelasticity Behavior of Cellulose–Chitin Composite Hydrogels during Ultrasound Irradiation." Gels 7, no. 3 (June 30, 2021): 81. http://dx.doi.org/10.3390/gels7030081.

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Composite hydrogels with different cellulose and chitin loading were prepared, and their in-situ viscoelastic properties were estimated under cyclic exposure of 43 kHz and 30 W ultrasound (US) using a sono-deviced rheometer. US transmitted into the hydrogel caused it to soften within about 10 sec, thus causing a decline in the storage modulus (G′) and loss modulus (G″). However, when the US was stopped, the G′ and G″ returned to their initial values. Here, G′ dropped gradually in response to the US irradiation, especially in the first cycle. After the second and third cycles, the decline was much quicker, within a few seconds. When the chitin component in the hydrogel was increased, the drop was significant. FTIR analysis of the hydrogels suggested that the peaks of -OH stretching and amide I vibration near 1655 cm−1 shifted towards lower wave numbers after the third cycle, meaning that the US influenced the hydrogen bonding interaction of the chitin amide group. This repetitive effect contributed to the breakage of hydrogen bonds and increased the interactions of the acetylamine group in chitin and in the -OH groups. Eventually, the matrix turned into a more stabilized hydrogel.

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Xu, Bo, Yuwei Liu, Lanlan Wang, Xiaodong Ge, Min Fu, Ping Wang, and Qiang Wang. "High-Strength Nanocomposite Hydrogels with Swelling-Resistant and Anti-Dehydration Properties." Polymers 10, no. 9 (September 14, 2018): 1025. http://dx.doi.org/10.3390/polym10091025.

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Hydrogels with excellent mechanical properties have potential for use in various fields. However, the swelling of hydrogels under water and the dehydration of hydrogels in air severely limits the practical applications of high-strength hydrogels due to the influence of air and water on the mechanical performance of hydrogels. In this study, we report on a kind of tough and strong nanocomposite hydrogels (NC-G gels) with both swelling-resistant and anti-dehydration properties via in situ free radical copolymerization of acrylic acid (AA) and N-vinyl-2-pyrrolidone (VP) in the water-glycerol bi-solvent solutions containing small amounts of alumina nanoparticles (Al2O3 NPs) as the inorganic cross-linking agents. The topotactic chelation reactions between Al2O3 NPs and polymer matrix are thought to contribute to the cross-linking structure, outstanding mechanical performance, and swelling-resistant property of NC-G gels, whereas the strong hydrogen bonds between water and glycerol endow them with anti-dehydration capacity. As a result, the NC-G gels could maintain mechanical properties comparable to other as-prepared high-strength hydrogels when utilized both under water and in air environments. Thus, this novel type of hydrogel would considerably enlarge the application range of hydrogel materials.

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Wang, Yangyang, and Yansong Wang. "A Composited Povidone-Iodine Silk Fibroin Hydrogel for Wound Infection." Journal of Biomaterials and Tissue Engineering 9, no. 6 (June 1, 2019): 719–30. http://dx.doi.org/10.1166/jbt.2019.2055.

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Wound infections have historically been an important global health concern which seriously affects human life and health. Reducing the number of bacteria at the site of the wound is essential to prevent wound infection and promote wound healing. Povidone-iodine (PVP-I) is widely used as an antiseptic providing useful properties for local anti-infective treatment in skin, mucous membranes, and wounds. In this study, we synthesized a new PVP-I/silk fibroin (SF) hydrogel through a simple preparation method, and to study the physicochemical properties, antibacterial properties and biocompatibility of the composited hydrogel. Compared with the pure SF hydrogel, the composition of PVP-I with SF hydrogels endowed the hydrogel new physicochemical characteristics especially enhanced hydrogel's structural stability and a sustained-release effect of iodine. Moreover, such composited hydrogels showed better antibacterial properties when the content of the compound PVP-I reached a certain degree. In vivo, the results indicate that the composited hydrogel displayed a good histocompatibility and biodegradability. All these results demonstrated that the composited povidone-iodine silk hydrogel can be fabricated as an anti-infective biomaterials with great potential using in wound infection.

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Han, Xiaoman, Guihua Meng, Qian Wang, Lin Cui, Hao Wang, Jianning Wu, Zhiyong Liu, and Xuhong Guo. "Mussel-inspired in situ forming adhesive hydrogels with anti-microbial and hemostatic capacities for wound healing." Journal of Biomaterials Applications 33, no. 7 (November 22, 2018): 915–23. http://dx.doi.org/10.1177/0885328218810552.

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All kinds of commercially available wound dressings are clinically used as fleshly obstacles and therapeutic materials in opposition to microbial incursion. Few researches focused on effective-bleeding and anti-bacteria at the same time. In order to better solve this problem, two hydrogels were synthetized in this study. One is phosphate buffer solution-activated dopamine-modified-γ-poly glutamic acid (PBS-PD) hydrogel, the other one is cirsium setosum extracts-activated dopamine-modified-γ-poly glutamic acid (CSE-PD) hydrogel. The two hydrogels are prepared by applying an enzyme-catalyzed crosslinking means in the presence of horseradish peroxidase (HRP) and hydrogen peroxide (H2O2). The chemical structures were characterized through 1H-NMR and FT-IR. In conclusion, both PBS-PD and CSE-PD hydrogels exhibit superior tissue adhesion properties, and remarkable anti-infection quality. In addition, these two hydrogels manifest prominent hemostatic efficiency. The bio adhesion performance can achieve 30 kPa, meanwhile the CSE-PD hydrogels show good germicidal properties, and the antibacterial rate can reach 98%. The hydrogels could reduce blood loss without any obvious side effect, and present a new prospect in the field of hemostasis rapidly.

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Okay, Oguz. "Re-Entrant Conformation Transition in Hydrogels." Gels 7, no. 3 (July 20, 2021): 98. http://dx.doi.org/10.3390/gels7030098.

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Hydrogels are attractive materials not only for their tremendous applications but also for theoretical studies as they provide macroscopic monitoring of the conformation change of polymer chains. The pioneering theoretical work of Dusek predicting the discontinuous volume phase transition in gels followed by the experimental observation of Tanaka opened up a new area, called smart hydrogels, in the gel science. Many ionic hydrogels exhibit a discontinuous volume phase transition due to the change of the polymer–solvent interaction parameter χ depending on the external stimuli such as temperature, pH, composition of the solvent, etc. The observation of a discontinuous volume phase transition in nonionic hydrogels or organogels is still a challenging task as it requires a polymer–solvent system with a strong polymer concentration dependent χ parameter. Such an observation may open up the use of organogels as smart and hydrophobic soft materials. The re-entrant phenomenon first observed by Tanaka is another characteristic of stimuli responsive hydrogels in which they are frustrated between the swollen and collapsed states in a given solvent mixture. Thus, the hydrogel first collapses and then reswells if an environmental parameter is continuously increased. The re-entrant phenomenon of hydrogels in water–cosolvent mixtures is due to the competitive hydrogen-bonding and hydrophobic interactions leading to flow-in and flow-out of the cosolvent molecules through the hydrogel moving boundary as the composition of the solvent mixture is varied. The experimental results reviewed here show that a re-entrant conformation transition in hydrogels requires a hydrophobically modified hydrophilic network, and a moderate hydrogen-bonding cosolvent having competitive attractions with water and polymer. The re-entrant phenomenon may widen the applications of the hydrogels in mechanochemical transducers, switches, memories, and sensors.

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Temel, Sinan, Elif Yaman, Nurgul Ozbay, and Gokmen Ozge. "Synthesis, characterization and adsorption studies of nano-composite hydrogels and the effect of SiO2 on the capacity for the removal of Methylene Blue dye." Journal of the Serbian Chemical Society 85, no. 7 (2020): 939–52. http://dx.doi.org/10.2298/jsc190517114t.

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Nanocomposite hydrogels were produced by free radical polymerization of acrylic acid and N-vinylpyrrolidone in the presence of SiO2 nanoparticles. The chemical and morphological structures of the hydrogels were determined using Fourier transform infra-red spectroscopy (FT-IR) and field emission scanning electron microscopy (FESEM). The nanocomposite hydrogels were used for the adsorption and desorption of Methylene Blue dye from wastewater. Wastewater was referred to distilled water that contained Methylene Blue dye under laboratory conditions. The carbon, hydrogen and nitrogen contents of the dye, hydrogels and dye-adsorbed hydrogels were determined by elemental analysis. The influences of SiO2 nanoparticles and copolymerization on the adsorption capacity were studied. The maximum dye removal of 98.3 % was obtained with AA-co-VP (3:1) copolymeric hydrogel. The synthesized hydrogels could be evaluated as adsorbents in wastewater treatment, effectively.

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Erikci, Saliha, Patricia Mundinger, and Heike Boehm. "Small Physical Cross-Linker Facilitates Hyaluronan Hydrogels." Molecules 25, no. 18 (September 11, 2020): 4166. http://dx.doi.org/10.3390/molecules25184166.

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In this study, we demonstrate that small charged molecules (NH4+, GluA+, dHA+) can form physical cross-links between hyaluronan chains, facilitating polymerization reactions between synthetically introduced thiol groups (HA-DTPH). These hybrid hydrogels can be obtained under physiological conditions ideally suited for 3D cell culture systems. The type and concentration of a physical crosslinker can be adjusted to precisely tune mechanical properties as well as degradability of the desired hydrogel system. We analyze the influence of hydrogen bond formation, concentration and additional ionic interactions on the polymerization reaction of HA-DTPH hydrogels and characterize the resulting hydrogels in regard to mechanical and biocompatibility aspects.

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Duan, Jiufang. "Self-Healing Hydrogels Based on Carboxymethyl Chitosan and Acryloyl-6-aminocaproic Acid." Journal of Polymers 2015 (August 10, 2015): 1–6. http://dx.doi.org/10.1155/2015/719529.

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Once cracks have formed within hydrogel materials, the integrity of the structure is signifcantly compromised, regardless of the application. Here, we demonstrate cross-linked CMCS hydrogels can be engineered to exhibit self-healing under mild conditions. CMCS hydrogels based on CMCS and acryloyl-6-aminocaproic acid (A6ACA) were synthesized by free radical aqueous copolymerization using ammonium persulfate as initiator. A series of hydrogels was synthesized varying the percentage of A6ACA. The hydrogels were characterized by Fourier transform infrared spectroscopy (FTIR) techniques and their morphologies were investigated by scanning electron microscope (SEM) images. When the proportion of A6ACA was increased, the compressive strength, stress, and strain of hydrogels were increased. The cross-linked hydrogel based on CMCS that can autonomously heal between cut surfaces after 1 h was formed under mild conditions. The increase of A6ACA content in the hydrogels will lead to increased mechanical properties and mechanical healing efficiencies for highly cross-linked polymeric networks. Hydrogen bond is the main reason for self-healing ability, and the covalent cross-linkss and noncovalent cross-links both bear loads in the hyrogel. Polymers with the ability to self-repair after sustaining damage could extend the lifetime of materials used in many applications.

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Xu, Bo, Yuwei Liu, Jiugang Yuan, Ping Wang, and Qiang Wang. "Synthesis, Characterization, and Antifogging Application of Polymer/Al2O3 Nanocomposite Hydrogels with High Strength and Self-Healing Capacity." Polymers 10, no. 12 (December 8, 2018): 1362. http://dx.doi.org/10.3390/polym10121362.

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Hydrogels with outstanding mechanical performance, self-healing capacity, and special functionality are highly desirable for their practical applications. However, it remains a great challenge to achieve such hydrogels by a facile approach. Here, we report a new type of nanocomposite hydrogels by in situ copolymerization of acrylic acid (AA) and 2-acrylamido-2-methylpropane sulfonic acid (AMPS) using alumina nanoparticles (Al2O3 NPs) as the cross-linkers. The obtained hydrogels are highly stretchable and compressible, which could sustain large-scale extension (>1700%) or compression (90%) without failure, and exhibit tensile and compressive strength up to 660 kPa and 8.3 MPa, respectively. Furthermore, this kind of hydrogel also display considerable self-healing capacity due to their noncovalent cross-linking mechanism, as well as the hydrogen-bonding interactions between polymer chains. More interestingly, it was found that the resultant gels possess a long-lasting antifogging property that could prevent the formation of fog on the glass plate above hot water for at least 90 min. It is expected that this novel type of hydrogel would show great promise for various applications, including soft robots, artificial muscles, and optical devices.

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Wen, Jie, Xiaopeng Zhang, Mingwang Pan, Jinfeng Yuan, Zhanyu Jia, and Lei Zhu. "A Robust, Tough and Multifunctional Polyurethane/Tannic Acid Hydrogel Fabricated by Physical-Chemical Dual Crosslinking." Polymers 12, no. 1 (January 19, 2020): 239. http://dx.doi.org/10.3390/polym12010239.

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Commonly synthetic polyethylene glycol polyurethane (PEG–PU) hydrogels possess poor mechanical properties, such as robustness and toughness, which limits their load-bearing application. Hence, it remains a challenge to prepare PEG–PU hydrogels with excellent mechanical properties. Herein, a novel double-crosslinked (DC) PEG–PU hydrogel was fabricated by combining chemical with physical crosslinking, where trimethylolpropane (TMP) was used as the first chemical crosslinker and polyphenol compound tannic acid (TA) was introduced into the single crosslinked PU network by simple immersion process. The second physical crosslinking was formed by numerous hydrogen bonds between urethane groups of PU and phenol hydroxyl groups in TA, which can endow PEG–PU hydrogel with good mechanical properties, self-recovery and a self-healing capability. The research results indicated that as little as a 30 mg·mL−1 TA solution enhanced the tensile strength and fracture energy of PEG–PU hydrogel from 0.27 to 2.2 MPa, 2.0 to 9.6 KJ·m−2, respectively. Moreover, the DC PEG–PU hydrogel possessed good adhesiveness to diverse substrates because of TA abundant catechol groups. This work shows a simple and versatile method to prepare a multifunctional DC single network PEG–PU hydrogel with excellent mechanical properties, and is expected to facilitate developments in the biomedical field.

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Dicker, Michael PM, Ian P. Bond, Jonathan M. Rossiter, Charl FJ Faul, and Paul M. Weaver. "Modelling and Analysis of pH Responsive Hydrogels for the Development of Biomimetic Photo-Actuating Structures." MRS Proceedings 1718 (2015): 65–70. http://dx.doi.org/10.1557/opl.2015.20.

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ABSTRACTPhoto-actuating structures inspired by the chemical sensing and signal transmission observed in sun-tracking leaves have recently been proposed by Dicker et al. The proposed light tracking structures are complex, multicomponent material systems, principally composed of a reversible photoacid or base, combined with a pH responsive hydrogel actuator. New modelling and characterization approaches for pH responsive hydrogels are presented in order to facilitate the development of the proposed structures. The model employs Donnan equilibrium for the prediction of hydrogel swelling in systems where the pH change is a variable resulting from the equilibrium interaction of all free and fixed (hydrogel) species. The model allows for the fast analysis of a variety of combinations of material parameters, allowing for the design space for the proposed photo-actuating structures to be quickly established. In addition, experimental examination of the swelling of a polyether-based polyurethane and poly(acrylic acid) interpenetrating network hydrogel is presented. The experiment involves simultaneously performing a titration of the hydrogel, and undertaking digital image correlation (DIC) to determine the hydrogel’s state of swelling. DIC allows for the recording of the hydrogel’s state of swelling with previously unattained levels of resolution. Experimental results provide both model material properties, and a means for model validation.

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Jiang, Yuheng, Ying Wang, Qin Li, Chen Yu, and Wanli Chu. "Natural Polymer-based Stimuli-responsive Hydrogels." Current Medicinal Chemistry 27, no. 16 (June 4, 2020): 2631–57. http://dx.doi.org/10.2174/0929867326666191122144916.

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The abilities of intelligent polymer hydrogels to change their structure and volume phase in response to external stimuli have provided new possibilities for various advanced technologies and great research and application potentials in the medical field. The natural polymer-based hydrogels have the advantages of environment-friendliness, rich sources and good biocompatibility. Based on their responsiveness to external stimuli, the natural polymer-based hydrogels can be classified into the temperature-responsive hydrogel, pH-responsive hydrogel, light-responsive hydrogel, electricresponsive hydrogel, redox-responsive hydrogel, enzyme-responsive hydrogel, magnetic-responsive hydrogel, multi-responsive hydrogel, etc. In this review, we have compiled some recent studies on natural polymer-based stimuli-responsive hydrogels, especially the hydrogels prepared from polysaccharides. The preparation methods, properties and applications of these hydrogels in the medical field are highlighted.

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Fawole, Olutosin, Subhashish Dolai, Hsuan-Yu Leu, Jules Magda, and Massood Tabib-Azar. "Remote Microwave and Field-Effect Sensing Techniques for Monitoring Hydrogel Sensor Response." Micromachines 9, no. 10 (October 17, 2018): 526. http://dx.doi.org/10.3390/mi9100526.

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This paper presents two novel techniques for monitoring the response of smart hydrogels composed of synthetic organic materials that can be engineered to respond (swell or shrink, change conductivity and optical properties) to specific chemicals, biomolecules or external stimuli. The first technique uses microwaves both in contact and remote monitoring of the hydrogel as it responds to chemicals. This method is of great interest because it can be used to non-invasively monitor the response of subcutaneously implanted hydrogels to blood chemicals such as oxygen and glucose. The second technique uses a metal-oxide-hydrogel field-effect transistor (MOHFET) and its associated current-voltage characteristics to monitor the hydrogel’s response to different chemicals. MOHFET can be easily integrated with on-board telemetry electronics for applications in implantable biosensors or it can be used as a transistor in an oscillator circuit where the oscillation frequency of the circuit depends on the analyte concentration.

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Stanzione, Antonella, Alessandro Polini, Velia La Pesa, Alessandro Romano, Angelo Quattrini, Giuseppe Gigli, Lorenzo Moroni, and Francesca Gervaso. "Development of Injectable Thermosensitive Chitosan-Based Hydrogels for Cell Encapsulation." Applied Sciences 10, no. 18 (September 19, 2020): 6550. http://dx.doi.org/10.3390/app10186550.

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The three-dimensional complexity of the native extracellular matrix (ECM) suggests switching from 2D to 3D culture systems for providing the cells with an architecture more similar to the physiological environment. Reproducing the three-dimensionality in vitro can guarantee beneficial effects in terms of cell growth, adhesion, proliferation, and/or their differentiation. Hydrogels have the same tailorable physico-chemical and biological characteristics as ECM materials. In this study, we propose a thermoresponsive chitosan-based hydrogel that gels thanks to the addition of organic and inorganic salt solutions (beta-glycerolphosphate and sodium hydrogen carbonate) and is suitable for cell encapsulation allowing obtaining 3D culture systems. Physico-chemical analyses showed that the hydrogel formulations jellify at physiological conditions (37 °C, pH 7.4), are stable in vitro up to three weeks, have high swelling ratios and mechanical stiffness suitable for cellular encapsulation. Moreover, preliminary biological tests underlined the pronounced biocompatibility of the system. Therefore, these chitosan-based hydrogels are proposed as valid biomaterials for cell encapsulation.

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Yi, Chengzhi, Xiaowei Zhang, Huixian Yan, and Bo Jin. "Finite Element Simulation and the Application of Amphoteric pH-sensitive Hydrogel." International Journal of Applied Mechanics 09, no. 05 (July 2017): 1750063. http://dx.doi.org/10.1142/s1758825117500636.

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Amphoteric hydrogels have been widely used in biologic and mechanic areas such as robot joints, biological cells, drug delivery systems. There are many factors that can influence the deformation of hydrogels, such as pH value, concentration of salt ions, solid constrains and external force, which all together makes the calculation very complicated. In this paper, an improved model for the calculation of amphoteric pH-sensitive hydrogels’ deformation is developed so that the behaviors of hydrogels in both acidic and alkaline solutions can be described quantitatively, and this model is implemented into finite element method (FEM) software ABAQUS in order to simulate hydrogel’s homogeneous and inhomogeneous deformations. The FEM results under free swelling state are compared with both analytical solution and FEM results existed before, and FEM results fit well with the experimental data. The buckling of amphoteric pH-sensitive hydrogel membrane is also analyzed, some natural phenomena, such as the wrinkling of human finger’s skin and the broad bean testa are successfully explained.

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Jeon, Dasom, Jinwoo Park, Changhwan Shin, Hyunwoo Kim, Ji-Wook Jang, Dong Woog Lee, and Jungki Ryu. "Superaerophobic hydrogels for enhanced electrochemical and photoelectrochemical hydrogen production." Science Advances 6, no. 15 (April 2020): eaaz3944. http://dx.doi.org/10.1126/sciadv.aaz3944.

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The efficient removal of gas bubbles in (photo)electrochemical gas evolution reactions is an important but underexplored issue. Conventionally, researchers have attempted to impart bubble-repellent properties (so-called superaerophobicity) to electrodes by controlling their microstructures. However, conventional approaches have limitations, as they are material specific, difficult to scale up, possibly detrimental to the electrodes’ catalytic activity and stability, and incompatible with photoelectrochemical applications. To address these issues, we report a simple strategy for the realization of superaerophobic (photo)electrodes via the deposition of hydrogels on a desired electrode surface. For a proof-of-concept demonstration, we deposited a transparent hydrogel assembled from M13 virus onto (photo)electrodes for a hydrogen evolution reaction. The hydrogel overlayer facilitated the elimination of hydrogen bubbles and substantially improved the (photo)electrodes’ performances by maintaining high catalytic activity and minimizing the concentration overpotential. This study can contribute to the practical application of various types of (photo)electrochemical gas evolution reactions.

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Luo, Huiyuan, Fuping Dong, Qian Wang, Yihang Li, and Yuzhu Xiong. "Construction of Porous Starch-Based Hydrogel via Regulating the Ratio of Amylopectin/Amylose for Enhanced Water-Retention." Molecules 26, no. 13 (June 30, 2021): 3999. http://dx.doi.org/10.3390/molecules26133999.

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The performance of hydrogels prepared with traditional natural starch as raw materials is considerable; the fixed ratio of amylose/amylopectin significantly limits the improvement of hydrogel structure and performance. In this paper, starch hydrogels were prepared by physical blending and chemical grafting, with the aid of ultrasonic heating. The effects of different amylose/amylopectin ratios on the microstructure and water retention properties of starch hydrogels were studied. The results show that an increase in amylopectin content is beneficial to improve the grafting ratio of acrylamide (AM). The interaction between the AM grafted on amylopectin and amylose molecules through hydrogen bonding increases the pores of the gel network and thins the pore walls. When the amylopectin content was 70%, the water absorption (swelling 45.25 times) and water retention performance (16 days water retention rate 44.17%) were optimal. This study provides new insights into the preparation of starch-based hydrogels with excellent physical and chemical properties.

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Timofejeva, Anna, and Dagnija Loca. "Hydroxyapatite/Polyvinyl Alcohol Composite Hydrogels for Bone and Cartilage Tissue Engineering." Key Engineering Materials 762 (February 2018): 54–58. http://dx.doi.org/10.4028/www.scientific.net/kem.762.54.

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Composite hydrogels on the basis of hydroxyapatite (HAp) and polyvinyl alcohol (PVA) has been proposed as a promising materials for bone and cartilage tissue engineering. HAp/PVA composite hydrogels with phase ratio 50:50wt% and 70:30wt% were obtained via in situ wet chemical precipitation technique in combination with the freeze-thawing approach. The XRD studies of sintered products revealed that HAp/PVA composite hydrogels synthesized from PVA with degree of hydrolysis (DH) 98% and molecular weights (MW) 25 kDa and 78 kDa are more suitable for biomedical purposes due to the formation of stoichiometric HAp. Swelling studies indicated that HAp/PVA 50:50 (78 kDa, 88% and 98%) hydrogels after 24h of immersion swell ~4.25-6.5 times less than identical samples with phase composition of 70:30wt%, which is accounted to different number of intermolecular hydrogen bonds formed. After 16 subsequent freeze-thawing cycles (FTC), HAp/PVA 50:50 (78 kDa, 88% and 98%) hydrogels contain ~1.2 times higher content of crosslinked PVA than HAp/PVA 70:30 (78 kDa, 88% and 98%) hydrogel samples.

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Eich and Stadler. "Differentiated local therapy of chronic wounds with modern wound dressings." Vasa 28, no. 1 (February 1, 1999): 3–9. http://dx.doi.org/10.1024/0301-1526.28.1.3.

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Die Therapie chronischer Wunden umfaßt neben der Behandlung der Grunderkrankung, z.B. Kompressionstherapie und Phlebochirurgie beim venösen Ulcus cruris, die moderne differenzierte Lokaltherapie. Die konventionelle Wundtherapie umfaßt in erster Linie Farbstoffe, diverse Topika, lokale antimikrobielle Substanzen und sterile Kompressen. Trotz nachweislich heilungshemmender Eigenschaften gegenüber modernen Wundauflagen sind die konventionellen Verfahren noch weit verbreitet. Demgegenüber bildet heute das Prinzip der feuchten Wundheilung die Grundlage der modernen differenzierten Wundtherapie. Vor diesem Hintergrund wurde in den letzten Jahren eine fast unüberschaubare Zahl moderner Verbandssysteme etabliert. Da nicht jede Wundauflage für jeden Wundtyp gleichermaßen geeignet ist, erfordert die Auswahl der im jeweiligen Fall geeignetsten Wundauflage die Kenntnis der verfügbaren modernen Wundverbände: in der Exsudations-/Reinigungsphase sind primär Polyurethanschaumstoffe, Alginate und aktivkohlehaltige Wundauflagen indiziert, die phasenübergreifend auch noch in der Granulationsphase Anwendung finden. Die Granulationsphase ist Hauptindikation für Hydrokolloide und Hydrogele. Diese werden neben nichthaftenden Wundauflagen und Alginaten auch in der Epithelisierungsphase eingesetzt. Neben den genannten synthetischen Wundauflagen halten zunehmend auch Zytokine und biologische Hautäquivalente Einzug in die moderne Wundtherapie. Biologische Hautäquivalente umfassen Epidermisäquivalente, Dermissubstitute und in neuerer Entwicklung befindliche kombinierte Epidermis-Dermisäquivalente. Diese führen möglicherweise zu einer noch höheren Effektivität beim Wundverschluß. Der phasenadaptierte Einsatz moderner Wundverbände ermöglicht meist eine rasche und komplikationslose Heilung von akuten und chronischen Wunden der Haut. Der Stellenwert von Zytokinen und neuerer vitaler Hautsubstitute wird derzeit klinisch geprüft, wobei sich interessante Möglichkeiten in der weiteren Verbesserung der Wundbehandlung bieten.

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Journal articles on the topic 'Hydrogele'

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