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Xu, Bo, Yuwei Liu, Lanlan Wang, Xiaodong Ge, Min Fu, Ping Wang e Qiang Wang. "High-Strength Nanocomposite Hydrogels with Swelling-Resistant and Anti-Dehydration Properties". Polymers 10, n.º 9 (14 de setembro de 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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Burchak, Vadym, Fritz Koch, Leonard Siebler, Sonja Haase, Verena K. Horner, Xenia Kempter, G. Björn Stark et al. "Evaluation of a Novel Thiol–Norbornene-Functionalized Gelatin Hydrogel for Bioprinting of Mesenchymal Stem Cells". International Journal of Molecular Sciences 23, n.º 14 (19 de julho de 2022): 7939. http://dx.doi.org/10.3390/ijms23147939.
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Introduction: Three-dimensional bioprinting can be considered as an advancement of the classical tissue engineering concept. For bioprinting, cells have to be dispersed in hydrogels. Recently, a novel semi-synthetic thiolene hydrogel system based on norbornene-functionalized gelatin (GelNB) and thiolated gelatin (GelS) was described that resulted in the photoclick hydrogel GelNB/GelS. In this study, we evaluated the printability and biocompatibility of this hydrogel system towards adipose-tissue-derived mesenchymal stem cells (ASCs). Methods: GelNB/GelS was synthesized with three different crosslinking densities (low, medium and high), resulting in different mechanical properties with moduli of elasticity between 206 Pa and 1383 Pa. These hydrogels were tested for their biocompatibility towards ASCs in terms of their viability, proliferation and differentiation. The extrusion-based bioprinting of ASCs in GelNB/GelS-high was performed to manufacture three-dimensional cubic constructs. Results: All three hydrogels supported the viability, proliferation and chondrogenic differentiation of ASCs to a similar extent. The adipogenic differentiation of ASCs was better supported by the softer hydrogel (GelNB/GelS-low), whereas the osteogenic differentiation was more pronounced in the harder hydrogel (GelNB/GelS-high), indicating that the differentiation fate of ASCs can be influenced via the adaption of the mechanical properties of the GelNB/GelS system. After the ex vivo chondrogenic differentiation and subcutaneous implantation of the bioprinted construct into immunocompromised mice, the production of negatively charged sulfated proteoglycans could be observed with only minimal inflammatory signs in the implanted material. Conclusions: Our results indicate that the GelNB/GelS hydrogels are very well suited for the bioprinting of ASCs and may represent attractive hydrogels for subsequent in vivo tissue engineering applications.
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Naficy, Sina, Hugh R. Brown, Joselito M. Razal, Geoffrey M. Spinks e Philip G. Whitten. "Progress Toward Robust Polymer Hydrogels". Australian Journal of Chemistry 64, n.º 8 (2011): 1007. http://dx.doi.org/10.1071/ch11156.
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In this review we highlight new developments in tough hydrogel materials in terms of their enhanced mechanical performance and their corresponding toughening mechanisms. These mechanically robust hydrogels have been developed over the past 10 years with many now showing mechanical properties comparable with those of natural tissues. By first reviewing the brittleness of conventional synthetic hydrogels, we introduce each new class of tough hydrogel: homogeneous gels, slip-link gels, double-network gels, nanocomposite gels and gels formed using poly-functional crosslinkers. In each case we provide a description of the fracture process that may be occurring. With the exception of double network gels where the enhanced toughness is quite well understood, these descriptions remain to be confirmed. We also introduce material property charts for conventional and tough synthetic hydrogels to illustrate the wide range of mechanical and swelling properties exhibited by these materials and to highlight links between these properties and the network topology. Finally, we provide some suggestions for further work particularly with regard to some unanswered questions and possible avenues for further enhancement of gel toughness.
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Bhuyan, Md Murshed, e Jae-Ho Jeong. "Gels/Hydrogels in Different Devices/Instruments—A Review". Gels 10, n.º 9 (23 de agosto de 2024): 548. http://dx.doi.org/10.3390/gels10090548.
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Owing to their physical and chemical properties and stimuli-responsive nature, gels and hydrogels play vital roles in diverse application fields. The three-dimensional polymeric network structure of hydrogels is considered an alternative to many materials, such as conductors, ordinary films, constituent components of machines and robots, etc. The most recent applications of gels are in different devices like sensors, actuators, flexible screens, touch panels, flexible storage, solar cells, batteries, and electronic skin. This review article addresses the devices where gels are used, the progress of research, the working mechanisms of hydrogels in those devices, and future prospects. Preparation methods are also important for obtaining a suitable hydrogel. This review discusses different methods of hydrogel preparation from the respective raw materials. Moreover, the mechanism by which gels act as a part of electronic devices is described.
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Shoukat, Hina, Fahad Pervaiz e Sobia Noreen. "Novel Crosslinking Methods to Design Hydrogels". Global Pharmaceutical Sciences Review I, n.º I (30 de dezembro de 2016): 1–5. http://dx.doi.org/10.31703/gpsr.2016(i-i).01.
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Hydrogels are presently under consideration as matrices for the controlled bioactive molecules delivery particularly proteins and for living cells encapsulation. For these applications, gels must undergo degradation under physiological conditions. This overview summarized and discussed the various physical and chemical crosslinking methods to design hydrogels that are biodegradable. Highly versatile method to prepare hydrogels with good mechanical stability is chemical crosslinking. However, the crosslinker employed can give undesirable reactions with the bioactive substances present in the hydrogel matrix and are often toxic. So, it required to be removed from the gels before application. Physically crosslinked gels can be developed to overcome these adverse effects. Distortion due to variations in environmental conditions like presence of solute particles, ionic strength, pH, temperature and stress are the major disadvantages of reversible gels
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Li, Peng, Nam Hoon Kim, Sambhu Bhadra e Joong Hee Lee. "Electroresponsive Property of Novel Poly(acrylate- acryloyloxyethyl trimethyl ammonium chloride)/Clay Nanocomposite Hydrogels". Advanced Materials Research 79-82 (agosto de 2009): 2263–66. http://dx.doi.org/10.4028/www.scientific.net/amr.79-82.2263.
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The poly(acrylate-acryloyloxyethyl trimethyl ammonium chloride)/clay nanocomposite hydrogels (poly(AAc-DAc)/clay NC gels) with different clay contents were prepared by using clay as a cross-linker. The hydrogel exhibited good electroresponsive property and excellent mechanical property. The hydrogels initially bent toward the cathode side followed by anode side under an electric field. Concentrations of NaCl solution, voltage of electric field and clay content of the hydrogels have significant effects on the electroresponsive property of the hydrogels. Clay exhibited two opposite effects on the electroresponsive property of NC gels.
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Gorantla, Srividya, Tejashree Waghule, Vamshi Krishna Rapalli, Prem Prakash Singh, Sunil Kumar Dubey, Ranendra Narayan Saha e Gautam Singhvi. "Advanced Hydrogels Based Drug Delivery Systems for Ophthalmic Delivery". Recent Patents on Drug Delivery & Formulation 13, n.º 4 (29 de abril de 2020): 291–300. http://dx.doi.org/10.2174/1872211314666200108094851.
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Hydrogels are aqueous gels composed of cross-linked networks of hydrophilic polymers. Stimuli-responsive based hydrogels have gained focus over the past 20 years for treating ophthalmic diseases. Different stimuli-responsive mechanisms are involved in forming polymer hydrogel networks, including change in temperature, pH, ions, and others including light, thrombin, pressure, antigen, and glucose-responsive. Incorporation of nanocarriers with these smart stimuli-responsive drug delivery systems that can extend the duration of action by increasing ocular bioavailability and reducing the dosing frequency. This review will focus on the hydrogel drug delivery systems highlighting the gelling mechanisms and emerging stimuli-responsive hydrogels from preformed gels, nanogels, and the role of advanced 3D printed hydrogels in vision-threatening diseases like age-related macular degeneration and retinitis pigmentosa. It also provides insight into the limitations of hydrogels along with the safety and biocompatibility of the hydrogel drug delivery systems.
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O’Connor, Naphtali A., Abdulhaq Syed, Madeline Wong, Josiah Hicks, Greisly Nunez, Andrei Jitianu, Zach Siler e Marnie Peterson. "Polydopamine Antioxidant Hydrogels for Wound Healing Applications". Gels 6, n.º 4 (31 de outubro de 2020): 39. http://dx.doi.org/10.3390/gels6040039.
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Antioxidants are known to improve the wound healing process and are researched as a therapeutic strategy to treat chronic wounds. Dopamine is a known neurotransmitter with antioxidant properties that can be polymerized to form polydopamine (PDA). Herein, polydopamine is demonstrated as an antioxidant biomaterial. In prior work, we developed methodology to prepare hydrogels by crosslinking polysaccharides with polyamines via epichlorohydrin and NaOH. Using this previously developed methodology, dextran hydrogels crosslinked with polydopamine were prepared. Darkening of the gels indicated the increasing incorporation of polydopamine within the hydrogels. In addition to basic pH, polydopamine can be formed by reaction with polyethylene imine (PEI), which results in PEI-PDA copolymer. Dextran was similarly crosslinked with the PEI-PDA copolymer and resulted in sturdier, darker gels, which had more polydopamine incorporated. Hydrogel morphology and strength were dependent on the feed ratios of dopamine. Antioxidant activity of polydopamine containing hydrogel was confirmed and shown to be dependent on the amount of dopamine used in hydrogel synthesis. Hydrogels with 0.5 dopamine to dextran feed ratio scavenged 78.8% of radicals in a 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) antioxidant assay while gels with no dopamine scavenged only 1.4% of radicals. An ex vivo wound healing assay showed considerable cell migration with the PEI-PDA containing hydrogel.
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Fallon, Halligan, Pezzoli, Geever e Higginbotham. "Synthesis and Characterisation of Novel Temperature and pH Sensitive Physically Cross-Linked Poly (N-vinylcaprolactam-co-itaconic Acid) Hydrogels for Drug Delivery". Gels 5, n.º 3 (29 de agosto de 2019): 41. http://dx.doi.org/10.3390/gels5030041.
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Previous studies involving poly N-vinylcaprolactam (PNVCL) and itaconic acid (IA) have synthesised the hydrogels with the presence of a solvent and a crosslinker, producing chemically crosslinked hydrogel systems. In this study, however, temperature sensitive PNVCL was physically crosslinked with a pH-sensitive comonomer IA through ultraviolet (UV) free-radical polymerization, without the presence of a solvent, to produce hydrogels with dual sensitivity. The attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy indicated successful polymerisation of the hydrogels. The temperature and pH sensitivity of the hydrogels was investigated. The lower critical solution temperature (LCST) of the gels was determined using the UV spectrometry and it was found that the incorporation of IA decreased the LCST. Rheology was conducted to investigate the mechanical and viscoelastic properties of the hydrogels, with results indicating IA that enhances the mechanical properties of the gels. Swelling studies were carried out at ~20 °C and 37 °C in different buffer solutions simulating the gastrointestinal tract (pH 2.2 and pH 6.8). In acidic conditions, the gels showed gradual increase in swelling while remaining structurally intact. While in basic conditions, the gels had a burst in swelling and began to gradually degrade after 30 min. Results were similar for drug release studies. Acetaminophen was incorporated into the hydrogels. Drug dissolution studies were carried out at 37 °C in pH 2.2 and pH 6.8. It was found that <20% of acetaminophen was released from the gels in pH 2.2, whereas the maximum drug released at pH 6.8 was 74%. Cytotoxicity studies also demonstrated the hydrogels to be highly biocompatible. These results indicate that physically crosslinked P(NVCL-IA) gels possess dual pH and temperature sensitive properties, which may be beneficial for biomedical applications such as drug delivery.
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Seida, Yoshimi, e Hideaki Tokuyama. "Hydrogel Adsorbents for the Removal of Hazardous Pollutants—Requirements and Available Functions as Adsorbent". Gels 8, n.º 4 (3 de abril de 2022): 220. http://dx.doi.org/10.3390/gels8040220.
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Over the last few decades, various adsorption functions of polymer hydrogels for the removal of hazardous pollutants have been developed. The performance of hydrogel adsorbents depends on the constituents of the gels and the functions produced by the polymer networks of the gels. Research on hydrogels utilizing the characteristic functions of polymer networks has increased over the last decade. The functions of polymer networks are key to the development of advanced adsorbents for the removal of various pollutants. No review has discussed hydrogel adsorbents from the perspective of the roles and functions of polymer networks in hydrogels. This paper briefly reviews the basic requirements of adsorbents and the general characteristics of hydrogels as adsorbents. Thereafter, hydrogels are reviewed on the basis of the roles and functions of the polymer networks in them for the removal of hazardous pollutants by introducing studies published over the last decade. The application of hydrogels as adsorbents for the removal of hazardous pollutants is discussed as well.
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Kaberova, Zhansaya, Evgeny Karpushkin, Martina Nevoralová, Miroslav Vetrík, Miroslav Šlouf e Miroslava Dušková-Smrčková. "Microscopic Structure of Swollen Hydrogels by Scanning Electron and Light Microscopies: Artifacts and Reality". Polymers 12, n.º 3 (5 de março de 2020): 578. http://dx.doi.org/10.3390/polym12030578.
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The exact knowledge of hydrogel microstructure, mainly its pore topology, is a key issue in hydrogel engineering. For visualization of the swollen hydrogels, the cryogenic or high vacuum scanning electron microscopies (cryo-SEM or HVSEM) are frequently used while the possibility of artifact-biased images is frequently underestimated. The major cause of artifacts is the formation of ice crystals upon freezing of the hydrated gel. Some porous hydrogels can be visualized with SEM without the danger of artifacts because the growing crystals are accommodated within already existing primary pores of the gel. In some non-porous hydrogels the secondary pores will also not be formed due to rigid network structure of gels that counteracts the crystal nucleation and growth. We have tested the limits of true reproduction of the hydrogel morphology imposed by the swelling degree and mechanical strength of gels by investigating a series of methacrylate hydrogels made by crosslinking polymerization of glycerol monomethacrylate and 2-hydroxyethyl methacrylate including their interpenetrating networks. The hydrogel morphology was studied using cryo-SEM, HVSEM, environmental scanning electron microscopy (ESEM), laser scanning confocal microscopy (LSCM) and classical wide-field light microscopy (LM). The cryo-SEM and HVSEM yielded artifact-free micrographs for limited range of non-porous hydrogels and for macroporous gels. A true non-porous structure was observed free of artifacts only for hydrogels exhibiting relatively low swelling and high elastic modulus above 0.5 MPa, whereas for highly swollen and/or mechanically weak hydrogels the cryo-SEM/HVSEM experiments resulted in secondary porosity. In this contribution we present several cases of severe artifact formation in PHEMA and PGMA hydrogels during their visualization by cryo-SEM and HVSEM. We also put forward empirical correlation between hydrogel morphological and mechanical parameters and the occurrence and intensity of artifacts.
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Feng, Huanhuan, Tingting Zheng, Xuezhen Wang e Huiliang Wang. "Poly(acrylamide)-MWNTs hybrid hydrogel with extremely high mechanical strength". Open Chemistry 14, n.º 1 (1 de janeiro de 2016): 150–57. http://dx.doi.org/10.1515/chem-2016-0017.
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AbstractPoly(acrylamide)-multiwalled carbon nanotubes (PAAm-MWNTs) hybrid hydrogels were prepared through the radiation-induced polymerization and crosslinking of the aqueous solution of acrylamide and well-dispersed MWNTs for the first time. The PAAm gels obtained by the radiation-induced polymerization and cosslinking showed very high mechanical strengths, and the PAAm-MWNTs hybrid hydrogels had improved mechanical properties compared with the PAAm gels, and hence the PAAm-MWNTs hybrid hydrogels showed extremely high compressive and tensile strengths. The hybrid hydrogels with water contents more than 80 wt.% usually did not fracture even at compressive strengths close to or even more than 60 MPa and strains more than 97%. And the hybrid hydrogels had very high elongations (more than 2000% in some cases), especially when the water content was high. The tensile strengths were in sub-MPa. The hybrid PAAm-MWNTs hydrogel is one of the strongest hydrogel even made.
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Chen, Miao, Weimin Lin, Le Hong, Ning Ji e Hang Zhao. "The Development and Lifetime Stability Improvement of Guanosine-Based Supramolecular Hydrogels through Optimized Structure". BioMed Research International 2019 (13 de junho de 2019): 1–18. http://dx.doi.org/10.1155/2019/6258248.
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Guanosine is an important building block for supramolecular gels owing to the unique self-assembly property that results from the unique hydrogen bond acceptors and donor groups. Guanosine-derived supramolecular hydrogels have promise in the fields of drug delivery, targeted release, tissue engineering applications,etc.However, the property of poor longevity and the need for excess cations hinder the widespread applications of guanosine hydrogels. Although guanosine-derived supramolecular hydrogels have been reviewed previously by Dash et al., the structural framework of this review is different, as the modification of guanosine is described at the molecular level. In this review, we summarize the development and lifetime stability improvement of guanosine-based supramolecular hydrogels through optimized structure and elaborate on three aspects: sugar modification, base modification, and binary gels. Additionally, we introduce the concept and recent research progress of self-healing gels, providing inspiration for the development of guanosine-derived supramolecular hydrogels with longer lifespans, unique physicochemical properties, and biological activities.
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Sun, Hong, Tao Wu, Yong Qiang He, Qiao Juan Gong, Jian Ping Gao e Yu Liu. "Fabrication of Stable PVA/PVP Hydrogels". Advanced Materials Research 815 (outubro de 2013): 321–24. http://dx.doi.org/10.4028/www.scientific.net/amr.815.321.
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PVA hydrogel has been used in the field of cartilage replacement in recent year. In order to improve the water-keeping ability of PVA gel and mechanical property, PVP was introduced into PVA and crosslinked by adding ammonium persulfate to form a composite gel. The crosslinkage of the gel was identified, and the effect of PVP and ammonium persulfate amount on the composite gel was studied. The crosslinkage, the degree of swelling and the compress stress of the composite gels have been tested. UV analysis was used to investigate the release of PVP from the composite gels. The dried composite gels were put into water to investigate the degree and velocity of the rehydration of different composite gels.
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Cui, Wei, Ting Li, Hang Li, Le Min Zhu, Huan Liu e Rong Ran. "Investigation of Mechanical Properties and Dye Adsorption Capacities of Novel Hydrophobic Association Nanocomposite Hydrogels". Materials Science Forum 815 (março de 2015): 568–75. http://dx.doi.org/10.4028/www.scientific.net/msf.815.568.
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The preparation of high performance hydrogels has always been one of the research focuses in the area of soft matters and functional polymers. In this paper, a facile method was developed for the preparation of high performance hydrophobic association nanocomposite hydrogels (HANC gels) via in situ copolymerization of acrylamide (AM) and octadecyl methacrylate (OMA) in the aqueous suspension of hectorite clay Laponite HZ-200 (clay) with sodium dodecyl benzene sulfonate (SDBS). Tensile hysteresis curves showed that the hysteresis degrees between HANC gels and conventional hydrophobic association hydrogels (HA gels) were almost the same, but the tensile strength of the HANC gel reinforced by just 0.4 wt% clay at the strain of 1500% was already as 630% as the strength of the HA gel, which indicated that the mechanical properties of the HA gel were greatly enhanced by the introduction of a small amount of clay without increasing the internal friction in the hydrogel network. The effects of clay on the structure of HANC gels were further confirmed by swelling test, it was found that the addition of clay effectively maintained the structural integrity of HANC gels in watery environment and prevented the collapse of gel network. Moreover, HANC gels exhibited superior cationic dye adsorption capacity compared to HA gels due to the existence of abundant negative charges on the surfaces of clay nanosheets
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Singh, Aditya Narayan, Abhishek Meena e Kyung-Wan Nam. "Gels in Motion: Recent Advancements in Energy Applications". Gels 10, n.º 2 (2 de fevereiro de 2024): 122. http://dx.doi.org/10.3390/gels10020122.
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Gels are attracting materials for energy storage technologies. The strategic development of hydrogels with enhanced physicochemical properties, such as superior mechanical strength, flexibility, and charge transport capabilities, introduces novel prospects for advancing next-generation batteries, fuel cells, and supercapacitors. Through a refined comprehension of gelation chemistry, researchers have achieved notable progress in fabricating hydrogels endowed with stimuli-responsive, self-healing, and highly stretchable characteristics. This mini-review delineates the integration of hydrogels into batteries, fuel cells, and supercapacitors, showcasing compelling instances that underscore the versatility of hydrogels, including tailorable architectures, conductive nanostructures, 3D frameworks, and multifunctionalities. The ongoing application of creative and combinatorial approaches in functional hydrogel design is poised to yield materials with immense potential within the domain of energy storage.
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Wu, Shuping, Chao Xu, Yiran Zhao, Weijian Shi, Hao Li, Jiawei Cai, Fuyuan Ding e Ping Qu. "Recent Advances in Chitosan-Based Hydrogels for Flexible Wearable Sensors". Chemosensors 11, n.º 1 (3 de janeiro de 2023): 39. http://dx.doi.org/10.3390/chemosensors11010039.
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Flexible wearable sensors show great potential for applications in wearable devices, remote health monitoring, artificial intelligence, soft robotics, and artificial skin due to their stretchability, bendability, thinness and portability, and excellent electrical properties. Hydrogels have tunable mechanical properties, excellent biocompatibility, and flexibility, making them attractive candidates for wearable flexible sensors. Among them, tremendous efforts have focused on the advancement of chitosan-based hydrogels (CS-Gels) to realize multifunctional wearable sensing by modifying hydrogel networks with additives/nanofillers/functional groups. Recently, remarkable progress has been made in flexible wearable sensors. Herein, this review summarizes recent advances in CS-Gels wearable sensors for applications such as human motion monitoring, health monitoring, human-machine interface and soft robotics. Representative synthesis methods and strategies for CS-Gels are briefly described, the problems and deficiencies of CS-Gels for wearable sensors are discussed. Finally, the possible opportunities and challenges for the future development of CS-Gels flexible wearable devices are proposed.
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Fekete, Erika, e Emília Csiszár. "Chitosan–Alginate Gels for Sorption of Hazardous Materials: The Effect of Chemical Composition and Physical State". International Journal of Molecular Sciences 25, n.º 15 (1 de agosto de 2024): 8406. http://dx.doi.org/10.3390/ijms25158406.
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Chitosan, alginate, and chitosan–alginate (50:50) mixed hydrogels were prepared by freeze casting, freeze-drying, and subsequent physical cross-linking. Chitosan was cross-linked with citrate and alginate with calcium ions, while the mixed gels were cross-linked with both cross-linking agents. Both cryogels and xerogels were obtained by lyophilization and drying of the hydrogels. We investigated the effect of the chemical composition and the physical state of gels on the gel structure and sorption of model dyes. Alginate and mixed gels cross-linked with Ca2+ ions sorbed 80–95% of cationic dye from the solutions. The chitosan gels are primarily capable of adsorbing anionic dyes, but at near-neutral pH, their capacity is lower than that of alginate gels, showing 50–60% dye sorption. In the case of alginate gels, the dye sorption capacity of xerogels, cryogels, and hydrogels was the same, but for chitosan gels, the hydrogels adsorbed slightly less dye than the dried gels.
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Popeyko, O. V., e E. I. Istomina. "Preparation and Properties of Hydrogel Matrices based on Pectins from Callus Cultures". Biotekhnologiya 36, n.º 3 (2020): 63–72. http://dx.doi.org/10.21519/0234-2758-2020-36-3-63-72.
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Hydrogel matrices have been obtained from pectins of Silene vulgaris (SVC), Tanacetum vulgare (TVC) and Lemna minor (LMC) callus cultures, and from apple pectin (AU701). They differed in gel strength, calcium ion content and surface morphology. During the incubation under simulated gastric conditions (pH 1.25), the gel strength and calcium content decreased. The degradation degree of hydrogels grew in the range TVC < SVC < LMC < AU701. The degradation degree of hydrogels from the SVC, LMC, and TVC pectins gradually increased over 4 hours, while hydrogels from the AU701 pectin were destroyed within 2 hours. The gels prepared from pectins with low methyl esterification, low branching and high linearity underwent less degradation. The TVC pectin gels had the highest strength and were most stable at pH 1.25. The data obtained can be used to produce hydrogel matrices with desired physicochemical and functional properties. callus culture, pectin polysaccharides, hydrogels, gastric medium
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Chippada, Uday, Bernard Yurke e Noshir A. Langrana. "Simultaneous determination of Young's modulus, shear modulus, and Poisson's ratio of soft hydrogels". Journal of Materials Research 25, n.º 3 (março de 2010): 545–55. http://dx.doi.org/10.1557/jmr.2010.0067.
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Besides biological and chemical cues, cellular behavior has been found to be affected by mechanical cues such as traction forces, surface topology, and in particular the mechanical properties of the substrate. The present study focuses on completely characterizing the bulk linear mechanical properties of such soft substrates, a good example of which are hydrogels. The complete characterization involves the measurement of Young's modulus, shear modulus, and Poisson's ratio of these hydrogels, which is achieved by manipulating nonspherical magnetic microneedles embedded inside them. Translating and rotating these microneedles under the influence of a known force or torque, respectively, allows us to determine the local mechanical properties of the hydrogels. Two specific hydrogels, namely bis-cross-linked polyacrylamide gels and DNA cross-linked polyacrylamide gels were used, and their properties were measured as a function of gel concentration. The bis-cross-linked gels were found to have a Poisson's ratio that varied between 0.38 and 0.49, while for the DNA-cross-linked gels, Poisson's ratio varied between 0.36 and 0.49. The local shear moduli, measured on the 10 μm scale, of these gels were in good agreement with the global shear modulus obtained from a rheology study. Also the local Young's modulus of the hydrogels was compared with the global modulus obtained using bead experiments, and it was observed that the inhomogeneities in the hydrogel increases with increasing cross-linker concentration. This study helps us fully characterize the properties of the substrate, which helps us to better understand the behavior of cells on these substrates.
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Skopinska-Wisniewska, Joanna, Silvia De la Flor e Justyna Kozlowska. "From Supramolecular Hydrogels to Multifunctional Carriers for Biologically Active Substances". International Journal of Molecular Sciences 22, n.º 14 (9 de julho de 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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Mahmood, Ayaz, Dev Patel, Brandon Hickson, John DesRochers e Xiao Hu. "Recent Progress in Biopolymer-Based Hydrogel Materials for Biomedical Applications". International Journal of Molecular Sciences 23, n.º 3 (26 de janeiro de 2022): 1415. http://dx.doi.org/10.3390/ijms23031415.
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Hydrogels from biopolymers are readily synthesized, can possess various characteristics for different applications, and have been widely used in biomedicine to help with patient treatments and outcomes. Polysaccharides, polypeptides, and nucleic acids can be produced into hydrogels, each for unique purposes depending on their qualities. Examples of polypeptide hydrogels include collagen, gelatin, and elastin, and polysaccharide hydrogels include alginate, cellulose, and glycosaminoglycan. Many different theories have been formulated to research hydrogels, which include Flory-Rehner theory, Rubber Elasticity Theory, and the calculation of porosity and pore size. All these theories take into consideration enthalpy, entropy, and other thermodynamic variables so that the structure and pore sizes of hydrogels can be formulated. Hydrogels can be fabricated in a straightforward process using a homogeneous mixture of different chemicals, depending on the intended purpose of the gel. Different types of hydrogels exist which include pH-sensitive gels, thermogels, electro-sensitive gels, and light-sensitive gels and each has its unique biomedical applications including structural capabilities, regenerative repair, or drug delivery. Major biopolymer-based hydrogels used for cell delivery include encapsulated skeletal muscle cells, osteochondral muscle cells, and stem cells being delivered to desired locations for tissue regeneration. Some examples of hydrogels used for drug and biomolecule delivery include insulin encapsulated hydrogels and hydrogels that encompass cancer drugs for desired controlled release. This review summarizes these newly developed biopolymer-based hydrogel materials that have been mainly made since 2015 and have shown to work and present more avenues for advanced medical applications.
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Marrale, Maurizio, e Francesco d’Errico. "Hydrogels for Three-Dimensional Ionizing-Radiation Dosimetry". Gels 7, n.º 2 (21 de junho de 2021): 74. http://dx.doi.org/10.3390/gels7020074.
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Radiation-sensitive gels are among the most recent and promising developments for radiation therapy (RT) dosimetry. RT dosimetry has the twofold goal of ensuring the quality of the treatment and the radiation protection of the patient. Benchmark dosimetry for acceptance testing and commissioning of RT systems is still based on ionization chambers. However, even the smallest chambers cannot resolve the steep dose gradients of up to 30–50% per mm generated with the most advanced techniques. While a multitude of systems based, e.g., on luminescence, silicon diodes and radiochromic materials have been developed, they do not allow the truly continuous 3D dose measurements offered by radiation-sensitive gels. The gels are tissue equivalent, so they also serve as phantoms, and their response is largely independent of radiation quality and dose rate. Some of them are infused with ferrous sulfate and rely on the radiation-induced oxidation of ferrous ions to ferric ions (Fricke-gels). Other formulations consist of monomers dispersed in a gelatinous medium (Polyacrylamide gels) and rely on radiation-induced polymerization, which creates a stable polymer structure. In both gel types, irradiation causes changes in proton relaxation rates that are proportional to locally absorbed dose and can be imaged using magnetic resonance imaging (MRI). Changes in color and/or opacification of the gels also occur upon irradiation, allowing the use of optical tomography techniques. In this work, we review both Fricke and polyacrylamide gels with emphasis on their chemical and physical properties and on their applications for radiation dosimetry.
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Liu, Chang, Naoya Morimoto, Lan Jiang, Sohei Kawahara, Takako Noritomi, Hideaki Yokoyama, Koichi Mayumi e Kohzo Ito. "Tough hydrogels with rapid self-reinforcement". Science 372, n.º 6546 (3 de junho de 2021): 1078–81. http://dx.doi.org/10.1126/science.aaz6694.
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Most tough hydrogels are reinforced by introducing sacrificial structures that can dissipate input energy. However, because the sacrificial damage cannot rapidly recover, the toughness of these gels drops substantially during consecutive cyclic loadings. We propose a damageless reinforcement strategy for hydrogels using strain-induced crystallization. For slide-ring gels in which polyethylene glycol chains are highly oriented and mutually exposed under large deformation, crystallinity forms and melts with elongation and retraction, resulting both in almost 100% rapid recovery of extension energy and excellent toughness of 6.6 to 22 megajoules per cubic meter, which is one order of magnitude larger than the toughness of covalently cross-linked homogeneous gels of polyethylene glycol.
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Arshad, Anam, Khadija Fakhar, Intsaf Usman Lodhi, Khadija Haroon e Rameen Khurram. "Gradient Gels: Exploring Diverse Starch Concentrations in Hydrogel Formulations". Summer 2023 VIII, n.º III (30 de outubro de 2022): 24–32. http://dx.doi.org/10.31703/gpsr.2023(viii-iii).03.
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Starch hydrogels can be used for both drug formulation and delivery; they have attracted a lot of interest in the pharmaceutical dispensing industry. Four pharmacy students were tasked with creating starch hydrogels in this study, with different concentrations (2%, 4%, 5%, and 10%) to see how concentration affected the hydrogels' chemical and physical characteristics. The goal of this study was to provide important new information about how to optimise starch hydrogel formulations for use in medicine. The students gained an understanding of how concentration affects properties like viscosity, mechanical strength, and transparency by methodically studying these important variables. Furthermore, the investigation examined the impact of environmental variables like pH and temperature on the stability and functionality of the starch hydrogels.
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Chen, Yi, Yueyun Zhou, Wenyong Liu, Hejie Pi e Guangsheng Zeng. "POSS Hybrid Robust Biomass IPN Hydrogels with Temperature Responsiveness". Polymers 11, n.º 3 (20 de março de 2019): 524. http://dx.doi.org/10.3390/polym11030524.
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In order to improve the performance of traditional sodium alginate (SA) hydrogels cross-linked by Ca2+ ions to meet greater application demand, a strategy was designed to structure novel SA-based gels (named OP-PN gels) to achieve both stimulus responsiveness and improved mechanical strength. In this strategy, the SA chains are co-cross-linked by CaCl2 and cationic octa-ammonium polyhedral oligomeric silsesquioxane (Oa-POSS) particles as the first network, and an organically cross-linked poly(N-isopropyl acrylamide) (PNIPA) network is introduced into the gels as the second network. Several main results are obtained from the synthesis and characterization of the gels. For OP-PN gels, their properties depend on the content of both uniformly dispersed Oa-POSS and PNIPA network directly. The increased Oa-POSS and PNIPA network content significantly improves both the strength and resilience of gels. Relatively, the increased Oa-POSS is greatly beneficial to the modulus of gels, and the increased PNIPA network is more favorable to advancing the tensile deformation of gels. The gels with hydrophilic PNIPA network exhibit better swelling ability and remarkable temperature responsiveness, and their volume phase transition temperature can be adjusted by altering the content of Oa-POSS. The deswelling rate of gels increases gradually with the increase of POSS content due to the hydrophobic Si–O skeleton of POSS. Moreover, the enhanced drug loading and sustained release ability of the target drug bovine serum albumin displays great potential for this hybrid gel in the biomedical field.
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Tokuyama, Hideaki. "Development of Emulsion Gels and Macroporous Hydrogels and their Applications to Metal Adsorption and Enzyme Reaction". Advanced Materials Research 1112 (julho de 2015): 141–44. http://dx.doi.org/10.4028/www.scientific.net/amr.1112.141.
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Emulsion gels, that is, hydrogels containing randomly distributed oil microdroplets, and macroporous hydrogels with randomly distributed, non-interconnected, sphere-like macropores with several micrometers in diameter were prepared by the emulsion-gelation method [1]. This method involves the synthesis of hydrogels in an oil-in-water (O/W) emulsion by free radical copolymerization of a monomer with a cross-linker, followed by the washing (removal) of the dispersed oil as a pore template (porogen). The observations of oil droplets in an emulsion and internal structure of a macroporous hydrogel demonstrate that the oil droplets act as a pore-template. The pore size and porosity can be adjusted by varying the O/W volume ratios and surfactant amounts [2]. These gels are used as a bulk and have excellent diffusional permeability to a solute and solvent. The emulsion-gelation method can yield potentially intelligent gels in which the macropores function as spaces for reaction, separation and storage. Novel emulsion gel adsorbents, that is, polymeric hydrogels containing randomly distributed microdroplets of an organic extractant (an oil-soluble complexing agent), were developed for metal adsorption [3,4]. The emulsion gel containing an organophosphorus extractant and organosulfur extractant successfully adsorbed In (III) and Pd (II) ions, respectively. Novel macroporous polymeric hydrogels were developed to entrap and immobilize lipase as a model enzyme [5]. The lipase immobilized within the macroporous hydrogel successfully catalyzed the hydrolysis of triacetin in a model enzyme reaction without leakage of lipase or loss of activity during repeated use.
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Bhattacharya, Dipsikha, Lipika Ray, Panchanan Pramanik e Jitendra Kumar Pandey. "Recent Advances in Various Inorganic Nanoparticle Embedded Chitosan-based Multifunctional Materials for Wound Healing". Current Nanomedicine 13, n.º 2 (julho de 2023): 75–90. http://dx.doi.org/10.2174/2468187313666230816095330.
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Abstract: Scarless wound management remains a clinical challenge worldwide because of its com-plicated and overlapping phases of inflammation, clearing, and regeneration. Among the currently available dressing materials, hydrogels have attracted emerging attention as potential wound dress-ing materials because of their specific properties, such as porosity, tissue-mimicking architecture, softness, and improved mechanical, biological as well as physicochemical properties. However, naturally driven hydrogels have shown several advantages over conventional hydrogels because of their biodegradability, biocompatibility, high mechanical strength, and functionality. Recently, na-noparticle (NPs) integrated polymeric hydrogels (metals, non-metals, metal oxides, and polymeric moieties) have been established as analogous to these naturally driven hydrogels because of the synergistic effects of the NPs and polymers in the three-dimensional composite material. Over the years, researchers have reported the synthesis and potential applications of diverse inorganic and organic nanocomposite gels with antioxidant or antibacterial properties where they have exploited the intelligent incorporation of biomolecules into the NP-polymeric network that are beneficial for wound healing. Among various natural polymers as hydrogel matrix, chitosan-mediated hydrogel dressings have received extensive interest resulting in improved mechanical, biological, and physi-cochemical properties due to the well-reported antibacterial, antitumor, antioxidant, and tissue re-generation efficacies of chitosan polymer. This review is intended to summarize the recent devel-opments of inorganic nanoparticle-incorporated chitosan-based hydrogels as wound dressing mate-rials where various synthetic methodologies of these nanocomposite gels are extensively discussed via incorporating nanoparticles, active biomolecules, and other substances into the intrinsic struc-ture of the gels. In addition, the future and prospects of chitosan-based nanocomposite hydrogels as a novel wound dressing as well as tissue engineering materials are also highlighted.
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Gourdie, Robert G., Tereance A. Myers, Alex McFadden, Yin-xiong Li e Jay D. Potts. "Self-Organizing Tissue-Engineered Constructs in Collagen Hydrogels". Microscopy and Microanalysis 18, n.º 1 (4 de janeiro de 2012): 99–106. http://dx.doi.org/10.1017/s1431927611012372.
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AbstractA novel self-organizing behavior of cellularized gels composed of collagen type 1 that may have utility for tissue engineering is described. Depending on the starting geometry of the tissue culture well, toroidal rings of cells or hollow spheroids were prompted to form autonomously when cells were seeded onto the top of gels and the gels released from attachment to the culture well 12 to 24 h after seeding. Cells within toroids assumed distinct patterns of alignment not seen in control gels in which cells had been mixed in. In control gels, cells formed complex three-dimensional arrangements and assumed relatively higher levels of heterogeneity in expression of the fibronectin splice variant ED-A—a marker of epithelial mesenchymal transformation. The tissue-like constructs resulting from this novel self-organizing behavior may have uses in wound healing and regenerative medicine, as well as building blocks for the iterative assembly of synthetic biological structures.
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Du, Yu Zhang, Dai Di Fan, Xiao Xuan Ma, Chen Hui Zhu e Li Jun Zhang. "Covalently Crosslinked Human-Like Collagen Hydrogel: Properties of Biocompatibility". Advanced Materials Research 550-553 (julho de 2012): 1114–19. http://dx.doi.org/10.4028/www.scientific.net/amr.550-553.1114.
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In this paper, the cross-linking injection hydrogel were synthesized by EDC crosslinker and Carboxymethyl chitosan (CMCS)/Human-like collagen (HLC). Cytotoxicity was assessed by Methylthiazolydiphenyl-tetrazolium bromide (MTT) assay which indicated that the hydrogels was non-toxic to the BHK21 cell .Chondrocyct-encapsulation of this hydrogel were studied in order to asses the cells compatibility of the injection gel. The result showed that the material has no cytotoxicity to the cells and promoted cell adhesion and proliferation. Injected those hydrogels into mice subcutaneous , the following parameters were evaluated: inflammatory response, vascularization, new hypoderm generation. After 2,4,12,and 24 weeks of healing, the rats were sacrilifced suggested that gels in animals did not induce inflammation obvious, vessel bestrid the material after 4 weeks injection, new hypoderm generated in 12 weeks and packaged the hydrogels after 24 weeks. Consequently the gels are promised for the application in the biomaterials area.
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Dannert, Corinna, Bjørn Torger Stokke e Rita S. Dias. "Nanoparticle-Hydrogel Composites: From Molecular Interactions to Macroscopic Behavior". Polymers 11, n.º 2 (6 de fevereiro de 2019): 275. http://dx.doi.org/10.3390/polym11020275.
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Hydrogels are materials used in a variety of applications, ranging from tissue engineering to drug delivery. The incorporation of nanoparticles to yield composite hydrogels has gained substantial momentum over the years since these afford tailor-making and extend material mechanical properties far beyond those achievable through molecular design of the network component. Here, we review different procedures that have been used to integrate nanoparticles into hydrogels; the types of interactions acting between polymers and nanoparticles; and how these underpin the improved mechanical and optical properties of the gels, including the self-healing ability of these composite gels, as well as serving as the basis for future development. In a less explored approach, hydrogels have been used as dispersants of nanomaterials, allowing a larger exposure of the surface of the nanomaterial and thus a better performance in catalytic and sensor applications. Furthermore, the reporting capacity of integrated nanoparticles in hydrogels to assess hydrogel properties, such as equilibrium swelling and elasticity, is highlighted.
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Brunette, Margaret, Hal Holmes, Michael G. Lancina, Weilue He, Bruce P. Lee, Megan C. Frost e Rupak M. Rajachar. "Inducible nitric oxide releasing poly-(ethylene glycol)-fibrinogen adhesive hydrogels for tissue regeneration". MRS Proceedings 1569 (2013): 39–44. http://dx.doi.org/10.1557/opl.2013.797.
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ABSTRACTNitric oxide (NO) release can promote healthy tissue regeneration. A PEG-fibrinogen adhesive hydrogel that would allow for inducible NO release was created with mechanical properties that could be tailored to specific applications and tissue types. PEG (4-arm)-fibrinogen hydrogels of varying ratios were derivatized with S-nitroso-N-acetyl-D, L-penicillamine (SNAP)-thiolactone to create an active NO donor material. Controlled release from gels was established using light as the activating source, although temperature, pH, and external mechanical loading are also means to induce active NO release. Gels with varying ratios of fibrinogen to PEG were made, derivatized, and tested. Gels below a ratio of 1.5:1 (fibrinogen:PEG) did not gel, while at ratio of 1.5:1 gelation occurs and NO release can be induced. Interestingly, the release from 1.5:1 gels was significantly lower compared to 2:1 and 3:1 gel formulations. Rheometric data show that lower ratio gels are more elastic than viscous. Derivatized gels exhibited linear elastic moduli, behaving more like other more synthetic hydrogels. Swelling data indicates that as the ratio of fibrinogen to PEG increases the swelling ratio decreases, likely due to the hydrophobic nature of the NO donor. Cells remain viable on both derivatized and non-derivatized gels.
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Joubert, Fanny, Peyton Cheong Phey Denn, Yujie Guo e George Pasparakis. "Comparison of Thermoresponsive Hydrogels Synthesized by Conventional Free Radical and RAFT Polymerization". Materials 12, n.º 17 (23 de agosto de 2019): 2697. http://dx.doi.org/10.3390/ma12172697.
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We compared the influence of the polymerization mechanism onto the physical characteristics of thermoresponsive hydrogels. The Poly(N-isopropylacrylamide) (PNIPAAm) hydrogels were successfully synthesized using reversible addition-fragmentation chain-transfer (RAFT) and free radical polymerization (FRP). The gels were prepared while using different crosslinker feed and monomer concentration. The swelling, dye release, and hydrolytic stability of the gels were investigated in water, or in representative komostrope and chaotrope salt solutions at room temperature and at 37 °C. It was found that the swelling ratio (SR) of the RAFT gels was significantly higher than that of the FRP gels; however, an increased crosslinking density resulted in a decrease of the SR of the RAFT gels as compared to the corresponding gels that are made by FRP, which indicates the limitation of the cross-linking efficiency that is attained in RAFT polymerization. Additionally, an increased monomer concentration decreased the SR of the RAFT gels, whereas a similar SR was observed for the FRP gels. However, the SR of both RAFT and FRP gels in NaSCN and Na2SO4 solutions were similar. Finally, the rate of dye release was significantly slower from the RAFT gels than the FRP gels and the hydrolytic stability of the RAFT gels was lower than that of FRP gels in water, but maintained similar stability in Na2SO4 and NaSCN solutions.
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Kamińska, Marta, Sławomir Kuberski, Waldemar Maniukiewicz, Piotr Owczarz, Piotr Komorowski, Zofia Modrzejewska e Bogdan Walkowiak. "Thermosensitive chitosan gels containing calcium glycerophosphate for bone cell culture". Journal of Bioactive and Compatible Polymers 32, n.º 2 (23 de novembro de 2016): 209–22. http://dx.doi.org/10.1177/0883911516671150.
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In this article, properties of thermosensitive chitosan hydrogels prepared with the use of chitosan chloride with β-glycerophosphate disodium salt pentahydrate enriched with calcium glycerophosphate are presented and compared with chitosan hydrogels with β-glycerophosphate disodium salt pentahydrate. The study is focused on the determination of hydrogel structure and biological testing of hydrogels with human osteoblasts line Saos-2. The structure of gels was visualized by scanning electron microscopy and was investigated by infrared spectroscopy. The crystallinity of gel structure was determined by X-ray diffraction analysis and thermal effects were determined using differential scanning calorimetry thermograms.
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Mohammed, Ali A., Siwei Li, Tian Sang, Julian R. Jones e Alessandra Pinna. "Nanocomposite Hydrogels with Polymer Grafted Silica Nanoparticles, Using Glucose Oxidase". Gels 9, n.º 6 (13 de junho de 2023): 486. http://dx.doi.org/10.3390/gels9060486.
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Nanocomposite hydrogels offer remarkable potential for applications in bone tissue engineering. They are synthesized through the chemical or physical crosslinking of polymers and nanomaterials, allowing for the enhancement of their behaviour by modifying the properties and compositions of the nanomaterials involved. However, their mechanical properties require further enhancement to meet the demands of bone tissue engineering. Here, we present an approach to improve the mechanical properties of nanocomposite hydrogels by incorporating polymer grafted silica nanoparticles into a double network inspired hydrogel (gSNP Gels). The gSNP Gels were synthesised via a graft polymerization process using a redox initiator. gSNP Gels were formed by grafting 2-acrylamido-2-methylpropanesulfonic acid (AMPS) as the first network gel followed by a sequential second network acrylamide (AAm) onto amine functionalized silica nanoparticles (ASNPs). We utilized glucose oxidase (GOx) to create an oxygen-free atmosphere during polymerization, resulting in higher polymer conversion compared to argon degassing. The gSNP Gels showed excellent compressive strengths of 13.9 ± 5.5 MPa, a strain of 69.6 ± 6.4%, and a water content of 63.4% ± 1.8. The synthesis technique demonstrates a promising approach to enhance the mechanical properties of hydrogels, which can have significant implications for bone tissue engineering and other soft tissue applications.
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Min, Qing, Ronghua Tan, Yuchen Zhang, Congcong Wang, Ying Wan e Jing Li. "Multi-Crosslinked Strong and Elastic Bioglass/Chitosan-Cysteine Hydrogels with Controlled Quercetin Delivery for Bone Tissue Engineering". Pharmaceutics 14, n.º 10 (26 de setembro de 2022): 2048. http://dx.doi.org/10.3390/pharmaceutics14102048.
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Chitosan-cysteine (CH-CY) conjugate with an optimal content of thiol groups was synthesized and combined with amino-functionalized mesoporous bioglass (ABG) nanoparticles (NPs) with radially-porous architecture to build multi-crosslinked ABG/CH-CY composite hydrogels. Besides the network formed by self-crosslinking of thiol groups in CY-derived side chains, difunctionalized PEG (DF-P) crosslinkers with varying lengths of PEG segments were used to crosslink amino groups on CH-CY or ABG NPs to form other networks in the composite gels. Quercetin (Que) was loaded into ABG NPs before these NPs were incorporated into the hydrogel, intending to achieve sustainable and controllable Que release from so-built ABG/CH-CY gels. The lengths of PEG segments in DF-P were found to impose remarkable impacts on the strength or elasticity of multi-crosslinked ABG/CH-CY hydrogels. Some ABG/CH-CY hydrogels had their elastic modulus of around 8.2 kPa or higher along with yielding strains higher than 70%, specifying their mechanically strong and elastic characteristics. In addition, these gels showed the ability to release Que and Si or Ca ions in controllable ways for various durations. The optimally achieved ABG/CH-CY hydrogels were injectable and also able to support the growth of seeded MC3T3-E1 cells as well as the specific matrix deposition. The obtained results suggest that these ABG/CH-CY gels have promising potential for bone repair and regeneration.
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Boffito, Monica, Rossella Laurano, Dimitra Giasafaki, Theodore Steriotis, Athanasios Papadopoulos, Chiara Tonda-Turo, Claudio Cassino, Georgia Charalambopoulou e Gianluca Ciardelli. "Embedding Ordered Mesoporous Carbons into Thermosensitive Hydrogels: A Cutting-Edge Strategy to Vehiculate a Cargo and Control Its Release Profile". Nanomaterials 10, n.º 11 (29 de outubro de 2020): 2165. http://dx.doi.org/10.3390/nano10112165.
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The high drug loading capacity, cytocompatibility and easy functionalization of ordered mesoporous carbons (OMCs) make them attractive nanocarriers to treat several pathologies. OMCs’ efficiency could be further increased by embedding them into a hydrogel phase for an in loco prolonged drug release. In this work, OMCs were embedded into injectable thermosensitive hydrogels. In detail, rod-like (diameter ca. 250 nm, length ca. 700 nm) and spherical (diameter approximately 120 nm) OMCs were synthesized by nanocasting selected templates and loaded with ibuprofen through a melt infiltration method to achieve complete filling of their pores (100% loading yield). In parallel, an amphiphilic Poloxamer® 407-based poly(ether urethane) was synthesized (Mn¯ 72 kDa) and solubilized at 15 and 20% w/v concentration in saline solution to design thermosensitive hydrogels. OMC incorporation into the hydrogels (10 mg/mL concentration) did not negatively affect their gelation potential. Hybrid systems successfully released ibuprofen at a slower rate compared to control gels (gels embedding ibuprofen as such), but with no significant differences between rod-like and spherical OMC-loaded gels. OMCs can thus work as effective drug reservoirs that progressively release their payload over time and also upon encapsulation in a hydrogel phase, thus opening the way to their application to treat many different pathological states (e.g., as topical medications).
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Xiong, Shu Qiang, Yan Wang, Jing Zhu, Zu Ming Hu e Jun Rong Yu. "Polydopamine Nanoparticle for Poly(N-Isopropylacrylamide)-Based Nanocomposite Hydrogel with Good Free-Radical-Scavenging Property". Materials Science Forum 848 (março de 2016): 94–98. http://dx.doi.org/10.4028/www.scientific.net/msf.848.94.
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Nanocomposite hydrogels (NC gels) consisting of poly (N-Isopropyl acrylamide) (pNIPAM)/polydopamine nanoparticles (PDAPs) were prepared by in-situ-free-radical polymerization of N-isopropyl acrylamide in the presence of modified PDAP in aqueous solution. The composition of the NC gels could be controlled directly by altering the composition of the initial reaction mixture. The lower critical solution temperature (LCST) of the NC gels were studied by DSC, and the LCST of both of pure pNIPAM hydrogel and NC gels was at 34°C. Besides, the NC gels showed superior antioxidant property, and the ability to scavenge activity of NC gel was up to 70% with the addition of 6 wt% modified PDAP into pNIPAM.
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Emani, Sravani, Anil Vangala, Federico Buonocore, Niousha Yarandi e Gianpiero Calabrese. "Chitosan Hydrogels Cross-Linked with Trimesic Acid for the Delivery of 5-Fluorouracil in Cancer Therapy". Pharmaceutics 15, n.º 4 (28 de março de 2023): 1084. http://dx.doi.org/10.3390/pharmaceutics15041084.
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Chitosan exhibits unique properties making it a suitable material for drug delivery. Considering the rising popularity of hydrogels in this field, this work offers a comprehensive study of hydrogels constituted by chitosan and cross-linked with 1,3,5-benzene tricarboxylic acid (BTC; also known as trimesic acid). Hydrogels were prepared by cross-linking chitosan with BTC in different concentrations. The nature of the gels was studied through oscillatory amplitude strain and frequency sweep tests within the linear viscoelastic region (LVE) limit. The flow curves of the gels revealed shear thinning behavior. High G′ values imply strong cross-linking with improved stability. The rheological tests revealed that the strength of the hydrogel network increased with the cross-linking degree. Hardness, cohesiveness, adhesiveness, compressibility, and elasticity of the gels were determined using a texture analyzer. The scanning electron microscopy (SEM) data of the cross-linked hydrogels showed distinctive pores with a pore size increasing according to increasing concentrations (pore size range between 3–18 µm). Computational analysis was performed by docking simulations between chitosan and BTC. Drug release studies employing 5-fluorouracil (5-FU) yielded a more sustained release profile with 35 to 50% release among the formulations studied in a 3 h period. Overall, this work demonstrated that the presence of BTC as cross-linker leads to satisfactory mechanical properties of the chitosan hydrogel, suggesting potential applications in the sustained release of cancer therapeutics.
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Marfoglia, Andrea, Fahd Tibourtine, Ludovic Pilloux e Sophie Cazalbou. "Tunable Double-Network GelMA/Alginate Hydrogels for Platelet Lysate-Derived Protein Delivery". Bioengineering 10, n.º 9 (5 de setembro de 2023): 1044. http://dx.doi.org/10.3390/bioengineering10091044.
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Hydrogels (gels) are attractive tools for tissue engineering and regenerative medicine due to their potential for drug delivery and ECM-like composition. In this study, we use rheology to characterize GelMA/alginate gels loaded with human platelet lysate (PL). We then characterize these gels from a physicochemical perspective and evaluate their ability to transport PL proteins, their pore size, and their rate of degradation. Finally, their biocompatibility is evaluated. We describe how alginate changes the mechanical behavior of the gels from elastic to viscoelastic after ionic (calcium-mediated) crosslinking. In addition, we report the release of ~90% of PL proteins from the gels and relate it to the degradation profile of the gels. Finally, we evaluated the biocompatibility of the gels. Thus, the developed gels represent attractive substrates for both cell studies and as bioactive materials.
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Kondo, Shinji, Ung-il Chung e Takamasa Sakai. "Mechanical properties of polymer gels with bimodal distribution in strand length". MRS Proceedings 1622 (2014): 31–36. http://dx.doi.org/10.1557/opl.2014.36.
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ABSTRACTThe understanding of the physical properties of hydrogels has been controversial because hydrogels inherently have a substantial amount of heterogeneities in their structures. In this study, we focused on one of the simplest heterogeneities, heterogeneous distribution of strand length, and investigated its influence on physical properties. We prepared Tetra-PEG gels with bimodal distribution in strand length (Tetra-PEG bimodal gels) by combining Tetra-PEG prepolymers with different molecular weights and measured the physical properties including elastic modulus and ultimate deformation ratio. The physical properties of Tetra-PEG bimodal gels were well described by the models for conventional Tetra-PEG gels with the average polymerization degrees between cross-links. We conclude that the mechanical properties of hydrogels that have heterogeneous distribution in strand length can be predicted from those of hydrogels with the average strand length in the range tested in this study.
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Chiang, Yi-Hua, Meng-Ju Wu, Wei-Chin Hsu e Teh-Min Hu. "Versatile composite hydrogels for drug delivery and beyond". Journal of Materials Chemistry B 8, n.º 38 (2020): 8830–37. http://dx.doi.org/10.1039/d0tb01360a.
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Albumin–organosilane composite hydrogels were prepared and characterized in both their wet and dry states. The wet gels were evaluated using an all-in-one-plate method for drug-delivery applications. Besides, the dry gels can withstand and absorb polar and nonpolar solvents.
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Sun, Manxi, Jianhui Qiu, Chunyin Lu, Shuping Jin, Guohong Zhang e Eiichi Sakai. "Multi-Sacrificial Bonds Enhanced Double Network Hydrogel with High Toughness, Resilience, Damping, and Notch-Insensitivity". Polymers 12, n.º 10 (1 de outubro de 2020): 2263. http://dx.doi.org/10.3390/polym12102263.
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The engineering applications of hydrogels are generally limited by the common problem of their softness and brittlness. In this study, a composite double network ionic hydrogel (CDN-gel) was obtained by the facile visible light triggered polymerization of acrylic acid (AA), polyvinyl alcohol (PVA), and hydrolyzed triethoxyvinylsilane (TEVS) and subsequent salt impregnation. The resulting CDN-gels exhibited high toughness, recovery ability, and notch-insensitivity. The tensile strength, fracture elongation, Young’s modulus, and toughness of the CDN-gels reached up to ~21 MPa, ~700%, ~3.5 MPa, and ~48 M/m3, respectively. The residual strain at a strain of 200% was only ~25% after stretch-release of 1000 cycles. These properties will enable greater application of these hydrogel materials, especially for the fatigue resistance of tough hydrogels, as well as broaden their applications in damping.
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Desbrieres, Jacques, Stephanie Reynaud, Pierre Marcasuzaa e Francis Ehrenfeld. "Actuator-Like Hydrogels Based on Conductive Chitosan". Advances in Science and Technology 84 (setembro de 2012): 29–38. http://dx.doi.org/10.4028/www.scientific.net/ast.84.29.
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Intrinsically conducting polymers are of great interest for a large number of applications. But among major drawbacks are their low solubility in common solvents and their poor mechanical properties. Elaboration of composites associating a matrix, bringing its mechanical properties, and polyaniline, as the conducting polymer is a way of overcoming these disadvantages. Chitosan-graft-polyaniline copolymers were synthesized by simple oxidative method. The grafting reaction was quite total and it was found that the copolymers crosslinked to yield a composite hydrogel in which the polyaniline was homogeneously embedded. The conductivity of precursor (block copolymer) and gels was found to be larger than 10-2 S.cm-1. The composite gels were characterized in terms of swelling and rheological properties. They can be classified as "superabsorbent" hydrogels and the swelling is reversible. The composite gels were then successfully used as actuators.
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Tokuyama, Hideaki, Ryo Iriki e Makino Kubota. "Thermosensitive Shape-Memory Poly(stearyl acrylate-co-methoxy poly(ethylene glycol) acrylate) Hydrogels". Gels 9, n.º 1 (10 de janeiro de 2023): 54. http://dx.doi.org/10.3390/gels9010054.
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Stimuli-sensitive hydrogels are highly desirable candidates for application in intelligent biomaterials. Thus, a novel thermosensitive hydrogel with shape-memory function was developed. Hydrophobic stearyl acrylate (SA), hydrophilic methoxy poly(ethylene glycol) acrylate (MPGA), and a crosslinking monomer were copolymerized to prepare poly(SA-co-MPGA) gels with various mole fractions of SA (xSA) in ethanol. Subsequently, the prepared gels were washed, dried, and re-swelled in water at 50 °C. Differential scanning calorimetric (DSC) and compression tests at different temperatures revealed that poly(SA-co-MPGA) hydrogels with xSA > 0.5 induce a crystalline-to-amorphous transition, which is a hard-to-soft transition at ~40 °C that is based on the formation/non-formation of a crystalline structure containing stearyl side chains. The hydrogels stored in water maintained an almost constant volume, independent of the temperature. The poly(SA-co-MPGA) hydrogel was soft, flexible, and deformed at 50 °C. However, the hydrogel stiffened when cooled to room temperature, and the deformation was reversible. The shape-memory function of poly(SA-co-MPGA) hydrogels is proposed for potential use in biomaterials; this is partially attributed to the use of MPGA, which consists of relatively biocompatible poly(ethylene glycol).
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Bharmoria, Pankaj, Nobuhiro Yanai e Nobuo Kimizuka. "Recent Progress in Photon Upconverting Gels". Gels 5, n.º 1 (26 de março de 2019): 18. http://dx.doi.org/10.3390/gels5010018.
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Recent progress in the development of gels showing triplet-triplet annihilation based photon upconversion (TTA-UC) is reviewed. Among the two families of upconverting gels reported, those display TTA-UC based on molecular diffusion show performances comparable to those in solutions, and the TTA-UC therein are affected by dissolved molecular oxygen. Meanwhile, air-stable TTA-UC is achieved in organogels and hydrogels by suitably accumulating TTA-UC chromophores which are stabilized by hydrogen bonding networks of the gelators. The unique feature of the air-stable upconverting gels is that the self-assembled nanostructures are protected from molecular oxygen dissolved in the microscopically interconnected solution phase. The presence of the bicontinuous structures formed by the upconverting fibrous nanoassemblies and the solution phase is utilized to design photochemical reaction systems induced by TTA-UC. Future challenges include in vivo applications of hydrogels showing near infrared-to-visible TTA-UC.
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Zhu, Wei, Jinyi Zhang, Zhanqi Wei, Baozhong Zhang e Xisheng Weng. "Advances and Progress in Self-Healing Hydrogel and Its Application in Regenerative Medicine". Materials 16, n.º 3 (31 de janeiro de 2023): 1215. http://dx.doi.org/10.3390/ma16031215.
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A hydrogel is a three-dimensional structure that holds plenty of water, but brittleness largely limits its application. Self-healing hydrogels, a new type of hydrogel that can be repaired by itself after external damage, have exhibited better fatigue resistance, reusability, hydrophilicity, and responsiveness to environmental stimuli. The past decade has seen rapid progress in self-healing hydrogels. Self-healing hydrogels can automatically self-repair after external damage. Different strategies have been proposed, including dynamic covalent bonds and reversible noncovalent interactions. Compared to traditional hydrogels, self-healing gels have better durability, responsiveness, and plasticity. These features allow the hydrogel to survive in harsh environments or even to be injected as a drug carrier. Here, we summarize the common strategies for designing self-healing hydrogels and their potential applications in clinical practice.
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Kwon, Hyuck Joon. "Tissue Engineering of Muscles and Cartilages Using Polyelectrolyte Hydrogels". Advances in Materials Science and Engineering 2014 (2014): 1–7. http://dx.doi.org/10.1155/2014/154071.
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The prevalent nature of osteoarthritis that causes the erosion of joint surfaces and loss of mobility and muscle dystrophy that weakens the musculoskeletal system and hampers locomotion underlies the importance of developing functional replacement or regeneration of muscle and cartilage tissues. Polyelectrolyte gels have high potential as cellular scaffolds due to characteristic properties similar to biological matrixes. A number of in vitro and in vivo studies demonstrated that polyelectrolyte gels are useful for replacement and regeneration of muscle and cartilage tissues. In addition, it was also found that polyelectrolyte gels have high biocompatibility, durability, and resistance to biodegradation. Moreover, polyelectrolyte gels can overcome their drawbacks of mechanical behavior by introducing double network into the gel. This paper reviews the current status and recent progress of polyelectrolyte gel-based tissue engineering for repairs of muscle and cartilage tissues.
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Au-Yong, Sophie, Melike Firlak, Emily R. Draper, Sofia Municoy, Mark D. Ashton, Geoffrey R. Akien, Nathan R. Halcovitch et al. "Electrochemically Enhanced Delivery of Pemetrexed from Electroactive Hydrogels". Polymers 14, n.º 22 (16 de novembro de 2022): 4953. http://dx.doi.org/10.3390/polym14224953.
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Electroactive hydrogels based on derivatives of polyethyleneglycol (PEG), chitosan and polypyrrole were prepared via a combination of photopolymerization and oxidative chemical polymerization, and optionally doped with anions (e.g., lignin, drugs, etc.). The products were analyzed with a variety of techniques, including: FT-IR, UV-Vis, 1H NMR (solution state), 13C NMR (solid state), XRD, TGA, SEM, swelling ratios and rheology. The conductive gels swell ca. 8 times less than the non-conductive gels due to the presence of the interpenetrating network (IPN) of polypyrrole and lignin. A rheological study showed that the non-conductive gels are soft (G′ 0.35 kPa, G″ 0.02 kPa) with properties analogous to brain tissue, whereas the conductive gels are significantly stronger (G′ 30 kPa, G″ 19 kPa) analogous to breast tissue due to the presence of the IPN of polypyrrole and lignin. The potential of these biomaterials to be used for biomedical applications was validated in vitro by cell culture studies (assessing adhesion and proliferation of fibroblasts) and drug delivery studies (electrochemically loading the FDA-approved chemotherapeutic pemetrexed and measuring passive and stimulated release); indeed, the application of electrical stimulus enhanced the release of PEM from gels by ca. 10–15% relative to the passive release control experiment for each application of electrical stimulation over a short period analogous to the duration of stimulation applied for electrochemotherapy. It is foreseeable that such materials could be integrated in electrochemotherapeutic medical devices, e.g., electrode arrays or plates currently used in the clinic.
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Cheng, Qiuhong, Zhuoer Wang, Aiyou Hao, Pengyao Xing e Yanli Zhao. "Aromatic vapor responsive molecular packing rearrangement in supramolecular gels". Materials Chemistry Frontiers 4, n.º 8 (2020): 2452–61. http://dx.doi.org/10.1039/d0qm00348d.
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Aromatic vapor responsive hydrogels are prepared by crystal transformation of commercially available β-cyclodextrin (β-CD). Hydrogel composites coassembled by clay with β-CD show haze evolution toward aromatic vapor under heating–cooling treatment.