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Abstract Diabetic mellitus is one of the leading causes of chronic wounds and remains a challenging issue to be resolved. Herein, a hydrogel with conformal tissue adhesivity, skin‐like conductivity, robust mechanical characterist...
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Abstract Diabetic mellitus is one of the leading causes of chronic wounds and remains a challenging issue to be resolved. Herein, a hydrogel with conformal tissue adhesivity, skin‐like conductivity, robust mechanical characteristics, as well as active antibacterial function is developed. In this hydrogel, silver nanoparticles decorated polypyrrole nanotubes (AgPPy) and cobalt ions (Co2+) are introduced into an in situ polymerized poly(acrylic acid) (PAA) and branched poly(ethylenimine) (PEI) network (PPCA hydrogel). The PPCA hydrogel provides active antibacterial function through synergic effects from protonated PEI and AgPPy nanotubes, with a tissue‐like mechanical property (≈16.8 ± 4.5?kPa) and skin‐like electrical conductivity (≈0.048 S m?1). The tensile and shear adhesive strength (≈15.88 and ≈12.76?kPa, respectively) of the PPCA hydrogel is about two‐ to threefold better than that of fibrin glue. In vitro studies show the PPCA hydrogel is highly effective against both gram‐positive and gram‐negative bacteria. In vivo results demonstrate that the PPCA hydrogel promotes diabetic wounds with accelerated healing, with notable inflammatory reduction and prominent angiogenesis regeneration. These results suggest the PPCA hydrogel provide a promising approach to promote diabetic wound healing.
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Photoluminescent hydrogels that function as both injectable scaffolds and fluorescent imaging probes hold great potential for therapeutics delivery and tissue engineering. Current fluorescent hydrogels are fabricated by either con...
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Photoluminescent hydrogels that function as both injectable scaffolds and fluorescent imaging probes hold great potential for therapeutics delivery and tissue engineering. Current fluorescent hydrogels are fabricated by either conjugating or doping a fluorescent dye, fluorescent protein, lanthanide chelate, or quantum dot into polymeric hydrogel matrix. Their biomedical applications are severely limited due to drawbacks such as photostability, carcinogenesis, and toxicity associated with the above-mentioned dopants. Here, a successful development of dopant-free photoluminescent hydrogels in situ formed by crosslinking of biocompatible polymer precursors is reported, which can be synthesized by incorporating an amino acid to a citric acid based polyester oligomer followed by functionalization of multivalent crosslinking group through a convenient transesterification reaction using Candida Antarctica Lipase B as a catalyst. It is demonstrated that the newly developed hydrogels possess tunable degradation, intrinsic photoluminescence, mechanical properties, and exhibit sustained release of various molecular weight dextrans. In vivo study shows that the hydrogels formed in situ following subcutaneous injection exhibit excellent biocompatibility and emit strong fluorescence under visible light excitation without the need of using any traditional organic dyes. Their in vivo degradation profiles are then depicted by noninvasively monitoring fluorescence intensity of the injected hydrogel implants.
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Human skin exhibits high stiffness of up to 100 MPa and high toughness of up to 3600 J m−2despite its high water content of 40–70 wt%. Engineering hydrogels have rarely possessed both high stiffness and toughness, because co...
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Human skin exhibits high stiffness of up to 100 MPa and high toughness of up to 3600 J m−2despite its high water content of 40–70 wt%. Engineering hydrogels have rarely possessed both high stiffness and toughness, because compliant hydrogels usually become brittle when excess crosslinker is added to make the gel stiff. Furthermore, conventional hydrogels usually swell under physiological conditions, weakening their mechanical properties. Here, we designed a non-swellable hydrogel with high stiffness and toughness by interpenetrating covalently and ionically crosslinked networks. The stiffness is enhanced by utilizing ionic crosslinking sites fully, and the toughness is enhanced by adopting synergistic effects between energy-dissipation by ionic networks and crack-bridging by covalent networks. Non-swelling behaviors of the gel are achieved by densifying covalent and ionic crosslinks. The hybrid gel shows high elastic moduli (up to 108 MPa) and high fracture energies (up to 8850 J m−2). In vitro and in vivo swelling tests prove non-swelling behaviors of the gel. Live/dead assays show 99% cell viability over a period of 60 days.
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摘要 :
Human skin exhibits high stiffness of up to 100 MPa and high toughness of up to 3600 J m(-2) despite its high water content of 40-70 wt%. Engineering hydrogels have rarely possessed both high stiffness and toughness, because compl...
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Human skin exhibits high stiffness of up to 100 MPa and high toughness of up to 3600 J m(-2) despite its high water content of 40-70 wt%. Engineering hydrogels have rarely possessed both high stiffness and toughness, because compliant hydrogels usually become brittle when excess crosslinker is added to make the gel stiff. Furthermore, conventional hydrogels usually swell under physiological conditions, weakening their mechanical properties. Here, we designed a non-swellable hydrogel with high stiffness and toughness by interpenetrating covalently and ionically crosslinked networks. The stiffness is enhanced by utilizing ionic crosslinking sites fully, and the toughness is enhanced by adopting synergistic effects between energy-dissipation by ionic networks and crack-bridging by covalent networks. Non-swelling behaviors of the gel are achieved by densifying covalent and ionic crosslinks. The hybrid gel shows high elastic moduli (up to 108 MPa) and high fracture energies (up to 8850 J m(-2)). In vitro and in vivo swelling tests prove non-swelling behaviors of the gel. Live/dead assays show 99% cell viability over a period of 60 days.
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Supramolecular structures are of great interest due to their applicability in various scientific and industrial fields. The sensible definition of supramolecular molecules is being set by investigators who, because of the differen...
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Supramolecular structures are of great interest due to their applicability in various scientific and industrial fields. The sensible definition of supramolecular molecules is being set by investigators who, because of the different sensitivities of their methods and observational timescales, may have different views on as to what constitutes these supramolecular structures. Furthermore, diverse polymers have been found to offer unique avenues for multifunctional systems with properties in industrial medicine applications. Aspects of this review provide different conceptual strategies to address the molecular design, properties, and potential applications of self-assembly materials and the use of metal coordination as a feasible and useful strategy for constructing complex supramolecular structures. This review also addresses systems that are based on hydrogel chemistry and the enormous opportunities to design specific structures for applications that demand enormous specificity. According to the current research status on supramolecular hydrogels, the central ideas in the present review are classic topics that, however, are and will be of great importance, especially the hydrogels that have substantial potential applications in drug delivery systems, ophthalmic products, adhesive hydrogels, and electrically conductive hydrogels. The potential interest shown in the technology involving supramolecular hydrogels is clear from what we can retrieve from the Web of Science.
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Synthetic hydrogels are unique tissue mimics but rarely reproduce the strain-stiffening properties of native tissues. This mechanical mismatch impairs the performance of hydrogels in practical applications. Inspired by the crimped...
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Synthetic hydrogels are unique tissue mimics but rarely reproduce the strain-stiffening properties of native tissues. This mechanical mismatch impairs the performance of hydrogels in practical applications. Inspired by the crimped structure of collagenous tissues, a series of strain-stiffening hydrogels composed of curved parallel fibers are developed. These fibers are constructed from a bundle of intertwisted nanofibrils composed of short alkyl side chain-modified polymer chains. This hierarchical organization enables exquisitely cascaded deformation that facilitates soft-to-firm and resilience-to-viscoelasticity transitions, thus synergically mimicking the strain-adaptive stiffening and damping behaviors of natural tissues. Together with structural evolution and a constitutive model, rationally tuning the tortuosity and flexibility of the curved fibers produces a diverse combination of strain-stiffening properties and unprecedented penetration into the regions of several tissues. The crimped structure and the resultant stiffening properties constitute major improvements to nanofiber-based scaffolds for use in collagenous tissue repair.
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A series of polyacrylamide nanocomposite hydrogels were synthesized by in situ free radical polymerization of acrylamide (AAm) with ethylene glycol dimethacrylate (EGDMA) as a crosslinker in the presence of sodium montmorillonite ...
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A series of polyacrylamide nanocomposite hydrogels were synthesized by in situ free radical polymerization of acrylamide (AAm) with ethylene glycol dimethacrylate (EGDMA) as a crosslinker in the presence of sodium montmorillonite (NaMMT) and organically modified montmorillonite (OrgMMT) clays. Modification of MMT was carried out with a quaternary salt of coco amine as intercalant having a styryl group whose contribution to both polymerization and crosslinking reactions via its reactive double bond was confirmed by solid state NMR. Exfoliation success was checked with X-ray diffraction (XRD) and atomic force microscopy (AFM) techniques whereas mechanical performance was followed with uniaxial compression experiment. It has been found that exfoliated PAAm nanocomposites having 0.5% OrgMMT had both the maximum equilibrium swelling in water and compression strength as well as improved thermal stability due to the special and beneficial morphology observed via scanning electron microscopy (SEM).
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Cell microenvironment plays critical roles in regulating cellular activities both spatially and temporally. Engineering cell microenvironment using hydrogels has attracted increasing attention given their native-mimicking properti...
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Cell microenvironment plays critical roles in regulating cellular activities both spatially and temporally. Engineering cell microenvironment using hydrogels has attracted increasing attention given their native-mimicking properties. In particular, developing hydrogels with specific functions has recently emerged as novel biocomposites to enable the regulation of cell microenvironment from a variety of aspects such as the biological, mechanical and electrical microenvironment. In this review, the state-of-the-art methods for the preparation and application of several novel functional hydrogels are presented, including magnetic hydrogels, photoresponsive hydrogels, conductive hydrogels, thermoresponsive hydrogels, molecule-response hydrogels, as well as tough and stretchable hydrogels. In particular, the applications of these functional hydrogels for engineering cell microenvironment are also reviewed. Concluding remarks and perspectives for the future development of functional hydrogels are addressed. (C) 2015 Elsevier Ltd. All rights reserved.
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Abstract We present the fabrication and application of a magnetically actuated, macro-porous, drug–delivery hydrogel exhibiting significant reversible volume change (down to 55% of its original size) in response to a small magnet...
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Abstract We present the fabrication and application of a magnetically actuated, macro-porous, drug–delivery hydrogel exhibiting significant reversible volume change (down to 55% of its original size) in response to a small magnetic field (23 Gauss) from a permanent magnet. When integrating the hydrogel in a microchannel, the system demonstrates a magnetically regulated flow dynamics, showing a wide range of controllable flow rate from 10 to 100 µL/s. It is fabricated via a straightforward and economical process in which macro-pores are incorporated into the hydrogel by generating micro-bubbles during its crosslinking process. The resulting hydrogel enables simultaneous control over liquid flow and drug release rate.
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This article aims to review the literature concerning the choice of selectivity for hydrogels based on classification, application and processing. Super porous hydrogels (SPHs) and superabsorbent polymers (SAPs) represent an innov...
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This article aims to review the literature concerning the choice of selectivity for hydrogels based on classification, application and processing. Super porous hydrogels (SPHs) and superabsorbent polymers (SAPs) represent an innovative category of recent generation highlighted as an ideal mould system for the study of solution-dependent phenomena. Hydrogels, also termed as smart and/or hungry networks, are currently subject of considerable scientific research due to their potential in hi-tech applications in the biomedical, pharmaceutical, biotechnology, bioseparation, biosensor, agriculture, oil recovery and cosmetics fields. Smart hydrogels display a significant physiochemical change in response to small changes in the surroundings. However, such changes are reversible; therefore, the hydrogels are capable of returning to its initial state after a reaction as soon as the trigger is removed.
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