Self-assembly of small molecules affords multifunctional supramolecular hydrogels for topically treating simulated uranium wounds

Yang, Zhimou; Xu, Keming; Wang, Ling; Gu, Hongwei; Wei, Heng; Zhang, Mingjie; Xu, Bing

doi:10.1039/b507314f

Cited by 162 publications

(79 citation statements)

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“…[12] Similar to the natural selection of peptide chains in enzymes, self-assembled nanofibers of derivatives of amino acids allow the incorporation of heme model compounds as the prosthetic group to mimic peroxidases. [3] In the artificial enzymes reported in this work, the hydrogels serve at least two functions: as the skeleton of the artificial enzyme to aid the function of the active site in organic solvent and as immobilization carriers to facilitate their various applications.…”

Section: Introductionmentioning

confidence: 99%

“…Supramolecular hydrogels of amphiphilic oligopeptides [8,9] or other small molecules [10][11][12] are being explored for various important applications, such as scaffolds for tissue engineering, [8] media for screening inhibitors, [11,13] matrices for biomineralization, [14] and biomaterials for wound healing. [12] Similar to the natural selection of peptide chains in enzymes, self-assembled nanofibers of derivatives of amino acids allow the incorporation of heme model compounds as the prosthetic group to mimic peroxidases.…”

Section: Introductionmentioning

confidence: 99%

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High Catalytic Activities of Artificial Peroxidases Based on Supramolecular Hydrogels That Contain Heme Models

Wang

Yang

et al. 2008

Chemistry A European J

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Composed of a supramolecular hydrogel and a heme model compound, a new type of artificial peroxidase shows high catalytic activity in organic media. The activity of this new type of artificial enzyme is significantly higher than that of the heme model compounds alone. Changes in the distal substituents above the coordinated-metal centers of the model compounds directly modulate catalytic activity. This supramolecular-hydrogel-based artificial enzyme is most active in toluene, reaching about 90% of the nascent activity of horseradish peroxidase. Moreover, this study confirms that the incorporation of the heme models into the nanofibers of gelators accounts for most of the enhancement of catalytic activity.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

High Catalytic Activities of Artificial Peroxidases Based on Supramolecular Hydrogels That Contain Heme Models

Wang

Yang

et al. 2008

Chemistry A European J

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Hybrid Biocomposites Based on Calcium Phosphate Mineralization of Self‐Assembled Supramolecular Hydrogels

2006

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Self-assembly of small organic molecules into supramolecular hydrogels represents a novel approach to the fabrication of new soft materials for increasingly advanced and specialized applications in numerous fields, such as, drug release, [1] biological assays, [2] wound treatment, [3] sensor arrays, [4] and tissue engineering. [5] These materials are based on noncovalent cooperative interactions, with the consequence that the hydrogels are formed spontaneously under appropriate physical and chemical conditions. Whilst the synthesis and characterization of supramolecular hydrogels is receiving significant attention, there are few examples in the literature of the use of these self-assembled matrices for the preparation of biomaterials in the form of inorganic-organic hybrid composites. Although extensive work has been undertaken on the mineralization of organogels, [6] these materials are unlikely to be of significant value in biomaterials research owing to their high hydrophobicity and preparation in organic solvents. In contrast, self-assembly of small-molecule-based supramolecular hydrogels occurs in water and should therefore be amenable to inorganic mineralization processes that are of immediate biological relevance, notably the deposition of biocompatible hybrid materials consisting of calcium phosphate. Calcium phosphate crystallization in conventional polymeric hydrogels has been widely reported, [7][8][9] but unlike their supramolecular counterparts, these gels are not readily tunable with regard to chemical functionality, or easily disassembled in situ, for example by triggering a sol-gel phase transition.[10]In this paper, supramolecular hydrogels produced by enzymatic dephosphorylation of N-fluorenylmethyloxycarbonyltyrosine-phosphate [11] (FMOC: fluorenylmethyloxycarbonyl, I, Scheme 1) are used as self-assembled matrices for calcium phosphate (hydroxyapatite, Ca 10 (PO 4 ) 6 (OH) 2 ) mineralization. Dephosphorylation of I in water produces compound II (Scheme 1) that spontaneously assembles into nanofilaments due to p-stacking of the fluorenyl end groups, which adopt a helical orientation due to superhelical arrangements of the amino-acid residues arising from hydrogen-bonding interactions between the terminal tyrosine groups. [11,12] By controlling the levels of calcium and phosphate ions associated with the supramolecular structure, we demonstrate that mineralized hydrogels of variable hardness can be prepared in the form of hybrid composites comprising interconnecting networks of calcified nanofilaments. At low mineral contents, nucleation of calcium phosphate occurs specifically on the supramolecular fibers to produce viscoelastic hybrid gels that exhibit enhanced thermal stability, stiffness, and critical stress for breakage. Moreover, we show that extensive mineralization of the hydrogels can be achieved without significant disruption of the supramolecular matrix, and that intact macroporous networks of calcium phosphate can be derived from these hybrids by facile disassembly of the embedded sup...

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“…[1][2][3][4][5][6][7][8][9][10][11][12][13] Gels, particularly hydrogels 14 where water is the fluid phase, are 15 everyday materials with applications in drug delivery, 15,16 wound healing, 17 templating both inorganic and organic nanostructures, such as metallic nanoparticles and porous polymers, [18][19][20][21][22] and in crystal growth. 23,24 LMWG aggregate into cross-linked fibres via non-covalent interactions such as hydrogen bonding and, in water 20 particularly, hydrophobic effects.…”

Section: Introductionmentioning

confidence: 99%

Triggered formation of thixotropic hydrogels by balancing competitive supramolecular synthons

Liu

Steed

2013

Soft Matter

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Publisher's copyright statement: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. Two component hydrogels have been obtained by formation of 1:1 complexes of bis(pyridyl urea)s with a range of dicarboxylic acids. The gels are thixotropic and undergo an assembly process in which short segments can reversibly assemble into an interconnected fibrous network. NMR and IR spectroscopic data suggest that the gelators form neutral gelator-acid complexes rather than salts. The use of dicarboxylic acids to trigger gelation in bis(pyridyl urea)s parallels analogous triggered gelation of metal 10 ions and halogen bond donors in related systems. IntroductionGels derived from low molecular weight gelators (LMWG) have experienced an explosion of interest in recent years. 14 The growing interest in their properties stems from their generally facile synthesis, their synthetic and structural versatility, and the possibility of adaptive or reversible gelation offered by the weak, dynamic supramolecular interactions holding the fibres together. 7 The 25 mechanism of the non-equilibrium self-assembly process involved in gel formation by LMWG is also fascinating from a fundamental viewpoint and is perhaps a more tractable problem in well-defined small molecules than in more conventional silica or biopolymer based hydrogels. Of particular current interest are 30 multicomponent gels. 25These systems may comprise stoichiometric co-gels in which two non-gelator components combine in a well-defined way to produce a gel-forming supermolecule, or they may be blends of LMWG (sometimes termed 'multi-gelator gels') that are individually gelators. 26-32 35 Some metallogels arising from metal cross-linking of gelating ligands, 4,6, 33 or anion influenced gels also fall into the broad category of multicomponent gels. [34][35][36] In previous work we have looked at triggered gelation in 'inhibited gelators', particularly pyridyl ureas. 37,38 Intramolecular CH O interactions coupled 40 with the good hydrogen bond acceptor ability of the pyridyl nitrogen atom make pyridyl ureas particularly poor gelators (Fig. 1b) 37, 39-41 because they cannot effectively form the typical urea -tape motif generally thought to be responsible for onedimensional fibre growth and hence gel formation (Fig. 1a). 42, 43 45 Addition of a co-gelator such as a metal ion 38,[44][45][46] or halogen bond donor 47 results in coordination to the pyridyl nitrogen atom hence freeing the urea functionality and switching the system from the urea-pyridyl hydrogen bonding motif to the ...

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Self-assembly of small molecules affords multifunctional supramolecular hydrogels for topically treating simulated uranium wounds

Abstract: Two types of therapeutic agents, which have discrete yet complementary functions, self-assemble into nanofibers in water to formulate a new supramolecular hydrogel as a self-delivery biomaterial to reduce the toxicity of uranyl oxide at the wound sites.

Cited by 162 publications

References 31 publications

High Catalytic Activities of Artificial Peroxidases Based on Supramolecular Hydrogels That Contain Heme Models

High Catalytic Activities of Artificial Peroxidases Based on Supramolecular Hydrogels That Contain Heme Models

Hybrid Biocomposites Based on Calcium Phosphate Mineralization of Self‐Assembled Supramolecular Hydrogels

Triggered formation of thixotropic hydrogels by balancing competitive supramolecular synthons

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