Variable gelation time and stiffness of low-molecular-weight hydrogels through catalytic control over self-assembly

Poolman, Jos M.; Boekhoven, Job; Besselink, Anneke; Olive, Alexandre G. L.; Esch, Jan H. van; Eelkema, Rienk

doi:10.1038/nprot.2014.055

Cited by 69 publications

(64 citation statements)

References 34 publications

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“…When HA 3 reaches concentrations above its critical aggregation concentration (CAC), it self-assembles into fibres and in situ forms a non-transparent supramolecular network. The rate of formation of the supramolecular network is controlled through the hydrazine-forming reaction, which depends on the concentration of reactants and the presence of an acid catalyst2728. In our RD-SA approach, reactants H and A diffuse over a distance and react on crossing of the moving fronts, forming HA 3 , which subsequently self-assembles into a supramolecular material.…”

Section: Resultsmentioning

confidence: 99%

Free-standing supramolecular hydrogel objects by reaction-diffusion

et al. 2017

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Self-assembly provides access to a variety of molecular materials, yet spatial control over structure formation remains difficult to achieve. Here we show how reaction–diffusion (RD) can be coupled to a molecular self-assembly process to generate macroscopic free-standing objects with control over shape, size, and functionality. In RD, two or more reactants diffuse from different positions to give rise to spatially defined structures on reaction. We demonstrate that RD can be used to locally control formation and self-assembly of hydrazone molecular gelators from their non-assembling precursors, leading to soft, free-standing hydrogel objects with sizes ranging from several hundred micrometres up to centimeters. Different chemical functionalities and gradients can easily be integrated in the hydrogel objects by using different reactants. Our methodology, together with the vast range of organic reactions and self-assembling building blocks, provides a general approach towards the programmed fabrication of soft microscale objects with controlled functionality and shape.

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Section: Resultsmentioning

confidence: 99%

Free-standing supramolecular hydrogel objects by reaction-diffusion

et al. 2017

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“…For hydrogel formation, super saturated solution of a molecule is required. 33 We have used FmocF as model molecule for hydrogel formation which consists of Fluorenylmethyloxycarbonyl (Fmoc) covalently linked to Lphenylalanine (Fig. 1a).…”

Section: Fmocf Hydrogel Formationmentioning

confidence: 99%

Understanding the self-assembly of Fmoc–phenylalanine to hydrogel formation

et al. 2015

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Hydrogels of low molecular weight molecules are important in biomedical applications. Multiple factors are responsible for hydrogel formation, but their role in governing self-assembly to hydrogel formation is poorly understood. Herein, we report the hydrogel formation of fluorenylmethyloxycarbonyl phenylalanine (FmocF) molecule. We used physical and thermal stimuli for solubilizing FmocF above the critical concentration to induce gel formation. The key role of Fmoc, Fmoc and phenylalanine covalent linkage, flexibility of phe side chain, pH, and buffer ions in self-assembly of FmocF to gel formation is described. We found that the collective action of different non-covalent interactions play a role in making FmocF hydrogel. Using powder diffraction and infrared spectroscopy, we also report a new polymorphic form of FmocF after transitioning to hydrogel. In addition, we are proposing a model for drug release from FmocF hydrogel.

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“…For the synthesis of cis,cis -cyclohexane-1,3,5-tricarbohydrazide 7 and 3,4-bis(2-(2-methoxyethoxy)ethoxy)benzaldehyde 8 we refer to procedures described in the literature 30 . Detailed procedures for the synthesis of pro-aniline 1 , hydrazone 5 and PEG-aldehyde copolymer 6 are described in the Supplementary Methods, NMR and GPC spectra are shown in Supplementary Figs 9–17.…”

Section: Methodsmentioning

confidence: 99%

Chemical signal activation of an organocatalyst enables control over soft material formation

et al. 2017

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Cells can react to their environment by changing the activity of enzymes in response to specific chemical signals. Artificial catalysts capable of being activated by chemical signals are rare, but of interest for creating autonomously responsive materials. We present an organocatalyst that is activated by a chemical signal, enabling temporal control over reaction rates and the formation of materials. Using self-immolative chemistry, we design a deactivated aniline organocatalyst that is activated by the chemical signal hydrogen peroxide and catalyses hydrazone formation. Upon activation of the catalyst, the rate of hydrazone formation increases 10-fold almost instantly. The responsive organocatalyst enables temporal control over the formation of gels featuring hydrazone bonds. The generic design should enable the use of a large range of triggers and organocatalysts, and appears a promising method for the introduction of signal response in materials, constituting a first step towards achieving communication between artificial chemical systems.

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Variable gelation time and stiffness of low-molecular-weight hydrogels through catalytic control over self-assembly

Cited by 69 publications

References 34 publications

Free-standing supramolecular hydrogel objects by reaction-diffusion

Free-standing supramolecular hydrogel objects by reaction-diffusion

Understanding the self-assembly of Fmoc–phenylalanine to hydrogel formation

Chemical signal activation of an organocatalyst enables control over soft material formation

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