Injectable Electroactive Hydrogels Formed via Host–Guest Interactions (original) (raw)
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Construction of Chemical-Responsive Supramolecular Hydrogels from Guest-Modified Cyclodextrins
Chemistry-an Asian Journal, 2008
A methodology for preparing supramolecular hydrogels from guest-modified cyclodextrins (CDs) based on the host–guest and hydrogen-bonding interactions of CDs is presented. Four types of modified CDs were synthesized to understand better the gelation mechanism. The 2D ROESY NMR spectrum of β-CD-AmTNB (Am=amino, TNB=trinitrobenzene) reveals that the TNB group was included in the β-CD cavity. Pulsed field gradient NMR (PFG NMR) spectroscopy and AFM show that β-CD-AmTNB formed a supramolecular polymer in aqueous solution through head-to-tail stacking. Although β-CD-AmTNB did not produce a hydrogel due to insufficient growth of supramolecular polymers, β-CD-CiAmTNB (Ci=cinnamoyl) formed supramolecular fibrils through host–guest interactions. Hydrogen bonds between the cross-linked fibrils resulted in the hydrogel, which displayed excellent chemical-responsive properties. Gel-to-sol transitions occurred by adding 1-adamantane carboxylic acid (AdCA) or urea. 1H NMR and induced circular dichroism (ICD) spectra reveal that AdCA released the guest parts from the CD cavity and that urea acts as a denaturing agent to break the hydrogen bonds between CDs. The hydrogel was also destroyed by adding β-CD, which acts as the competitive host to reduce the fibrils. Furthermore, the gel changed to a sol by adding methyl orange (MO) as a guest compound, but the gel reappeared upon addition of α-CD, which is a stronger host for MO.
Tailoring Polymeric Hydrogels through Cyclodextrin Host-Guest Complexation
Macromolecular rapid communications, 2010
A close correllation between molecular-level interactions and macroscopic characteristics of polymer networks exists. The characteristics of the polymeric hydrogels assembled from β-cyclodextrin (β-CD) and adamantyl (AD) substituted poly(acrylate)s can be tailored through selective host-guest complexation between β-CD and AD substituents and their tethers. Dominantly, steric effects and competitive intra- and intermolecular host-guest complexation are found to control poly(acrylate) isomeric inter-strand linkage in polymer network formation. This understanding of the factors involved in polymeric hydrogel formation points the way towards the construction of increasingly sophisticated biocompatible materials.
Cyclodextrin-based supramolecular assemblies and hydrogels: recent advances and future perspectives
Macromolecular rapid communications, 2014
The application of cyclodextrin (CD)-based host-guest interactions towards the fabrication of functional supramolecular assemblies and hydrogels is of particular interest in the field of biomedicine. However, as of late they have found new applications as advanced functional materials (e.g., actuators and self-healing materials), which have renewed interest across a wide range of fields. Advanced supramolecular materials synthesized using this noncovalent interaction, exhibit specificity and reversibility, which can be used to impart reversible cross-linking, specific binding sites, and functionality. In this review, various functional CD-based supramolecular assemblies and hydrogels will be outlined with the focus on recent advances. In addition, an outlook will be provided on the direction of this rapidly developing field.
α-Cyclodextrin-Based Polypseudorotaxane Hydrogels
Materials, 2019
Supramolecular hydrogels that are based on inclusion complexes between α-cyclodextrin and (co)polymers have gained significant attention over the last decade. They are formed via dynamic noncovalent bonds, such as host–guest interactions and hydrogen bonds, between various building blocks. In contrast to typical chemical crosslinking (covalent linkages), supramolecular crosslinking is a type of physical interaction that is characterized by great flexibility and it can be used with ease to create a variety of “smart” hydrogels. Supramolecular hydrogels based on the self-assembly of polypseudorotaxanes formed by a polymer chain “guest” and α-cyclodextrin “host” are promising materials for a wide range of applications. α-cyclodextrin-based polypseudorotaxane hydrogels are an attractive platform for engineering novel functional materials due to their excellent biocompatibility, thixotropic nature, and reversible and stimuli-responsiveness properties. The aim of this review is to provide...
Beilstein Journal of Organic Chemistry, 2012
Supramolecular materials with noncovalent bonds have attracted much attention due to their exclusive properties differentiating them from materials formed solely by covalent bonds. Especially interesting are rotor molecules of topological complexes that shuttle along a polymer chain. The shuttling of these molecules should greatly improve the tension strength. Our research employs cyclodextrin (CD) as a host molecule, because CD effectively forms polyrotaxanes with polymers. Herein we report the formation of supramolecular hydrogels with an α-CD dimer (α,α-CD dimer) as a topological linker molecule, and a viologen polymer (VP) as the polymer chain. The supramolecular hydrogel of α,α-CD dimer/VP forms a self-standing gel, which does not relax (G' > G'') in the frequency range 0.01–10 rad·s−1. On the other hand, the supramolecular hydrogel decomposes upon addition of bispyridyl decamethylene (PyC10Py) as a competitive guest. Moreover, the β-CD dimer (β,β-CD dimer) with ...
RSC Advances, 2014
The supramolecular hydrogel network formed from the association of poly(ethylene glycol) and a-cyclodextrin-based polypseudorotaxanes has been successfully replicated into a silica scaffold with a three-dimensional hierarchical pore structure by using a sol-gel process. The examination of the replicas indicates that the columnar polypseudorotaxane-based nanocrystallites act as crosslinkers maintaining the supramolecular hydrogel in a water-swollen state. Depending on the poly(ethylene glycol)/a-cyclodextrin formulation and the pH value, the resulting silica materials may exhibit a pore structure comprised of large mesopores (4-10 nm) interconnected by smaller ones (2-2.5 nm) in a framework where the pore walls are made-up of a microporous corona (<1.8 nm).
Supramolecular Hydrogel Based on pNIPAm Microgels Connected via Host–Guest Interactions
Polymers, 2018
In this work, host-guest supramolecular hydrogels were prepared from poly(N-isopropylacrylamide) (pNIPAm) microgels utilizing electrostatic and host/guest self-assembly. First, pNIPAm microgels bearing a poly(acrylic acid) (pAAc) shell were coated with positively charged β-cyclodextrin polymers. Addition of adamantane-substituted dextrans (Dex-Ada) allowed us to establish interparticle connections through β-cyclodextrin-adamantane (βCD-Ada) inclusion complex formation, and thus to prepare hierarchical hydrogels. Under the conditions of hydrogel formation, close contact between the microgels was ensured. To the best of our knowledge, this is the first example of doubly crosslinked microgels prepared by noncovalent crosslinking via host-guest interactions. The prepared macrogels were studied with rheology, and fast mechanical response to temperature variation was found. Furthermore, the hydrogels exhibit fully reversible temperature-induced gel-sol transition at the physiological temperature range (37-41 • C), due to the synergetic effect between shrinking of the microgels and dissociation of βCD-Ada crosslinks at higher temperatures. This opens up attractive prospects of their potential use in biomedical applications.
Recent advances in the role of supramolecular hydrogels in drug delivery
Introduction: Supramolecular hydrogels, formed by noncovalent crosslinking of polymeric chains in water, constitute an interesting class of materials that can be developed specifically for drug delivery and biomedical applications. The biocompatibility, stimuli responsiveness to various external factors, and powerful functionalization capacity of these polymeric networks make them attractive candidates for novel advanced dosage form design. Areas covered: This review summarizes the significance of supramolecular hydrogels in various biomedical and drug delivery applications. The recent advancement of these hydrogels as potential advanced drug delivery systems (for gene, protein, anticancer and other drugs) is discussed. The importance of these hydrogels in biomedical applications, particularly in tissue engineering, biosensing, cell-culture research and wound treatment is briefly described. Expert opinion: The use of supramolecular hydrogels in drug delivery is still in very early stages. However, the potential of such a system is undeniably important and very promising. A number of recent studies have been conducted, which mainly focus on the use of cyclodextrin-based host–guest complex as well as other supramolecular motifs to form supramolecular hydrogels for delivery of various classes of drugs, therapeutic agents, proteins and genes. However, there are still plenty of opportunities for further development in this area for drug delivery and other biomedical applications.