In this review we intend to provide a relatively comprehensive summary of the work of supramolecular hydrogelators after 2004 and to put emphasis particularly on the applications of supramolecular hydrogels/hydrogelators as molecular biomaterials. After a brief introduction of methods for generating supramolecular hydrogels, we discuss supramolecular hydrogelators on the basis of their categories, such as small organic molecules, coordination complexes, peptides, nucleobases, and saccharides. Following molecular design, we focus on various potential applications of supramolecular hydrogels as molecular biomaterials, classified by their applications in cell cultures, tissue engineering, cell behavior, imaging, and unique applications of hydrogelators. Particularly, we discuss the applications of supramolecular hydrogelators after they form supramolecular assemblies but prior to reaching the critical gelation concentration because this subject is less explored but may hold equally great promise for helping ...

Supramolecular Hydrogelators and Hydrogels: From Soft Matter to Molecular Biomaterials

Hydrogels, due to their excellent biochemical and mechnical property, have shown attractive advantages in the field of wound dressings. However, a comprehensive review of the functional hydrogel as a wound dressing is still lacking. This work first summarizes the skin wound healing process and relates evaluation parameters and then reviews the advanced functions of hydrogel dressings such as antimicrobial property, adhesion and hemostasis, anti-inflammatory and anti-oxidation, substance delivery, self-healing, stimulus response, conductivity, and the recently emerged wound monitoring feature, and the strategies adopted to achieve these functions are all classified and discussed. Furthermore, applications of hydrogel wound dressing for the treatment of different types of wounds such as incisional wound and the excisional wound are summarized. Chronic wounds are also mentioned, and the focus of attention on infected wounds, burn wounds, and diabetic wounds is discussed. Finally, the future directions of hydrogel wound dressings for wound healing are further proposed.

Functional Hydrogels as Wound Dressing to Enhance Wound Healing.

3D printing of layered brain-like structures using peptide modified gellan gum substrates

The use of physical hydrogels of chitosan for skin regeneration following third-degree burns

Peptide-based hydrogels have been proven to be preeminent biomedical materials due to their high water content, tunable mechanical stability, great biocompatibility and excellent injectability. The ability of peptide-based hydrogels to provide extracellular matrix-mimicking environments opens up opportunities for their biomedical applications in fields such as drug delivery, tissue engineering, and wound healing. In this review, we first describe several methods commonly used for the fabrication of robust peptide-based hydrogels, including spontaneous hydrogelation, enzyme-controlled hydrogelation and cross-linking-enhanced hydrogelation. We then introduce some representative studies on their applications in drug delivery and antitumor therapy, antimicrobial and wound healing materials, and 3D bioprinting and tissue engineering. We hope that this review facilitates the advances of hydrogels in biomedical applications.

Recent advances of self-assembling peptide-based hydrogels for biomedical applications

Short to ultrashort peptide hydrogels for biomedical uses

Oxidation as a Facile Strategy To Reduce the Surface Charge and Toxicity of Polyethyleneimine Gene Carriers

Wound healing is a major burden of healthcare systems worldwide and hydrogel dressings offer a moist environment conducive to healing. We describe cysteine-containing ultrashort peptides that self-assemble spontaneously into hydrogels. After disulfide crosslinking, the optically-transparent hydrogels became significantly stiffer and exhibited high shape fidelity. The peptide sequence (LIVAGKC or LK6C) was then chosen for evaluation on mice with full-thickness excision wounds. Crosslinked LK6C hydrogels are handled easily with forceps during surgical procedures and offer an improvement over our earlier study of a non-crosslinked peptide hydrogel for burn wounds. LK6C showed low allergenic potential and failed to provoke any sensitivity when administered to guinea pigs in the Magnusson-Kligman maximization test. When applied topically as a dressing, the medium-infused LK6C hydrogel accelerated re-epithelialization compared to controls. The peptide hydrogel is thus safe for topical application and promotes a superior rate and quality of wound healing.

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Transparent crosslinked ultrashort peptide hydrogel dressing with high shape-fidelity accelerates healing of full-thickness excision wounds

A disulfide-crosslinked hydrogel made from ultrasmall peptides is introduced. Crosslinked gels are more elastic and better able to maintain shape integrity. Using facile chemistry, RGD (or other bioactive signals) can be conjugated onto the peptide fibers. Gels formed are biocompatible and support the three-dimensional distribution of cells.

Tunable mechanical properties of ultrasmall peptide hydrogels by crosslinking and functionalization to achieve the 3D distribution of cells.

Dye colourants are being produced yearly on the kilotonne-scale and a significant percentage end up as highly-polluting industrial effluents. Freeze–dried agarose gels are demonstrated here to be efficient adsorbents for the removal of methylene blue, an important industrial dye. A hydrogel adsorbent offers advantages over powdered formulations, which can be difficult to handle. Freeze-drying further allows the adsorbent to be packaged, transported and stored in a dry format, thus conferring cost savings. Parameters such as the volume or concentration of agarose or dye, exposure time, pH and gel/water contact area influenced adsorption capacity and kinetics. Salt inhibited adsorption in a dose-dependent manner and this was exploited for the recycling of adsorbent and dye. Langmuir and Freundlich isotherms were also applied to model the adsorption process. The freeze–dried agarose gel achieved an adsorption capacity of 10.4 ± 0.2 mg/g, which was comparable to commercial activated carbon assessed under similar conditions. Additionally, unlike most activated carbon, agarose is derived from a renewable source. Since agarose is cheaply available commercially, this method can enjoy rapid industrial translation.

Wei Yang Seow

Papers

Short to ultrashort peptide hydrogels for biomedical uses

Oxidation as a Facile Strategy To Reduce the Surface Charge and Toxicity of Polyethyleneimine Gene Carriers

Transparent crosslinked ultrashort peptide hydrogel dressing with high shape-fidelity accelerates healing of full-thickness excision wounds

Tunable mechanical properties of ultrasmall peptide hydrogels by crosslinking and functionalization to achieve the 3D distribution of cells.

Freeze–dried agarose gels: A cheap, simple and recyclable adsorbent for the purification of methylene blue from industrial wastewater