Polyelectrolyte Gels: Fundamentals, Fabrication and Applications.

Polyelectrolyte gels are an important class of polymer gels and a versatile platform with charged polymer networks with ionisable groups. They have drawn significant recent attention as a class of smart material and have demonstrated potential for a variety of applications. This review begins with the fundamentals of polyelectrolyte gels, which encompass various classifications (i.

3D Printable Soy/Silk Hybrid Hydrogels for Tissue Engineering Applications.

The development of protein-based 3D printable hydrogel systems with tunable structure and properties is a critical challenge in contemporary biomedicine. Particularly, 3D printing of modular hydrogels comprising different types of protein tertiary structure, such as globular and fibrous, has not yet been achieved. Here we report the extrusion-based 3D printing of hybrid hydrogels photochemically co-cross-linked between globular soy protein isolate (SPI) and fibrous silk fibroin (SF) for the first time.

Tuning the Hierarchical Structure and Resilience of Resilin-like Polypeptide Hydrogels Using Graphene Oxide.

Resilin-like polypeptides (RLPs) are an important class of intrinsically disordered multistimuli-responsive bioelastomers. The nanostructure of RLPs in solution has been extensively studied in the past few years, from dilute to molecular crowding conditions, and with the addition of rigid biopolymers. Modification of the hierarchical network structure of RLP hydrogels using graphene oxide (GO) as an additive is a burgeoning prospect for their application in the bioelectronic and biomedical fields.

Silk fibroins in multiscale dimensions for diverse applications.

Silk biomaterials in different forms such as particles, coatings and their assemblies, represent unique type of materials in multiple scales and dimensions. Herein, we provide an overview of multi-scale silk fibroin materials including silk particles, silk coatings and silk assemblies, each of which represents a unique type of material with wide range of applications. They feature tunable structures and mechanical properties with excellent biocompatibility, which are essentially required for various biomedical and drug delivery applications.

Bioprintable tough hydrogels for tissue engineering applications.

Bioprinting is an advanced fabrication approach to engineer complex living structures as the conventional fabrication methods are incapable of integrating structural and biological complexities. It offers the versatility of printing different cell incorporated hydrogels (bioink) layer by layer; offering control over spatial resolution and cell distribution to mimic native tissue architectures. However, the bioprinting of tough hydrogels involve additional complexities, such as employing complex crosslinking or reinforcing mechanisms during printing and pre/post printing cellular activities.

A Low-Molecular-Weight Gelator Composed of Pyrene and Fluorene Moieties for Effective Charge Transfer in Supramolecular Ambidextrous Gel.

Charge-transfer (CT) gel materials obtained from low-molecular-weight (LMW) compounds through a supramolecular self-assembly approach have received fascinating attention by many researchers because of their interesting material property and potential applications. However, most of the CT gel materials constructed were of organogels while the construction of CT gels in the form of a hydrogel is a challenge because of the solubility issue in water, which considerably limits the use of CT hydrogels. Herein, for the first time, we report a new LMW gelator [N-(fluorenylmethoxycarbonyl)-N-(δ-butyric-1-pyrenyl)-l-lysine, (FmKPy)], composed of two functional moieties such as fluorenylmethoxycarbonyl and pyrene, which not only parade both hydro and organo (ambidextrous) supramolecular gel formation but also exhibit CT ambidextrous gels when mixed with an electron acceptor such as 2,4,7-trinitro-9-fluorenone (TNF).

Hydrogelation Induced by Change in Hydrophobicity of Amino Acid Side Chain in Fmoc-Functionalised Amino Acid: Significance of Sulfur on Hydrogelation.

Although a few Fmoc-functionalised amino acids (Fmoc-AA) are capable of forming hydrogels, the exact levels of hydrophobicity, hydrogen bonding, and ionic nature of the Fmoc-AA gelator required for hydrogel formation remains uncertain. Here, the role of hydrophobicity of amino acid side chain, particularly in the formation of hydrogel, was studied by using Fmoc-norleucine (Fmoc-Nle) and its simple sulfur analogues such as Fmoc-methionine (Fmoc-M) in which the γCH2 of Fmoc-Nle is replaced by sulfur. Results indicate that Fmoc-M forms thermally reversible hydrogels in water (pH ca.