Characterization of enzyme-crosslinked albumin hydrogel for cell encapsulation.

Albumin is an attractive component for the development of biomaterials applied as biomedical implants, including drug carriers and tissue engineering scaffolds, because of its high biocompatibility and low immunogenicity. Additionally, albumin-based gelators facilitate cross-linking reactions under mild conditions, which maintains the high viability of encapsulated living cells. In this study, we synthesized albumin derivatives to undergo gelation under physiological conditions via the peroxidase-catalyzed formation of cross-links.

Dual-Functionalizable Streptavidin-SpyCatcher-Fused Protein-Polymer Hydrogels as Scaffolds for Cell Culture.

Hydrogels possessing the ability to control cell functions have great potential as artificial substrates for cell culture. Herein, we report dual-functionalizable protein-polymer hybrid hydrogels prepared by thiol oxidation catalyzed by horseradish peroxidase and a phenolic molecule. A chimera protein of streptavidin (SA) and the SpyCatcher protein, with a cysteine residue at its N-terminus, (C-SA-SC) was constructed and co-cross-linked with thiol-functionalized four-arm polyethylene glycol (PEG-SH) to obtain hydrogels possessing two orthogonal conjugation moieties.

Redox-responsive functionalized hydrogel marble for the generation of cellular spheroids.

Liquid marbles (LMs) have recently shown a great promise as microbioreactors to construct self-supported aqueous compartments for chemical and biological reactions. However, the evaporation of the inner aqueous liquid core has limited their application, especially in studying cellular functions. Hydrogels are promising scaffolds that provide a spatial environment suitable for three-dimensional cell culture.

Construction of higher-order cellular microstructures by a self-wrapping co-culture strategy using a redox-responsive hydrogel.

In this report, a strategy for constructing three-dimensional (3D) cellular architectures comprising viable cells is presented. The strategy uses a redox-responsive hydrogel that degrades under mild reductive conditions, and a confluent monolayer of cells (i.e.

General cellular durotaxis induced with cell-scale heterogeneity of matrix-elasticity.

Stiffness-gradient-induced cellular taxis, so-called durotaxis, has been extensively studied on a substrate with a single broad or steep stiffness gradient. However, in actual living tissues, cells should sense cell-scaled heterogeneous elasticity distribution in the extracellular matrix. In this study, to clarify the effect of the cell-scale heterogeneity of matrix-elasticity on durotaxis, we examined the motility of different types of cells on microelastically-striped patterned gels with different cell-sized widths.

Enzymatically Prepared Dual Functionalized Hydrogels with Gelatin and Heparin To Facilitate Cellular Attachment and Proliferation.

Biologically active artificial scaffolds for cell seeding are developed by mimicking extracellular matrices using synthetic materials. Here, we propose a feasible approach employing biocatalysis to integrate natural components, that is, gelatin and heparin, into a synthetic scaffold, namely a polyethylene glycol (PEG)-based hydrogel. Initiation of horseradish peroxidase-mediated redox reaction enabled both hydrogel formation of tetra-thiolated PEG via disulfide linkage and incorporation of chemically thiolated gelatin (Gela-SH) and heparin (Hepa-SH) into the polymeric network.

Cellular Durotaxis Revisited: Initial-Position-Dependent Determination of the Threshold Stiffness Gradient to Induce Durotaxis.

Directional cell movement from a softer to a stiffer region on a culture substrate with a stiffness gradient, so-called durotaxis, has attracted considerable interest in the field of mechanobiology. Although the strength of a stiffness gradient has been known to influence durotaxis, the precise manipulation of durotactic cells has not been established due to the limited knowledge available on how the threshold stiffness gradient (TG) for durotaxis is determined. In the present study, to clarify the principles for the manipulation of durotaxis, we focused on the absolute stiffness of the soft region and evaluated its effect on the determination of TG required to induce durotaxis.

Persistent random deformation model of cells crawling on a gel surface.

In general, cells move on a substrate through extension and contraction of the cell body. Though cell movement should be explained by taking into account the effect of such shape fluctuations, past approaches to formulate cell-crawling have not sufficiently quantified the relationship between cell movement (velocity and trajectory) and shape fluctuations based on experimental data regarding actual shaping dynamics. To clarify this relationship, we experimentally characterized cell-crawling in terms of shape fluctuations, especially extension and contraction, by using an elasticity-tunable gel substrate to modulate cell shape.

Enzymatically prepared redox-responsive hydrogels as potent matrices for hepatocellular carcinoma cell spheroid formation.

Cellular spheroids have been received much attention in the biological and biomedical fields, especially as a base material for drug assays, regenerative medicine, and tissue engineering. Hydrogels have potential for scalable preparation of spheroids because they provide a spatial environment suitable for three-dimensional cell cultivation. Herein, the potential use of a redox-responsive hydrogel as a scaffold for preparation and recovery of spheroids is reported.

Peptide Tag-Induced Horseradish Peroxidase-Mediated Preparation of a Streptavidin-Immobilized Redox-Sensitive Hydrogel.

Several methods have recently been reported for the preparation of redox-sensitive hydrogels using enzymatic reactions, which are useful for encapsulating sensitive materials such as proteins and cells. However, most of the reported hydrogels is difficult to add further function efficiently, limiting the application of the redox-sensitive hydrogels. In this study, peptide sequences of HHHHHHC and GGGGY (Y-tag) were genetically fused to the N- and C-termini of streptavidin (C-SA-Y), respectively, and C-SA-Y was mixed with horseradish peroxidase and thiol-functionalized 4-arm polyethylene glycol to yield a redox-sensitive C-SA-Y immobilized hydrogel (C-SA-Y gel).

Enzymatic preparation of a redox-responsive hydrogel for encapsulating and releasing living cells.

Horseradish peroxidase-mediated oxidative cross-linking of a thiolated poly(ethylene glycol) is promoted in the absence of exogenous hydrogen peroxide, by adding a small amount of a phenolic compound under physiological conditions. The prepared hydrogel can encapsulate and release living mammalian cells.

Immobilization of alkaline phosphatase on magnetic particles by site-specific and covalent cross-linking catalyzed by microbial transglutaminase.

Bacterial alkaline phosphatase (BAP) was site-specifically and covalently immobilized on magnetic particles (MPs) using the enzymatic reaction of microbial transglutaminase (MTG). Immobilization efficiency was affected by the chemical surface treatment of MPs and immobilized BAP exhibited more than 90% of the initial activity after 10 rounds of recycling.

Hematin is an alternative catalyst to horseradish peroxidase for in situ hydrogelation of polymers with phenolic hydroxyl groups in vivo.

Hematin, an iron-containing porphyrin used in the management of porphyria attacks, was evaluated as an alternative catalyst to horseradish peroxidase (HRP) for in situ gelation of polymers with phenolic hydroxyl (Ph) moieties in vivo. An aqueous solution of gelatin derivative with Ph moieties was gellable in the presence of both hematin and H2O2. A total of 98.

Controlling thermo-reversibility of gelatin gels through a peroxidase-catalyzed reaction under mild conditions for mammalian cells.

A variety of cross-linking methods is used for obtaining gelatin gels having a tolerance to thermo-reversible gel-sol transition at physiological temperature. In this paper, we investigated the applicability of horseradish peroxidase-catalyzed cross-linking of tyrosine residues originally contained in native gelatin molecules for preparing such gelatin gels. The gelatin gels obtained through exposure to the enzymatic reaction showed a higher resistance to thermo-reversibility at 37°C than gels obtained through a thermally-induced gelation alone.