Shinji Sakai

Chitosan with phenolic hydroxyl groups (Chit-Ph) was synthesized by conjugating chitosan with 3-(p-hydroxyphenyl)propionic acid using aqueous-phase carbodiimide activation chemistry. By this conjugation, we could obtain chitosan derivatives soluble at neutral pH and gellable via a peroxidase-catalyzed reaction within seconds: The Chit-Ph with higher content of Ph groups showed higher solubility at neutral pH. The neutral Chit-Ph solutions gelated via an enzymatic reaction by consuming H2O2. The

Glucose is a common component of body fluids. We describe a hydrogel wound dressing that can be obtained by pouring an aqueous solution of a polyvinyl alcohol derivative possessing phenolic hydroxyl moieties (PVA-Ph), containing glucose oxidase (GOx) and horseradish peroxidase (HRP), onto a wound. The in situ hydrogelation progresses through GOx-catalysed hydrogen peroxide (H₂O₂) generation from glucose in the wound exudate and HRP-catalysed cross-linking between phenolic h

Bioprinting has a great potential to fabricate three-dimensional (3D) functional tissues and organs. In particular, the technique enables fabrication of 3D constructs containing stem cells while maintaining cell proliferation and differentiation abilities, which is believed to be promising in the fields of tissue engineering and regenerative medicine. We aimed to demonstrate the utility of the bioprinting technique to create hydrogel constructs consisting of hyaluronic acid (HA) and gelatin deri

Hydrogel fibers that possessed a cell-adhesive surface and were degradable via enzymatic reactions were developed for fabricating tubular constructs with smooth muscle cell (SMC) and endothelial cell (EC) layers, similar to native blood vessels, in collagen gels. The fibers were prepared by soaking hydrogel fibers prepared from a solution of sodium alginate and gelatin containing bovine ECs (BECs) in medium containing oxidized alginate (AO). BECs soaked in 8.0% (w/v) AO showed no reduction in vi

Gelatin-based microcapsule production using a microfluidic system and the feasibility of the resultant microcapsules for constructing spherical tissues surrounded by heterogeneous cells were studied. The first cell-encapsulation and subsequent cell-enclosing microparticle encapsulation were achieved using a microfluidic flow-focusing droplet production system. A hollow-core structure of about 150 μm in diameter was developed by incubating the resultant microparticles at 37 °C, which induced ther

Visible light-induced hydrogelation is attractive for various biomedical applications. In this study, hydrogels of alginate with phenolic hydroxyl groups (Alg-Ph) were obtained by irradiating a solution containing the polymer, ruthenium II trisbipyridyl chloride ([Ru(bpy)₃]²⁺) and sodium persulfate (SPS), with visible light. The hydrogelation kinetics and the mechanical properties of the resultant hydrogels were tunable by controlling the intensity of the light and the conc