The Toughness-Enhanced Atelocollagen Double-Network Gel for Biomaterials.

A tough gel composed of atelocollagen, which lacks an immunogenetic site, is a promising material for biomedical application. In this study, we created a composite hydrogel composed of atelocollagen gel cross-linked with glutaraldehyde (GA) and poly-(N,N-dimethylacrylamide) gel exhibiting biocompatibility based on the double-network (DN) gel principle. The tensile toughness of atelocollagen gel remained constant regardless of the amount of cross-linker (GA) used. In contrast, tensile tests of the DN gel indicated that mechanical properties, such as fracture stress and toughness, were significantly higher than those of the atelocollagen gel. Moreover, fibroblast cells adhered and spread on the gels, the Schiff bases of which were treated via reductive amination for detoxification from GA. These findings demonstrate the potential of the proposed gel materials as artificial alternative materials to soft tissues with sub-MPa fracture stress.

Construction of a spheroid array culture system on a suspended permeable hydrogel membrane scaffold for improving the expression of a liver-specific drug-metabolizing enzyme of HepG2 cells.

Herein, we constructed a spheroid array culture system on a flexible hydrogel membrane suspended in the culture medium. When we applied this culture system to HepG2 cells, the results suggested that an aerobic culture environment was implemented, and the gene expression of a liver-specific drug-metabolizing enzyme was improved in comparison with that of the conventional immobilized monolayer culture.

Photolithographic Fabrication of Semi 3-D Microstructures Composed of Flexible Hydrogel Sheet for in Vivo-like Cell Culture System.

Insufficient reliability of current drug screening by cell-based assay has been one of the factors in the poor success rate in drug development. To improve the situation, we proposed a cell culture system using semi 3-D hydrogel microstructures as cell culture scaffolds. Because of its flexibility and permeability, the microstructure was expected to enhance the physiological function of cells. We developed a simple method of fabricating the unique hydrogel microstructures composed of hydroxypropyl cellulose through photolithography. Functionalization with poly(styrene-co-maleic anhydride) gained their cell adhesion, and it was demonstrated that several kinds of cells were incubated on the cell culture scaffolds.