Dehydrothermal (DHT) treatment was used to improve the properties of collagen casings because of its non-cytotoxicity. Understanding the effects of DHT treatment on the structure and mechanical properties of collagen films is beneficial to developing satisfying collagen casings. Herein, DHT treatment with various temperatures (85–145 °C) and timescales (1–7 days) were investigated. It was clarified that the chemical crosslinking covalent bond between collagen molecules was formed after the DHT treatment. Crosslinking density increased with increasing DHT treatment temperatures, contributing to the increase of tensile strength up to over three times of that of the untreated collagen film. The increased crosslinking density was also found when increasing the DHT treatment time, and the maximum was obtained in 3 days. Further DHT treatment time did not change the crosslinking density. The damage in the triple helix structure and the self-assembly of collagen molecules were observed from IR and SAXS. The extent of denaturation increased with increasing DHT treatment temperature and time, although the effect of the DHT treatment time on the denaturation was more moderate. When the DHT treatment temperature was as high as 145 °C or the DHT treatment time exceeded 5 days, serious denaturation occurs, leading to the deterioration of mechanical properties.

Despite lacking Na + -ATPase as a sodium pump in vascular plants, a gene encoding KPA (K + P-type ATPase), a putative animal type-Na + /K + -ATPase, has been isolated from the marine red alga Porphyra yezoensis and designated PyKPA1. To characterize the properties of PyKPA1 and also to confirm its ability to confer salinity tolerance in land plants, transgenic rice plants were produced that expressed the full-length PyKPA1 cDNA under the control of cauliflower mosaic virus 35S RNA promoter. We observed transcriptional activation of the transgene, plasma membrane-localization of the gene product fused with green fluorescent protein in onion epidermal cells, and Na + -ATPase activity in the plasma membrane fraction from transgenic rice plants, indicating that PyKPA1 was functionally expressed in rice plants. Transgenic lines were examined in terms of growth in salinity stress conditions, resulting in protection from a decrease in biomass, although growth of control rice plants was repressed. These results demonstrate the utility of a red algal animal type-sodium pump for conferring salinity tolerance to land plants.

Tissue engineered scaffold was regarded as a promising approach instead of the autograft. In this study, small diameter electrospun collagen tubular scaffold with random continuous smooth nanofibers was successfully fabricated. However, the dissolution of collagen in concentrated aqueous (conc. aq.) acetic acid caused to the serious denaturation of collagen. A novel method ammonia treatment here was adopted which recovered the collagen triple helix structure according to the analysis of IR spectra. Further dehydrothermal (DHT) and glutaraldehyde (GTA) treatments were applied to introduce the crosslinks to improve the properties of collagen tube. The nanofibrous structure of collagen tube in a wet state was preserved by the crosslinking treatments. Swelling ratio and weight loss decreased by at least two times compared to those of the untreated collagen tube. Moreover, tensile strength was significantly enhanced by DHT treatment (about 0.0076 cN/dTex) and by GTA treatment (about 0.075 cN/dTex). In addition, the surface of crosslinked collagen tube kept the hydrophilic property. These results suggest that DHT and GTA treatments can be utilized to improve the properties of electrospun collagen tube which could become a suitable candidate for tissue engineered scaffold.

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