Background Prehydrolyzate, which is from the prehydrolysis process in dissolving pulps industry, contains various sugar-derived and lignin compounds such as xylooligosaccharides (XOS), gluco-oligosaccharides, xylose, glucose, and soluble lignin (S-L). The XOS has several beneficial effects on human physiology. XOS and S-L in prehydrolyzate are difficult to efficiently fractionate due to their similar molecular weights and water solubility. In this work, we proposed a sustainable and green process using polystyrene divinylbenzene (PS-DVB) resin to simultaneously separate and recover XOS and S-L. Enzymatic hydrolysis with endo-1,4-β-xylanase and fermentation with P. stipites were sequentially applied to purify XOS to minimize xylose content as well as amplify contents of xylobiose and xylotriose. In addition, 2D-HSQC NMR was used to analyze the structural characteristics of XOS and S-L. Furthermore, the biological abilities of antioxidants and prebiotics of these fractions were investigated by scavenging radicals and cultivating intestinally beneficial bacterias, respectively. Results Results showed that PS-DVB resin could simultaneously separate XOS and solubilized lignin with excellent yields of 93.2% and 85.3%, respectively. The obtained XOS after being purified by enzymatic hydrolysis and fermentation contained 57.7% of xylobiose and xylotriose. 10.4% amount of inherent xylan was found in the S-L fraction obtained by PS-DVB resin separation. 2D-HSQC NMR revealed that lignin carbohydrate complexes existed in both XOS and S-L as covalent linkages between lignin and 4- O -methylglucuronoarabinoxylan. The biological application results showed that the antioxidant capacity of S-L was stronger than XOS, while XOS was superior in promoting growth of intestinal Bifidobacteria adolescentis and stimulating production of short-chain fatty acids by Lactobacillus acidophilus. Conclusions The proposed strategy of sequentially combining hydrophobic resin separation, enzymatic hydrolysis, and fermentation was successfully demonstrated and resulted in simultaneous production of high-quality XOS and solubilized lignin. These biomass-derived products in prehydrolyzate can be regarded as value-adding prebiotics and antioxidants. Electronic supplementary material The online version of this article (10.1186/s13068-019-1527-3) contains supplementary material, which is available to authorized users.

The skin plays an important role in protecting the human body, and wound healing must be set in motion immediately following injury or trauma to restore the normal structure and function of skin. The extracellular matrix component of the skin mainly consists of collagen, glycosaminoglycan (GAG), elastin and hyaluronic acid (HA). Recently, natural collagen, polysaccharide and their derivatives such as collagen, gelatin, alginate, chitosan and pectin have been selected as the matrix materials of bioink to construct a functional artificial skin due to their biocompatible and biodegradable properties by 3D bioprinting, which is a revolutionary technology with the potential to transform both research and medical therapeutics. In this review, we outline the current skin bioprinting technologies and the bioink components for skin bioprinting. We also summarize the bioink products practiced in research recently and current challenges to guide future research to develop in a promising direction. While there are challenges regarding currently available skin bioprinting, addressing these issues will facilitate the rapid advancement of 3D skin bioprinting and its ability to mimic the native anatomy and physiology of skin and surrounding tissues in the future.

We investigated a novel polyepoxide crosslinker that was hypothesized to confer both material stabilization and calcification resistance when used to prepare bioprosthetic heart valves. Triglycidylamine (TGA) was synthesized via reacting epichlorhydrin and NH(3). TGA was used to crosslink porcine aortic cusps, bovine pericardium, and type I collagen. Control materials were crosslinked with glutaraldehyde (Glut). TGA-pretreated materials had shrink temperatures comparable to Glut fixation. However, TGA crosslinking conferred significantly greater collagenase resistance than Glut pretreatment, and significantly improved biomechanical compliance. Sheep aortic valve interstitial cells grown on TGA-pretreated collagen did not calcify, whereas sheep aortic valve interstitial cells grown on control substrates calcified extensively. Rat subdermal implants (porcine aortic cusps/bovine pericardium) pretreated with TGA demonstrated significantly less calcification than Glut pretreated implants. Investigations of extracellular matrix proteins associated with calcification, matrix metalloproteinases (MMPs) 2 and 9, tenascin-C, and osteopontin, revealed that MMP-9 and tenascin-C demonstrated reduced expression both in vitro and in vivo with TGA crosslinking compared to controls, whereas osteopontin and MMP-2 expression were not affected. TGA pretreatment of heterograft biomaterials results in improved stability compared to Glut, confers biomechanical properties superior to Glut crosslinking, and demonstrates significant calcification resistance.

Surface topography, microstructure, and micromechanical properties of human lamellar bone were characterized by atomic force microscopy and nanoindentation. The lamellar bone surfaces were prepared by two different methods: microtome sectioning and mechanical polishing. The lamellar bone surfaces prepared by mechanical polishing revealed that thin lamellae formed depressions approximately 200 nm deep, whereas the surfaces prepared by microtome sectioning were flat. Atomic force microscopy surface topographic images at higher magnification showed differences between thick and thin lamellae in polished samples, but these differences were less pronounced in microtomed samples. Roughness measurements confirmed that there was a significant difference between thick (21.0 nm) and thin lamellae (8.3 nm) in polished samples (p < 0.001). The difference in surface roughness between thick (13.9 nm) and thin lamellae (12.7 nm) in microtomed sample was statistically insignificant (p = 0.74). Higher elastic modulus values were observed for thick lamella in microtomed samples compared with that of thin lamellae, whereas measured elastic modulus differences between thick and thin lamellae in polished samples were found to be statistically insignificant.

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