Synthesis of Amylose-b-P2VP Block Copolymers

Bottom-Up Synthesized Glucan Materials: Opportunities from Applied Biocatalysis

Linear d-glucans are natural polysaccharides of simple chemical structure. They are comprised of d-glucosyl units linked by a single type of glycosidic bond. Noncovalent interactions within, and between, the d-glucan chains give rise to a broad variety of macromolecular nanostructures that can assemble into crystalline-organized materials of tunable morphology. Structure design and functionalization of d-glucans for diverse material applications largely relies on top-down processing and chemical derivatization of naturally derived starting materials. The top-down approach encounters critical limitations in efficiency, selectivity, and flexibility. Bottom-up approaches of d-glucan synthesis offer different, and often more precise, ways of polymer structure control and provide means of functional diversification widely inaccessible to top-down routes of polysaccharide material processing. Here the natural and engineered enzymes (glycosyltransferases, glycoside hydrolases and phosphorylases, glycosynthases) for d-glucan polymerization are described and the use of applied biocatalysis for the bottom-up assembly of specific d-glucan structures is shown. Advanced material applications of the resulting polymeric products are further shown and their important role in the development of sustainable macromolecular materials in a bio-based circular economy is discussed.

Physicochemical properties of heat-moisture treated, stearic acid complexed starch: The effect of complexation time and temperature

Starch modification has been extensively studied to alter its physicochemical properties based on human needs. Lowering the digestion rate of starch is one of the interests in food science research, since when it is nutritionally improved, it can reduce the risk of human chronic diseases. In this study, heat-moisture treatment (HMT) followed by inclusion complexation with stearic acid at various temperatures and times was applied to improve the functional properties of starch. Thermal analysis suggested the formation of type I and type II complexes after complexation at 90 °C, indicated by a endothermal peak at 107 and 122 °C, respectively, while native starch after complexation only resulted in type I complexes. The formation of crystalline complexes was also confirmed by XRD showing peaks at 2θ = 13.1° and 20.1°. Furthermore, the modified starch displayed a higher pasting temperature, considerably less swelling and significantly lower viscosity behavior. This implied that the starch granules were thermally and mechanically more stable. The granular appearance of the modified starch was confirmed with light microscopy that presented more intact granules and less ruptured granules, even after heating to 90 °C. This study offers a way to upgrade the nutritional properties of starch.

Deciphering Structures of Inclusion Complexes of Amylose with Natural Phenolic Amphiphiles

Amylose inclusion complexes were prepared in aqueous solution with the amphiphilic moiety 3-pentadecylphenol via a direct mixing method. Attenuated total reflection Fourier transform infrared spectroscopy as well as differential scanning calorimetry confirmed the formation of amylose inclusion complexes. The morphology of the synthesized complexes is sensitive to temperature, and X-ray data revealed that the inclusion complexes exhibited distinct structures at different temperatures. Small-angle X-ray scattering data indicated ordered lamellar structures of the synthesized complexes at room temperature, and wide-angle X-ray scattering profiles showed the transformation of the crystalline structure as a function of the temperature. The results of this research will help to understand the relationship between the inclusion complex structures with temperature.

Amylose engineering: phosphorylase-catalyzed polymerization of functional saccharide primers for glycobiomaterials

Interest in amylose and its hybrids has grown over many decades, and a great deal of work has been devoted to developing methods for designing functional amylose hybrids. In this context, phosphorylase-catalyzed polymerization shows considerable promise as a tool for preparing diverse amylose hybrids. Recently, advances have been made in the chemoenzymatic synthesis and characterization of amylose-block-polymers, amylose-graft-polymers, amylose-modified surfaces, hetero-oligosaccharides, and cellodextrin hybrids. Many of these saccharides provide clear opportunities for advances in biomaterials because of their biocompatibility and biodegradability. Important developments in bioapplications of amylose hybrids have also been made, and such newly developed amylose hybrids will help promote the development of new generations of glyco materials. WIREs Nanomed Nanobiotechnol 2017, 9:e1423. doi: 10.1002/wnan.1423 For further resources related to this article, please visit the WIREs website.