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 we describe the natural and engineered enzymes (glycosyltransferases, glycoside hydrolases and phosphorylases, glycosynthases) for D-glucan polymerization and show the use of applied biocatalysis for the bottom-up assembly of specific D-glucan structures. We further show advanced material applications of the resulting polymeric products and discuss their important role in the development of sustainable macromolecular materials in a bio-based circular economy. This article is protected by copyright. All rights reserved.