Bottom‐Up Synthesized Glucan Materials: Opportunities from Applied Biocatalysis

Abstract 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.