Hemicellulose Extraction and Applications as Hydrogels: A Review

Hemicellulose, as one of the key components of the plant cell wall, is the second most abundant plant polysaccharide in nature, after cellulose. It is highly valued by both the academic and industrial communities because of its low cost, environmental friendliness, renewability, and biodegradability. In this review, we provide a comprehensive elaboration of the mechanisms and the latest research advancements in hemicellulose extraction using various methods, including alkali extraction, hydrothermal pretreatment, acid extraction, and deep eutectic solvent extraction. Furthermore, applications of hemicellulose-based hydrogels as adsorbent, drug delivery materials, wound dressings, bone tissue engineering materials, and flexible sensors are presented. The four most commonly used types of hemicellulose polysaccharides regarding wound healing, including xyloglucan, xylan, konjac glucomannan, and seed-derived galactomannan, are systematically addressed. At last, perspectives on current challenges and future development trends of hemicellulose are briefly presented. The purpose of this review is to provide actionable strategies for biomass valorization.