Functional Biopolymers: Innovating Alginate Systems for versatile Bioactive Applications

The growing demand for sustainable materials has prompted significant attention to bio-based chemical building blocks. Biomasses—particularly lignocellulosic and algal—are proving to be excellent renewable sources for obtaining biopolymers1. Alginate, a natural polysaccharide extracted from brown seaweed, consists of β-D-mannuronic acid (M) and α-L-guluronic acid (G) units linked by 1,4-glycosidic bonds2. Its biodegradability, low cytotoxicity, and unique gel forming capabilities make it an ideal building block for eco-friendly applications. In fact, in this study, sodium alginate was chemically modified to design innovative materials with multifunctional properties. Specifically, through click chemistry, alginate was functionalized with quaternary ammonium compounds (QACs),3 known for their antimicrobial properties, resulting in a material with improved antimicrobial activity. Encouraged by the successful functionalization with QACs, a macrocyclic compound, cucurbituril4, was incorporated into the alginate backbone, known for its ability to form highly selective host–guest complexes through non-covalent interactions. This modification aims to create a supramolecular hydrogel with potential applications in drug delivery and catalysis.