Interactions Between Microplastics and Marine-Derived Polysaccharides: Binding Mechanisms and Bioavailability in Aquatic Systems.

Microplastics (MPs) are increasingly recognized as persistent pollutants in marine and freshwater systems. Their small size, widespread distribution, and ability to adsorb chemical contaminants raise concerns about ecological impacts and human exposure through aquatic food webs. In parallel, marine polysaccharides such as alginate, chitosan, and carrageenan have drawn interest as natural biopolymers with the capacity to interact with MPs. These interactions occur via electrostatic forces, hydrophobic effects, hydrogen bonding, and physical entrapment, influencing the fate and mobility of MPs in aquatic environments. This review critically examines the current state of knowledge on the binding mechanisms between MPs and marine-derived polysaccharides, emphasizing their role in modulating the transport, aggregation, and bioavailability of plastic particles. Recent efforts to modify these biopolymers for improved performance in sorption and stabilization applications are also discussed. Furthermore, analytical strategies for investigating MP-polysaccharide systems are outlined, and the practical limitations associated with scaling up these approaches are considered. The potential use of such materials in environmentally sustainable remediation technologies is explored, along with future research needs related to safety evaluation, lifecycle impact, and feasibility in real-world conditions.