Polysaccharide-based hydrogels as controlled-transport networks: Chemistry-to-performance design rules

Polysaccharide-based hydrogels are increasingly being developed for applications requiring regulated mass transport, hydrated structural stability, and compatibility with biological or environmental settings. Their performance depends on how polysaccharide functional groups are translated into ionic, covalent, dynamic, or hybrid junctions that govern swelling, mesh size, mechanical integrity, degradation, and solute mobility. This review examines polysaccharide-based hydrogels as transport-regulating networks rather than as materials defined primarily by precursor identity or application category. The central focus is the chemistry-to-performance relationship through which substitution chemistry, crosslink type, charge density, mesh size, porosity, multicomponent reinforcement, and degradation behavior regulate retention, release, regeneration, and interfacial function. Representative applications in agriculture, water purification, drug delivery, and wound healing are used to show how shared network features are redirected toward distinct performance outcomes by environmental and biological boundary conditions. By integrating precursor chemistry, network formation, structure-transport relationships, benchmarking constraints, and translation considerations, this review establishes a framework for using polysaccharide chemistry to design application-specific hydrogels with interpretable and controllable performance.