Construction strategies and detection application progress of colorimetric sensors in polysaccharide-metal...

Colorimetric detection is widely used in diagnostics and environmental monitoring due to its simplicity and visual readout, yet traditional metal nanoparticle probes suffer from poor biocompatibility, limited optical tunability, and aggregation issues. This review highlights polysaccharide-metal nanoparticle composites as a solution, with polysaccharides acting as architectural and functional directors. Three progressive design strategies are presented: (1) direct use of natural polysaccharides for nucleation and stabilization; (2) chemical modification to introduce surface charge and recognition functions; and (3) multivalent assembly leveraging chain-organized groups for reversible aggregation and tunable optical responses. Key structural parameters, molecular weight, functional group density, chain conformation, govern plasmonic and catalytic properties. Beyond metal ions and small metabolites, the application scope extends to organophosphorus pesticides and azo dyes. By combining biocompatibility and optical tunability, these polysaccharide-enabled composites overcome traditional bottlenecks, offering broad prospects in precision diagnostics, environmental screening, and food safety monitoring.