Electroactive Copper–Cyanurate Coordination Polymer for Thiosulfate Monitoring in Biological Fluids

The precise and noninvasive detection of thiosulfate, an essential antidote for cyanide poisoning, is critical for both clinical toxicology and environmental monitoring. In this work, the development of an electroactive copper-cyanurate (Cu-CYA) coordination polymer, engineered as a highly sensitive and selective electrochemical sensor for thiosulfate detection in biological fluids, is reported. The sensor material is synthesized via a straightforward coordination-driven self-assembly process, yielding a porous framework with abundant active sites, excellent redox properties, and superior electron transfer capability. Comprehensive physicochemical characterization confirms the structural integrity and favorable interfacial kinetics of the Cu-CYA/graphite pencil electrode (GPE) sensor. Cyclic voltammetry and differential pulse voltammetry analyses reveal a robust and linear response to thiosulfate concentrations ranging from 100 to 500 nM, with a remarkable sensitivity of 2.94 µA cm^-2 nM^-1 and an exceptionally low limit of detection of 0.32 nM. The sensor exhibits high selectivity against potential interferents and maintains 93.3% of its initial response after 30 days, underscoring its long-term functional reliability. Notably, real sample analysis using human saliva demonstrates a mean recovery of 97.5%, validating the sensor's practical applicability in complex biological matrices. This study establishes Cu-CYA as a powerful electrochemical sensing platform for thiosulfate monitoring, offering new prospects for portable diagnostics in healthcare and environmental safety.