Ionophore-Based Electrochemical Sensors for Metal Ion Detection: Materials, Designs and Applications

The accurate monitoring of metal ions is essential for applications that include environmental protection, food safety, and biomedical diagnostics. These areas depend on highly sensitive and selective methods for detecting both toxic and biologically relevant ions. Electrochemical sensors have emerged as promising devices due to their excellent sensitivity, cost-effectiveness, and ease of use. Within these sensor systems, ionophores, either synthetic or natural ligands that exhibit selective ion binding, are fundamental in boosting analytical performance. This review outlines the current progress of ionophore-based electrochemical sensors for metal-ion analysis, emphasizing material selection, architectural strategies, and practical applications. Key classes of ionophores, such as crown ethers, calixarenes, Schiff bases, porphyrins, and oxime derivatives, are discussed with an emphasis on their recognition mechanisms. We also examine strategies for incorporating ionophores into diverse electrochemical sensor configurations and explore recent advances in technologies, such as all-solid-state sensor construction and the development of portable analytical devices. This review bridges the chemistry of ionophores with sensor engineering and serves as a resource for the rational development of advanced platforms for metal-ion sensing.