Cross-scale design of chemosensor arrays: from molecular self-assembly in water to paper-based devices for metal ion detection

Monitoring metal ions in aquatic environments is essential for understanding ecosystem dynamics and assessing water quality. Chemosensors have emerged as powerful analytical tools at the molecular level that transduce ion-recognition events into optical signals. In particular, coordination with metal ions enables cross-reactive sensing, allowing for simultaneous detection of multiple analytes based on pattern recognition. This perspective summarizes advances in self-assembled chemosensor systems for metal ion detection and further developments to solid-state chemosensor array devices based on nanotechnologies. In practical chemosensor designs, dynamic covalent bonds between catechol and phenylboronic acid derivatives have been employed to provide a versatile strategy for the spontaneous preparation of chemosensor elements without extensive synthetic effort. Furthermore, integration of these self-assembled chemosensors into paper substrates enables portable detection platforms for on-site analysis without using stationary laboratory instruments. This cross-scale design strategy provides a promising approach for simultaneous detection of metal ions in various water environments across microscopic and macroscopic scales.