Advances and future prospects in colorimetric and fluorescence sensors for Pb 2+ , Hg 2+ , and Cd 2+ Ion detection: a review

This review critically evaluates recent progress in colorimetric and fluorescence sensors for Pb2+, Hg2+, and Cd2+, focusing on molecular design and nanoscale engineering. It uniquely compares sensing mechanisms such as aggregation-induced emission, photoinduced electron transfer, and chemodosimetry while linking structure–property relationships to performance metrics. Unlike previous reviews, it emphasizes the underexplored translation of laboratory probes into field-deployable systems, addressing challenges like ultra-trace detection in complex matrices, interference from coexisting ions, and long-term stability/reusability. By identifying persistent gaps, including poor selectivity in real waters, limited shelf life, and lack of standardized testing protocols, this work offers strategic directions for developing robust, practical sensors. The goal is to bridge the gap between fundamental research and real-world environmental monitoring, supporting public health protection through reliable, on-site heavy metal ion detection.