Selective Amphiphile‐Probed Liquid Crystal‐Based Sensing Platform for Monitoring Heavy Metal Ions in Drinking Water

Abstract This study presents a new method for detecting and monitoring heavy metal ions in water samples. The method uses liquid crystal‐based optical sensors and a molecular probe called dodecyl‐N‐iminodiacetic acid (DIDAA). The probe's hydrophilic polar diacetate head group acts as a chelator for heavy metal ions, while its hydrophobic non‐polar tail aligns the liquid crystal molecules. When heavy metal ion‐contaminated water samples are introduced, the LC alignment is rapidly disrupted, resulting in bright optical signals. The sensor has a detection limit of 0.1, 0.3, 1.0, and 5.0 μM for for Mercury (Hg 2+ ), Copper (Cu 2+ ), Cadmium (Cd 2+ ), and Lead (Pb 2+ ) respectively. The diacetate probe remains effective even after multiple uses and was not affected by changes in pH. Its activity could persist for over 5 days. Furthermore, this sensor could be reversed and reused to detect HMIs in the presence of EDTA, making it a potential candidate for developing logic gates at the molecular level.