Non-Enzymatic Liquid Crystal-Based Detection of Copper Ions in Water

The fabrication of liquid crystal (LC) based sensor with amphiphilic ligands give label free and real time detection of heavy metals in water. In this study, Dodecyloxyurea (DDOU) is synthesized and doped with 4-cyano-4'-pentyl biphenyl (5CB) to form LC sensor for detection of Cu2+ ions in water. The non-polar tail of DDOU align the liquid crystal molecules homeotropically and polar urea head forms stable complex with Cu2+ ions at aqueous interface. The complexation between oxyurea and Cu2+ ion triggers the orientation transitions of LC molecules to give dark to bright optical signal. The sensor is selective towards Cu2+ ions and did not respond to common metal interferences in water like Hg2+, Pb2+, Cd2+, Zn2+, Na+, Co2+ and Ca2+. The sensor has limit of detection for Cu2+ ions is 10 mu M in tap water.