Liquid crystal based sensor for antimony ions detection using poly-adenine oligonucleotides

Antimony is highly toxic and a key water pollutant , which needs to be monitored closely. To date, however, most analytical methods for antimony detection are quite limited because they are complicated, expensive, and not suitable for real-time monitoring of antimony. In this study, a label-free and rapid method for antimony ions (Sb 3+ ) detection is developed based on liquid crystals and a 10-mer poly-adenine oligonucleotide as a specific recognition probe for the first time. The working principle is based on the binding of the oligonucleotide to Sb 3+ , which weakens the interaction between the oligonucleotide and cationic surfactants . As a result, the event induces a planar-to-homeotropic orientational change of liquid crystals and a bright-to-dark optical change under crossed polars. This liquid crystal-based optical sensor exhibits a rapid response to Sb 3+ in 10 s, a detection range between 20 nM and 5 μM, and a detection limit at 6.7 nM calculated from 10-mins assay time. It also shows good selectivity against other metal ions including Ag + , Cd 2+ , Cu 2+ , Fe 3+ , K + , Mg 2+ , Mn 2+ , Na + , Pb 2+ , and Zn 2+ . Moreover, this system can be used to detect Sb 3+ in aqueous solutions with different pH or ionic strengths . This simple, fast, and low-cost liquid crystal-based sensing approach with high sensitivity and selectivity has a high potential for detecting Sb 3+ in natural environments and industrial wastewater.