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 (Sb3+) 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 Sb3+, which weakens the interaction between the oligonucleotide and cationic surfactants. As a result, the event in-duces 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 Sb3+ in 10 s, a detection range between 20 nM and 5 mu M, 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+, Cd2+, Cu2+, Fe3+, K+, Mg2+, Mn2+, Na+, Pb2+, and Zn2+. Moreover, this system can be used to detect Sb3+ 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 Sb3+ in natural environments and industrial wastewater.