Design of Liquid Crystal-Based Sensor for Arsenic (III)

Abstract

Arsenic (As3+) is one of the most carcinogenic and toxic elements present in the earth's crust and groundwater. Thus, WHO recommends a maximum contamination limit of less than 10 ppb in drinking water. Existing methods can detect trace amounts of arsenic, but are time consuming, expensive equipment, and must be analyzed in well-equipped laboratories. This study proposes an inexpensive detection method that anyone can use for fast and stable detection of As3+. Sensitivity was given using liquid crystals (LCs), and carbon dots (BCDs) obtained from biomass were used to give selectivity. Specifically, the sensor consists of LC film and L-cysteine(Cys)-coated BCDs that self-assemble at the LC-Aqueous interface. The selective adsorption of As3+ by Cys in the BCDs results in molecular reorientation of LCs, which produces a noticeable macroscopic optical signal. Thus, the limitations of conventional As3+ sensors can be overcome by combining an inexpensive BCDs and LCs with optical reporting. This work was supported by the Korea National Research Foundation (NRF-2021R1A2C2095010 & 2021R1A4A1030944)