Design of Arsenic (III) Sensor Using Liquid Crystalline Film Doped with Biomass Carbon Dot

Abstract

Several types of arsenic, like arsenite (As3+), arsenate (As5+) or other organoarsenic species can be produced or encountered in soil and natural waters. In particular, As3+ is notably more poisonous than As5+, with a toxicity level 60 to 70 times higher. The World Health Organization recommends that the maximum allowable level of arsenic in drinking water should be below 10 parts per billion. Unfortunately, the existing techniques for detecting As3+ are not appropriate for the thrid world's people who are afflicted by As3+ poisoning due to their high expense and complex procedures. In this study, we suggest a liquid crystal(LC)-based sensor that can be optically report the selective detection of As3+ in aqueous (Aq) systems. More precisely, the sensor is composed of a LC film and biomass-derived carbon dots (BCDs) coated with L-cysteine (L-Cys) at the interface between the LC and the Aq medium. When As3+ binds to the L-Cys of the BCDs, the ordering of the LCs is altered, which is then reported by a macroscopic optical transition. Therefore, the combination of affordable and readily available BCDs and LCs with automatic optical reporting can address the shortcomings of conventional arsenic sensors. This work was supported by the Korea National Research Foundation (NRF-2021R1A2C2095010 & 2021R1A4A1030944)