Gold Nanoparticles Coated Aptamer-based Fiber Optic LSPR Biosensor for Arsenic Detection

Arsenic has been a serious risk to all life forms because of its toxic and carcinogenic nature. It has been an unavoidable contaminant in the groundwater sources for millions of people in India and Bangladesh. Some of those contaminated regions have arsenic way beyond the World Health Organization (WHO) specified maximum allowed limit of $10 \mu \mathrm{g} / \mathrm{L}$ or 10 PPB (Parts Per Billion). Hence, in this study, we have developed| a fiber-optic arsenic sensing scheme utilizing arsenic-specific aptamer immobilized on cysteamine-capped gold nanoparticles. The developed sensing scheme is highly sensitive and selective toward the detection of arsenic in water samples. We have achieved an experimental limit of detection of $1 \mu \mathrm{g} / \mathrm{L}$ (1 PPB) which is well under the limits set by WHO for drinking water.