Self-assembled Optical Diffraction Patterns for Applications in Water Quality Monitoring

In this paper, we present a novel method with unique surface modification technique to detect dissolved arsenite contamination of water. It features self-assembled patterns of thiol ligand like glutathione (GSH) on the gold-coated glass. Thiol easily binds with gold through Au-S linkage. In addition to this, As(III) has an affinity towards amino acids, amines, peptides and organic micro-molecules due to As-O or As-S linkages. Hence, GSH binds with gold-coated glass and arsenic. The patterns are obtained through a micro-contact printing (µCP) procedure. When these patterns are exposed to arsenic-contaminated water, the arsenic layer forms on the GSH pattern which produces an optical diffraction grating for the detection system. These self-assembled optical diffraction patterns can detect dissolved arsenite up to 20 µg/L. Our findings suggest that the proposed method can also be used for detection of a variety of other metallic and pathogenic contaminants like E. coli for water Quality monitoring.