Acetylcholinesterase-functionalized two-dimensional photonic crystals for the detection of organophosphates

Due to the indiscriminate usage of organophosphates in military and agriculture, there is an increasing demand to develop sensors for monitoring organophosphorus nerve agents and pesticides. Herein, a sensitive two-dimensional photonic crystal (2D-PC) biosensor as a part of a portable device for the detection of Dipterex is presented. The 2D-PC array was self-organized on the water-air interface using 600 nm polystyrene (PS) colloidal particles, and it was further embedded into a polyacrylamide-acrylic acid (PAM-AA) hydrogel. After condensation between the amine groups of acetylcholinesterase (AChE) and the carboxyl groups of the hydrogel, a novel sensing platform of 2D-PC hydrogel with AChE as the recognition agent was constructed. The lattice spacing of AChE-functionalized 2D-PC was inversely proportional to the logarithm of the Dipterex concentration from 10^-14 mol L^-1 to 10^-4 mol L^-1 with estimated limit of detection (LOD) of 7.7 × 10^-15 mol L^-1. Simultaneously, the structural color of AChE-functionalized 2D-PC varied from yellow to blue. The biosensor achieved "naked-eye" detection due to which the use of AChE-functionalized 2D-PC is a promising technique for onsite and fast screening of organophosphates.