Water-compatible Molecularly Imprinted Photonic Hydrogels for Fast Screening of Morphine in Urine

A smart label-free colorimetric chemosensor was developed for the convenient and fast screening of morphine with high sensitivity and specificity based on colloidal-crystal and molecular imprinting technique which was named molecularly imprinted photonic hydrogels (MIPHs). The voids of photonic crystal template were completely filled with hydrogel with target template molecule. Then the silica particles and template molecule in it were fully etched to form 3D ordered interconnected macroporeus arrays structure. Due to the unique inverse opal arrays with a thin polymer wall in which the imprinted nanocavities of morphine molecules distributed, the photonic hydrogels would be obvious swelling in responsive for the specific morphine molecular recognition process to induce the Bragg diffractive shifts of ordered macroporeus arrays, which transferred into visually perceptible optical signal (change in color) directly detected by the naked eye. The MIPHs were designed as water-compatible and synthesized in a water-methanol system to enhance the recognition ability in aqueous media. The proposed MIPHs were successfully employed to screen trace level morphine in human urine samples, exhibited high sensitive (as low as 0.1 ng/mL), rapid responsive (less than 40 s) and specific detection of morphine in complex biological matrix. It can provide a powerful tool for fast screening of morphine on the spot for forensic investigations.