Highly sensitive folic acid colorimetric sensor enabled by free-standing molecularly imprinted photonic hydrogels

Abstract

Folic acid is an important biological compound for human disease diagnosis. Traditional detection methods of folic acid are mostly time-consuming or dependent on analytical equipment. Here we demonstrate the rapid and colorimetric detection of folic acid using a novel colorimetric sensor enabled by molecularly imprinted photonic hydrogels, which are prepared by the polymerization of precursor solution in the interstitial voids of the polystyrene colloidal crystal and subsequent removal of colloidal crystal and folic acid molecules. As folic acid is instable under the preparation process of molecularly imprinted photonic hydrogels, we introduce folic acid (imprinted molecule) in the form of supramolecular complex with β-CD units to improve its stability and further create stable molecular recognition sites. The folic acid recognition can be directly transferred into a visually perceptible color change due to the highly ordered macroporous structure. With this novel sensory system, the highly selective, high sensitive (as low as 10–12 M), and rapid response (< 60 s) to folic acid is achieved without the use of instruments. A novel folic acid colorimetric sensor enabled by molecularly imprinted photonic hydrogels is successfully prepared.