Molecularly Imprinted Polymer‐Coated APTES Cellulose Nanocrystal Thin Films for Selective Sensing of Carbofuran

Abstract Molecularly imprinted polymers hold great promise for advancing detection of analytes relevant to healthcare and environmental protection. However, their selectivity and sensitivity are limited, and one of the influencing factors is the substrate on which they are immobilized. Films made from bio‐based materials, such as cellulose nanocrystals (CNCs) and their derivatives, could help by improving the surface area and compatibility, thus increasing the sensitivity. In this work, sulfated CNCs were modified with (3‐aminopropyl) triethoxysilane (APTES) to form hydrolytically stable films and coated with a molecular imprinted polymer formulated for the selective detection of a target contaminant, carbofuran. After chemical characterization, MIP coated CNC‐APTES thin model films were fabricated, and their sensitivity, kinetics, and selectivity were investigated using a quartz crystal dissipative microbalance (QCMD) and the kinetic adsorption models: pseudo‐first‐order, and pseudo‐second‐order. The material showed selective sensing and improved kinetics for carbofuran compared to the herbicide 2,4‐dichlorophenoxyacetic acid (2,4‐D), which has a similar benzene‐based structure. The sensitivity was as low as 0.03 ppm (ca. 2.2 ng/mL), lower than standard commercial sensors that are limited to 1–2 µg/L. These results highlight the potential of CNCs for sensing a wide range of analytes and their potential use in multiplexed devices for simultaneous detection of multiple analytes.