Rapid polymerization of molecularly imprinted hydrogels with self-adhesion, conductivity and specificity triggered by tannic acid-silver nanoparticles for electrochemical detection of methyl parathion in foods.

Abstract

In this work, an electrochemical sensor based on a graphene@tannic acid-silver nanoparticles@molecularly imprinted hydrogel (GR@TA-AgNPs@MIH) with self-adhesion, electrical conductivity, and specificity characteristics was developed for detection methyl parathion (MP). Combining hydrogels with molecular imprinting technology can not only improve the tendency of molecular imprinting polymers to fall off but can also endow the hydrogel with a specific recognition property. The GR@TA-AgNPs@MIH was rapidly synthesized in 5 min via radical polymerization at room temperature. The rapid polymerization was ascribed to the tannic acid-silver nanoparticles (TA-AgNPs) formed a dynamic dual-catalytic system: catechol molecules on TA reduced Ag+ to AgNPs and were oxidized by Ag+ to semiquinone or quinone molecules. The oxidized catechol derivatives could activate ammonium persulfate and then triggered the free radical polymerization of acrylamide monomers. TA-AgNPs with polyphenolic hydroxyl groups imparted adhesive properties to the GR@TA-AgNPs@MIH. The incorporation of graphene further enhanced the conductivity of the GR@TA-AgNPs@MIH, which was beneficial to realize signal amplification. Under optimized conditions, the proposed sensor had a linear range of 1-100 μM, a low limit of detection (LOD) of 0.099 μM, and a limit of quantitation (LOQ) of 0.3 μM. The obtained sensor showed excellent selectivity, reproducibility and stability. Upon applying the proposed sensor to detect MP in carrot, spinach, and rice samples, excellent recovery rates were obtained (84.87 %-109.73 %). This research provides a promising strategy for developing stable detection technology to analyze hazards in food.