Molecularly imprinted electrochemiluminescence-colorimetric dual-mode sensor based on Mn@NC nanozyme amplification for the detection of phoxim

Abstract

The common detection methods of phoxim mostly rely on the output mode of single signal, which is easily disturbed by complex environmental media and causes errors. Herein, in order to improve the reliability of detection, we developed a dual-mode detection strategy based on nanozyme for the detection of phoxim. Firstly, manganese-nitrogen co-doped carbon nanozyme (Mn@NC) with peroxidase-like activity was synthesized by one-step pyrolysis, which was used to construct in the luminol-H2O2 electrochemiluminescence (ECL) system with molecularly imprinted polymer (MIP) technology. Among them, Mn@NC can act as a co-reaction promoter to catalyze H2O2 to produce large amounts of hydroxyl radicals (•OH), thereby significantly amplifying the cathode signal of luminol and improving the stability of the signal. Benefiting from the specific selection of phoxim by MIP, this molecularly imprinted electrochemiluminescence (MIECL) mode has considerable sensitivity and selectivity, with a low limit of detection (LOD) of 0.011 ng/mL (S/N = 3). Moreover, the •OH produced by Mn@NC-catalyzed H2O2 oxidized the colorless 3,3′,5,5′-tetramethylbenzidine (TMB) to blue oxidized TMB (oxTMB). Taking advantage of the fact that the simultaneous presence of acetylcholinesterase (AChE) and acetylthiocholine (ATCh) inhibited the activity of Mn@NC. A sensitive and simple colorimetric pesticide sensing platform was constructed by combining the nanozyme with the TMB-H2O2 system to achieve the colorimetric detection of phoxim, with the LOD as low as 1.27 ng/mL. The dual-mode sensor was successfully applied to the determination of phoxim in agricultural products with satisfactory results, showing its great potential in the monitoring of food hazards.