Magnetic Electrochemical Sensing Platform for Biomonitoring of Exposure to Organophosphorus Pesticides and Nerve Agents Based on Simultaneous Measurement of Total Enzyme Amount and Enzyme Activity

Abstract

We report a new approach for electrochemical quantification of enzymatic inhibition and phosphorylation for biomonitoring of exposure to organophosphorus (OP) pesticides and nerve agents based on a magnetic bead (MB) immunosensing platform. The principle of this approach is based on the combination of MB immunocapture-based enzyme activity assay and competitive immunoassay of the total amount of enzyme for simultaneous detection of enzyme inhibition and phosphorylation in biological fluids. Butyrylcholinesterase (BChE) was chosen as a model enzyme. In competitive immunoassay, the target BChE in a sample competes with the BChE immobilized on the MBs to bind to the limited sites of anti-BChE antibody labeled with quantum dots (QD-anti-BChE), followed by stripping voltammetric analysis of the bound QD conjugate on the MBs. This assay shows a linear response over the total BChE concentration range of 0.1-20 nM. Simultaneous real time BChE activity was measured on an electrochemical carbon nanotube-based sensor coupled with a microflow injection system after immunocapture by the MB-anti-BChE conjugate. Therefore, the formed phosphorylated BChE adduct (OP-BChE) can be estimated by the difference values of the total amount of BChE (including active and OP-inhibited) and active BChE from established calibration curves. This approach not only eliminates the difficulty in screening of low-dose OP exposure (less than 20% inhibition of BChE) because of individual variation of BChE values but also avoids the drawback of the scarce availability of OP-BChE antibody. It is sensitive enough to detect 0.5 nM OP-BChE, which is less than 2% BChE inhibition. This method offers a new method for rapid, accurate, selective, and inexpensive quantification of OP-BChE and enzyme inhibition for biomonitoring of OP and nerve agent exposures.

Electrochemical biosensing strategy for highly sensitive pesticide assay based on mercury ion-mediated DNA conformational switch coupled with signal amplification by hybridization chain reaction

“…Although these methods show high selectivity and adequate sensitivity, and allow for the discrimination of pesticides, they usually rely on sophisticated instruments and skilled manpower, making such approaches impractical for routine environment and food safety monitoring. To address these issues, several alternative techniques have been designed and successfully employed in pesticide detection, such as colorimetric methods [9], fluorometric approaches [10,11], surface plasmon resonance [12], electrochemiluminescence [13], electrochemical methods [14][15][16][17][18][19][20][21][22], and so on [1,3]. Among them, electrochemical strategies are attractive for pesticide detection due to their outstanding advantages of simple operation, rapid response, low cost, and compatibility with micromanufacturing technology [23][24][25].…”

“…Among them, electrochemical strategies are attractive for pesticide detection due to their outstanding advantages of simple operation, rapid response, low cost, and compatibility with micromanufacturing technology [23][24][25]. Therefore, much effort has been made toward developing electrochemical methods, especially the enzyme-based electrochemical biosensors [14][15][16][17][18][19][20]. Typically, acetylcholinesterase (AChE), a commercially available enzyme, is usually used based on the inhibition effect of these pesticides on AChE activity.…”

Electrochemical Biosensors for Determination of Organophosphorus Compounds: Review

“…AchE enzyme was used in combination with different types of supports for the fabrication of bio-sensing devices [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34]. Table 1 summarizes the characteristics of different AchE-based biosensors.…”

Selective detection of parathion-methyl based on near-infrared CuInS2 quantum dots

“…Therefore, some OPs sensors have been established based on the inhibition mechanism of AChE or other technologies, for example, bi-enzymes of AChE and choline oxidase (Gao, Tang, & Su, 2012;Meng, Wei, Ren, Ren, & Tang, 2013;Zheng, Li, Dai, Liu, & Tang, 2011). Du et al reported a sensor for electrochemical quantification of enzymatic inhibition for biomonitoring of OPs (Du et al, 2011). But such inhibition sensors are not selective to OPs since AChE activity is also inhibited by carbamates pesticide .…”