Direct competitive immunosensor for Imidacloprid pesticide detection on gold nanoparticle-modified electrodes

Abstract

A direct competitive immunosensor for the electrochemical determination of Imidacloprid (IMD) pesticide on gold nanoparticle-modified screen-printed carbon electrodes (AuNP-SPCE) is here reported for the first time. Self-obtained specific monoclonal antibodies are immobilized on the AuNP-SPCE taking advantage of the AuNPs biofunctionalization abilities. In our biosensor design, free IMD in the sample competes with IMD conjugated with horseradish peroxidase (IMD-HRP) for the recognition by the antibodies. After that, 3,3′,5,5′-Tetramethylbenzidine (TMB) is enzymatically oxidized by HRP, followed by the oxidized TMB reduction back at the surface of the SPCE. This process gives an associated catalytic current (analytical signal) that is inversely proportional to the IMD amount. The main parameters affecting the analytical signal have been optimized, reaching a good precision (repeatability with a RSD of 6%), accuracy (relative error of 6%), stability (up to one month), selectivity and an excellent limit of detection (LOD of 22 pmol L -1 ), below the maximum levels allowed by the legislation, with a wide response range (50 -10000 pmol L -1 ). The detection through antibodies also allows to have an excellent selectivity against other pesticides potentially present in real samples. Low matrix effects were found when analysisng IMD in tap water and watermelon samples. The electrochemical immunosensor was also validated with HPLC-MS/MS, the reference method used in official laboratories for IMD analysis, through statistical tests. Our findings make the electrochemical immunosensor as an outstanding method for the rapid and sensitive determination of IMD at the point-of-use.

Electrochemical (Bio)Sensors for Pesticides Detection Using Screen-Printed Electrodes

“…Representative examples of competitive immunosensors are those based on the use of enzymatic tags proposed for the determination of Chlorsulfuron [178] and Imidacloprid [179] at levels as low as 22 pM, also taking advantage of the use of AuNPs [180] for the immobilization of the antibody. Tap water, watermelon and tomato samples were analyzed here without the need of pretreatment (Figure 6B).…”

“…Tap water, watermelon and tomato samples were analyzed here without the need of pretreatment (Figure 6B). Reprinted from [180], Copyright 2020, with permission from Elsevier.…”

Development of a functional impedimetric immunosensor for accurate detection of thy- roid-stimulating hormone

“…Immunosensors offer a number of advantages over traditional analytical techniques, including portability, specificity, cheapness and real-time monitoring as well as having good versatility, robustness, selectivity and sensitivity depending on the transducer [25]. Hence immunosensors have exhibited a significant development in the immune-analytical field in the last decade, which facilitate sensitive and accurate determination of a vast number of target molecules such as cancer biomarkers [26], pathogens [27], cardiac markers [28], drugs [29], pesticides [30],…”

Rapid Multi-Residue Detection Methods for Pesticides and Veterinary Drugs

“…Therefore, novel analysis methods for the rapid and sensitive detection of pesticides and veterinary drugs are highly desired. Common rapid methods are capable of detecting a single target with high specificity [12], whereas real food samples generally always contain more than one pesticide or veterinary drug. Therefore, multi-residue detection methods are more favorable for the actual analytical needs of end-users.…”