Development of electrochemical based sensor for rapid and specific detection of fluoroquinolones residues in dairy products

Abstract

Abstract

Introduction: Antibiotics have been broadly implemented indiscriminately by livestock farmers in treating livestock. Ciprofloxacin is the most commonly used fluoroquinolone that can be easily transferred into dairy products such as milk, yogurt, cheese and cream due to its high thermal resistance and stability. In this regard, we are now facing major concern about the risks on the food safety and environment owing to their uncontrolled disposal. Hence, the progress of simple and sensitive approaches for fast monitoring of antibiotic levels is highly desirable. Here, we tried to describe two new sensitive and easy-to-use strategies based on Apt/3D-Au-PAMAM/rGO/GCE and Apt-GO-PEI-AuNPs for electrochemical apta-assay towards of ciprofloxacin residues (CFX). Materials and Methods: In this study, raw milk and pasteurized milk sapmles were randomly collected from different supermarkets in Tabriz, Iran and then the spirofloxacin residues was examined by electrochemical biosensing method. At first, the Apt/3D-Au-PAMAM/rGO/GCE platform has been designed via full electrochemically technique on the surface of glassy carbon electrodes (GCE) and evaluated with cyclic voltammetry method. For that, rGO with a large amount of active functional groups was fabricated on the GCE electrode. Then, the 3D Au-PAMAM nanocomposite was synthesized and covalently electrodeposited onto the rGO-GCE modified surface. Nanoparticles not only increase the active surface of the electrode but also provide a suitable, reactive, and stable site for the binding of a biological detector (aptamer) for a specific response to ciprofloxacin. In the second platform, aminated aptamer and graphene oxide nanogold-functionalized branched polyethyleneimine (GO-PEI-AuNPs) nanocomposite was prepared. For that, the gold electrode (AuE) was modified with GO-PEI-AuNPs. After further modification of substrate with CFX specific aptamer, a recognition probe enabling selective and sensitive determination of CFX was realized. All of the aptasensor fabrication steps were surveyed via the cyclic voltammetry (CV) method. Herein, after blocking non-specific sites on the electrode surface, the designed aptasensor was used to detect CFX in standard samples as well as pasteurized and local milk samples. Conclusion: After characterization of parameters, Apt/rGO/3D Au-PAMAM/GCE as the first novel biocompatible interface offer a suitable, cost-effective, reliable, rapid, and user-friendly sensing device for direct determination of CFX in real milk samples with a low limit of quantification (LLOQ) of 1 nM and a linear range of 1 μM-1 nM. For the second platform, the suggested scaffold can offer an acceptable linear range of 0.001 to 100 µM and a low limit of quantification (LLOQ) of 0.001 µM for selectivity and sensitivity monitoring of CFX in pasteurized and local milk samples. Discussion: It can be deduced that both Apt/rGO/3D Au-PAMAM/GCE and Apt-GO-PEI-AuNPs as two novel biocompatible interfaces could offer suitable, cost-effective, reliable, rapid, and user-friendly sensing devices for direct determination of CFX in actual food and environmental samples. Keywords: Ciprofloxacin; Aptasensor; Polyamide amine; Gold nanoparticles; Electrochemical tecnique