Development of the first enzymatic biosensor for oxytetracycline

Oxytetracycline (OTC) is a common tetracycline antibiotic with a broad range of activity anda low cost. It widely used in swine and animal farming. Its low absorption on oraladministration causes the contamination of swine manure by unmetabolized material [1] andmakes it as most frequently detected tetracyclines in water bodies and sediments around theworld [2]. It is reported OTC can prevent the bioactivity of various microorganisms [3]. OTCabuse can seriously affect human health. According to these reasons, the developing of anaccurate and reliable method to detect the OTC in environments has particular importance.There are only a few reports on the electrochemical measurement of OTC [4]. As far as weknow, rare paper reports the direct determination of OTC based on rapid, selective andsensitive electrochemical method [5]. This work provides a selective, sensitive and repeatablemethod to determine the OTC with proper applicability in real samples. This electrochemicalmethod is based on electrocatalytical oxidation of phenolic functional group of OTC byhorseradish peroxidase (HRP) in presence of H2O2. Optimized amount of HRP andMWCNTs were completely mixed by some graphite and mineral oil and the obtained pastewas packed into a tip of 1 ml insulin to prepare the modified electrode. Electrochemicalmeasurements were carried out by differential pulse voltammetry (DPV) technique.