Biosensor for a Pioneer Monitoring of Antibiotics in Food
The use of veterinary drugs has played an important role in the field of animal husbandry and agro-industry to prevent and treat diseases and as growth promoting agents, but they have the potential to generate residues in animal derived products (meat, milk, eggs and honey) and cause a health hazard to the consumer. Contamination of food in low-levels may not generate a serious problem on public health. However, extensive use of drugs as well their irregular use may increase the risk of occurrence of microbial drug resistance. Quinolones are among the most widely used antibiotics in veterinary medicine for treatment and prevention of diseases. Therefore, quantification and determination of even low levels of these residuals is crucial for food safety.
Enzyme - Linked immunosorbent assays (ELISA) have become very popular for antibiotics analysis due to their many advantages such as sensitivity, high sample throughput, and need of small sample volumes. However, they present some disadvantages related to enzyme activity measurement (e.g. presence of natural inhibitors, nonspecific binding of enzyme, temperature effect on enzyme activity,…). In this work, an electrochemically active derivative of quinolone was synthesized to realize a sensitive and pioneering immunosensor. Difloxacin (6-fluoro-1-(4-fluorophenyl)-7-(4-methylpiperazin-1-yl)-4-oxo-1,4-dihydroquinoline-3-carboxylic-acid)was modified with a ferrocene group to perform a competitive detection. Monoclonal IgM antibodies were immobilized on a carbon screen-printed electrode through carbodiimide immobilization after diazonium activation of the sensing surface. Electrochemical impedance spectroscopy, Differential pulse voltammetry (DVP) and cyclic voltammetry were used to characterize each step of the immunosensor development. A one-step competitive measurement allowed the determination of 4 quinolones in buffer, the method was based on pre-mixing 50 µL of the sample with 50µL of difloxacin modified with ferrocene. The obtained performances were compatible with the levels set by European Union (100µg/kg). This work is part of the whole Interreg project entitled: “ TESTACOS : Pioneering solution of self-monitoring to minimize the presence of antibiotic residues in animals”.The project is coordinated by the University of Zaragoza(Spain), with the participation of the University of La Rioja, the Bilbao Laboratory of Public Health(Spain), the University of Perpignan (France), the French National Institute of Agronomic Research (INRA, France), and ZEULAB (Spain), a SME specialized in developing new analytical tools. Working together, these organizations elaborate new tools to control antibiotic residues of both sulphonamides and quinolones in live animals as well as in meat commercialized for retail sale, with the purpose of assisting the meat production sector to minimize the presence of antibiotic residues in meat.