Wavelength-interrogated optical biosensor for multi-analyte screening of sulfonamide, fluoroquinolone, β-lactam and tetracycline antibiotics in milk

Major research efforts are focusing on the development of multi-analyte-residue analysis and the design of user-friendly analytical devices for continuous or on-site measurements. Advances in microtechnology and nanotechnology make possible novel analytical solutions to meet these needs. With specific bioreceptors and antibodies, immunosensors may become excellent analytical tools.A portable wavelength-interrogated optical system (WIOS) exploits class-selective bioreceptors for simultaneous screening of the most frequently used antibiotics in the veterinary field (e.g., sulfonamides, fluoroquinolones, β-lactams and tetracyclines). The label-free sensor uses the evanescent-wave principle, by which changes in the refractive index close to the modified chip surface are detected by scanning the resonance condition at which a light wave is coupled in the waveguide through a conveniently designed grating. The bioreagents used in this study were developed to detect a wide range of congeners of each selected family of antibiotics below the maximum residue limit (MRL) values established for milk samples.The WIOS made it possible to detect more than 30 different antibiotics and it was successfully applied to analyze different antibiotic residues in milk samples.