Surface Acoustic Wave (SAW) Biosensor for Rapid and Label-Free Detection of Penicillin G in Milk

Abstract

Surface acoustic wave (SAW) biosensors were introduced for rapid and label-free detection of penicillin G in milk. This is the first time that the use of SAW biosensors for antibiotic detection is reported. Penicillin G belongs to the β-lactam antibiotics which are commonly used in human and veterinary medicine. Particularly because of the latter, the detection of antibiotics in foodstuffs of animal origin is essential. Current methods for specific antibiotic detection often require complex laboratory equipment and procedures. SAW biosensors, however, offer rapid detection of analyte concentrations with a minimum of experimental effort. They use label-free acoustic (gravimetric) detection. Owing to the small mass of antibiotics, detection via binding inhibition assay was preferred to direct detection in this work. Samples containing penicillin G were preincubated with the corresponding antibody, and SAW biosensor surfaces were coated with penicillin G epitopes. The antibody in the sample bound to the biosensor surface, unless it was inhibited by penicillin G. The assay allowed the detection of 2 ng/ml penicillin G in buffer and 2.2 ng/ml in low-fat milk. This is below the maximum residue limit of 4 ng/ml given by the European Commission for penicillin G and other β-lactam residues in food.