9.3. Biosensors

Biosensor is one of the screening analytical methods for veterinary drug residue analysis. Various types of biosensors (such as immunobiosensor, bacterial biosensor, optical biosensor) have been developed to determine antimicrobial drug residues. Biosensors employ biological molecules, such as enzymes or antibodies, which are efficient for recognizing particular targeted analytes or residues. In the detection process, the molecules are paired to a transducer, which response to the reaction between the residue and the bound biological molecule. The resulting biochemical alert is observed optically or changed to an electronic signal, which is additionally clarified by a suitable instrument. Biosensor tests are capable of identifying concurrent multiclass antibiotics and pesticides in biological samples at the same time. As some authors described, there is no need for sample cleanup for biosensor analytical technique [61]. A report from Möhrle et al. [62] showed that the biosensor method was used for the screening of macrolide antibiotics. Using an electrochemical biosensor, Ferrini et al. [63] determined β-lactams in milk samples by means of CO₂ measurement. The production of CO₂ was related to the microbial growth of the test microorganism, and the presence of β-lactams in milk inhibits the microbial growth.