Biosensor Based on New Delhi metal-β-Lactamase-1 for Electrochemical Determination of Penicillin in Milk

There is an urgent need to develop convenient, rapid and sensitive detection methods to determine antibiotic residues in food. New Delhi metal-β-lactamase-1 (NDM-1) is a β-lactamase enzyme that catalyzes removal of all β-lactam antibiotics other than aztreonam via a spectral hydrolysis mechanism. In the present study, a new biosensor based on NDM-1 was designed and tested to detect penicillin antibiotics namely penicillin sodium (Pen G) and ampicillin sodium (AMP) without using any pH redox probe. The glassy carbon electrode (GCE) was modified by electro-polymerization of methylene blue (PMB), and the biosensor (NDM-1/PMB/GCE) was prepared by immobilizing NDM-1 enzyme with glutaraldehyde (GA). Penicillin was detected by differential pulse voltammetry (DPV). This study seems to be one of the first kind to apply NDM-1 enzyme to detect antibiotic residues in food. It can be used repeatedly and can successfully detect penicillin in actual milk samples by spike recovery experiment.