Magnetic bead-based electrochemical aptasensor doped with multi-wall carbon nanotubes for the detection of ampicillin in milk

Given the ubiquitous presence of antibiotic residues in foodstuff, establishing an efficient method to determine antibiotic residuals is extremely urgent to ensure food safety. This work reports a magnetic bead-based electrochemical aptasensor doped with multi-wall carbon nanotubes for the determination of ampicillin, an important antibiotic. In this aptasesnsor, ampicillin-coated magnetic beads were used to compete with a sample for biotinylated aptamers and to recognize streptavidin-horse radish peroxidase. Multi-wall carbon nanotubes were introduced to simply mix with magnetic beads to improve electrochemical performance. A magnetic glass carbon electrode was employed to draw these magnetic beads for subsequent electrochemical detection. Under optimal conditions, the net peak current had a linear relationship with the logarithm of ampicillin concentration in the range of 1.0 x 10(-13) mol/L to 1.0 x 10(-8) mol/L and a detection limit of 1.0 x 10(-13) mol/L (3 sigma). In addition, this aptasensor was used to detect ampicillin in milk with recoveries of 95.02% - 101.83%. The proposed aptasensor platform is easy to fabricate and process, can be produced pre-equipped with the aid of a magnet, and possesses great promise for antibiotic residue detection in the food safety field.