A Piezoelectric Immunosensor Based on Magnetic Carbon Nanocomposites for the Determination of Ciprofloxacin

A piezoelectric immunosensor with a recognition layer based on magnetic carbon nanocomposites is developed for the determination of ciprofloxacin. The receptor coating of the sensor is formed by the action of a magnetic field on magnetic particles located on the surface of carbon nanotubes modified with a ciprofloxacin conjugate. The sizes of magnetic particles in the composition of the nanocomposite are determined by scanning electron microscopy. A dependence of the mass of the recognition coating on the size of magnetic particles on the surface of carbon nanotubes is shown. A detection cell with a sensor located above a neodymium magnet is proposed. The analytical characteristics of the immunosensor are determined, the limit of detection for ciprofloxacin is 2 ng/mL, and the linear range of determined concentrations is 5–400 ng/mL. The use of magnetic carbon nanocomposites in the creation of a recognition layer ensures the reduction of the time of sensor preparation to analysis from 24 to 1.5 h and extends its service life. The sensor is tested in the detection of antibiotics in milk and meat.