Determination of aristolochic acid using a piezoelectric immunosensor based on magnetic carbon nanocomposites

A technique for the determination of aristolochic acid (AA) in food products using a piezoelectric immunosensor is presented. Magnetic carbon nanocomposites (MCNC) were used as the recognition layer of the sensor, on the surface of which protein conjugates of AA were immobilized. Abstract-Methods for the synthesis of Fe3O4 magnetic nuclei and their attachment to the surface of multi-walled carbon nanotubes (CNTs) have been studied. Using IR spectrometry, it was found that the formation of the recognition layer of the sensor occurs due to the formation of covalent bonds between the amino groups of AA conjugates and carboxyl groups of CNTs. The concentrations of protein conjugates based on ovalbumin (OVA) and bovine serum albumin (BSA) (0.3 and 0.2 mg/ml) and the degree of antibody dilution (0.25) were determined, which provide optimal characteristics of the piezoelectric immunosensor. The metrological characteristics of the method for determining AA have been established. The range of determined concentrations of AA and the limit of detection when using a piezoelectric immunosensor with a recognition layer based on MUNA/AA-OVA and MUNA/AA-BSA are (ng/ml): 50 – 400 and 10; 100 – 300 and 50, respectively. The sensor has been tested in the determination of AA in samples of Chinese herbal tea and dietary supplements for weight loss. No acid was found in tea, and in dietary supplements, the acid content is 3.2 μg/g.