Determination of the Fluoroquinolones Levofloxacin and Ciprofloxacin by a Piezoelectric Immunosensor Modified with Multiwalled Carbon Nanotubes (MWCNTs)

Abstract

Methods for the high-sensitivity determination of fluoroquinolones using a piezoelectric immunosensor based on multi-walled carbon nanotubes (MWCNTs) are developed. The use of MWCNTs in the formation of a stable piezoelectric sensor detection layer increases the active specific surface area which is necessary for receptor molecule binding. The concentrations of hapten-protein conjugates (35/65 serial concentration) and polyclonal antibodies are determined in the direct (15/85 for levofloxacin, 18/82 for ciprofloxacin) and in the competitive immunoassay formats (14/86 for levofloxacin, 10/90 for ciprofloxacin). Conditions for the analysis in the flow-injection mode were studied. The carrier flow rate was 30 and 50 µl/min depending on the detection layer formation method. The characteristics of MWCNTs-based piezoelectric immunosensors were characterized for the determination of fluoroquinolones in the static and in the flow-injection modes. The direct and competitive immunoassay formats (detection limit, linear range of target concentrations, reproducibility) were determined. The detection limits were 9 and 8 ng/ml for levofloxacin and ciprofloxacin in the competitive format and 25 and 21 ng/ml in the direct assay. The piezoelectric immunosensors were employed for the analysis of milk.

Keywords:

• affinity interactions
• ciprofloxacin
• levofloxacin
• multi-walled carbon nanotubes (MWCNTs)
• piezoelectric immunosensor

Conflict of interest

The authors declare that they have no competing interests.

Ethical approval

This article does not involve human participants or animals.

Author contributions

All authors contributed to the study conception, and design; to the preparation of materials, data collection, and analysis; and read and approved the final manuscript.

Informed consent

Informed consent is not applicable to this study.

Additional information

Funding

The research was funded by RFBR and Lipetsk Region, project number 20-43-480001.