The use of carbon nanotubes to increase the sensitivity of the antibiotic determination with a piezoelectric immunosensor

Conditions for the preparation of carbon nanomaterials for embedding into the discerning layer of a piezoelectric immunosensor are described. The effect of the oxidation method, temperature, and the duration of treatment of nanomaterials with an oxidizing agent on the surface concentration of active functional groups is demonstrated. It is shown that the use of carboxylated carbon nanotubes (CNT) increases the efficiency of their binding to biomolecules and increases the stability of the discerning layer of a piezoelectric sensor when measurements are carried out in liquid media. Conditions for the determination of antibiotics using piezoelectric immunosensors modified with carbon nanomaterial were studied including the choice of immunoreagent concentrations and assessment of the selectivity of antibiotic determination. The CNT-based piezoelectric immunosensors providing rapid, highly sensitive, and selective determination of the analyte at the MRL level and below it in food products and biological fluids are proposed.

Development of a high frequency piezoelectric immunosensor for the detection and quantification of BSA

In this work, we developed a High Fundamental Frequency –Quartz Crystal Microbalance (HFF-QCM) immunosensor for the quantification of Bovine Serum Albumin (BSA) protein. Immobilization of BSA was achieved by means of mixed self-assembled monolayers (SAM), and we found that the largest phase shifts were produced with a concentration of 10 mg/mL. Then, we plotted an anti-BSA vs phase shift calibration curve, and obtained the analytical parameters that allowed us to compare our sensor to another anti–BSA QCM-based sensors. Our HFF-QCM immunosensor displays more sensitivity than low frequency QCM-based biosensors: its limit of detection (LOD) is 100 ng/mL and its linear range extends from 100 ng/mL to 5000 ng/mL. Finally, we fitted different adsorption isotherms models to our experimental data. We chose the Hill isotherm as it presented the highest coefficient of determination (R2), and we determined that the interaction between BSA and anti-BSA displays a positively cooperative binding behavior.