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.