A Simple and Sensitive Piezoelectric Immunosensor for Cholera Toxin Based on GM1‐Incorporated Liposome Agglutination

Abstract

A sensitive piezoelelctric immunosensor has been developed for the direct detection of cholera toxin. The proposed technique is based on specific interface agglutination of GM1 incorporated liposome vesicles in the presence of the cholera toxin, which causes a frequency change and is monitored by a piezoelectric device. The interface agglutination reaction would take place as soon as the cholera toxin (CT) was captured by the antibodies modified on the probe surface and the GM1 incorporated liposome in the probe cell. Meanwhile, the agglutination reaction induced both the mass effect and viscoelastic effect acting on the probe surface. The results indicate that the probe signal can be observably multiplied. In addition, an optimization of liposome composition and assay medium were investigated. Moreover, no cross-reactivates were observed with the common protein, such as goat anti-mouse IgG (1 mg/mL), mouse IgG (1 mg/mL), goat anti-human IgG (1 mg/mL), and thrombin (1 mg/mL). The frequency responses of the developed piezoelelctric immunosensor are linearly correlated to cholera toxin concentration in the range of 0.5 to 7.5 µg/mL with a detection limit of 0.27 µg/mL while showed no significant loss in activity over 3 d under storage at 4 ℃.