A Piezoelectric Immunosensor Based on Agglutination Reaction with Amplification of Silica Nanoparticles

Abstract

AbstractA simple piezoelectric immunoagglutination assay technique with antibody‐modified nanoparticles has been developed for direct quantitative detection of protein. The proposed technique is based on the specific agglutination of goat anti‐hIgG‐coated silica (or gold) nanoparticles in the presence of human immunoglobulin G (hIgG), which causes a frequency change and is monitored by a piezoelectric device. The antibody modified on the probe surface would combine with antibody‐coated nanoparticles in the presence of antigen (hIgG) when the surface agglutination reaction took place, which couples both the mass effect and viscoelastic effect acting on the probe. The results indicate that the background interference can be substantially minimized and the probe signal can be observably multiplied. In addition, the surface of the modified probe and that after combining the complex of immunoagglutination were imaged by scanning electronic microscopy (SEM). Moreover, an optimization of assay medium composition with the addition of poly(ethylene glycol) (PEG) serving as immunoagglutination enhancer and sodium chloride to control the ion‐strength was investigated. The frequency responses of the immunoagglutination assay were found to correlate well with the hIgG concentration with a detection limit of 84 ng·mL−1.