Detection of Escherichia coli O157:H7 with piezoelectric immunosensor based on enhancement with immuno-nanoparticles

Abstract:

Abstract: [Objective] We developed a sensitive method to detect Escherichia coli O157:H7 based on enhancement with immuno-nanoparticles. [Method] About 10 nm ultrafine immunomagnetic particles were prepared by a co-precipitation method, about 20 nm immuno-colloid-gold was prepared by sodium citrate reduction. The immunosensor was fabricated by using Protein A from Staphylococcus aureus (SPA) for the antibody immobilization. Two immuno-nanoparticles by two antibodies were used to amplify frequency changing. [Result] The most suitable immobilization concentration and time for SPA was 1.2 mg/ml and 40 min, and dose for the antibody was 1.0 mg/ml and 60 min. With the signal amplification of the two immuno-nanoparticles, the detection limit of E. coli O157 : H7 was increased from 104 colony-forming units (cfu) /mL to 101 cfu/mL. [Conclusion] The prepared immuno-nanoparticles might be used to significantly amplify the frequency signal of the piezoelectric immunosensor and improve the detect sensitivity.