[Detection of Escherichia coli O157:H7 with piezoelectric immunosensor based on enhancement with immuno-nanoparticles].
OBJECTIVE
We developed a sensitive method to detect Escherichia coli O157:H7 based on enhancement with immuno-nanoparticles.


METHODS
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.


RESULTS
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 10(4) colony-forming units (cfu)/mL to 10(1) cfu/mL.


CONCLUSIONS
The prepared immuno-nanoparticles might be used to significantly amplify the frequency signal of the piezoelectric immunosensor and improve the detect sensitivity.
Shen
Zhiqiang
Z
Institute of Hygiene and Environmental Medicine, Academy of Military Medical Sciences, Tianjin 300050, China. szq922990@126.com
Wang
Jingfeng
J
Qiu
Zhigang
Z
Jin
Min
M
Wang
Xinwei
X
Chen
Zhaoli
Z
Li
Junwen
J
Cao
Fuhuan
F
D000907:Antibodies, Bacterial / Q000276:immunology*; D055910:Antibodies, Immobilized / Q000276:immunology; D015374:Biosensing Techniques; D004563:Electrochemistry; D019453:Escherichia coli O157 / Q000276:immunology*; D053758:Nanoparticles / Q000737:chemistry*; D012680:Sensitivity and Specificity; D013211:Staphylococcus aureus / Q000737:chemistry / Q000276:immunology; D020349:Surface Plasmon Resonance
D000907:Antibodies, Bacterial; D055910:Antibodies, Immobilized