Abstract
Silica coated silver (Ag@SiO2) nanoparticles were prepared and characterized by transmission electron microscope (TEM) and UV-vis absorption, and the nanoparticles were used as labels in sandwich-type immunosensor of Escherichia coli O157:H7 (E. coli O157:H7). The labels involved in immunoreaction were dissolved by mixed acid of hydrofluoric acid and nitric acid, and the released Ag+ ions were electrochemical stripping analyzed (via differential pulse voltammetry, DPV) at poly(acrylic acid)/poly(diallyldimethylammonium chloride)/carbon nanotubes (PAA/PDCNT) modified glass carbon electrode (GCE), which obviously enhanced the signal of Ag+ stripping. Then, the number of E. coli O157:H7 could be indirectly reflected by the signal intensity of labeled Ag+. And the results showed that the DPV signals were proportional to the logarithm of the E. coli O157:H7 concentration in the range from 20 cfu/mL to 8.0 × 103 cfu/mL with the detection limit of 13 cfu/mL.
Highlights
Pathogenic bacteria, which are distributed in soil, the intestinal tract of animals, and water contaminated with fecal matter, marine, and estuarine water have profound effects on mammals including various infectious diseases [1, 2]
Escherichia coli O157:H7 (E. coli O157:H7) is one of the most dangerous pathogenic bacteria that is of most concern today since a low number of E. coli O157:H7 is sufficient to cause severe illnesses, such as hemorrhagic colitis and hemolyticuremic syndrome, sometimes life-threatening illness, especially in cases involving children and elderly [3, 4]
The results showed that this electrochemical immunoassay could be used to detect E. coli O157:H7 in the presence of high concentrations of other microorganisms
Summary
Pathogenic bacteria, which are distributed in soil, the intestinal tract of animals, and water contaminated with fecal matter, marine, and estuarine water have profound effects on mammals including various infectious diseases [1, 2]. Escherichia coli O157:H7 (E. coli O157:H7) is one of the most dangerous pathogenic bacteria that is of most concern today since a low number of E. coli O157:H7 is sufficient to cause severe illnesses, such as hemorrhagic colitis and hemolyticuremic syndrome, sometimes life-threatening illness, especially in cases involving children and elderly [3, 4]. In view of the fast replication under normal environmental conditions, early detection of E. coli O157:H7 in very low numbers is very crucial to prevent the consumption of contaminated foods by consumers, and to alert a foodborne disease outbreak well in advance [5, 6]
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