Abstract
The purpose of this study was to develop a portable surface plasmon resonance (SPR) bioanalyzer for the sensitive detection of Escherichia coli O157:H7 in comparison with an enzyme-linked immunosorbent assay (ELISA). The experimental setup mainly consisted of an integrated biosensor and a homemade microfluidic cell with a three-way solenoid valve. In order to detect Escherichia coli O157:H7 using the SPR immunoassay, 3-mercaptopropionic acid (3-MPA) was chemisorbed onto a gold surface via covalent bond for the immobilization of biological species. 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) were used as crosslinker reagents to enable the reaction between 3-MPA and Escherichia coli O157:H7 antibodies by covalent –CO–NH– amide bonding. The experimental results were obtained from the Escherichia coli O157:H7 positive samples prepared by 10-, 20-, 40-, 80-, and 160-fold dilution respectively, which show that a good linear relationship with the correlation coefficient R of 0.982 existed between the response units from the portable SPR bioanalyzer and the concentration of Escherichia coli O157:H7 positive samples. Moreover, the theoretical detection limit of 1.87 × 103 cfu/mL was calculated from the positive control samples. Compared with the Escherichia coli O157:H7 ELISA kit, the sensitivity of this portable SPR bioanalyzer is four orders of magnitude higher than the ELISA kit. The results demonstrate that the portable SPR bioanalyzer could provide an alternative method for the quantitative and sensitive determination of Escherichia coli O157:H7 in field.
Highlights
For the prevention of infection, illness, and economic loss, rapid detection of pathogenic microorganisms in food and water has been a challenge for decades
The activation time, which is defined as the time that it takes for the covalent attachment of the E. coli O157:H7 antibody on the surface of the ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC)-NHS to activate 3-MBA/Au surface plasmon resonance (SPR) chip, approximately one hour
(3) The 50-fold diluted antibody of E. coli O157:H7 was injected into the microfluidic cell, and the response signals were monitored in real time until the occurrence of the stable response signals
Summary
For the prevention of infection, illness, and economic loss, rapid detection of pathogenic microorganisms in food and water has been a challenge for decades. Most food poisoning cases are caused by microbial pollution, where Escherichia coli (E. coli) is one of the most common pathogenic bacteria and brings great harm to human body health. As is widely known to the public, E. coli O157:H7 can cause human enteritis and hemorrhagic diarrhea. Annual economic losses due to human norovirus, E. coli O157:H7, have been estimated to be $0.27 billion [1]. Some novel, rapid, and more practical techniques for the identification of bacterial contamination in food are urgently required.
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