Establishment Of Portable Detection Method For E.coli O157:H7 Based On Nanoflowers

It is well known that food-borne pathogens such as Escherichia coli O157:H7,which exist in human life,can cause serious harm to human health.Therefore,it is particularly important to establish a sensitive,specific and portable detection method for foodborne pathogens such as E.coli O157:H7.In recent years,a variety of new rapid detection methods for food-borne pathogens have been established,which have solved the shortcomings of traditional bacteria culture methods,polymerase chain reaction?PCR?nucleic acid amplification methods and other food-borne pathogen detection methods which are time-consuming,require complex instruments,and high professional requirements for testing personnel.Based on organic-inorganic nano-flower technology,handheld barometer,and color development technology,this study established two portable detection methods for E.coli O157:H7:?1?Establishment of a portable detection method for E.coli O157:H7 based on aptamer@Pt NP and aptamer@Fe₃O₄nanoflowersThis method was based on the aptamer-copper phosphate organic-inorganic nano-flower technology.One kind of nanoflower?aptamer@Pt NP?embedding platinum particles?Pt NP?was used as a signal probe,and the other embedding magnetic iron oxide Fe₃O₄)nanoflowers of particles?aptamer@Fe₃O₄?was used as capture probes.In the presence of target E.coli O157:H7,aptamer@Fe₃O₄-bacteria-aptamer@Pt NP sandwich sandwich complex was specifically formed and magnetically separated.In a closed vial,the signal probe aptamer@Pt NP nano-enzyme Pt NP catalyzes H₂O₂to O₂,and the generated O₂can cause pressure changes.A handheld barometer was used to detect the pressure changes.The pressure change was linearly correlated with the detection target E.coli O157:H7 concentration.The optimal capture time for aptamer@Fe₃O₄was 90minutes,the optimal recognition time for aptamer@Pt NP was 30 minutes,the incubation temperature was 37?and the p H of the buffer solution was 7.4.The linear range of this detection method was 10³-10⁸CFU/m L,and the minimum detection limit was 10³CFU/m L.?2?E.coli O157:H7 visual detection method based on aptamer@G-Hemin and aptamer@Fe₃O₄nanoflowersThis method synthesizes two E.coli O157:H7 aptamers-copper phosphate organic-inorganic nanoflowers,one nanoflower?aptamer@G-Hemin?was composed of aptamers and G-quadruplex-Hemin as its organic components,Cu₃?PO₄?₂was easily synthesized as an inorganic component and was used as a signal probe.Another nanoflower embedding magnetic ferroferric oxide?Fe₃O₄?particles?aptamer@Fe₃O₄?was used as a capture probe.In the presence of the detection target E.coli O157:H7,aptamer@Fe₃O₄-bacteria-aptamer@G-Hemin sandwich sandwich complex was specifically formed and magnetically separated.After adding H₂O₂and ABTS,the reaction system appears green.Visual inspection can determine the detection target E.coli O157:H7.The absorbance value was detected by the colorimetric detection platform.The absorbance value was proportional to the target concentration.The optimal incubation time was 60 minutes,the optimal incubation temperature was37?,and the p H of the buffer solution was 7.4.The linear range of this method was10¹-10⁶CFU/m L,and the minimum detection limit was 10¹CFU/m L.The two E.coli O157:H7 detection methods established in this study have the advantages of sensitivity,specificity,quickness,simplicity,visualization,low price,and no need for complex instruments.They provide a theoretical basis and experimental basis for the rapid development of the field of foodborne pathogen detection in the future.