Fabrication Of Aptamer-Functionalized Gold Nanobones Substrates And Study Of The Sers Detection Method For Escherichia Coli O157:H7

Foodborne pathogens contamination is one of the main reason for frequent food safety incidents,which has seriously affected the health of our citizens and the economic development of our country.Therefore,rapid screening of foodborne pathogens is of great significant to prevent the outbreaks and spread of foodborne diseases.Surface-enhanced Raman scattering?SERS?has great potential for the rapid detection of pathogens in the food safety field,due to its unique advantages of rapid detection,high sensitivity,and fingerprint identification.However,there are some defects in the SERS substrate,such as signal instability and low detection efficiency.In this project,we innovatively fabricated the aptamer-functionalized gold nanobones substrates,and emphatically analyze d the influencing factors and structural stability in its one-step synthesis process.Based on the“gold nanobones”signal probe,Escherichia coli O157:H7?E.coli O157:H7?as the representative strain for detection,the ultrasensitive detection and specific recognition SERS sensor was constructed combined with magnetic separation technology.The main results are as follows:?1?Fabrication of aptamer-functionalized gold nanobones substrates:A20 and signal molecule Rhodamine B?RhB?were used to comediate GNRs growing into aptamer-functionalized gold nanobones substrates by one-step fabrication method?Enhancement Factor:6.07×10⁵?.The concentrations of RhB?30?M?,the incubation time of Rh B with GNRs?60 min?,and the regrowth time?90 min?of gold nanobones substrates were optimized,then the microcosmic morphology and structural composition of gold nanobones substrates were characterized by UV-visible spectrophotometer,high resolution-transmission electron microscope,and X-ray energy dispersive spectrometer.The gold nanobones substrates showed good signal stability in different conditions,such as different detection positions,storage time,reagent substitution,centrifugation and salt solution.The fabrication of gold nanobones substrates provided scientific guidance for the realization of SERS substrate with stable aptamer connection,controllable microcosmic morphology,and enhanced and stable Raman signal.?2?Study of the SERS detection method for Escherichia coli O157:H7:With aptamer-functionalized gold nanobones as signal probe and Fe₃O₄ magnetic nanoparticles as capture probe,the SERS sensor with high sensitivity,high stability,and high specificity was constructed for E.coli O157:H7 detection.After the characterization and concentration optimization of gold signal probe and magnetic capture probe,the local electromagnetic field distribution between gold signal probes was simulated by FDTD,which proved that the enhancement mechanism of SERS sensor was attributed to more Raman"hot spots".SERS sensor could realize the linear detection of E.coli O157:H7 in the range from 10 CFU/m L to 10,000CFU/mL,and the detection limit was 3 CFU/ml.Non target bacteria interference experiment and detection components missing experiment verified good specificity and superiority of the established SERS sensor.And it showed good detection adaptability in commercial drinking water,romaine lettuce and citrus actual samples.Compared with related SERS analytical platforms,the established SERS sensor had obvious advantages in linear range,LOD and recovery rate.The results provide d theoretical foundation and scientific basis for the rapid and ultrasensitive detection of E.coli O157:H7 in the complex food matrix samples.