Detection And Antimicrobial Activity Of Foodborne Pathogens Based On Fluorescent Nanoprobe

Pathogenic bacteria pollution in agriculture and food related products is the mostprominent factor leading to food safety problems.Accurate detection and on-demand sterilization of pathogenic bacteria and source control of pathogenic bacteria are the key points to ensure food safety.After being infected by pathogenic bacteria,people will suffer from different degrees of food-borne diseases,such as food poisoning,meningitis,pneumonia,sepsis and so on.The outbreak of foodborne diseases seriously endangers people’s life and health.Therefore,it is of great significance to develop a rapid,simple,sensitive and specific integrated strategy for the detection and antibacterial of foodborne pathogens for food safety.Based on the F?rster resonance energy transfer(FRET)mechanism,we have constructed intelligent fluorescent nanoprobes with the integration of functional fluorescence sensing and antibacterial,respectively,to realize the detection of foodborne pathogens,photothermal sterilization,biofilm clearance and other research.The main research contents are as follows:Part 1:Firstly,in this study,we synthesized a batch of polydopamine nanospheres(PDANSs)with different particle sizes based on size-dependence.Based on high efficiency fluorescence quenching efficiency,they can be used as energy receptors in FRET sensors.Secondly,the aptamer(FAM-Apt)modified by 6-carboxyfluorescein(FAM)was used as the energy donor of the sensor to construct a responsive fluorescent nanoprobe PDANSs-FAM-Apt for the accurate detection of Staphylococcus aureus(S.aureus).According to the photothermal conversion performance of PDANSs,the probe can also be used for photothermal sterilization and biofilm removal.The detection range of S.aureus was 3.3-3.5×10~7 CFU/m L,and the satisfactory detection limit was 1CFU/m L.The recoveries of S.aureus in milk and juice were 96.84%-104.43%with RSD of 1.67%-4.43%.This work found a method with good specificity,high sensitivity and simple assembly for the detection of foodborne pathogens,which has important theoretical significance for accurate detection of pathogens and effective sterilization.Part 2:In this work,we utilized the dual recognition of vancomycin(Van)and aptamer for bacteria and the excellent fluorescence properties of quantum dots(QDs)to construct FRET sensors for simultaneous detection of two pathogenic bacteria.Using Listeria monocytogenes(L.M)and S.aureus as the target bacteria,Van and Aptamer modified QDs(QDs-Apt-Van)and PDANSs as energy donors and acceptors in the sensor,respectively,the fluorescent probe PDANSs-QDs-Apt-Van was constructed to realize the simultaneous detection of L.M and S.aureus.The detection range of L.M was 28-2.8×10~7 CFU/m L,and the detection limit was 1 CFU/m L;the detection range of S.aureus was 46-4.6×10~7 CFU/m L,and the detection limit was 1 CFU/m L.The strategy was applied to real food samples with a recovery of 96.4%-103.23%and RSD of 1.30%-3.6%.