Detection of Broad Spectrum Bacteria Using a FITC-Lysozyme and Positively Charged AuNPs Constructed FRET Platform
  
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KeyWord:bacteria  ?lysozyme  ?gold nanoparticle  ?FRET
  
AuthorInstitution
WANG Ling,ZHANG Ya-qing,TAO Xiao-qi,SONG Er-qun 1. College of Food Science,Southwest University,Chongqing ,China;2. College of Pharmaceutical Sciences,Southwest University,Chongqing ,China
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Abstract:
      This manuscript demonstrated a universal platform for bacteria assay by using a fluorescein isothiocyanate-labeled lysozyme(FITC-Lys) and polyethylenimine-modified positively charged gold nanoparticles(PEI-AuNPs) constructed fluorescence resonance energy transfer(FRET) sensor based on its electrostatic binding with bacteria. In the presence of the bacteria,the energy donor of positively charged FITC-Lys bond with the bacteria through both the recognition to peptidoglycan of cell wall and electrostatic interaction while the energy acceptor of positively charged PEI-AuNPs bond with the bacteria based on the electrostatic interaction,which decreases the distance between energy donor and acceptor and then causes fluorescence quenching,showing FRET“on”signal readout mode with the low fluorescence intensity. PEI-AuNPs were synthesized by hydrothermal method and characterized by ultraviolet spectrum,transmission electron microscope,and laser particle size analyzer. The results shown that PEI-AuNPs with diameter about 9.6 nm had maximum ultraviolet absorption at 526.5 nm,and they were positively charged. The method developed in this study could detect 10 different kinds of bacteria such as?Staphylococcus aureus,Streptococcus pneumoniae,Enterococcus faecalis,Staphylococcus epidermidis,Listeria monocytogenes,Escherichia coli,Salmonella typhimurium,Salmonella paratyphoid A,Vibrio parahaemolyticus,and?Pseudomonas aeruginosa. Then,the interference of possible interfering components in actual samples(taking milk and juice as examples) on the detection was further discussed. The results showed that under our experimental conditions,the interfering components such as proteins,ions,and others in the samples would not interfere with the analysis results after ten times dilution. This strategy showed feasibility as a universal assay platform for broad spectrum bacteria,which is interesting for the control of pathogenic bacteria.
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