Detection Of Foodborne Pathogenic Bacteria Based On Fluorescence Resonance Energy Transfer

Foodborne pathogenic bacteria are pathogenic microorganisms that use food as a vector to invade the human body and cause infections and even infectious diseases.Food safety issues and infectious diseases caused by pathogenic bacteria have always been a huge hidden danger to human health.Common pathogenic bacteria such as Escherichia coli?E.coli?and Staphylococcus aureus?S.aureus?can easily cause bacterial food poisoning,and even endangering human life.Therefore,the development of rapid and efficient detection methods for foodborne pathogenic bacteria is of great significance for the prevention and control of food safety risks and the prevention of human bacterial infectious diseases.However,traditional microbial detection methods are time-consuming.Rapid detection methods such as polymerase chain reaction?PCR?and enzyme linked immunosorbent assay?ELISA?also involves complicated operations and expensive instrument materials,and suffering from high false positives.Hence,it is of great practical significance to develop a simple,fast,sensitive and highly selective detection method to monitor pathogenic bacteria.Based on the excellent optical properties of quantum dots?QDs?and gold nanoparticles?AuNPs?,a dual molecular recognition-based fluorescence resonance energy transfer?FRET?sensor based on specific recognition of aptamer and broad-spectrum recognition of lectins or antibiotics was established for the detection of foodborne E.coli And intracellular S.aureus.The main contents are as follows:Part I:In this section,the cheap and available biomolecules lectin concanavalin A?Con A?was employed as stabilizer,NaBH₄ as reducer to reduce HAuCl₄ to obtain Con A modified gold nanoparticles?Con A-AuPNs?.The synthesis method is simple and fast?about 40 min?.The synthesized product Con A-AuPNs is uniformly dispersed,has a characteristic absorption at 518 nm,and has a high light absorption coefficient.E.coli was used as the pathogenic bacteria model to be detected.Based on the dual recognition of lectin and aptamer,the aptamer modified quantum dots?Aptamer-QDs??525nm emission?and Con A-AuPNs were employed as energy donor and acceptor respectively to construct FRET sensor to achieve quantitative detection of E.coli within 0.5 h.The FRET signal shows a linear variation with the concentration of E.coli in the range from 10² to 2×10⁸cfu/mL with a detection limit of 45 cfu/mL.When this strategy was used to detect E.coli in real samples of milk and orange juice,the recovery was 83.1%¹12.5%,and the relative standard deviation was 0.05⁰.50%,showing potential for practical application The simple,rapid and specific universal pathogen detection method established in this work is of great significance for the effective monitoring of food safety.Part II:In this section,S.aureus specific aptamer-modified quantum dots?Aptamer-QDs?and one-pot synthetic antibiotic Teicoplanin?Teicoplanin,Teico?modified gold nanoparticles?Teico-AuNPs?were employed as energy donor and acceptor respectively to construct FRET sensor for S.aureus detection.S.aureus-infected cell model was constructed and intracellular S.aureus activity was confirmed confocal microscopy and plate coating.The FRET sensor can effectively detect intracellular S.aureus within 2 h,and it has obvious fluorescence signal discrimination for different degrees of S.aureus infected RAW 264.7,which has certain potential application value in judging the degree of bacterial infection of cells.This work established a simple,specific,time-saving and intracellular S.aureus detection method suitable for the analysis of a large number of samples,which has potential significance for the diagnosis and treatment of food animal bacterial infectious disease.