A Novel Method For Fast Analysis Of Food Hazards Based On Functional Quantum Dots

In recent years,frequent food safety problems have seriously damaged the physical and mental health of consumers.It is of great theoretical and practical significance to develop efficient new food contaminant detection technologies and methods to promote and gradually improve the food safety monitoring and early warning mechanism and guarantee the life safety of people.Based on this,an intelligent sensor platform for rapid on-site monitoring of fluoroquinolone antibiotics in food samples was developed in this paper using inorganic luminescent CdTe quantum dots(CdTe QDs)as sensing substrate.At the same time,a ratiometric fluorescence sensing system for dual-targeted identification of food-borne pathogens was built based on carbon quantum dots,which successfully realized the accurate detection of food-borne pathogens in drinking water and tea drinks,mainly including the following aspects:(1)A ratiometric fluorescence sensing system based on CdTe QDs and portable smartphone sensor is jointly constructed.Gatifloxacin(GFLX)was selected as the target model for analysis,and the fluorescence color of quantum dots was effectively triggered from bright yellow-green(557 nm)to blue(448 nm)by a photoinduced electron-transfer(PET)process,resulting in a significant ratiometric response.Portable smartphone devices are used to obtain fluorescence images and color picking APP is used to convert the images into values,which can more intuitively and accurately display the experimental results.This method has a good linear relationship in the range of 0.85 n M-3.6μM and high sensitivity.The detection limit is 0.26 n M with the detection time of 10.0 min,which could be fully qualified the onsite requirements,providing a broad application prospect for future onsite real-time detection of food safety.(2)Polyethylenimine(PEI)functionalized carbon quantum dots(CQDs)were synthesized by one-pot hydrothermal method.Combined with the dual-targeting of DNA molecular beacons(MB,containing G-quadruplex structure and pathogen specific recognition sequence)and vancomycin,in the presence of Methicillin-resistant Staphylococcus aureus(MRSA),the fluorescence of N-methyl porphyrin IX(NMM)was enhanced by inducing the release of G-quadruplex structure to construct a dual-targeting ratiometric fluorescent probe Van-MB-CQDs/NMM for the detection of MRSA in drinking water and tea drinks.This method has a low detection limit,the linear range is 0-10~5 CFU/m L,and the response time is 30.0 min.It provides a new idea for the detection of food-borne pathogens by surface modification of quantum dots.