Construction Of Fluorescence Resonance Energy Transfer System Between Graphene Quantum Dots And Porphyrins And Its Application In Food Detection

In recent years,fluorescence resonance energy transfer technology?FRET?has attracted wide attention and has been applied in many fields.In order to better develop this technology,many new methods have emerged.In this paper,graphene quantum dots?GQDs?were used as energy donors,and porphyrins with different functional groups were used as energy acceptors to construct different fluorescence resonance energy transfer systems,which were applied as fluorescent probes for biological detection,environmental detection and food safety detection.It will provides technical support for the development of FRET in the future.The main research contents of this paper were as follow:Nanomaterials,semiconductor nanoparticles?the semiconductor nanoparticles mainly introduce GQDs?,the physical and chemical properties and applications of porphyrins,and the principles and research progress of FRET were reviewed.In this paper,a sensitive and selective fluorescence resonance energy transfer biosensor based on GQDs and protoporphyrin IX?PpIX?was developed for melamine detection.PpIX was bound to the surface of GQDs to produce self-assembled nanosensors,and the process of FRET between GQDs and PpIX occurred.However,the process of FRET was switched off with the addition of melamine,due to the combination between PpIX and melamine.Under the optimized experimental conditions,melamine could be detected based on the fluorescence intensity ratio IPpIX/IGQDs?IPpIX and IGQDs refer to the fluorescence intensity of PpIX and GQDs?in the FRET system.We could get a linear relationship between the fluorescence intensity ratio I_PpIX/I_GQDsQDs and the concentration of melamine in the range of 1.0×10^-8-2.0×10^-66 mol/L and the detection limit was 3.6×10^-99 mol/L.The proposed method was applied for the determination of melamine in milk samples with satisfactory results.Based on the rapid and specific Michael addition reaction between biothiol and maleimide-derived probes,two fluorescent probes were designed to detect biothiol content in foods.Firstly,GQDs functionalized directly with maleimide units?M-GQDs?can be synthesized according to the Michael addition principle and used for biothiol identification.The M-GQDs probe was found to have high sensitivity and high selectivity.The biothiol can be detected in the range of 5×10^-99 mol/L to 4×10^-7mol/L in an aqueous solution at pH 7.4.The detection limit is 1.69×10^-9mol/L.On the other hand,we modified with maleimide to link GQDs with amino groups to Tetrakis?4-aminophenyl?porphyrin and formed a FRET system.The system can quickly and accurately detect biothiol with a detection range of 6.7×10^-1010 mol/L to 2×10^-77 mol/L.The detection limit was 2.34×10^-1010 mol/L.By comparison,we found that the FRET system has a wider detection range and lower detection limit,and the related biomolecules do not interfere with the quantitative identification of biothiol.The probe shows high sensitivity,specificity and selectivity for the detection of biothiols in actual samples and can be used for the determination of biothiol in foods.