| Food safety problem caused by the mycotoxin has become the focus of all the world.The researches increasingly incline to the trace detection technology and development ofmycotoxins. Some detection methods has been reported, but there are varieties of shortcoming.In order to meet the inspection requirements, it is important to establish a new, rapid, highsensitivity detection method. Quantum dots has advantages such as high fluorescent yields,photo stability and long fluorescence lifetime, good biocompatibility, and wide stimulatewavelength range, widely used in biomedical including bio-chip, protein and DNA testing,target tracer and so on. However, the study has been reported, which the quantum dots wereintroduced as a fluorescent probe to detect the mycotoxins is not very sensitivity, and there arefew research reports about simultaneous detection of multiple mycotoxins. So, in this paper,we combined fluorescence analysis, nano-probe technology with immunoassay and aptamertechnology,using aflotoxin B1, ochratoxin A as model analytes, aim to establish a new traceanalytical methodology.Firstly, CdTe quantum dots was synthesized and characterized by fluorescencespectroscopy, TEM, UV-visible absorption spectroscopy. The probe of the fluorescence signalwas constructed by combination of CdTe light-emitting quantum dots coated by themercaptopropionic acid parcels, with goat anti-rabbit IgG. The Fe3O4magnetic nanoparticleswere successful synthesized in this experiment and characterized by TEM and X-diffraction（XRD） and infrared spectroscopy. The combination of the artificial antigen of aflatoxinB1（AFB1-BSA） prepared in experiment and Fe3O4magnetic nanoparticles form a captureprobe （AFB1-BSA-of Fe3O4NPs）, which take part in competition reaction with aflatoxinmonoclonal antibody, then establish the new method of aflatoxin B1fluorescenceimmunoassay. Under the optimal conditions, the liner range for the AFB1concentrationdetection is1.0×10-10g/mL1.0×10-7g/mL with a detection limit of3×10-11g/mL.The RSD is3.0%（1×10-9g/mL,n=9）.Evaluating the feasibility and accuracy of the new method bycomparing with the GB detection method of aflatoxin B1in corn flour, it showed goodapplication prospects.Secondly, CdTe quantum dots with different emission wavelengths were successfullyprepared, and was used to label antibodies of aflatoxin B1and ochratoxin A as a fluorescentdisplay probe. The prepared artificial antigens of aflatoxin B1and ochratoxin A combinedwith Fe3O4magnetic nanoparticles respectively to form capture probes. Under the conditionsof immune competition reaction, magnetic preconcentration separation and the sameexcitation wavelength, the new method of simultaneous detection of aflatoxin B1andochratoxin A was constructed. Under the optimal conditions, the liner range for the AFB1 concentration detection is1.0×10-10g/mL1.0×10-7g/mL with a detection limit of1.0×10-10g/mL.The RSD is1.87%(1×10-9g/mL，n=9).The liner range for the OTA concentrationdetection is5×10-11g/mL1.0×10-7g/mL with a detection limit of5.0×10-11g/mL.The RSD is2.90%(1×10-9g/mL，n=9).It showed good accuracy by comparing with the GB detectionmethod and good application prospects.Finally, Fe3O4magnetic nanoparticles were functionalized withochratoxin A aptamers.CdTe quantum dots were linked with the OTA aptamer complementary DNA short-strand.Because of priority binding of OTA and aptamer, it led to DNA strand dissociation. Being theseparation under external magnetic field led to the decline of the fluorescenceintensity.Combined the fluorescence analysis, aptamer technology with magnetic separationenrichment technology. We established a new ochratoxin A detection technology with highspecificity and sensitivity. Under the optimal conditions,the liner range for the AFB1concentration detection is5×10-11g/mL1.0×10-7g/mL with a detection limit of5.0×10-11g/mL.The RSD is2.10%(1×10-10g/mL，n=9).Evaluating the feasibility and accuracy of thenew method by comparing with the GB detection method, it showed good applicationprospects. |
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