Construction Of CdSe/ZnS Quantum Dots To Detect Ochratoxin By Fluoroimmunoassay

Mycotoxins exhibit a very great harmfulness,which are widely distributed in nature and as a potential threat to food safety.Research on mycotoxin detection technology has always been aroused general interest.Nowadays,many detection methods of ochratoxin A have been reported,but these methods always exist some shortcomings such as complex for sample pre-treatment,equipment is expensive,time-consuming.The detection process could not be conducive to a large number of samples.In order to meet the inspection requirements,it is important to establish a new,rapid,high sensitivity detection method.Quantum dots has advantages such as high fluorescent yields,photo stability and long fluorescence lifetime,good biocompatibility,and wide stimulate wavelength range,widely used in biomedical including bio-chip,protein and DNA testing,target tracer and so on.We combined fluorescence analysis,nano-probe technology with immunoassay,established a new method to detect ochratoxin A(OTA)and this method can be applied to ochratoxin A quantitative determination in wheat flour.In this paper,we have prepared OTA detection probe successfully using EDC as activator.Carboxyl groups modified CdSe/ZnS core/shell quantum dots could be coupled with ochratoxin A monoclonal antibodies through the activation reaction of EDC.The prepared probe was characterized using ultraviolet lighting,SDS-PAGE electrophoresis and fluorescence spectrophotometers.The preparing condition of probe have been optimized,the best pH condition is 7.0 and the optimal reaction ratio of the monoclonal antibodies was 1.3:1.Fluorescence intensity of the as-prepared detection probe decreased 10.3%and 47.3%when the probes was preserved at 4? for 3d and 6d respectively,indicating that the detection probe has certain short-time preservation stability.In order to establish the OTA detection curve,a series of concentration gradientthe ochratoxin A were detected using the as-prepared probe.The result show that the relative luminescent intensity of detection probe has a good linear range relationship against the concentration of ochratoxin A with a correlation coefficients of 0.9963(R2)when OTA concentration is in the range of 1.0×10-10g/mL to 9×10-10g/mL,and the detection limit was found to be 0.0177 ng/mL.Evaluating the feasibility of the new method by comparing with the GB/T 23502-2009 detection method of Ochratoxin A in aqueous solution,the detection results of four samples showd the new method has centain feasibility.OTA was mixed with AFB1 and DON respectively,and then the concentration of OTA was detected using the as-prepared detection probe.The variation coefficient of OTA detection datas is 2.63%,indicating that adding other toxins has no interference with the detection of OTA.Therefore,the as-prepared detection probe has good detection specificity.Accuracy of method was evaluated using OTA spiked recovery test in wheat flour.The result showed that the recovery yeild is 96.0%?102.7%,indicating that this method has great accuracy.Fluorescent quantum dots Immunoassay methods constructed in this paper could meet the basic requirements of rapid detection methods,showing good prospects in the rapid detection of ochratoxin A.