| The agricultural products and their processed foods were easy to be contaminated in the process of storage,production and sale,which producing the most toxic and highly carcinogenic aspergillus flavus(AFs).They are serious harmful to human health,and easy to cause liver poisoning,cancer and even death.Aflatoxin Bi(AFB1)is a kind of biological toxin with the highest content and toxicity.Therefore,it is urgent to establish a simple,rapid and sensitive method for the detection of AFB1 in food.ObjectivesA novel instantaneous magnetic responsive photonic crystals(MRPCs)encoding technology with magnetic material as building block was studied.The magnetic separation technology and the aptamer technology were combined to realize the fast detection of AFB1 in food.Methods1.We made a series of research on the control of MRPCs particle sizes,synthetic conditions and its basic properties,and modified the surface with functional groups.We adjusted the particle sizes of magnetic nanoparticles for constructing MRPCs structure by controlling the amount of water or tetraethyl silane(TEOs).We also optimized the amount of NaOH and surfactant added in the synthesis process;and the diffraction colors of MRPCs were encoded by controlling the sizes of the particle or the magnetic field strength;The functional groups amino,carboxyl or sulfhydryl was modified on the surface of MRPCs and was characterized both in qualitative and quantitative properties.2.The carboxyl modified magnetic beads were used as a carrier,after coupling with amino-group aptamers and hybridizing with the fluorescent modified complementary chain,the magnetic-aptamer molecular probe was prepared.After competing with the target AFB1 for 30 min,the fluorescent modified complementary chain was released.The fluorescence intensity of the complementary chain which was replaced by the fluorescent modified complementary chain was correlated with the concentration of the added AFB1.Results1.The sizes of the magnetic nanoparticles used to construct the MRPCs structure were adjusted in the range of 110 nm to 230 nm by controlling the amount of H2O and TEOS.60 mmol of NaOH and 3 g of surfactant were selected to obtain proper properties.The colors red shifted with inducing the strength of external magnetic strength(EMF)form 2500 Gs to 0 Gs,which covered the full spectrum range.Four sizes of MRPCs were responsed to red,yellow,blue and green under the same strength of magnetic field respectively,and realized the photon coding under EMF.The results showed the successfully modified of the amino,carboxyl and sulfhydryl on the suface of MRPCs.2.We use the method of magnetic-aptamer for the rapid detection of AFB1,in the concentration range in 5-100 ng/mL,the fluorescence intensity exhibited a linear correlation response to AFB1,the equation was y=1.544 x+65.741(R2=0.9931),and the lowest detection limit was 2.59 ng/mL.Trials of this method in the infant nutrition rice flour with satisfactory recovery in the range of 95.02%?102.70%.The results showed no statistically significant difference(P>0.05)compared with the ELISA detection method.ConclusionsThe novel MRPCs encoding microspheres have many advantages,such as rapid assemble,reversible,readable,easy to get in lab and low price.The functionalized MRPCs have expanded its application in detection,separation and clinical diagnosis,etc.By using the magnetic-aptamer technology in the detection of AFB1,a rapid,simple,low consumption and specific detection method has been developed.we believe that this new method could be potential applied for the detection of AFB1 in food,and shows great potential in the field of food safety analysis. |
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