The Research Of Photonic Crystal Sensing Technology For Rapid Detection Of Aflatoxin B1

Mycotoxins are secondary metabolites by fungi in foods,the foods which contaminated by mycotoxins threaten human health seriously.It can lead to immunosuppression and blocked the synthesis of protein,and can even cause cancer,teratogenicity,and mutagenesis.In recent years,the mycotoxins were detected by the large-scale machine mainly,these technologies have the advantages of high sensitivity and specificity.However,these detection methods are costly,require professional operators,and are cumbersome in pre-processing,thus causing great difficulties for the popularization of these technologies,especially for on-site detection.Photonic crystals have the advantages of self-expression of response signals,no need of additional reagents for coloration,simple operation,etc.It is an ideal sensing material,especially for on-site rapid detection.In this study,the photonic crystal was used as a sensing platform,and mycotoxin?Aflatoxin B1?AFB1??was used as target,combined with molecular imprinting and bioassay technology,a new method for the detection of mycotoxins was explored.And then a simple,rapid,and sensitive screening technology for AFB1 was established.The specific work is as follows:Firstly,the research of photonic crystal sensing technology based on molecular imprinting for mycotoxin.Monodisperse,uniform particle size of Si O₂ microspheres were synthesized.After the optimization of synthesis conditions,280 nm SiO₂microspheres were selected as photonic crystal precursors,and the opal photonic crystals were prepared by vertical convective self-assembly method.An AFB1imprinted inverse opal photonic crystal?MIPP IOPC?was prepared by designing a"sandwich"structure small chamber using molecular imprinting technology.Simultaneously,the AFB1 templates were eluted with an eluent to obtain the imprinted cavities.In the experiment,a plurality of matching pre-polymerized imprinted photonic crystals has been tried to detect the AFB1,but there were no obvious response signals.The reason for this result may be that AFB1 has low solubility in solution,resulting in a too low concentration of template molecules in the polymerization solution to form enough imprinted cavities,thus failing to cause significant detection signals.The imprinted polymer was then prepared using a more soluble 5,7-dimethoxycoumarin?5,7-DMC?substitute?in place of AFB1?as template,at the same time,Methacrylic Acid?MAA?was used as the monomer and Ethylene Glycol Dimethacrylate?EGDMA?was used as the cross-linker,there was a weak response signal.Therefore,the preparation of new photonic crystals was investigated in the next step of the experiment and the feasibility of detection for mycotoxins was analyzed.Secondly,the research of photonic crystal sensing technology based on co-assembly method for the preparation of SiO₂ inverse opal photonic crystals.Suspension polymerization method was used to synthesize Polymethyl Methacrylate?PMMA?microspheres with a diameter of about 280 nm.An appropriate amount of Tetraethyl orthosilicate?TEOS?solution was added to the suspension of PMMA microspheres,and a SiO₂ inverse opal photonic crystal material was prepared by a colloid/template co-assembly method.During the experiment,the mass fraction of PMMA microspheres,ratio of PMMA microsphere suspension to TEOS solution,and the temperature of evaporation were optimized.The TEOS?80?L?solution was added to PMMA?10 m L,0.3%,?microsphere suspension and the mixture was placed in a drying oven at 60°C and evaporated for 48 h to prepare crack-free SiO₂ inverse opal photonic crystals.The 3-Aminopropyltriethoxysilane?APTES?was used to modify the amino group on the inverse opal photonic crystal,and then the aldehyde group was modified with glutaraldehyde.After the amino-modified aptamer was hybridized to its complementary strand,it is linked to the inverse opal photonic crystal by the amino group with an aldehyde group.Finally,the aptamer photonic crystal sensing material was obtained.UV-Vis spectrophotometer and circular dichroism spectrometer were used to verify that the aptamer could recognize the AFB1 effectively.The fluorescence detection method confirmed that the complementary strand of aptamer could be replaced by AFB1 and then it could be used for detection.The response of the aptamer photonic crystal sensing material to AFB1 was studied by fiber optic spectroscopy.It was found that this sensing material can be used for rapid detection of AFB1 with the limit of detection as low as 1 pg/m L.This method can avoid the generation of cracks and can prevent the non-uniform penetration and over-coverage during the preparation of the inverse opal photonic crystals.In short,this method greatly reduced the random defects and simplified the preparation steps and the photonic crystal have a stable structure.In addition,the functionalized photonic crystal sensor is also possible to connect other recognition groups such as antibodies and receptors to expand the application range of it.The sensors prepared by this method has the advantages of high sensitivity,easy operation and wide application range,and it has a better application prospects.