The Research On Photonic Crystal Sensing Technology For Ultrasensitive Detection Of FB1 And SEB In Food

At present,biological toxins are widely present in food,causing a major threat to the health of humans and animals.In order to ensure food safety and quality,scientific application of food detection technology is extremely critical.At present,the existing detection methods are mainly completed by large-scale instrumental analysis or immunoanalysis.The former requires professional personnel,expensive equipment and complicated sample pretreatment process,while the latter mainly relies on monoclonal antibody,which has high preparation cost and harsh storage conditions,greatly limiting the practical application of these technologies.Therefore,it is particularly important to develop a new detection technology with simple operation,low cost,good stability and high sensitivity.As an emerging optical sensing material,Photonic Crystal(PC)has the advantages of self-expression of response signal,no marking,multi-level cross-linking,continuous and orderly structure,and has a broad application prospect in the field of food detection.Therefore,this paper uses highly ordered photonic crystals as a sensing platform,and amplifies the local Surface Plasmon Resonance(LSPR)signal generated by Au NPs.A simple,responsive and specific sensing technique has been developed and successfully applied to the detection of biological toxins.The main results are as follows:1.A sensitive and specific photonic crystal sensing technique was developed to detect fumonavin B1.Firstly,Si O₂ microspheres with different particle sizes were synthesized by TEOS hydrolytic polycondensation under alkaline conditions.APTES was used as silane coupling agent to carry out amino modification on the surface of Si O₂ microspheres.HAu Cl₄was then reduced to gold nanoparticles(Au NPs)using THPC as a reducing agent.Si O₂-Au NPs microsphere suspension was prepared by forming n-Au bond between amino group and Au NPs,and a highly ordered photonic crystal sensing material(Si O₂-Au NPs PC)was obtained by vertical sedimentation self-assembly method.When fumonavin B1 solution was added to the sensor material,the intensity of the reflection peak of the photonic crystal decreased gradually with the increase of the concentration of fumonavin B1.The intensity of the reflection peak decreased linearly with the logarithm of the concentration of fumonavin B1 in the range of 1 pg m L^–1–100 ng m L^–1,and the detection limit was 0.5 pg m L^-1.The sensing technology has fast response speed and high detection sensitivity.2.Compared with opal photonic crystals,inverse opal photonic crystals have larger specific surface area and regular ordered three-dimensional porous array structure.Thus,a highly ordered,plasmonic-enhanced sensing signal inverse opal photonic crystal(IOPC)material was developed,and based on this,a photonic crystal sensing technology was constructed to realize the detection of Staphylococcus aureus enterotoxin(SEB).Co-assembly of the colloidal template with the substrate material avoids the step of liquid penetration into the preassembled colloidal crystal and minimizes the resulting cracks and inhomogeneity of the IOPC structure.Au NPs not only act as a"bridge"between aptamer and IOPC,but also have the function of signal amplification.In addition,COMSOL simulation software was used to simulate the photoelectric enhancement mechanism of Au NPs.During the detection process,Au-Apt IOPC sensing materials responded effectively to SEB in the concentration range of 10^-2–10~3 pg m L^–1,with a detection limit of 2.820 fg m L^-1.The application of this method is proved by the experiment of sample adding standard.Au-Apt IOPC sensing materials can not only realize the ultra-sensitive detection of biological toxins,but also provide a broad biosensing platform for the monitoring of toxic and harmful substances.In summary,opal photonic crystals and reverse opal photonic crystals were prepared by vertical deposition method.Based on these two responsive sensing materials and aptamers as recognition elements,the ultra-sensitive detection of fumaumatoxin and Staphylococcus aureus enterotoxin B was achieved.At the same time,Au NPs was introduced to enhance the signal and further improve the detection sensitivity.On the other hand,as a bridge connecting aptamer and photonic crystal,the construction of new photonic crystal sensing technology is realized.The photonic crystal sensing technology proposed in this paper is simple in operation,sensitive in signal,environmentally friendly,and has excellent specificity,showing a good application prospect in food safety,environmental monitoring and clinical diagnosis.