| With the improvement of living standards,the balance of people’s diet structure has been tilted from plant food to animal food.Environmental estrogens are abused by illegal traders as illegal additives in animal food production,which seriously harm human health.Traditional environmental estrogen detection techniques mainly rely on expensive equipment and professional operators.In view of the lack of real-time,highly sensitive,and rapid detection technology for trace environmental estrogen pollutants.In this paper,the surface-enhanced Raman scattering（SERS）technique is used,which is combined with the molecular beacon technique and aptamer technique,using a rhombus DNA origami template to realize addressable self-assembly of dimer plasma nanoantennas to construct a method for SERS detection of diethylstilbestrol which is one of the typical environmental estrogens.A series of 20-80 nm spherical gold nanoparticles（Au NPs）with regular morphology and uniform particle size were synthesized by seed-mediated method,providing technical support for repeatedly preparing dimer plasma nanoantennas.In order to realize the self-assembly of Au NPs to specific sites of rhombus DNA origami templates on the nanoscale,and to control particle spacing below 10 nm,a large particle size of 50 nm Au NPs was selected.The mercapto DNA modified to the surface of Au NPs was fully hybridized with the extended capture chain of rhomboid DNA origami,and Au NPs were arranged into dimer plasma nanoantennas with a gap width of 8.5±1.0 nm.By optimizing the preparation technology of dimer plasma nanoantenna,the optimal concentration of triangle DNA origami for synthesizing rhombus origami was 5.0 n M.According to the changes of circular dichroism before and after the aptamer binding with the target,the Apt2 with a stronger affinity for diethylstilbestrol and significant changes in the secondary structure after the specific binding was selected with what the specific sequence of bases is 5’-GAAGGATGGATGCTTTGGTGTGTAGTATGAGCGAGCGTTGCGA-3’,and is used to capture design and application of chain.Through the SERS effect of incident laser with three wavelengths acting on dimer plasma nanoantennas,the optimum laser wavelength for the surface plasmon resonance coupling of dimer plasma nanoantennas is 785 nm.The preparation process of dimer plasma nanoantennas was analyzed by agarose gel electrophoresis.The optimal molar concentration ratio of rhombus DNA origami to metal nanoparticles was 1∶3.By directly wrapping Au NPs with 4-MBA signal marker molecule,the Cy5 signal molecule marker DNA chain extending from the center of rhombus origami was replaced to achieve a more efficient and reliable molecular beacon,which improved the sensitivity and linearity of dimer plasma nanoantenna for diethylbestrol detection.Through further exploration,it was found that under the same excitation condition,Ag@Au NPs dimer plasma nanoantennas were constructed after Au NPs was coated with a layer of 2-3 nm silver shell through silver enhancemen.The SERS effect of Ag@Au NPs dimer plasma nanoantennas was 1.6 times as high as Au NPs dimer plasma nanoantennas,which had a good application potential.Dimer plasma nanoantenna was used for quantitative detection of diethylstilbestrol.The results showed that the SERS intensity of 4-MBA signal molecules increased linearly with the decrease of diethylstilbestrol concentration in the range of 10-5 M to 10-10 M.The linear regression equation is y=144.6224-301.9450lg C（C is the molar concentration of diethylstilbestrol in the system）,and the correlation coefficient is 0.9992.The detection limit of this method is 0.2170 n M（equivalent to 0.0582μg/L）.Far lower than the maximum residue limit（2μg/kg）of diethylstilbestrol in a food regulated by the European Union.The recoveries of diethylstilbestrol in commercial milk samples were 96.8-110.0%,and the relative standard deviation was 0.22-0.73%.Dimer plasma nanoantennas have the advantages of fewer samples,short time,high sensitivity,and good reproducibility in the detection of trace diethylstilbestrol,which can be used for the rapid detection of diethylstilbestrol in the field.In addition,by changing the aptamer sequence of the capture chain,the dimer plasma nanoantenna is expected to become a universal ser detection platform.This study is multidisciplinary research on food detection,nano-biotechnology,and biosensing technology.The established detection method is expected to be used in food safety,inspection and quarantine,environmental monitoring,and other fields,which has good theoretical value and application prospects for promoting the development of new technology for the accurate and rapid detection of environmental estrogen in food. |
