Preparation Of SERS Sensor And Its Application In The Detection Of Aflatoxin B₁

Aflatixon B₁（AFB₁）,as a small molecule secondary metabolite produced by Aspergillus flavus and Aspergillus parasiticus,can damage the organs of animals and humans,causing teratogenic,carcinogenic and mutagenic negative effects.One of the most harmful mycotoxins to humans.Therefore,in order to protect people from economic losses and protect their health,it is necessary to develop a rapid and sensitive technology for detecting AFB₁.Surface-enhanced Raman spectroscopy（SERS）has the advantages of high sensitivity,in situ non-destructive testing and resistance to water interference.In this paper,based on DNA nanotechnology,combined with three-dimensional cicada wing substrate and magnetic separation technology,two SERS sensors for the detection of AFB₁were designed and constructed.1.Construction of a three-dimensional cicada wing substrate and its highly sensitive detection of AFB₁A three-dimensional cicada wing substrate and HCR dual signal amplification SERS sensor was designed and constructed for highly sensitive detection of AFB₁.On the basis of natural cicada wings,it was subjected to plasma sputtering.Then,the thiol-complementary DNA duplex was incubated on the substrate,and when AFB₁ is present,AFB₁ would specifically bind to the aptamer,releasing Complentary-DNA.Subsequently,Complentary-DNA could be combined with Au NPs modified with Primer-DNA,thereby triggering the subsequent HCR reaction and greatly enhancing the Raman signal intensity.The higher the concentration of AFB₁ added,the stronger the Raman signal produced.Finally,the detection range of the sensor was 0.01-1000 pg/m L,and the limit of detection was 9.4 fg/m L,and the sensor has high sensitivity and specificity,realizing the highly sensitive detection of AFB₁.2.HCR signal amplification and bead-bound SERS sensor for rapid and sensitive detection of AFB₁A SERS sensor combining magnetic beads with DNA nanotechnology was designed and constructed.First,gold was plated on the glass rod using a plasma sputtering apparatus,and then thiol Aptamer-DNA was incubated on the surface of the gold glass rod,and then the magnetic beads modified with Primer chains were incubated.Due to the complementary pairing effect of DNA,Aptamer-DNA will bind to MBs-DNA.When AFB₁ was present,AFB₁ would specifically bind to Aptamer-DNA to release MBs-DNA,and then the released MBs-DNA could be easily separated by an external magnetic field.DNA complex separation and enrichment.The Primer chain on MBs-DNA was used to trigger the subsequent HCR reaction to form a long DNA chain with a large number of SERS probes.Finally,the MBs and SERS probes were separated and enriched together by a magnet,which realizes the output and enhancement of Raman signals,the quantitative detection of AFB₁ was realized by the corresponding relationship between the change of Raman signal intensity and the concentration of AFB₁.The sensor detected AFB₁ in the concentration range of 0.01-1000 pg/m L with limit of detection as low as 7.5 fg/m L.Compared with the cicada-wing sensor,the magnetic bead sensor achieved rapid detection of AFB₁.