Research On SERS Sensors Constructed With Gold Nanoparticle And Magnetic Bead For PEDV Detection

Porcine epidemic diarrhea virus?PEDV?,one of the six coronaviruses about pigs,has brought huge economic losses to China since 2010.PEDV caused up to 100%mortality in newborn piglets by various transmission media.Not only can PEDV infect cells from some wild species like bats,but weeks after clinical signs ceased,they could be found in the stools of infected pigs.It means they exist widely and chronically.Conventional tests such as enzyme linked immunosorbent assay?ELISA?and strips ofter failed to avoid the problem of inaccuracy and false positive.Therefore,for food safety and potential ecocrisis,it's urgent to develop rapid diagnostic platform for monitoring the viruses quantificationally.Surface-enhanced Raman scattering?SERS?has advantages like resisting water interference,and providing fingerprint characters,so it has been widely and effectively used in the field of food safety testing,environmental monitoring and bioanalysis.Based on the“Sandwich like”sensing structure,two SERS sensors were designed to detect the virus based on the biotinylated Au nanoparticles in combination with the system of the SA-Bio amplification function,and on magnetic bead loading Au nanoparticles SERS tags combined with magnetic separation and enrichment technology.The main content and results of the article are clarified as below:1. A SERS sensor platform constructed with Au NP tag on Au film and its application for PEDV antibodies detectionA method for quick and biocompatible,biotinylated SERS tag was first established with gold nanoparticles?Au NP?.Then,a layer of gold was sputted onto slide to surve as the sensing platform.The biosensor was constructed by using the virion as the capture unit for trapping antibodies to be tested.After being captured,biotinylated second antibodies against the target were added.More than one SERS tag was immobilized on each second antibody by using SA as the bridging molecule to which up to three biotins could be specifically conjugated,realizing amplification of the detective signal and sensitively quantitative detection of PEDV antibody.It turned out that there was a good linear relation with target concentration from 1×10^-4 ng/m L to 100 ng/m L,and the limit of detection?LOD?was 0.04 pg/m L.The recoveries in swine serum samples were in the range of 109.6%?119.4%.2. The MB tag used in Sandwich-like SERS sensing platform on GCE for PEDV detection.Magnetic SERS tags were prepared by coating magnetic beads?MB?with Au NP,Ab₁,and signal molecules p-nitrobenzenethiol?4-NTP?.Glassy carbon electrode?GCE?was used as supporting substrate to construct the sensing interface.Capture antibodies 1 were first immobilized on GCE,and then GSH was incubated on GCE.After PEDV was captured,magnetic SERS tags were introduced to the sensing interface by antigen-angibody recognition effect,realizeing the establishment of stable and convincing biosensing platform.Here,the concentration and separation effect of MB were employed to provide abundant signal source and simplify the preparation of signal tag,and the gap among Ab₁could be blocked more completely by low molecular sealing agent?GSH?.The linear range of the sensor is 1×10^-4 ng/m L to 1 ng/m L and the detection limit is 0.09 pg/m L.The recoveries in swine serum samples were in the range of 94.6%?102.6%.