Design Of SERS Sensors And Their Applications In Detection Of Aflatoxin B₁

Aflatoxin B₁（AFB₁）is one of the most abundant and carcinogenic food contaminating mycotoxins around the world.It could be found in wide range of pollution,such as peanuts,corn,nuts and other 100 kinds of agricultural products.Aflatoxin B₁ was extremely toxic,easily lead to acute poisoning,but also resulting in teratogenic and carcinogenic effects,has a great threat to to human and animal health.Therefore,the developmenting of aflatoxin B₁ detection technology to avoid contaminated agricultural products and food into the market,provideing technical support for food safety has become very important.Surface-enhanced Raman scattering has high sensitivity,resisted water interference,provided fingerprint spectrum and other advantages,so it has been more and more widely used in the field of food safety testing.Based on the AFB₁ aptamer,using Au @ Ag NRs and Au NPs as SERS signal probes,combined with magnetic separation technology and exonuclease Ⅲ of the circular amplification function,two SERS sensors were designed to detect aflatoxin B₁.The main contents and innovations of this research are as follows:1.A SERS sensor for rapid detection of aflatoxin B₁ was constructed based on the dissociation of aptamers and separation of magnetic beads.Biotinylated AFB₁ aptamer was modified on the carboxylated magnetic beads as a detection probe using streptavidin and biotin interaction;Synthetic signal molecules（4-MBA）embedded gold-silver core shell nanorods,and modified with thiolated complementary DNA,assembled into a SERS probe.Through the base complementary,the gold-silver core shell nanorods and magnetic beads were constructed as a AFB₁ detection sensor.The competitive response between AFB₁ and DNA separated the magnetic beads from the gold-silver core shell nanorods,so the intensity of SERS was reduced,through the changes to achieve the purpose of rapid detection of AFB₁.The linear range of this sensor was 1 to 1000 pg/mL and the detection limit is 0.4 pg/mL.2.Designed a SERS sensor for ultrasensitive detection of AFB₁.Gold nanoparticles modified with signal molecules（4-NTP）and signal DNA were used as SERS probes,and the gold-plated slide modified with hairpin DNA used as a capture base.AFB₁ induced exonuclease Ⅲ hydrolysis hairpin DNA,exposed a large number of capture sites,so the captured SERS probes were increased,leading to a signal amplification,thus a SERS detection method for ultrasensitive detection of AFB₁ was established.The AFB₁ concentration was determined by detecting the intensity changes of SERS probe captured by the DNA short chain on the substrate.The linear range of the sensor is 1 × 10-6 to 1 ng/mL and the detection limit is 6 × 10^-7 ng/mL.