Preparation Of Gold/metal Oxide Composite SERS Substrate And Its Application In SERS Detection

Surface-enhanced Raman scattering(SERS)spectroscopy has high sensitivity and can detect analytes at single-molecular level.As a good technique to study interface,SERS can provide fingerprint information of molecules absorbed onto the surface of noble metals.SERS substrates play a vital role in detecting molecules,among which mostly used are noble metal colloids.However,these substrates lack uniformity,reproducibility and stability.Composite SERS substrates can achieve other qualities and extend the research field of SERS substrates.This work combined Au nanoparticles with Al2O3,Fe3O4 and TiO2 respectively to form 3 composite substrates for SERS detection.The main research contents are listed as follows:1.Au nanoparticles were combined with γ-Al2O3 to prepare Au/Al2O3nanocomposites(NCs).Al2O3 is chemically inert and durable in high temperature and oxidation environment.γ-Al2O3 has large surface areas and can load more analytes.At the same time,Al2O3 is widely used as a polar adsorbent in chromatographic separations and has high affinity to molecules with strong polarity.Based on the above properties of γ-Al2O3,Au/Al2O3 NCs were applied to sensitively detect adenosine triphosphate(ATP)due to the aluminum phosphate chelation.The lowest detectable concentration was 5×10-9M,and a good linear relationship from 5×10-5M to 5×10-9 M.2.Pancreatic cancer is a digestive tract malignant tumor and the diagnosis and treatment are difficult.CA19-9 is one of the important biological markers of pancreatic cancer and is the only pancreatic cancer marker approved by the U.S.food and drug administration.The present methods for detecting CA19-9 are most electrochemical methods and are laborious.This work constructed Au/Fe3O4 NCs and modified antibody onto its surface to obtain capture substrates.At the same time,Au nanoparticles were immobilized with 4-MBA as Raman reporter and antibody to form SERS tags.A sandwich structure was acquired with the existence of CA19-9 and can be separated with a magnet.The Raman signal was in proportion to the concentration of CA19-9 and the indirect detection of CA19-9 was realized.The lowest detectable concentration was 1 U/mL and a good linear range from 10-1000 U/mL.3.As the mostly studied semiconductor,TiO2 has good physical and chemical stability and high catalytic property.It is widely studied to degrade organic pollutant.This work synthesized TiO2 nanobelts with single-crystalline anatase TiO2(110),which was proved to have enhanced photocatalytic reactivity.Au nanoparticles were deposited onto the surface of TiO2 nanobelts to form Au/TiO2 NCs.The composite substrates had good sensitivity and could detect CV down to 10-6 M.Au/TiO2 NCs also had good recyclability and could remain SERS performance after 5 degradations.