Synthesis Of SERS Active Magnetic Nano-composite And Its Application In The Detection Of Tumor Marker

With the development of modern medicine, a large number of researchs show that the emergence of tumor is often accompanied by the emergence of some specific proteins or concertration change. These proteins were called the tumor marker proteins, and the accurate detection of tumor marker proteins is expected to realize early diagnose of cancer. Surface-enhanced Raman scattering(SERS)-based protein detection has been expected to be a promising and significant technique for highly sensitive protein detection, since SERS technique possesses the unique features with ultrahigh sensitivity, anti-photobleaching and multiplex detection capability. One of the most widely adopted formats of SERS-based protein detection is the antibody-based sandwich immunoassay, including immuno-substrate(i.e., supporting substrates), SERS-active immunosensor(i.e., SERS tags) and the target protein.Magnetic nanomaterials which show prominent advantage in separation and purification of biological samples can be served as ideal immuno-substrate in antibody-based sandwich immunoassay. In this work, the SERS-active magnetic nanocomposite(Fe3O4@SiO2@Au) have been tunably fabricated, and the ultrasensitive detections of tumor marker proteins have been developed by using the as sythensized SERS-active magnetic nanocomposite as immuno-substrate and flower-like gold nanoparticles as SERS tags. The main works are as follows:(1) Synthesis of Fe3O4@SiO2@AuThe as synthesized Fe3O4 nanoparticles coated with a layer of silica to fabericate Fe3O4@SiO2 core-shell nanostructure. The thickness of silica layer and the number of Fe3O4 can be tuned by varying the dosage of TEOS. Finally, the as prepared Fe3O4@SiO2 was wrapped by gold, and the SERS-active magnetic nanoparticles were achieved.(2) Detection of tumor markersThe tumor marker proteins were detected by antibody-based sandwich immunoassay, and the SERS-active magnetic nanoparticles were served as immuno-substrate. The experimental results indicate that a good linear relationship is found between the peakintensity at 1068 cm-1 and the logarithm of CEA concentration in the range between 1 ng/m L and 0.01 fg/mL, and the limit of detection(LOD) is 0.01 fg/m L(3) The simultaneous detection of dual tumor marker proteins(CEA and NSE) The as synthesized Fe3O4@SiO2@Au nanoparticles were modified by two kinds of antibodies(anti-CEA and anti NSE) to fabricate immuno-substrate that can capture anti-CEA and anti NSE at the same time. The immuno-substrate was used to the simultaneous detection of dual tumor marker proteins(CEA and NSE), and the limit of detections(LOD) both are 1 fg/mL.