Carcinoembryonic Antigens Were Determined By SERS Immunoassay Based On Nanogold And Core-shell Magnetic Nanoparticles

Au nanoparticles are small gold particles have a diameter of 1?100 nm with good stability,low toxicity and other advantages.Magnetic complexes with Au shell has been used for magnetic separation and detection in many different fields due to the well established surface modification and functionalization,surface enhanced optical properties and the magnetism of the core.Au shell with appropriate thickness could contribute giant surface enhanced Raman scattering(SERS)activity which exhibited high sensitivity and provided rich structural information.Nanomaterials with immune modification have high specificity in immunoassay.The combination of those advantages of SERS and specificity analysis of the immunoassay enable us develop new powerful ways for specific separation and high sensitivity detection.In this work,we made the combination of immune modified AuNPs,?-Fe2O3@Au and SERS to detect carcinoembryonic antigen.1.The AuNPs were synthesized by the reduction reaction of sodium citrate and chlorauric acid.The AuNPs were characterized by UV-vis spectrometer and TEM.The size of the AuNPs was small(about 3 5nm)with good dispersability.The factors affecting the SERS active of the AuNPs were studied,such as precursor ratio and solution concentration.2.Water-soluble paramagnetic ?-Fe2O3@Au core@shell nanoparticles have been prepared and the features were characterized by different techniques.The size of the?-Fe2O3@Au was about 85nm with good dispersability.The factors affecting the SERS active of the ?-Fe2O3@Au were studied,such as precursor ratio.3.The immuno-?-Fe2O3@Au and MBA-labeled immunogold were prepared and linked by target antigens,and combined with magnetic separation to achieve the high sensitivity detection of target antigen.The specificity,detection limits and sensitivity of this method were investigated.In this study,the immune system was made to the quantitative detection of carcinoembryonic antigen and used MBA as the Raman reporter.Under the optimum conditions,the intensity of SERS versus CEA concentration from 1 to 50 ng/mL gave a linear response with an excellent correlation coefficient of 0.9942,and the limit of detection was 0.1 ng/mL.The concentration of CEA in human blood was determined by the proposed method.The recoveries of the samples were in the range of 88.60?105.8%.The discrepancies of the analysis results between Light-emitting electrochemical immunoassay and this method were all smaller than 16.72%.This work also made a partial least squares(PLS)analysis of the SERS immunoassay by TQ Analyst.The RMSEC was 2.71 and R was 0.9883,respectively.PLS analysis was convenient,reliable and had an anti-interference ability.It further demonstrated the accuracy of the experimental method.