Study On ICP-MS Based Magnetic Multiplex Immunoassay Method

ICP-MS can realize multicomponent immunoassay,and has great potential applications in the field of clinical detection.However,conventional microtitration plate,as the solid phase carrier,is with limited active sites per micropore and affected by the discrimination effect coating different antibodies to the same micropore,which limits the ICP-MS based immunoassay applied to clinical multicomponent detection.We constructed an ICP-MS based magnetic immunoassay by replacing microtitration plate with streptavidin magnetic beads as the solid phase carrier.We coated different antibodies to the magnetic beads seperately and combined them flexibly.We also adjusted the orders between capture step and immune reaction step acccording to the combination types of different antigens(multi-macromolecular combination,or macromolecularmicromolecular combination),so that we realized the simultaneous determination of biological macromolecules and biological micromolecules.The main research results are as follows:1.We constructed an ICP-MS based magnetic sandwhich immunoassay.We realized simultaneous determination of three crucial gynecological tumor markers HER-2,HE4 and CA15-3,the concentrations of which are very different,by coating magnetic beads with biotinylated antibody seperately and optimization of magnetic immunoassay parameters.The dynamic range was 12~1000 ng/mL for HER-2,8~2000 pmol/L for HE4,and 5~200 U/mL for CA15-3,while the limit of detection was 3.94 ng/mL(HER-2),2.59 pmol/L(HE4)and 1.62 U/mL(CA15-3).The relative standard deviations(RSDs)were 2.61%(15 ng/mL HER-2),4.90%(25 pmol/L HE4)and 6.68%(10 U/mL CA15-3).The results of spiking test indicated that matrix did not affect the analysis results.The comparison between the results of our method with those of time-resolved fluorescence immunoassay showed good linear correlation,which revealed that our method can be applied to the simultaneous determinaton of the three tumor biomarkers.2.We constructed an ICP-MS based magnetic competitive immunoassay.we explored the simultaneous determination of biological maromolecules HER-2 and biological micromolecules FT3 and FT4 by placing the capture step after the immune reaction and optimizing the assay parameters.We investigated the impact of concentration of lanthanide-tagged antibody and magnetic beads on the ICP-MS signal intensities of FT3 and FT4,and the influence of time of capiture by magnetic beads on the detection of three target molecules.The results showed that there was interference between the immue reactions of FT3 and FT4,and no interference between the immue reactions of HER-2 and FT4.The linear correlations were 0.9975 for HER-2 and 0.9977 for FT4,while the limits of detection were 7.14 ng/mL and 2.11 pmol/L.