Chemiluminescent Immunoassay For Multi-Analytes Based On Magnetic Mesoporous Materials

In this paper, a series of novel nanohybrids have been prepared, such as magnetic mesoporous SBA-15, carboxylated graphite oxide and CdS/SBA-15, to immobilize protein or enzyme biomolecules. The main contents are as follows:1. A sensitive dual immunoassay was proposed for sequential determination of carcinoembryonic antigen(CEA) and a-fetoprotein(AFP) based on signal amplification combined with flow injection chemiluminescence (CL) analysis. Magnetic mesoporous silica particles (Fe3O4/SBA-15) were synthesized to immobilize the monoclonal antibodies as the primary probe. Horseradish peroxidase (HRP) labeled antibodies co-coated on gold nanoparticles (Au NPs) were used as the secondary probe to achieve the signal amplification. After the sandwich immunoassay, the HRP tags were retained in the flow cells due to a sandwich immunological reaction. By controlling two switches on the two channels, CL substrate solutions were injected orderly, and then different signals for CEA and AFP were sequentially detected by the CL system of HRP-luminol-H2O2. Under the optimal conditions, CEA and AFP could be detected in the linear ranges of1.0-80and1.0-75ng/mL with detection limits of0.25and0.5ng/mL, respectively.2. A sensitive dual flow injection CL immunoassay was proposed for sequential determination of AFP and CEA based on the signal amplification by using graphite oxide (GO) with functioned carboxyl groups. Fe3O4/SBA-15nanoparticles were synthesized to immobilize the monoclonal antibodies as the primary probe. HRP labeled antibodies co-coated on GO were used as the secondary probe. Due to the increased amount of HRP tags on GO surface, the signal amplification was achieved. After the sandwich immunoassay, the immunological complexes of AFP and CEA were injected orderly into flow cells, and retained in the flow cells by the magnetic tube. By controlling two switches on the two channels, CL substrate solutions were injected, and then different signals for AFP and CEA were sequentially detected by the CL system of HRP-luminol-H2O2. Under the optimal conditions, the linear range of AFP is0.005-0.5ng/mL and0.5-100ng/mL, with a detection limit of5.0pg/mL. The linear range of CEA is0.0025-1.0ng/mL and1.0-80ng/mL, with a detection limit of 2.5pg/mL3. A novel CL immunoassay was proposed for sequential determination of AFP and CEA based on HRP labels coated on CdS/SBA-15nanoparticles. The monoclonal antibodies were immobilized on CdS/SBA-15as the primary probe. HRP labeled antibodies were co-coated on magnetic beads (MBs) as the secondary probe to achieve the signal sensitization. After the sandwich immunoassay, the HRP tags were retained in the flow cells due to a sandwich immunological reaction. By controlling two switches on the two channels, CL substrate solutions were injected orderly, and then different signals for CEA and AFP were sequentially detected by the CL system of HRP-luminol-HiO2. After the sandwich immnuoassay, the immune complexes of AFP and CEA were injected orderly the double-channel immunosensing systems, AFP and CEA were sequentially detected by the CL system of HRP-luminol-H2O2. The results indicated that the co-coated CdS QDs could enhance the CL intensity of HRP-luminol-HiO2. Due to the large surface area of SBA-15, the immobilized amounts of CdS QDs increased. Thus, the detection signal were further enhanced.