title: Nanoparticle-based sandwich electrochemical immunoassay for carbohydrate antigen 125 with signal enhancement using enzyme-coated nanometer-sized enzyme-doped silica beads.
abstract: A novel nanoparticle-based electrochemical immunoassay of carbohydrate antigen 125 (CA125) as a model was designed to couple with a microfluidic strategy using anti-CA125-functionalized magnetic beads as immunosensing probes. To construct the immunoassay, thionine-horseradish peroxidase conjugation (TH-HRP) was initially doped into nanosilica particles using the reverse micelle method, and then HRP-labeled anti-CA125 antibodies (HRP-anti-CA125) were bound onto the surface of the synthesized nanoparticles, which were used as recognition elements. Different from conventional nanoparticle-based electrochemical immunoassays, the recognition elements of the immunoassay simultaneously contained electron mediator and enzyme labels and simplified the electrochemical measurement process. The sandwich-type immunoassay format was used for the online formation of the immunocomplex in an incubation cell and captured in the detection cell with an external magnet. The electrochemical signals derived from the carried HRP toward the reduction of H(2)O(2) using the doped thionine as electron mediator. Under optimal conditions, the electrochemical immunoassay exhibited a wide working range from 0.1 to 450 U/mL with a detection limit of 0.1 U/mL CA125. The precision, reproducibility, and stability of the immunoassay were acceptable. The assay was evaluated for clinical serum samples, receiving in excellent accordance with results obtained from the standard enzyme-linked immunosorbent assay (ELISA) method. Concluding, the nanoparticle-based assay format provides a promising approach in clinical application and thus represents a versatile detection method.
authors.affiliation: Key Laboratory of Analysis and Detection for Food Safety (Ministry of Education), and Fujian Provincial Key Laboratory of Analysis and Detection for Food Safety, Department of Chemistry, Fuzhou University, Fuzhou 350108, China. dianping.tang@fzu.edu.cn
authors.forename: Dianping
authors.initials: D
authors.lastname: Tang
authors.forename: Biling
authors.initials: B
authors.lastname: Su
authors.forename: Juan
authors.initials: J
authors.lastname: Tang
authors.forename: Jingjing
authors.initials: J
authors.lastname: Ren
authors.forename: Guonan
authors.initials: G
authors.lastname: Chen
mesh_terms: D000818:Animals; D000906:Antibodies / Q000737:chemistry / Q000276:immunology; D055162:Biocatalysis; D018394:CA-125 Antigen / Q000032:analysis* / Q000276:immunology; D002138:Calibration; D004563:Electrochemistry; D006735:Horseradish Peroxidase / Q000378:metabolism*; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D007118:Immunoassay / Q000379:methods*; D008863:Microspheres; D053758:Nanoparticles / Q000737:chemistry*; D010640:Phenothiazines / Q000378:metabolism; D015203:Reproducibility of Results; D012822:Silicon Dioxide / Q000737:chemistry*; D013997:Time Factors
chemical_list: D000906:Antibodies; D018394:CA-125 Antigen; D010640:Phenothiazines; D012822:Silicon Dioxide; D006861:Hydrogen Peroxide; D006735:Horseradish Peroxidase; C009469:thionine