title: Effects of particle characteristics on magnetic immunoassay in a thin channel.
abstract: The effects of size and porosity of particles on magnetic immunoassay in a thin channel were studied. Experimental parameters were investigated and compared using a model immunoassay complex of carcinoembryonic antigen (CEA)/anti-CEA. The rate constant for the affinity reaction between functional particles increased as the size of magnetic nanoparticles (800-80 nm) decreased. The affinity reaction between functional particles had no significant effect on the sizes of microparticles (1.0-4.4 μm) at commonly used thin channel flow-rates of 0.001-0.025 ml/min. Competitive and sandwich reactions of CEA/anti-CEA were studied for CEA detection. Microparticles of different porosities produced similar linear ranges of detection and limits of detection. The limits of detection for CEA were 0.29 pg/ml and 0.21 pg/ml for competitive and sandwich reactions, respectively. The linear ranges of detection were from 0.49 pg/ml to 4.9 ng/ml for both competitive and sandwich reactions. The detection limits were lower, and the linear ranges were wider than those of literature. There was a 9% difference in CEA detection measurements between competitive and sandwich magnetic immunoassay. The measurements of two magnetic immunoassays differed by less than 13% from the ELISA reference measurements. The running time was less than 30 min. Magnetic immunoassay in a thin channel has great potential for biochemical analysis and immunoassay-related applications.
authors.affiliation: Department of Applied Chemistry, Chung Shan Medical University, Taichung 402, Taiwan.
authors.forename: H Y
authors.initials: HY
authors.lastname: Tsai
authors.forename: Y C
authors.initials: YC
authors.lastname: Hsieh
authors.forename: Y M
authors.initials: YM
authors.lastname: Su
authors.forename: J R
authors.initials: JR
authors.lastname: Chan
authors.forename: Y C
authors.initials: YC
authors.lastname: Chang
authors.forename: C Bor
authors.initials: CB
authors.lastname: Fuh
mesh_terms: D002272:Carcinoembryonic Antigen / Q000032:analysis*; D005290:Ferric Compounds / Q000737:chemistry; D007118:Immunoassay / Q000379:methods*; D008280:Magnetics; D053758:Nanoparticles; D010316:Particle Size; D016062:Porosity; D012822:Silicon Dioxide / Q000737:chemistry
chemical_list: D002272:Carcinoembryonic Antigen; D005290:Ferric Compounds; C000499:ferric oxide; D012822:Silicon Dioxide