title: Rapid one-step whole blood C-reactive protein magnetic permeability immunoassay with monoclonal antibody conjugated nanoparticles as superparamagnetic labels and enhanced sedimentation.
abstract: A rapid (5.5 min) one-step whole blood C-reactive protein (CRP) magnetic permeability immunoassay utilizing monoclonal antibody conjugated dextran iron oxide nanoparticles (70 nm) as superparamagnetic labels and mixed fractions (1:1 ratio of 15-40 and 60 microm) of polyclonal anti-CRP conjugated silica microparticles for enhanced sedimentation is described. In this one-step assay procedure, a whole blood sample (4 microl) is applied to an assay glass vial, containing both antibody conjugates, and mixed for 30 s. The target analyte, CRP, forms a sandwich complex between the conjugated nanoparticles and microparticles, and, subsequently, the complex sediments under normal gravitation within 5 min to the bottom of the vial. The magnetic permeability increase of the sediment due to the presence of the complexed superparamagnetic nanoparticles is determined using an inductance-based transducer. Assayed patient whole blood samples were compared with the Abbott Diagnostics Architect reference method. A strong linear correlation was observed for the CRP concentration range 0-260 mg/l in whole blood (y=1.001x+0.42, R2=0.982, n=50). The CRP assay presented showed a limit of detection of 3 mg/l and a total imprecision (coefficient of variation) of 10.5%. On the basis of our observations, we propose a rapid, one-step, CRP assay for near-patient testing.
authors.affiliation: Department of Pure and Applied Biochemistry, Lund University, P.O. Box 124, 221 00, Lund, Sweden.
authors.forename: Filiz
authors.initials: F
authors.lastname: Ibraimi
authors.forename: Dario
authors.initials: D
authors.lastname: Kriz
authors.forename: Min
authors.initials: M
authors.lastname: Lu
authors.forename: Lars-Olof
authors.initials: LO
authors.lastname: Hansson
authors.forename: Kirstin
authors.initials: K
authors.lastname: Kriz
mesh_terms: D000911:Antibodies, Monoclonal / Q000737:chemistry*; D002097:C-Reactive Protein / Q000032:analysis*; D002138:Calibration; D006801:Humans; D007118:Immunoassay / Q000379:methods; D008280:Magnetics; D053758:Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012822:Silicon Dioxide / Q000737:chemistry; D013499:Surface Properties
chemical_list: D000911:Antibodies, Monoclonal; D012822:Silicon Dioxide; D002097:C-Reactive Protein