A combination of magnetic permeability detection with nanometer-scaled superparamagnetic tracer and its application for one-step detection of human urinary albumin in undiluted urine

• Published in: Biosensors & bioelectronics Vol. 21; no. 12; pp. 2248 - 2254
• Main Authors: Lu, Min, Ibraimi, Filiz, Kriz, Dario, Kriz, Kirstin
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 15.06.2006; Elsevier Science
• Subjects: albumin-conjugated silica particles; Albumins - analysis; Albuminuria - urine; anti-human; anti-human albumin-conjugated; Anti-human albumin-conjugated silica particles; Anti-human albumin-conjugated superparamagnetic tracer; Biochemistry and Molecular Biology; Biokemi och molekylärbiologi; Biologi; Biological and medical sciences; Biological Sciences; Biotechnology; Equipment Design; Equipment Failure Analysis; Feasibility Studies; Fundamental and applied biological sciences. Psychology; Human urinary albumin; Humans; Immunomagnetic Separation - instrumentation; Immunomagnetic Separation - methods; Magnetic immunoassay (MIA); Magnetics; Methods. Procedures. Technologies; Nanotechnology - instrumentation; Nanotechnology - methods; Natural Sciences; Naturvetenskap; Others; superparamagnetic; tracer; Urinalysis - instrumentation; Urinalysis - methods; Urine; Various methods and equipments; Anti-human albumin-conjugated silica particles; Magnetic immunoassay (MIA); Human urinary albumin; Anti-human albumin-conjugated superparamagnetic tracer; Human; Urine; Antibody; Albumin; Permeability; Silica; Inorganic compound; Immunological method; Magnetic method; Microparticle; Detection
• ISSN: 0956-5663; 1873-4235; 1873-4235
• DOI: 10.1016/j.bios.2005.11.008

A rapid (6.5 min) and simple one-step magnetic immunoassay (MIA) has been developed for analysis of human urinary albumin in near patient settings. Polyclonal rabbit anti-human albumin was used as a capture antibody and monoclonal mouse anti-human albumin as a detection antibody in a two-site immunometric assay requiring no additional washing procedures. The polyclonal anti-human albumin was conjugated to silica microparticles (solid phase) and the monoclonal antibody to dextran-coated nanoscaled superparamagnetic particles (tracer). Quantification of human albumin in undiluted urine was performed by adding 2 μL urine to a measuring vial containing solid-phase, superparamagnetic tracer and reaction buffer and then inverting the vial by hand for 20 s. The measuring vial was allowed to stand for 6 min prior to detection, in order for the solid-phase sediment to form at the bottom of the vial. Lastly, the measuring vial was placed into a magnetic permeability detector, which measured the enrichment of superparamagnetic tracer in the sediment due to complex formation with human albumin. Total analysis time was 6.5 min. A linear response was obtained for 0–400 mg/L albumin with a detection limit of 5 mg/L. The total coefficient of variation (CV) was 11% calculated from four consecutive runs on a urine sample containing 11.1 mg/L human albumin during 3 consecutive days. Human urinary albumin analysis was performed on 149 patient samples using the MIA technique and the obtained results showed good correlation with the hospital immunoturbidimetric reference method ( y = 1.004 x + 4.01, R 2 = 0.978, N = 149) and a commercially available point of care albumin analysis provided by HemoCue Inc. ( y = 0.98 x + 5.8, R 2 = 0.833, N = 90).