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Quantitative Detection in the Attomole Range for Immunochromatographic Tests by Means of a Flatbed Scanner

2001; Elsevier BV; Volume: 293; Issue: 2 Linguagem: Inglês

10.1006/abio.2001.5130

1096-0309

Maria Lönnberg, Jan Carlsson,

Advanced Biosensing Techniques and Applications

This work describes the use of the combination of carbon black as an antibody label, a membrane-based immunochromatographic device, and a flatbed scanner as a quantitative test system. The scanner detected 0.4–345 ng carbon black/mm2 on a nitrocellulose membrane (0.2–170 amol carbon black/mm2) with an imprecision (coefficient of variation, CV) lower than 2% for the carbon black determination and a detection limit of 0.04 ng carbon black/mm2 (0.02 amol/mm2). The detection ability was compared to that obtained with alkaline phosphatase (ALP) using a substrate yielding a chemiluminescent signal (0.02 amol ALP/well), β-galactosidase using a substrate yielding a fluorescent signal (0.3 amol β-galactosidase/well), and horseradish peroxidase (HRP) using a substrate yielding a colored signal (5 amol HRP/microtiter well). The carbon black immunochromatographic test for immunoglobulin E (IgE) showed a detection limit of 0.13 pM IgE (0.01 kU/L) after a testing time of 10 min. The scanner detection imprecision for the IgE determination was 0.6% CV in the range 1–10 kU IgE/L when 2.3 mm2 was used for detection and 1% CV when 0.19 mm2 was used. A flatbed scanner is an inexpensive instrument with multiple uses, which now also includes the sensitive evaluation of immunoassays.