Magnetic immunoassay detection of tumor necrosis factor-alpha in different deposited zones of thin channels using functional particles

[[abstract]]This study reports the magnetic immunoassay detection of tumor necrosis factor-alpha (TNF-alpha) in different deposited zones of thin channels using functional particles. Deposited zones with linear and s-shape geometries were tested and compared to detect a TNF-alpha model biomarker. Results show that the deposited zone of s-shape geometry is faster than that of linear geometry for affinity reactions. Using the s-shape deposited zones, the running time can be reduced to less than 20 min. The detection limits of linear and s-shape deposited zones were found to be the same as 1.0 pg/mL within experimental errors. The detection limit is lower than that of ELISA. The linear ranges of TNF-alpha detection were from 1.7 pg/mL to 1.7 ng/mL for two deposited zones in sandwiched magnetic immunoassay. The linear range of this method is wider than those of ELISA and other methods. The measurements of TNF-alpha in serum samples from this method differed from ELISA results by about 10%. The proposed method can provide simple, fast, and sensitive detection for biomarkers. (C) 2012 Elsevier B.V. All rights reserved.[[note]]SC