Microfluidic immunosensor design for the quantification of interleukin-6 in human serum samples

GERMÁN ALEJANDRO MESSINA; NANCY V. PANINI; NOELIA A. MARTINEZ; JULIO RABA

ANALYTICAL BIOCHEMISTRY

Año: 2008 vol. 380 p. 262 - 267

0003-2697

Interleukin-6 (IL-6), an inflammatory cytokine, is one of the most important mediators of fever, the acutephase response, and inflammatory conditions. Described here is an integrated microfluidic immunosensorcapable of detecting the concentration of IL-6 in human serum samples by use of an electrochemicalmethod in a microfluidic biochip format. The detection of IL-6 was carried out using a sandwich immunoassaymethod based on the use of anti-IL-6 monoclonal antibodies, immobilized on a 3-aminopropylmodifiedcontrolled-pore glass (APCPG) packet in a central channel (CC) of the microfluidic system. TheIL-6 in the serum sample is allowed to react immunologically with the immobilized anti-IL-6 and biotinlabeledsecond antibodies specific to IL-6. After washing, the streptavidin–alkaline phosphatase conjugateis added. p-Aminophenyl phosphate is converted to p-aminophenol by alkaline phosphatase, andthe electroactive product is quantified on a gold electrode at 0.10 V. For electrochemical detection andenzyme immunoassay, the LOD was 0.41 and 1.56 pg mL1, respectively. Reproducibility assaysemployed repetitive standards of IL-6, and the intra- and inter-assay coefficients of variation were below6.5%. Compared with the traditional IL-6 sensing method, the integrated microfluidic immunosensorrequired smaller amounts of sample to perform faster detection.