Microchip based and immunochromatographic strip assays for the visual detection of interleukin-6 and of tumor necrosis factor α using gold nanoparticles as labels

The enzyme-linked immunesorbent assay (ELISA) is most frequently used for the determination of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α). However, this technique is time-consuming and requires a substantial sample volume. We have developed (a) a new kind of colloidal gold-based immunochromatographic strip, and (b) a colloidal gold-based immunochromatographic microchip for simultaneous, rapid, and visual detection of IL-6 and TNF-α. The lowest limit of detection is 62.5 ng mL⁻¹ for IL-6, and 30 ng mL⁻¹ for TNF-α. Both the strip method and the microchip method are highly specific, user-friendly, and can be read out without the need for instrumentation.