Spatial confined enzyme-linked immunoassay for ultrasensitive biomarker detection using a microfluidic magnetic delivery disc

Herein, a spatial confined enzyme-linked immunoassay (ELIA) is developed for ultrasensitive biomarker detection using a microfluidic magnetic delivery (mu MD) disc. In mu MD-ELIA, magnetic immunocomplexes are delivered into microchannel and trapping/preconcentration in the microchamber of mu MD disc for fluorescence detection. The microchamber offers a confined space both for effective magnetic preconcentration and accelerated concentration of enzyme products. After mu MD disc optimization, the assay performances of mu MD-ELIA have been evaluated by model targets of human monocyte differentiation antigen cluster of differentiation14 (CD14) and interleukin (IL)-8. The limits of detection (LOD) of mu MD-ELIA for CD14 and IL-8 are 0.17 pg/mL and 0.012 pg/ mL, respectively, which corresponded to an over 300-fold LOD sensitivity enhancement compared to their standard ELISA results. In human serum analysis, good accuracy is obtained on both CD14 and IL-8 when compared to the results of ELISA kits, and satisfied recoveries of 81.3-112 % with RSDs of 1.0-9.7 % for IL-8 were obtained. Moreover, the mu MD-ELIA is than applied to IL-6 concentration variation monitor in rat plasma during the progression of inflammatory reaction successfully, which further confirmed that the mu MD-ELIA has enormous potential in disease early diagnosis and curative effect monitoring.

Automated summary

A spatial confined enzyme-linked immunoassay using a microfluidic magnetic delivery disc has been developed for ultrasensitive biomarker detection. The method offers high sensitivity and accuracy with magnetic preconcentration and fluorescence detection in a confined space.