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 (μMD) disc. In μMD-ELIA, magnetic immunocomplexes are delivered into microchannel and trapping/preconcentration in the microchamber of μMD disc for fluorescence detection. The microchamber offers a confined space both for effective magnetic preconcentration and accelerated concentration of enzyme products. After μMD disc optimization, the assay performances of μMD-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 μMD-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 μMD-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 μMD-ELIA has enormous potential in disease early diagnosis and curative effect monitoring.