An Electrochemiluminescent Magneto Immunosensor for Ultrasensitive Detection of Hs-Ctni on a Microfluidic Chip

Abstract

Sensitive detection and precise quantitation of trace-level crucial biomarkers in a complex sample matrix have always been research focuses. Taking the detection of high-sensitivity cardiac troponin I (hs-cTnI) as an example, it is strongly recommended by clinical guidelines for early diagnosis of acute myocardial infarction. In the past decades, electrochemiluminescent (ECL) magneto immunoassay has been a powerful technique in the biosensing field due to its high sensitivity and low background signal. Herein we proposed a novel integrated microfluidic chip with multiple signal amplification strategy for ultrasensitive detection of hs-cTnI using ECL magneto immunoassay. We fabricated hierarchical micropillar arrays microstructures and two magnets placed at both ends to efficiently confine single-layer immunomagnetic microbeads on the surface of the electrode for 7.5-fold signal enhancement. In addition, in combination of single wall carbon nanotube (SWCNT) with excellent electrocatalysis of tripropylamine and Ru(bpy)32+-doped silica (Ru@SiO2) with great loading capacity, the ECL detection of hs-cTnI on the microfluidic chip exhibited excellent sensitivity. Particularly, SWCNTs modified transparent ITO electrode exhibit two-order ECL signal amplification. A good linear calibration curve was developed for hs-cTnI concentrations in a wide range from 10 fg/mL to 10 ng mL−1, with the limit of detection calculated as 8.720 fg/mL (S/N=3). The ultrasensitive immunosensor showed superior detection performance with remarkable stability, repeatability and selectivity. Satisfactory recoveries were obtained in the detection of hs-cTnI in human serum. The results demonstrated the great potential of the microfluidic chip as a platform to investigate a large-scale ECL imaging of single magnetic bead in the future.

Keywords: electrochemiluminescent magneto immunosensor, Microfluidic chip, high-sensitivity cardiac troponin I, single well carbon nanotube, [Ru(bpy)3]2+-doped silica nanoparticles