Direct electrochemiluminescent immunosensing for an early indication of coronary heart disease using dual biomarkers

Abstract

In this paper, a promising technology for obtaining an early indication and making a clinical diagnosis of coronary heart disease (CHD) is successfully designed. Specifically, label-free biosensors based on Au–Co nanoparticles (Au–Co NPs) were utilized to detect low-density lipoprotein (LDL) and oxidized low-density lipoprotein (ox-LDL), which are both CHD biomarkers. Conductive Au–Co NPs provided a prominent sensing platform and played the role of an efficient electrochemiluminescent (ECL) signaling amplifier. Conductive Au–Co NPs were fabricated using a simple method of water phase synthesis and were characterized using transmission electron microscope (TEM) and scanning electron microscope (SEM) images. An antibody was immobilized onto Au–Co NP-decorated indium tin oxide coated glass. After the formation of an immune complex between the antigen and antibody, using luminol as a sensing probe, it was found that the ECL signal was inhibited. Under the optimized conditions, the immunosensor exhibited sensitive detection of LDL over a wide linear range from 0.420 to 100 pg mL−1 with a detection limit of 0.256 pg mL−1. Likewise, a linear regression of the concentration of ox-LDL was obtained over the range from 0.500 pg mL−1 to 60.0 pg mL−1, with a detection limit of 0.330 pg mL−1. This research provides a new method for making a clinical diagnosis and obtaining an early indication of CHD due to the high performance sensing of these two biomarkers.