Magnetic nanoparticles functionalized with immobilized apolipoprotein antibodies for direct detection of non-high density lipoprotein cholesterol in human serum

Non-high density lipoprotein (non-HDL) cholesterol is a risk factor for atherosclerotic cardiovascular diseases. Monitoring serum non-HDL-cholesterol is a key challenge in clinical tests due to the lack of a direct measurement method. In this study, we developed a simple strategy for directly detecting serum non-HDL-cholesterol based on magnetic core/functionalized antibody against apolipoprotein AI (anti-apoAI) materials. Anti-apoAI was successfully achieved oriented immobilization on the surface of superparamagnetic nanoparticles. The magnetic nanoparticles functionalized with immobilized anti-apoAI had a clear three-dimensional core-shell structure with an average diameter of about 750 nm and a high saturation magnetization. These nanoparticles rapidly captured HDL in serum, and the complex could be separated from the solution by application of an external magnetic field. Non-HDL-cholesterol in the supernatant was identified by liquid chromatography tandem mass spectrometry without requiring complex sample preparation steps. The efficient removal of HDL from the serum sample was attributable to the good biocompatible microenvironment provided by the prepared magnetic nanocomposites, which preserved the biological activity of immobilized antibody. In addition, the clinical utility of the method was evaluated using serum samples from healthy individuals and atherosclerosis patients. This protocol combines the advantages of immobilized antibodies and magnetic medium for capture of target molecules, and can be used in clinical settings to directly measure non-HDL-cholesterol and served as an efficient tool for atherosclerosis risk assessments.