Novel electro-magnetophoretic separation method for the highly sensitive detection of analytes

Abstract

The detection of a low concentration of biomarkers required for an early diagnosis remains a tricky task to pursue. In this context, magnetic nanoparticles (MNPs) have been widely used to isolate/concentrate diluted samples. However, by applying the magnetic field, all MNPs are isolated, both those conjugated with the analyte and free MNPs. This excess of MNP can interfere with the analyte quantification. Herein, we propose a novel and versatile approach that ensures the selective isolation of the analyte-conjugated MNP by exploiting the electrophoretic and magnetophoretic behavior of respectively charged silica nanoparticles (SiNPs) and MNPs. In this work, the robustness and sensitivity of the developed isolation and fluorescence-based detection procedure were confirmed by comparing them with the standard method based on simple magnetic isolation of the analyte. The limit of detection (LOD) is improved by two orders of magnitude, namely, from 1 nM to 10 pM. This finding confirms the potentiality of the method and its possible application in the development of rapid and easy-to-use point-of-care devices.