A simple antigen-antibody reaction using ultrasmall FeCo nanoparticles

Abstract

In this study, we prepared ultrasmall FeCo nanoparticles (NPs) with a high magnetic moment and examined their antigen-antibody reaction for biodetection applications. The FeCo NPs were collected from the FeCo-BaF2 nanogranular film with Fe:Co:Ba:F = 14:11:21:54 at.%, by dissolving the film in water since the BaF2 matrix was deliquescent. The size of FeCo NPs was ∼5 nm and the saturation magnetization was estimated to be ∼15.30 kG (149.0 emu/g). The Candida albicans antibodies (abcam ab53891)-conjugated FeCo NPs were collected by using an ultracentrifugal separation (110 000 rpm, 90 min), they were then reacted with Candida albicans. The obtained result indicates that Candida albicans were absorbed successfully onto FeCo NPs, and the number of Candida albicans bound to FeCo NPs counted from the micrographs of the aggregates of FeCo NPs and Candida albicans increased significantly by adding sonication treatment of the film in water before binding them to the antibodies. The success of antigen-antibody reaction of ultrasmall NPs with high magnetic moment improves detection sensitivity as well as offers potential detection for smaller biomolecules.