PNNL

Abstract

A versatile bioassay label based on marker-loaded-apoferritin nanoparticles (MLAN) have been developed for sensitive protein detection. Dissociation and reconstitution characteristics at different pH as well as the special cavity structure of apoferritin provide a facile route to prepare nanoparticle labels, and avoid complicated and tedious synthesis process of conventional nanoparticle labels. The optical and electrochemical characteristics of the prepared nanoparticle labels are easily controlled by loading different optical or electrochemical markers. A fluorescence marker (fluorescein anion) and a redox marker [hexacyanoferrate (III)] were used as model markers to load into the cavity of apoferritin nanoparticle and developed for microscopic fluorescence immunoassay and electrochemical immunoassay, respectively. Detection limits of 0.06 ng mL-1 (0.39 pM) and 0.08 ng mL-1 (0.51 pM) of IgG were obtained with fluorescein MLAP and hexacyanoferrate MLAN, respectively. The new nanoparticle labels hold great promise for multiplex protein detection (in connection to nanoparticles loaded with different markers) and for enhancing the sensitivity of other bioassay.