Loading of chromenones on superparamagnetic iron oxide-modified dextran core–shell nanoparticles: openness to bind to β-cyclodextrin and DNA

Abstract

This paper presents the loading of chromenones, viz., flavanone, hesperetin, naringenin, coumarin 6 and coumarin 7 onto aminoethylamino-modified dextran-coated superparamagnetic iron oxide core–shell nanoparticles. The chemically modified iron oxide core–shell nanoparticles retain their superparamagnetic behaviour even upon chromenone loading. The accessibility of loaded chromenones to DNA for binding is analysed using UV-visible absorption and fluorescence spectroscopy. β-Cyclodextrin is used as an aid to detect whether the chromenones are buried inside the aminoethylamino-modified dextran-coated superparamagnetic iron oxide core–shell nanoparticle shell or available on the surface to readily bind to the macromolecular target. The stoichiometry of the loaded chromenones with the β-cyclodextrin inclusion complex is 1 : 1 in all cases, except with naringenin which binds to two β-cyclodextrin molecules. Coumarin 7 shows a fluorescence quenching upon binding to calf thymus DNA. This study could improve the understanding of the mode of binding of small molecules loaded on magnetic nanoparticles to DNA.