Acridine orange coated magnetic nanoparticles for nucleus labeling and DNA adsorption

The magnetic–fluorescent nanoparticles are the integration of fluorophores and magnetic nanoparticles (MNP), which are superior to traditional single-modal nanoparticles. Here, we develop magnetic nanoparticles functionalized by acridine orange (ACO) for labeling nucleus and separating DNA. The ACO, a cell-permeant nucleic acid binding dye, is conjugated with amine on magnetic nanoparticles by glutaraldehyde-mediated coupling and characterized by TEM and FT-IR. Fluorescence spectroscopy, INCell analyzer, and confocal microscopy analyses confirmed the fluorescent property of ACO modified MNP. Furthermore, the modified magnetic nanoparticles showed strong intracellular fluorescence when incubated with 293T cells for a short period of time. The adsorption capacities measured at various concentrations showed enhanced adsorption capacities for double or single stranded DNA when compared to amine MNP conjugated with glutaraldehyde. The cell viability tests of the composite nanoparticles on 293T cells showed low cytotoxicity indicating the safeness of the nanoparticles. The modified magnetic nanoparticles pave a versatile platform for biological applications such as cell labeling and DNA adsorption.