Polyethylenimine-coated Fe₃O₄ nanoparticles effectively quench fluorescent DNA, which can be developed as a novel platform for protein detection

We report a novel assembly of polyethyleneimine (PEI)-coated Fe3O4 nanoparticles (NPs) with single-stranded DNA (ssDNA), and the fluorescence of the dye labeled in the DNA is remarkably quenched. In the presence of a target protein, the protein-DNA aptamer mutual interaction releases the ssDNA from this assembly and hence restores the fluorescence. This feature could be adopted to develop an aptasensor for protein detection. As a...