Metal-enhanced fluorescence of nano-core–shell structure used for sensitive detection of prion protein with a dual-aptamer strategy

•We report a solution-based MEF sensing platform.•Metallic surface-dye distance is controlled by changing the thickness of silica shell.•Dual-aptamer was involved to recognize distinct binding epitopes of the same target.•Ag@Si NPs was used as an excellent probe for darkfield light scattering imaging.

Metal-enhanced fluorescence (MEF) as a newly recognized technology is widespread throughout biological research. The use of fluorophore–metal interactions is recognized to be able to alleviate some of fluorophore photophysical constraints, favorably increase both the fluorophore emission intensity and photostability. In this contribution, we developed a novel metal-enhanced fluorescence (MEF) and dual-aptamer-based strategy to achieve the prion detection in solution and intracellular protein imaging simultaneously, which shows high promise for nanostructure-based biosensing. In the presence of prion protein, core–shell Ag@SiO2, which are functionalized covalently by single stranded aptamer (Apt1) of prions and Cyanine 3 (Cy3) decorated the other aptamer (Apt2) were coupled together by the specific interaction between prions and the anti-prion aptamers in solution. By adjusting shell thickness of the pariticles, a dual-aptamer strategy combined MEF can be realized by the excitation and/or emission rates of Cy3. It was found that the enhanced fluorescence intensities followed a linear relationship in the range of 0.05–0.30 nM, which is successfully applied to the detection of PrP in mice brain homogenates.

Graphical abstractMetal-enhanced fluorescence of core–shell structure of Ag@Si NPs was proposed for the detection and cellular imaging of prion protein with a dual aptamer strategy, which shows high promise for nanostructure-based biosensing.Figure optionsDownload full-size imageDownload as PowerPoint slide