We report a large amplification of surface plasmon signals for a double hybridization microarray chip assembly that bridges localized gold and detection probe-carrying-core/shell Fe3O4@Au nanoparticles for detection of as low as 80 aM miRNA-155 marker in solution. The plasmonic wavelength match of the gold shell with surface localized gold nanoparticles and the additional scattering band of the core/shell material in resonance with the incident 800 nm light source are the underlying factors for the observed remarkable analyte signal at ultra-low (10-18 order) concentrations.