Grating-based surface plasmon resonance detection of core-shell nanoparticle mediated DNA hybridization

► We investigate enhanced surface plasmon resonance detection of DNA hybridization. ► We used gold core-silica shell particles in plasmon fields created by gratings. ► Core-shell nanoparticles enhanced by 36 times over conventional SPR detection. ► The enhancement is associated with increased surface area and index contrast. ► The combined approach is expected to lower the LOD to the order of 10 fg/mm 2. In this report, we have investigated enhanced surface plasmon resonance (SPR) detection of DNA hybridization using gold core – silica shell nanoparticles in localized plasmonic fields. The plasmonic fields were localized by periodic linear gratings. Experimental results measured for hybridization of 24-mer single-stranded DNA oligomers suggest that core-shell nanoparticles (CSNPs) on gratings of 400 nm period provide enhanced optical signatures by 36 times over conventional thin film-based SPR detection. CSNP-mediated DNA hybridization produced 3 times larger angular shift compared to gold nanoparticles of the same core size. We have also analyzed the effect of structural variation. The enhancement using CSNPs was associated with increased surface area and index contrast that is combined by improved plasmon coupling with localized fields on gratings. The combined approach for conjugated measurement of a biomolecular interaction on grating structures is expected to lower the limit of detection to the order of a few tens of fg/mm 2.