Target-Localized Nanograting-Based Surface Plasmon Resonance Detection toward Label-free Molecular Biosensing

We explore the sensitivity enhancement of label-free detection based on localized surface plasmon resonance using surface-relief nanograting structures. A nanograting structure was modeled, so that target molecular interactions are localized in hot spots of the near fields. The nanograting structure was optimized numerically for the highest enhancement of sensitivity with hybridization between complementary strands of DNA as the model target interaction. Experimentally, angled evaporation was performed to fabricate the target-localized nanograting samples. Measured data confirm the numerical results that sensitivity enhancement by an order of magnitude may be feasible on a per-unit-volume basis through target localization.