Long-range surface plasmon resonance imaging for bioaffinity sensors

A novel bioaffinity sensor based on surface plasmon resonance (SPR) imaging measurements of a multiple-layered structure that supports the generation of long-range surface plasmons (LRSPs) at the water-metal interface is reported. LRSPs possess longer surface propagation lengths, higher electric field strengths, and sharper angular resonance curves than conventional surface plasmons. LRSPR imaging is a version of SPR imaging that requires a symmetric dielectric arrangement around the gold thin film. This arrangement is created using an SF10 prism/Cytop/gold/water multilayer film structure where Cytop is an amorphous fluoropolymer with a refractive index very close to that of water. LRSPR imaging experiments are performed at a fixed incident angle and lead to an enhanced response for the detection of surface binding interactions. As an example, the hybridization adsorption of a 16-mer single-stranded DNA (ssDNA) onto a two-component ssDNA array was monitored with LRSPR imaging. The ssDNA array was created using a new fabrication technology appropriate for the LRSPR multilayers.