Abstract:

Surface Plasmon Resonance (SPR) and other evanescent wave techniques are widely used in materials and life sciences to study activity at or very near interfaces. However, current SPR instrumentation is not sufficiently sensitive for demanding applications such as small-molecule binding, and compromises imaging capability for sensitivity. In this talk I will describe a novel type of imaging SPR sensor. The static light source used in imaging SPR sensors was replaced by a tunable laser capable of sweeping an arbitrary wavelength range between 1480 and 1640 nm at a rate of 80 nm/s. Sweeping this laser allowed the reflectivity of an SPR to be measured as a function of wavelength.  In contrast, existing imaging SPR sensors are limited to measuring the reflectivity at just one wavelength.  Using a photodiode array, the baseline root-mean-squared (RMS) noise was approximately 2x10^-8 refractive index units (RIU) for a 2 mm² sample region.  A similar baseline noise level was observed using a 320 x 240 pixel InGaAs camera as the detector.

Long wavelength SPR also enables the study diffusion and adsorption of polymers and biomolecules in relatively thick (ca >600nm) nanoporous materials. I will describe the transition from high surface area (open pore) to low surface area (blocked pores) of a nanoporous silica film by the adsorption of polylectrolytes of alternating charge.