Abstract
Surface plasmon resonance (SPR) imaging is a powerful technique for high-throughput, real-time, label-free characterization of molecular interactions in a microarray format. In this paper, we demonstrate SPR imaging with nanohole arrays illuminated by a laser source. Periodic nanoholes couple incident photons into SPs, obviating the need for the prism used in conventional SPR instruments, while a laser source provides the intensity, stability and spectral coherence to improve the detection sensitivity. The formation of a self-assembled monolayer of alkanethiolates on gold changed the laser transmission by more than 35%, and binding kinetics were measured in parallel from a 5 x 3 microarray of nanohole sensors. These results demonstrate the potential of nanohole sensors for high-throughput SPR imaging on microarrays.
Highlights
Surface plasmon resonance (SPR) sensing is the gold standard for measuring the binding kinetics of biomolecules [1]
In conventional SPR instruments, e.g. BIAcoreTM, a convergent light cone illuminates the detection spot via prism coupling in a total internal reflection mode, known as the Kretschmann configuration, and the angular distribution of the reflected light intensity is measured in real time
SPR microscopy [2,3] is one such technique with multiplex screening capability, wherein a refractive index variation across a sample surface, e.g. microarray, due to molecular binding events is translated into a contrast distribution in the reflected image that is captured by a charge coupled device (CCD) camera
Summary
Surface plasmon resonance (SPR) sensing is the gold standard for measuring the binding kinetics of biomolecules [1]. In conventional SPR instruments, e.g. BIAcoreTM, a convergent light cone illuminates the detection spot via prism coupling in a total internal reflection mode, known as the Kretschmann configuration, and the angular distribution of the reflected light intensity is measured in real time. Using this label-free approach, binding kinetics (on/off rates and equilibrium constants) can be precisely measured and the concentrations of ligands present in complex mixtures quantified. Several research groups have demonstrated SPR imaging with the Kretschmann configuration [4,5,6], but the prism coupling method results in a tilted image plane with a narrow field of view, i.e. a small array size, and prohibits the use of high numerical aperture (NA) optics and the potential for miniaturization
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