Quantitative Angle-Resolved SPR Imaging of DNA−DNA and DNA−Drug Kinetics

We demonstrate the quantitative characterization of DNA-DNA and DNA-drug interactions by angle-resolved surface plasmon resonance (SPR) imaging. Combining the angle-scanning capabilities of traditional SPR with the spatial definition capabilities of imaging, we directly measure DNA and drug surface coverages and kinetics simultaneously for multiple patterned spots. We find excellent agreement of DNA-DNA hybridization kinetics and thermodynamics measured by both the imaging system and traditional SPR. Instrument response and sensitivity is further demonstrated by successful measurement of association and dissociation kinetics of actinomycin-D binding to a low-density doubled-stranded DNA binding sequence. Without independent calibration, analysis of angle-resolved SPR imaging data yields 2.9 +/- 0.1 drugs per duplex at saturation coverage, consistent with all available duplex binding sites being occupied.