  We report a comparison of two photonic techniques for single-molecule
sensing: fluorescence nanoscopy and optoplasmonic sensing. As the test system,
oligonucleotides with and without fluorescent labels are transiently hybridized
to complementary docking strands attached to gold nanorods. Comparing the
measured single-molecule kinetics helps to examine the influence of fluorescent
labels as well as factors arising from different sensing geometries. Our
results demonstrate that DNA dissociation is not significantly altered by the
fluorescent label, while DNA association is affected by geometric factors in
the two techniques. These findings open the door to exploiting plasmonic
sensing and fluorescence nanoscopy in a complementary fashion, which will aid
in building more powerful sensors and uncovering the intricate effects that
influence the behavior of single molecules.

Optics;Mesoscale and Nanoscale Physics;Soft Condensed Matter;Instrumentation and Detectors