Subdiffraction-limited plasmonic imaging with anisotropic metal nanoparticles.

We have developed a high-resolution nonfluorescent imaging method based on superlocalization of gold nanorods (AuNRs). By taking advantage of their anisotropic optical property of the plasmonic scattering of AuNRs, selective imaging of only a fraction of AuNRs can be achieved by rotating the sample relative to the linear polarized illumination under cross-polarization microscopy with a high NA objective. The AuNR positions obtained from a series of images could then be used to reconstruct the overall image. Two AuNRs with center-to-center distances of 80 nm were successfully resolved. This simple but deterministic super-resolution imaging technique can potentially be used to fingerprint optically anisotropic metal nanoparticles and their assemblies for labeling, sensing, and encryption applications.