PSF Distortion in Dye–Plasmonic Nanomaterial Interactions: Friend or Foe?

Abstract

Plasmonic nanostructures offer promising applications as nanocatalysts, but optimizing their structure−function relationship using optical superlocalization techniques is hindered by the formation of distorted point spread functions (PSFs). Previously reported localization bias for remotely excited Alexa-647 adsorbed to Ag nanowires is investigated here for its potential to provide useful information about surface interactions. Two main classes of abnormal PSFs are examined: single-lobed PSFs, in which the localization bias arises from various emitter positions around the nanowire, and bilobed PSFs arising from emitters near the top edge of the nanowire. The amount of localization bias for these two populations diverges for ground truth widths less than 300 nm and suggests the latter adsorption and resulting orientation arise more frequently under experimental conditions than is predicted by simulation. Nanowires with widths in the range of 200 to 300 nm are found to have the greatest potential for distinguishing between single-lobed and bilobed PSFs in experiment. Finally, we present a fitting method for abnormal PSFs using a basis of Hermite−Gaussian functions and show that orientation information is encoded in bilobed PSFs.

Imaging and Localization of Single Emitters near Plasmonic Particles of Different Size, Shape, and Material

“…Furthermore, by fixing the orientation of the emitter, not only the effect of emitter location but also orientation could be studied to reveal polarization-dependent properties that are usually lost due to orientation averaging. Ideally, multimodal imaging may enable the collection of emission intensity, PSF shape, 17 fluorescence lifetime, 29 emission polarization, 42 and single-molecule spectra 43 to obtain a complete picture of particle–emitter coupling. Such experiments will shed light on the effect of a 3D photonic environment on optical imaging and will extend the realm of super-resolution microscopy to nano- and micrometer-sized colloids.…”

“… 19 In some studies mislocalization was observed as a dominant effect, 16 , 18 − 22 other studies reported it to be negligible compared to the localization precision of the microscope, 4 , 35 and some studies reported exotic multilobed PSFs. 15 , 17 The variation in reported effects has its root largely in the different particle size, shape, and material used as well as the particle–emitter spacing and spectral detuning.…”

Super-resolution imaging: when biophysics meets nanophotonics

“…[136]. (b) Baiyasi et al [139] provide clear observation of the dramatic change of PSFs for emitters near a nanostructure. Instead of simple Gaussian-like PSFs this includes multi-lobed PSFs.…”

“…Numerical simulations reproduced these measured systematic artifacts. The significant shape changes of the PSF near nanostructures were thoroughly studied in the specific case of a silver nanowire in [138] and subsequently used by Baiyasi et al [139] to associate the measured PSF to a specific orientation of the dipole moment. Figure 7b illustrates this effect.…”

Probing Biosensing Interfaces With Single Molecule Localization Microscopy (SMLM)

“…The second is that it could produce significant signal enhancement which leads to higher localization precision, and is hence preferred. Hence, whether in this context, working with plasmonic metal is necessary or not is yet to be determined (Baiyasi et al, 2019 ).…”