scholarly journals Photon count estimation in single-molecule localization microscopy

2018 ◽  
Author(s):  
Rasmus Ø. Thorsen ◽  
Christiaan N. Hulleman ◽  
Mathias Hammer ◽  
David Grünwald ◽  
Sjoerd Stallinga ◽  
...  

Recently, Franke, Sauer and van de Linde1 introduced a way to estimate the axial position of single-molecules (TRABI). To this end, they compared the detected photon count from a temporal radial-aperture-based intensity estimation to the estimated count from Gaussian point-spread function (PSF) fitting to the data. Empirically they found this photometric ratio to be around 0.7-0.8 close to focus and decreasing away from it. Here, we explain this reported but unexplained discrepancy and furthermore show that the photometric ratio as indicator for axial position is susceptible even to typical optical aberrations.

2018 ◽  
Author(s):  
Taehwan Kim ◽  
Seonah Moon ◽  
Ke Xu

While current single-molecule localization microscopy (SMLM) methods often rely on the target-specific alteration of the point spread function (PSF) to encode the multidimensional contents of single fluorophores, we argue that the details of the PSF in an unmodified microscope already contain rich, multidimensional information. We introduce a data-driven approach in which artificial neural networks (ANNs) are trained to make a direct link between an experimental PSF image and its underlying parameters. To demonstrate this concept in real systems, we decipher in fixed cells both the colors and the axial positions of single molecules in regular SMLM data.


2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Alan M. Szalai ◽  
Bruno Siarry ◽  
Jerónimo Lukin ◽  
David J. Williamson ◽  
Nicolás Unsain ◽  
...  

AbstractSingle-molecule localization microscopy enables far-field imaging with lateral resolution in the range of 10 to 20 nanometres, exploiting the fact that the centre position of a single-molecule’s image can be determined with much higher accuracy than the size of that image itself. However, attaining the same level of resolution in the axial (third) dimension remains challenging. Here, we present Supercritical Illumination Microscopy Photometric z-Localization with Enhanced Resolution (SIMPLER), a photometric method to decode the axial position of single molecules in a total internal reflection fluorescence microscope. SIMPLER requires no hardware modification whatsoever to a conventional total internal reflection fluorescence microscope and complements any 2D single-molecule localization microscopy method to deliver 3D images with nearly isotropic nanometric resolution. Performance examples include SIMPLER-direct stochastic optical reconstruction microscopy images of the nuclear pore complex with sub-20 nm axial localization precision and visualization of microtubule cross-sections through SIMPLER-DNA points accumulation for imaging in nanoscale topography with sub-10 nm axial localization precision.


2018 ◽  
Author(s):  
Ting Yan ◽  
Charles J. Richardson ◽  
Mingxing Zhang ◽  
Andreas Gahlmann

3D single-molecule localization microscopy relies on fitting the shape of point-spread-functions (PSFs) recorded on a wide-field detector. However, optical aberrations distort those shapes, which compromise the accuracy and precision of single-molecule localization microscopy. Here we employ a computational phase retrieval based on a vectorial PSF model to quantify the spatially-variance of optical aberrations in a two-channel ultrawide-field single-molecule localization microscope. The use of a spatially-variant PSF model enables accurate and precise emitter localization in x, y- and z- directions throughout the entire field-of-view.


2020 ◽  
Author(s):  
Koen J.A. Martens ◽  
Abbas Jabermoradi ◽  
Suyeon Yang ◽  
Johannes Hohlbein

The point spread function (PSF) of single molecule emitters can be engineered in the Fourier plane to encode three-dimensional localization information, creating double-helix, saddle-point or tetra-pod PSFs. Here, we describe and assess adaptations of the phasor-based single-molecule localization microscopy (pSMLM) algorithm to localize single molecules using these PSFs with sub-pixel accuracy. For double-helix, pSMLM identifies the two individual lobes and uses their relative rotation for obtaining z-resolved localizations, while for saddle-point or tetra-pod, a novel phasor-based deconvolution approach is used. The pSMLM software package delivers similar precision and recall rates to the best-in-class software package (SMAP) at signal-to-noise ratios typical for organic fluorophores. pSMLM substantially improves the localization rate by a factor of 2 - 4x on a standard CPU, with 1-1.5·104 (double-helix) or 2.5·105 (saddle-point/tetra-pod) localizations/second.


2020 ◽  
Author(s):  
Christiaan N. Hulleman ◽  
Rasmus Ø. Thorsen ◽  
Sjoerd Stallinga ◽  
Bernd Rieger

We have developed an engineered Point Spread Function (PSF) to enable the simultaneous estimation of dipole orientation, 3D position and degree of rotational constraint of single-molecule emitters from a single 2D focal plane. Besides giving access to orientation information, the Vortex PSF along with the vectorial PSF fitter avoids localization bias common in localization microscopy for fixed dipole emitters. We demonstrate this technique on reorienting single-molecules and using binding-activated localization microscopy on DNA intercalators, corroborating perpendicular azimuthal angles to the DNA axis for in-plane emitters but find a non-uniform distribution as a function of the polar angle. The Vortex PSF is realized by an affordable glass phase mask and has a compact footprint that can easily be combined with localization microscopy techniques on rotationally constrained emitters.


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