Ultrasensitive Refractometry <i>via</i> Supercritical Angle Fluorescence

Ferdman, Boris; Weiss, Lucien E.; Alalouf, Onit; Haimovich, Yonathan; Shechtman, Yoav

doi:10.1021/acsnano.8b05849

Cited by 17 publications

(24 citation statements)

References 39 publications

(53 reference statements)

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“…This means that the same PSF shape (up to a lateral scaling by the objective magnification) can be obtained using the same phase-mask pattern, with appropriate lateral scaling (see insets in Fig. 5) (44).…”

Section: Scaling Of the Depth Rangementioning

confidence: 89%

Microscopic scan-free surface profiling over extended axial ranges by point-spread-function engineering

et al. 2020

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The shape of a surface, i.e., its topography, influences many functional properties of a material; hence, characterization is critical in a wide variety of applications. Two notable challenges are profiling temporally changing structures, which requires high-speed acquisition, and capturing geometries with large axial steps. Here, we leverage point-spread-function engineering for scan-free, dynamic, microsurface profiling. The presented method is robust to axial steps and acquires full fields of view at camera-limited framerates. We present two approaches for implementation: fluorescence-based and label-free surface profiling, demonstrating the applicability to a variety of sample geometries and surface types.

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Section: Scaling Of the Depth Rangementioning

confidence: 89%

Microscopic scan-free surface profiling over extended axial ranges by point-spread-function engineering

et al. 2020

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“…Label-free RI-based SAF assay. An interesting variant of this refractometric readout is SAF detection from a fluorophore-coated glass microcapillary (63). Here, the analyte is nonfluorescent and its presence sensed indirectly via the RI change.…”

Section: Saf Applications With Aperture Filteringmentioning

confidence: 99%

“…Label-free RI-based SAF assay. An interesting variant of this refractometric readout is SAF detection from a fluorophore-coated glass microcapillary (63). Here, the analyte is nonfluorescent and the RI change induced by a medium change or -as shown by the authorsbacterial growth on the capillary bottom, is detected as a shift in rc and hence <n1>.…”

Section: Saf Refractometry Conversely With Naeff Known An Interesting...mentioning

confidence: 99%

Supercritical Angle Fluorescence Microscopy and Spectroscopy

Oheim

Salomon

Brunstein

2020

Biophysical Journal

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Fluorescence detection, either involving propagating or near-field emission, is widely being used in spectroscopy, sensing, and microscopy. Total internal reflection fluorescence (TIRF) confines fluorescence excitation by an evanescent (near) field, and it is a popular contrast generator for surface-selective fluorescence assays. Its emission equivalent, supercritical angle fluorescence (SAF), is comparably less established, although it achieves a similar optical sectioning as TIRF does. SAF emerges when a fluorescing molecule is located very close to an interface and its near-field emission couples to the higher refractive index medium (n 2 > n 1 ) and becomes propagative. Then, most fluorescence is detectable on the side of the higher-index substrate, and a large fraction of this fluorescence is emitted into angles forbidden by Snell's law. SAF, as well as the undercritical angle fluorescence (UAF; far-field emission) components, can be collected with microscope objectives having a high-enough detection aperture (numerical aperture > n 2 ) and be separated in the back focal plane by Fourier filtering. The back focal plane image encodes information about the fluorophore radiation pattern, and it can be analyzed to yield precise information about the refractive index in which the emitters are embedded, their nanometric distance from the interface, and their orientation. A SAF microscope can retrieve this near-field information through wide-field optics in a spatially resolved manner, and this functionality can be added to an existing inverted microscope. Here, we describe the potential underpinning of SAF microscopy and spectroscopy, particularly in comparison with TIRF. We review the challenges and opportunities that SAF presents from a biophysical perspective, and we discuss areas in which we see potential.

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“…Our research group will continue to pursue various directions in computational microscopy development, as well as to apply existing techniques to possible bio-medical applications; these include observing chromatin dynamics in live cells by single-particle tracking (Nehme et al 2020a, b), developing diagnostic tools for bacterial growth detection (Ferdman et al 2018), dynamic microscopic surface profiling (Gordon-Soffer et al 2020), and sensitive bio-molecule measurements.…”

Section: The Futurementioning

confidence: 99%