7 research outputs found
Supplement 1: Subnanometer-accuracy optical distance ruler based on fluorescence quenching by transparent conductors
Supplemental document Originally published in Optica on 20 February 2016 (optica-3-2-112
Nanoscale Imaging of Light-Matter Coupling Inside Metal-Coated Cavities with a Pulsed Electron Beam
Many
applications in (quantum) nanophotonics rely on controlling
light-matter interaction through strong, nanoscale modification of
the local density of states (LDOS). All-optical techniques probing
emission dynamics in active media are commonly used to measure the
LDOS and benchmark experimental performance against theoretical predictions.
However, metal coatings needed to obtain strong LDOS modifications
in, for instance, nanocavities, are incompatible with all-optical
characterization. So far, no reliable method exists to validate theoretical
predictions. Here, we use subnanosecond pulses of focused electrons
to penetrate the metal and excite a buried active medium at precisely
defined locations inside subwavelength resonant nanocavities. We reveal
the spatial layout of the spontaneous-emission decay dynamics inside
the cavities with deep-subwavelength detail, directly mapping the
LDOS. We show that emission enhancement converts to inhibition despite
an increased number of modes, emphasizing the critical role of optimal
emitter location. Our approach yields fundamental insight in dynamics
at deep-subwavelength scales for a wide range of nano-optical systems
Electron Microscopy of Living Cells During <i>in Situ</i> Fluorescence Microscopy
We present an approach toward dynamic
nanoimaging: live fluorescence
of cells encapsulated in a bionanoreactor is complemented with <i>in situ</i> scanning electron microscopy (SEM) on an integrated
microscope. This allows us to take SEM snapshots on-demand, that is,
at a specific location in time, at a desired region of interest, guided
by the dynamic fluorescence imaging. We show that this approach enables
direct visualization, with EM resolution, of the distribution of bioconjugated
quantum dots on cellular extensions during uptake and internalization
Selective Functionalization of Tailored Nanostructures
The controlled positioning of nanostructures with active molecular components is of importance throughout nanoscience and nanotechnology. We present a novel three-step method to produce nanostructures that are selectively decorated with functional molecules. We use fluorophores and nanoparticles to functionalize SiO features with defined shapes and with sizes ranging from micrometers to 25 nm. The method is called MACE-ID: molecular assembly controlled by electron-beam-induced deposition. In the first step, SiO nanostructures are written with focused electron-beam-induced deposition, a direct-writing technique. In the second step, the deposits are selectively silanized. In the final step, the silanes are functionalized with fluorescent dyes, polystyrene spheres, or gold nanoparticles. This recipe gives exciting new possibilities for combining the highly accurate control of top-down patterning (e-beam direct writing) with the rich variety of the bottom-up approach (self-assembly), leading to active or responsive surfaces. An important advantage of MACE-ID is that it can be used on substrates that already contain complex features, such as plasmonic structures, nanoantennas, and cavities
SCLEM of whole uncoated cells.
<p>(a) FM image of three adenocarcinoma cells actin labeled with Alexa488. The three cells are connected via tentacles and larger extrusions. Scalebar 5 µm. (b) SEM image of the boxed area in (a), showing detailed information on the connections between the cells. A dense network of tentacles and lamellae stretches between the upper and the right cell. Scalebar 3 µm(c) FM image of an extension connecting another two adenocarcinoma cells. Clear variations in actin concentration along the extrusion can be observed. (b) BSE image of the extrusion in (a). Red arrows mark areas with increased concentration of tentacles that occur before and after the thinner parts of the extrusion. Scale bar is 10 µm. (d, e) SE and BSE high-magnification images of the boxed areas in (b) showing a region rich in tentacles and small lamellar extrusions. Scale bars are 2 µm. (f) Fluorescence intensity profiles, normalized on the maximum, taken along the red and blue lines in (a). (g) Normalized SE intensity profile taken at the corresponding locations marked in (c).</p
SCLEM on FM and EM stained tissue sections.
<p>(a) FM image of human skin tissue stained with DiIC18 fluorescence and uranyl acetate and osmium tetroxide for EM contrast. Scalebar 5 µm (b) BSE image of a selected region from (a), showing a cell nucleus not discernible in (a) (marked with a red arrow), and bundles of longitudinally and transversally cut collagen fibers. Scalebar is 5 µm (c, d) High-magnification images of the areas marked with (c) a red star, scalebar 1 µm, and (d) a yellow star, scalebar 2 µm.</p
Simultaneous Correlative Light and Electron Microscopy.
<p>(a) schematic lay-out for SCLEM, BSE: backscattered electrons, SE: secondary electrons, ETD: Everhard-Thornley detector, LED: light emitting diode, CCD: charge coupled device camera. (b) inside view of the integrated microscope for SCLEM showing optical objective lens in epi-configuration underneath sample holder and electron lens.</p