38 research outputs found
Three-Dimensional Orientation Determination of Stationary Anisotropic Nanoparticles with Sub-Degree Precision under Total Internal Reflection Scattering Microscopy
Single-particle
and single-molecule orientation determination plays
a vital role in deciphering nanoscale motion in complex environments.
Previous attempts to determine the absolute three-dimensional orientation
of anisotropic particles rely on subjective pattern matching and are
inherently plagued by high degrees of uncertainty. Herein, we describe
a method utilizing total internal reflection scattering microscopy
to determine the 3D orientation of gold nanorods with subdegree uncertainty.
The method is then applied to the biologically relevant system of
microtubule cargo loading. Finally, we demonstrate the method holds
potential for identifying single particles versus proximate neighbors
within the diffraction limited area
Simultaneous Single-Particle Superlocalization and Rotational Tracking
Superlocalization of single molecules and nanoparticles has become an essential procedure to bring new insights into nanoscale structures and dynamics of biological systems. In the present study, superlocalization is combined with the newly introduced differential interference contrast (DIC) microscopy-based single-particle orientation and rotational tracking. The new technique overcomes the difficulty in localization of the antisymmetric DIC point spread function by using a dual-modality microscope configuration for simultaneous rotational tracking and localization of single gold nanorods with nanometer-scale precision. The new imaging setup has been applied to study the steric hindrance induced by relatively large cargos in the microtubule gliding assay and to track nanocargos in the crowded cellular environment. This technique has great potential in the study of biological processes where both localization and rotational information are required
Simultaneous Single-Particle Superlocalization and Rotational Tracking
Superlocalization of single molecules and nanoparticles has become an essential procedure to bring new insights into nanoscale structures and dynamics of biological systems. In the present study, superlocalization is combined with the newly introduced differential interference contrast (DIC) microscopy-based single-particle orientation and rotational tracking. The new technique overcomes the difficulty in localization of the antisymmetric DIC point spread function by using a dual-modality microscope configuration for simultaneous rotational tracking and localization of single gold nanorods with nanometer-scale precision. The new imaging setup has been applied to study the steric hindrance induced by relatively large cargos in the microtubule gliding assay and to track nanocargos in the crowded cellular environment. This technique has great potential in the study of biological processes where both localization and rotational information are required
Simultaneous Single-Particle Superlocalization and Rotational Tracking
Superlocalization of single molecules and nanoparticles has become an essential procedure to bring new insights into nanoscale structures and dynamics of biological systems. In the present study, superlocalization is combined with the newly introduced differential interference contrast (DIC) microscopy-based single-particle orientation and rotational tracking. The new technique overcomes the difficulty in localization of the antisymmetric DIC point spread function by using a dual-modality microscope configuration for simultaneous rotational tracking and localization of single gold nanorods with nanometer-scale precision. The new imaging setup has been applied to study the steric hindrance induced by relatively large cargos in the microtubule gliding assay and to track nanocargos in the crowded cellular environment. This technique has great potential in the study of biological processes where both localization and rotational information are required
Three-Dimensional High-Resolution Rotational Tracking with Superlocalization Reveals Conformations of Surface-Bound Anisotropic Nanoparticles
The ability to directly follow three-dimensional rotational
movement
of anisotropic nanoparticles will greatly enhance our understanding
of the way nanoparticles interact with surfaces. Herein, we demonstrate
dual-color total internal reflection scattering microscopy as a tool
to probe the interactions of plasmonic gold nanorods with functional
surfaces. By taking advantage of both the short and long axis surface
plasmon resonance scattering enhancement, we are able to decipher
both in-plane and out-of-plane gold nanorod motion relative to the
sample surface with equally high resolution. In combination with superlocalization
through point spread function fitting, we overcome the four-quadrant
angular degeneracy of gold nanorods in the focal plane of the objective
and resolve conformations of surface-bound anisotropic nanoparticles
in unprecedented detail
Focused Orientation and Position Imaging (FOPI) of Single Anisotropic Plasmonic Nanoparticles by Total Internal Reflection Scattering Microscopy
The defocused orientation and position imaging (DOPI)
and polarization-based
in-focus imaging techniques have been widely used for detecting rotational
motions with anisotropic gold nanorods (AuNRs) as orientation probes.
However, these techniques have a number of significant limitations,
such as the greatly reduced signal intensity and relatively low spatial
and temporal resolutions for out-of-focus AuNRs and the angular degeneracy
for in-focus AuNRs. Herein, we present a total internal reflection
(TIR) scattering-based focused orientation and position imaging (FOPI)
of AuNRs supported on a 50 nm thick gold film, which enables us to
overcome the aforementioned limitations. Imaging AuNRs under the TIR
scattering microscope provides excellent signal-to-noise ratio and
results in no deteriorating images. The scattering patterns of AuNRs
on the gold substrate are affected by the strong interaction of the
excited dipole in the AuNR with the image dipole in the gold substrate.
The doughnut-shaped scattering field distribution allows for high-throughput
determination of the three-dimensional spatial orientation of in-focus
AuNRs within a single frame without angular degeneracy. Therefore,
the TIR scattering-based FOPI method is demonstrated to be an outstanding
candidate for studying dynamics of functionalized nanoparticles on
a large variety of functional surfaces
Three-Dimensional High-Resolution Rotational Tracking with Superlocalization Reveals Conformations of Surface-Bound Anisotropic Nanoparticles
The ability to directly follow three-dimensional rotational
movement
of anisotropic nanoparticles will greatly enhance our understanding
of the way nanoparticles interact with surfaces. Herein, we demonstrate
dual-color total internal reflection scattering microscopy as a tool
to probe the interactions of plasmonic gold nanorods with functional
surfaces. By taking advantage of both the short and long axis surface
plasmon resonance scattering enhancement, we are able to decipher
both in-plane and out-of-plane gold nanorod motion relative to the
sample surface with equally high resolution. In combination with superlocalization
through point spread function fitting, we overcome the four-quadrant
angular degeneracy of gold nanorods in the focal plane of the objective
and resolve conformations of surface-bound anisotropic nanoparticles
in unprecedented detail
Dual-Wavelength Detection of Rotational Diffusion of Single Anisotropic Nanocarriers on Live Cell Membranes
Single-particle rotational tracking is of great importance
to monitor
orientation changes of biomolecules and to understand their functions
and mechanisms in biological systems. Differential interference contrast
(DIC) microscopy has been found to be an excellent tool to measure
polarization anisotropy for tracking rotational dynamics of gold nanorod
(AuNR) probes. DIC polarization anisotropy can be conveniently obtained
from the bright and dark intensities of a single DIC image of an AuNR.
Here, DIC microscopy-based dual-wavelength detection of rotational
motions of AuNRs at both transverse and longitudinal surface plasmon
resonance (SPR) wavelengths is demonstrated. The transverse SPR mode
was successfully used to track fast rotational dynamics of individual
AuNRs on live cell membranes. This is important since the transverse
SPR mode is mostly insensitive to the medium refractive index, AuNR
aspect ratio, and adsorption of biomolecules. DIC polarization anisotropy
was simultaneously obtained from the two SPR wavelengths during the
dynamic process. Both wavelengths showed good agreement and provided
accurate and reliable measurement of AuNR orientation
Detecting Plasmon Resonance Energy Transfer with Differential Interference Contrast Microscopy
Gold nanoparticles are ideal probes
for studying intracellular
environments and energy transfer mechanisms due to their plasmonic
properties. Plasmon resonance energy transfer (PRET) relies on a plasmonic
nanoparticle to donate energy to a nearby resonant acceptor molecule,
a process which can be observed due to the plasmonic quenching of
the donor nanoparticle. In this study, a gold nanosphere was used
as the plasmonic donor, while the metalloprotein cytochrome c was
used as the acceptor molecule. Differential interference contrast
(DIC) microscopy allows for simultaneous monitoring of complex environments
and noble metal nanoparticles in real time. Using DIC and specially
designed microfluidic channels, we were able to monitor PRET at the
single gold particle level and observe the reversibility of PRET upon
the introduction of phosphate-buffered saline to the channel. In an
additional experiment, single gold particles were internalized by
HeLa cells and were subsequently observed undergoing PRET as the cell
hosts underwent morphological changes brought about by ethanol-induced
apoptosis
Plasmonic Behavior of Single Gold Dumbbells and Simple Dumbbell Geometries
Dumbbell-shaped
nanoparticles are similar in size to their nanorod
counterparts, but their optical properties have not been studied as
extensively as the nanorod. In this paper, the spectra of a single
dumbbell, several dumbbell dimers, and a pentamer were collected experimentally
and compared with simulated spectra. Surface charge density plots
were also obtained in order to elucidate the nature of the plasmonic
modes. The dumbbell is shown to be a particle that acts as a transition
from the nanorod to the nanosphere. Because the dumbbell shape allows
adjacent particles to interlock like puzzle pieces, dumbbells can
be thought of as optical building blocks that can combine into designs
that are capable of supporting localized hot spots, Fano resonance,
and tunable plasmon peaks