14 research outputs found
Optical Injection of Gold Nanoparticles into Living Cells
The controlled injection
of nanoscopic objects into living cells with light offers promising
prospects for the development of novel molecular delivery strategies
or intracellular biosensor applications. Here, we show that single
gold nanoparticles from solution can be patterned on the surface of
living cells with a continuous wave laser beam. In a second step,
we demonstrate how the same particles can then be injected into the
cells through a combination of plasmonic heating and optical force.
We find that short exposure times are sufficient to perforate the
cell membrane and inject the particles into cells with a survival
rate of >70%
Nanoscale Obstacle Arrays Frustrate Transport of EphA2–Ephrin-A1 Clusters in Cancer Cell Lines
Juxtacrine signaling interactions
between the EphA2 receptor tyrosine
kinase and its ephrin-A1 ligand contribute to healthy tissue maintenance
and misregulation of this system is observed in at least 40% of human
breast cancer. Hybrid live cell–supported membrane experiments
in which membrane-linked ephrin-A1 displayed in supported membranes
interacts with EphA2 in living cells have revealed large scale clustering
of EphA2/ephrin-A1 complexes as well as their lateral transport across
the cell surface during triggering. Here, we utilize 100 nm spaced
hexagonally ordered arrays of gold nanodots embedded within supported
membranes to present defined obstacles to the movement and assembly
of EphA2 clusters. By functionalizing both the supported membrane
and the nanodots with ephrin-A1, we perform a type of affinity chromatography
on EphA2 signaling clusters in live cell membranes. Analysis of 10
different breast cancer cell lines reveals that EphA2 transport is
most frustrated by nanodot arrays in the most diseased cell lines.
These observations suggest that strong physical association among
EphA2 receptors, as well as their assembly into larger clusters, correlates
with and may contribute to the pathological misregulation of the EphA2/ephrin-A1
pathway in breast cancer
Plasmonic Nanoantenna Arrays for Surface-Enhanced Raman Spectroscopy of Lipid Molecules Embedded in a Bilayer Membrane
We demonstrate a strategy for surface-enhanced
Raman spectroscopy (SERS) of supported lipid membranes with arrays
of plasmonic nanoantennas. Colloidal lithography refined with plasma
etching is used to synthesize arrays of triangular shaped gold nanoparticles.
Reducing the separation distance between the triangle tips leads to
plasmonic coupling and to a strong enhancement of the electromagnetic
field in the nanotriangle gap. As a result, the Raman scattering intensity
of molecules that are located at this plasmonic “hot-spot”
can be increased by several orders of magnitude. The nanoantenna array
is then embedded with a supported phospholipid membrane which is fluid
at room temperature and spans the antenna gap. This configuration
offers the advantage that molecules that are mobile within the bilayer
membrane can enter the “hot-spot” region via diffusion
and can therefore be measured by SERS without static entrapment or
adsorption of the molecules to the antenna itself
Nanolithography by Plasmonic Heating and Optical Manipulation of Gold Nanoparticles
Noble-metal particles feature intriguing optical properties, which can be utilized to manipulate them by means of light. Light absorbed by gold nanoparticles, for example, is very efficiently converted into heat, and single particles can thus be used as a fine tool to apply heat to a nanoscopic area. At the same time, gold nanoparticles are subject to optical forces when they are irradiated with a focused laser beam, which renders it possible to print, manipulate, and optically trap them in two and three dimensions. Here, we demonstrate how these properties can be used to control the polymerization reaction and thermal curing of polydimethylsiloxane (PDMS) at the nanoscale and how these findings can be applied to synthesize polymer nanostructures such as particles and nanowires with subdiffraction limited resolution
Bending Gold Nanorods with Light
V-shaped
gold nanoantennas are the functional components of plasmonic
metasurfaces, which are capable of manipulating light in unprecedented
ways. Designing a metasurface requires the custom arrangement of individual
antennas with controlled shape and orientation. Here, we show how
highly crystalline gold nanorods in solution can be bent, one-by-one,
into a V-shaped geometry and printed to the surface of a solid support
through a combination of plasmonic heating and optical force. Significantly,
we demonstrate that both the bending angle and the orientation of
each rod-antenna can be adjusted independent from each other by tuning
the laser intensity and polarization. This approach is applicable
for the patterning of V-shaped plasmonic antennas on almost any substrate,
which holds great potential for the fabrication of ultrathin optical
components and devices
Postsynthetic Photocontrol of Giant Liposomes via Fusion-Based Photolipid Doping
We report on photolipid
doping of giant unilamellar vesicles
(GUVs) via vesicle fusion with small unilamellar
photolipid vesicles
(pSUVs), which enables retroactive optical control of the membrane
properties. We observe that vesicle fusion is light-dependent, if
the phospholipids are neutral. Charge-mediated fusion involving anionic
and cationic lipid molecules augments the overall fusion performance
and doping efficiency, even in the absence of light exposure. Using
phosphatidylcholine analogs with one or two azobenzene photoswitches
(azo-PC and dazo-PC) affects domain formation, bending stiffness, and
shape of the resulting vesicles in response to irradiation. Moreover,
we show that optical membrane control can be extended to long wavelengths
using red-absorbing photolipids (red-azo-PC). Combined, our findings present
an attractive and practical method for the precise delivery of photolipids,
which offers new prospects for the optical control of membrane function
Postsynthetic Photocontrol of Giant Liposomes via Fusion-Based Photolipid Doping
We report on photolipid
doping of giant unilamellar vesicles
(GUVs) via vesicle fusion with small unilamellar
photolipid vesicles
(pSUVs), which enables retroactive optical control of the membrane
properties. We observe that vesicle fusion is light-dependent, if
the phospholipids are neutral. Charge-mediated fusion involving anionic
and cationic lipid molecules augments the overall fusion performance
and doping efficiency, even in the absence of light exposure. Using
phosphatidylcholine analogs with one or two azobenzene photoswitches
(azo-PC and dazo-PC) affects domain formation, bending stiffness, and
shape of the resulting vesicles in response to irradiation. Moreover,
we show that optical membrane control can be extended to long wavelengths
using red-absorbing photolipids (red-azo-PC). Combined, our findings present
an attractive and practical method for the precise delivery of photolipids,
which offers new prospects for the optical control of membrane function
Postsynthetic Photocontrol of Giant Liposomes via Fusion-Based Photolipid Doping
We report on photolipid
doping of giant unilamellar vesicles
(GUVs) via vesicle fusion with small unilamellar
photolipid vesicles
(pSUVs), which enables retroactive optical control of the membrane
properties. We observe that vesicle fusion is light-dependent, if
the phospholipids are neutral. Charge-mediated fusion involving anionic
and cationic lipid molecules augments the overall fusion performance
and doping efficiency, even in the absence of light exposure. Using
phosphatidylcholine analogs with one or two azobenzene photoswitches
(azo-PC and dazo-PC) affects domain formation, bending stiffness, and
shape of the resulting vesicles in response to irradiation. Moreover,
we show that optical membrane control can be extended to long wavelengths
using red-absorbing photolipids (red-azo-PC). Combined, our findings present
an attractive and practical method for the precise delivery of photolipids,
which offers new prospects for the optical control of membrane function
Postsynthetic Photocontrol of Giant Liposomes via Fusion-Based Photolipid Doping
We report on photolipid
doping of giant unilamellar vesicles
(GUVs) via vesicle fusion with small unilamellar
photolipid vesicles
(pSUVs), which enables retroactive optical control of the membrane
properties. We observe that vesicle fusion is light-dependent, if
the phospholipids are neutral. Charge-mediated fusion involving anionic
and cationic lipid molecules augments the overall fusion performance
and doping efficiency, even in the absence of light exposure. Using
phosphatidylcholine analogs with one or two azobenzene photoswitches
(azo-PC and dazo-PC) affects domain formation, bending stiffness, and
shape of the resulting vesicles in response to irradiation. Moreover,
we show that optical membrane control can be extended to long wavelengths
using red-absorbing photolipids (red-azo-PC). Combined, our findings present
an attractive and practical method for the precise delivery of photolipids,
which offers new prospects for the optical control of membrane function
Postsynthetic Photocontrol of Giant Liposomes via Fusion-Based Photolipid Doping
We report on photolipid
doping of giant unilamellar vesicles
(GUVs) via vesicle fusion with small unilamellar
photolipid vesicles
(pSUVs), which enables retroactive optical control of the membrane
properties. We observe that vesicle fusion is light-dependent, if
the phospholipids are neutral. Charge-mediated fusion involving anionic
and cationic lipid molecules augments the overall fusion performance
and doping efficiency, even in the absence of light exposure. Using
phosphatidylcholine analogs with one or two azobenzene photoswitches
(azo-PC and dazo-PC) affects domain formation, bending stiffness, and
shape of the resulting vesicles in response to irradiation. Moreover,
we show that optical membrane control can be extended to long wavelengths
using red-absorbing photolipids (red-azo-PC). Combined, our findings present
an attractive and practical method for the precise delivery of photolipids,
which offers new prospects for the optical control of membrane function