56 research outputs found
Photoluminescent diamond nanoparticles for cell labeling: study of the uptake mechanism in mammalian cells
Diamond nanoparticles (nanodiamonds) have been recently proposed as new
labels for cellular imaging. For small nanodiamonds (size <40 nm) resonant
laser scattering and Raman scattering cross-sections are too small to allow
single nanoparticle observation. Nanodiamonds can however be rendered
photoluminescent with a perfect photostability at room temperature. Such a
remarkable property allows easier single-particle tracking over long
time-scales. In this work we use photoluminescent nanodiamonds of size <50 nm
for intracellular labeling and investigate the mechanism of their uptake by
living cells . By blocking selectively different uptake processes we show that
nanodiamonds enter cells mainly by endocytosis and converging data indicate
that it is clathrin mediated. We also examine nanodiamonds intracellular
localization in endocytic vesicles using immunofluorescence and transmission
electron microscopy. We find a high degree of colocalization between vesicles
and the biggest nanoparticles or aggregates, while the smallest particles
appear free in the cytosol. Our results pave the way for the use of
photoluminescent nanodiamonds in targeted intracellular labeling or biomolecule
deliver
Fluorescent oxide nanoparticles adapted to active tips for near-field optics
We present a new kind of fluorescent oxide nanoparticles with properties well
suited to active-tip based near-field optics. These particles with an average
diameter in the range 5-10 nm are produced by Low Energy Cluster Beam
Deposition (LECBD) from a YAG:Ce3+ target. They are studied by transmission
electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), classical
photoluminescence, cathodoluminescence and near-field scanning optical
microscopy (NSOM). Particles of extreme photo-stability as small as 10 nm in
size are observed. These emitters are validated as building blocks of active
NSOM tips by coating a standard optical tip with a 10 nm thick layer of
YAG:Ce3+ particles directly in the LECBD reactor and by subsequently performing
NSOM imaging of test surfaces.Comment: Changes made following Referee's comments; added references; one
added figure. See story on this article at:
http://nanotechweb.org/cws/article/tech/3606
High spatial and temporal resolution wide-field imaging of neuron activity using quantum NV-diamond
A quantitative understanding of the dynamics of biological neural networks is fundamental to gaining insight into information processing in the brain. While techniques exist to measure spatial or temporal properties of these networks, it remains a significant challenge to resolve the neural dynamics with subcellular spatial resolution. In this work we consider a fundamentally new form of wide-field imaging for neuronal networks based on the nanoscale magnetic field sensing properties of optically active spins in a diamond substrate. We analyse the sensitivity of the system to the magnetic field generated by an axon transmembrane potential and confirm these predictions experimentally using electronically-generated neuron signals. By numerical simulation of the time dependent transmembrane potential of a morphologically reconstructed hippocampal CA1 pyramidal neuron, we show that the imaging system is capable of imaging planar neuron activity non-invasively at millisecond temporal resolution and micron spatial resolution over wide-fields
Diamond nanoparticles as photoluminescent nanoprobes
Proceedings of COLOQ'10 - 10ème COlloque sur les Lasers et l'Optique Quantique, Grenoble, July 2007We present preliminary results showing the potential of diamond nanoparticles with size <50 nm as photoluminescent nanoprobes (i) for biological applications like biomolecule tracking in living cell and (ii) for serving as stable point-like emitters attached at the tip apex of a near-field optical microscope to achieve enhanced spatial resolution
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