Functional nanoscale materials are being extensively investigated for applications in biology and medicine and are ready to make significant contributions in the realization of exciting advancements in diverse areas of diagnostics and therapeutics. Aiming for more accurate, efficient, non-invasive and fast diagnostic tools, the use of near-infrared (NIR) light in the range of the 1st and 2nd biological window (NIR-I: 0.70-0.95 µm; NIR-II: 1.00-1.35 µm) provides deeper penetration depth into biological tissue, better image contrast, reduced phototoxicity and photobleaching. Consequently, NIR-based bioimaging became a quickly emerging field and manifold new NIR-emitting bioprobes have been reported. Since commercially available microscopes are not optimized for this kind of NPs, a new microscopy hyperspectral confocal imager has been developed to cover a broad spectral range (400 to 1700 nm) with high spectral resolution. The smallest spectral variation can be easily monitored thanks to the high spectral resolution (as low as 0.2 nm). This is possible thanks to a combination of an EMCCD and an InGaAs camera with a high resolution spectrometer. An extended number of NPs can be excited with a Ti:Sapphire laser, which provides tunable illumination within 690-1040 nm. Cells and tissues can be mapped in less than 100 ms, allowing in-vivo imaging. As a proof of concept, here we present the preliminary results of the spatial distribution of the fluorescence signal intensity from lanthanide doped nanoparticles incorporated into a system of biological interest. The temperature sub-mm gradient – analyzing the spectral features so gathered through an all-optical route is also thoroughly discussed.
Daniel Heller, Daniel Roxbury, Prakrit Jena, Ryan Williams, Balázs Enyedi, Philipp Niethammer, Stéphane Marcet, Francesca Mangiarini, Marc Verhaegen, Sébastien Blais-Ouellette
The intrinsic near-infrared photoluminescence (fluorescence) of single-walled carbon nanotubes exhibits unique photostability, narrow bandwidth, penetration through biological media, environmental sensitivity, and both chromatic variety and range. Biomedical applications exploiting this large family of fluorophores will require the spectral and spatial resolution of individual (n,m) nanotube species’ fluorescence and its modulation within live cells and tissues, which is not possible with current microscopy methods. We present a wide-field hyperspectral approach to spatially delineate and spectroscopically measure single nanotube fluorescence in living systems. This approach resolved up to 17 distinct (n,m) species (chiralities) with single nanotube spatial resolution in live mammalian cells, murine tissues ex vivo, and zebrafish endothelium in vivo. We anticipate that this approach will facilitate multiplexed nanotube imaging in biomedical applications while enabling deep-tissue optical penetration, exceptional photostability, and single-molecule resolution in vivo.
The efficacy of existing therapies and the discovery of innovative treatments for central nervous system (CNS) diseases have been limited by the lack of appropriate methods to investigate complex molecular processes at the synaptic level. To improve our capability to investigate complex mechanisms of synaptic signaling and remodeling, we designed a fluorescence hyperspectral imaging platform to simultaneously track different subtypes of individual neurotransmitter receptors trafficking in and out of synapses. This imaging platform allows simultaneous image acquisition of at least five fluorescent markers in living neurons with a high-spatial resolution. We used quantum dots emitting at different wavelengths and functionalized to specifically bind to single receptors on the membrane of living neurons. The hyperspectral imaging platform enabled the simultaneous optical tracking of five different synaptic proteins, including subtypes of glutamate receptors (mGluR and AMPAR) and postsynaptic signaling proteins. It also permitted the quantification of their mobility after treatments with various pharmacological agents. This technique provides an efficient method to monitor several synaptic proteins at the same time, which could accelerate the screening of effective compounds for treatment of CNS disorders.
In the past decade, the efficacy of existing therapies and the discovery of innovative treatments for Central Nervous System (CNS) diseases have been limited by the lack of appropriate methods to investigate complex molecular processes at the synaptic level. In order to better understand the fundamental mechanisms that regulate diseases of the CNS, a fast fluorescence hyperspectral imaging platform was designed to track simultaneously various neurotransmitter receptors trafficking in and out of synapses. With this hyperspectral imaging platform, it was possible to image simultaneously five different synaptic proteins, including subtypes of glutamate receptors (mGluR, NMDAR, AMPAR), postsynaptic density proteins, and signaling proteins. This new imaging platform allows fast simultaneous acquisitions of at least five fluorescent markers in living neurons with a high spatial resolution. This technique provides an effective method to observe several synaptic proteins at the same time, thus study how drugs for CNS impact the spatial dynamics of these proteins.
A new type of Raman spectroscopy hyperspectral imager based on Bragg tunable filter has been developed by University of Montreal and Photon etc. The technology of Bragg tunable filter significantly reduces the acquisition time by selecting a single wavelength in a full camera field and scanning the wavelength with a high efficiency. The transmission is continuously tunable over 400 nm range with a spectral resolution of 0.2 nm. We here present the principle of this novel Raman imaging system as well as hyperspectral images of a Si/Ti structured wafer and carbon nanotubes taken with a spectral resolution of 0.2 nm on the whole field of view of the microscope.
Volume Bragg grating technology has enabled the development of a new type of staring
hyperspectral camera. Based on Bragg Tunable filters, these hyperspectral cameras have both high
spectral and spatial resolution, and significantly higher sensitivity than competing technologies like
push broom spectrometer, liquid crystal tunable filters, or acousto-optic tunable filters. They are
minimally sensitive to polarization and their spectral isolation can reach 106. Here we thus present
an innovative tool to collect SWIR hyperspectral data with high spectral and spatial resolution. This
new instrument is based on a 3nm bandwidth Bragg Tunable Filter, continuously tunable from
1.0um and 2.5um. Because high spectral resolution also means less light per channel, a low noise
custom HgCdTe (MCT) camera was also developed to meet the requirement of the filter. The high
speed capability of more than 300 fps and the low operating temperature of 200K (deep cooled
option to 77K) allow full frame 500 spectral channel datacube acquisitions in minimal time. Basic
principle of this imaging filter will be reviewed as well as the custom MCT camera performances.
High resolution hyperspectral measurements will be demonstrated between 1.0um and 2.5um on
different objects.
A new type of Raman spectroscopy hyperspectral imager based on Bragg tunable filter has been developed by
University of Montreal and Photon etc. The technology of Bragg tunable filter significantly reduces the acquisition time
by selecting a single wavelength in a full camera field and scanning the wavelength with a high efficiency. The
transmission is continuously tunable over 400 nm range with a spectral resolution of 0.2 nm. We here present the
principle of this novel Raman imaging system as well as hyperspectral images of Si taken with a spectral resolution of
0.2 nm on the whole field of view of the microscope.
Electric discharge and CO2 laser exposure can produce long period gratings in standard telecommunication fibers. These two
fabrication techniques are examined and compared to the UV laser exposure technique. Cladding modes involved in these
gratings have been measured and identified using a computer simulation based on coupled mode equations. Fundamental
mechanisms of the gratings production are also examined.
High energy MeV ion implantation of fused silica and Ge- doped silica renders these materials photosensitive. The physical processes involved are closely related to the photosensitization of Ge-doped silica by UV irradiation but present certain characteristics that are different. We discuss the results of studied of the induced absorption and refractive index changes under different preparation conditions, annealing sequences and subsequent bleaching by ArF and KrF excimer radiation. We include the results of a study using positron annihilation spectroscopy of the defects introduced by ion implantation and subsequent annealing and bleaching.
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