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High-resolution 3D Chemical Imaging In Vivo

High-resolution, in vivo imaging of brain has garnered a lot of interest lately among the imaging optics, neurophysics, and neurophysiology researchers alike.


Traditional techniques like confocal fluorescence microscopy use ultraviolet or visible light for excitation which causes high scattering in the living tissue and results in low penetration and poor signal-to-noise ratio. These problems can be avoided by utilizing advanced nonlinear optical methods such as two-photon microscopy. The benefits of nonlinear optics based imaging modalities stem from the two facts: (a) the use of near infrared light for excitation, which scatters significantly less in the living tissue, provides for deeper penetration and higher signal-to-noise ratio and (b) two-photon induced luminescence is extremely localized which enables 3D imaging without requiring a pinhole and provides for a much better photon economy.


While advances in two-photon microscopy technology allow for faster and deeper imaging in vivo, quantitative chemical imaging still remains challenging. There exists only a few probes that show sensitivity to biologically relevant chemical species such as dissolved oxygen. An even fewer of them are water-soluble which makes high-resolution quantitative oxygen imaging in vivo difficult and expensive. In the search of hydrophilic dyes that are sensitive to dissolved oxygen, several techniques have been developed, such as attaching hydrophilic dendrimers and immobilizing the dye in a polymer matrix.

Our work presents another technique to prepare hydrophobic dyes for aqueous media applications. We achieve this by encapsulating an oxygen-sensitive hydrophobic dye, \rudppcl,\footnote[2]{Tris(4,7-diphenyl-1,10-phenanthroline)ruthenium(II) dichloride.} in a surfactant, poloxamer 407. The paper describes the preparation method and the photophysical properties of the probes in Sec.~2 and 3 respectively. 3D intravital imaging of a mouse brain in vivo using ruthenium-poloxamer probes with a commercial multiphoton microscopy setup is shown in Sec.~4. The last section (Sec.~5) discusses the future work with the nanoprobes and some potential applications.



projects/invivo_3d_chemical_imaging.txt ยท Last modified: 2015/06/25 16:02 by akhan3