scholarly journals Two-photon excitation fluorescent spectral and decay properties of retrograde neuronal tracer Fluoro-Gold

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Matthew Q. Miller ◽  
Iván Coto Hernández ◽  
Jenu V. Chacko ◽  
Steven Minderler ◽  
Nate Jowett

AbstractFluoro-Gold is a fluorescent neuronal tracer suitable for targeted deep imaging of the nervous system. Widefield fluorescence microscopy enables visualization of Fluoro-Gold, but lacks depth discrimination. Though scanning laser confocal microscopy yields volumetric data, imaging depth is limited, and optimal single-photon excitation of Fluoro-Gold requires an unconventional ultraviolet excitation line. Two-photon excitation microscopy employs ultrafast pulsed infrared lasers to image fluorophores at high-resolution at unparalleled depths in opaque tissue. Deep imaging of Fluoro-Gold-labeled neurons carries potential to advance understanding of the central and peripheral nervous systems, yet its two-photon spectral and temporal properties remain uncharacterized. Herein, we report the two-photon excitation spectrum of Fluoro-Gold between 720 and 990 nm, and its fluorescence decay rate in aqueous solution and murine brainstem tissue. We demonstrate unprecedented imaging depth of whole-mounted murine brainstem via two-photon excitation microscopy of Fluoro-Gold labeled facial motor nuclei. Optimal two-photon excitation of Fluoro-Gold within microscope tuning range occurred at 720 nm, while maximum lifetime contrast was observed at 760 nm with mean fluorescence lifetime of 1.4 ns. Whole-mount brainstem explants were readily imaged to depths in excess of 450 µm via immersion in refractive-index matching solution.

2021 ◽  
Author(s):  
Matthew Q. Miller ◽  
Iván Coto Hernández ◽  
Jenu V. Chacko ◽  
Steven Minderler ◽  
Nate Jowett

Abstract Fluoro-Gold is a fluorescent neuronal tracer suitable for targeted deep imaging of the nervous system. Widefield fluorescence microscopy enables visualization of fluoro-gold, but lacks depth discrimination. Though scanning laser confocal microscopy yields volumetric data, imaging depth is limited, and optimal single-photon excitation of fluoro-gold requires an unconventional ultraviolet excitation line. Two-photon excitation microscopy employs ultrafast pulsed infrared lasers to image fluorophores at high-resolution at unparalleled depths in opaque tissue. Deep imaging of fluoro-gold-labeled neurons carries potential to advance understanding of the central and peripheral nervous systems, yet its two-photon spectral and temporal properties remain uncharacterized. Herein, we report the relative two-photon excitation spectrum of fluoro-gold between 720 nm and 1100 nm, and its fluorescence decay rate in aqueous solution and murine brainstem tissue. We demonstrate unprecedented imaging depth of whole-mounted murine brainstem via two-photon excitation microscopy of fluoro-gold-labeled facial motor nuclei. Optimal two-photon excitation of fluoro-gold occurred at 730 nm, while maximum lifetime contrast was observed at 760 nm with mean fluorescence lifetime of 1.4 ns. Whole-mount brainstem explants were readily imaged to depths in excess of 450 µm via immersion in refractive-index matching solution.


2008 ◽  
Vol 13 (5) ◽  
pp. 054010 ◽  
Author(s):  
Wei Zheng ◽  
Yicong Wu ◽  
Dong Li ◽  
Jianan Y. Qu

1983 ◽  
Vol 61 (5) ◽  
pp. 1023-1026 ◽  
Author(s):  
R. J. Donovan ◽  
C. Fotakis ◽  
A. Hopkirk ◽  
C. B. McKendrick ◽  
A. Torre

Rotationally resolved photofragment fluorescence from OH(A2Σ+) following the coherent two-photon excitation of H2O with a KrF laser (248 nm), is reported and the dynamics of the dissociation process are discussed. Fluorescence from CN(B2Σ+) following two-photon excitation of ICN is also described. In both cases the energy distribution in the photofragments is shown to differ significantly from that observed with single-photon excitation at closely similar energies.Two further examples of multiphoton excitation, involving CS2 and SO2, are briefly discussed. In these cases absorption of a further photon, by fragments produced in the primary step, gives rise to strong laser-induced fluorescence.


2008 ◽  
Vol 14 (6) ◽  
pp. 492-506 ◽  
Author(s):  
John A. Scherschel ◽  
Michael Rubart

AbstractTwo-photon excitation microscopy has become the standard technique for high resolution deep tissue and intravital imaging. It provides intrinsic three-dimensional resolution in combination with increased penetration depth compared to single-photon confocal microscopy. This article will describe the basic physical principles of two-photon excitation and will review its multiple applications to cardiovascular imaging, including second harmonic generation and fluorescence laser scanning microscopy. In particular, the capability and limitations of multiphoton microscopy to assess functional heterogeneity on a cellular scale deep within intact, Langendorff-perfused hearts are demonstrated. It will also discuss the use of two-photon excitation-induced release of caged compounds for the study of intracellular calcium signaling and intercellular dye transfer.


1997 ◽  
Vol 17 (3) ◽  
pp. 161-174 ◽  
Author(s):  
M. Nickoleit ◽  
A. Uhl ◽  
J. Bendig

The simultaneous two-photon excitation energy transfer (SEET) was demonstrated for the first time using trichromophoric model compounds. Two identical donors (A–antenna) were covalently linked to an energy acceptor unit (T–target) with different energy levels preventing energy transfer of a single photon. At high intensity illumination (laser exposure) of a trichromophoric system A∼T∼A (A–fluorescein, erythrosin; T-Estilbene), sufficient to excite both of the appended donor subunits, population of the target excited state may occur via simultaneous energy transfer of two photons, one from each donor. In order to restrict reverse energy transfer from the higher energy target to the lower energy donor(s) it is necessary that the excited target unit undergoes an efficient photoreaction. In the investigated case this was achieved by photoisomerization of the stilbene unit used for monitoring of the SEET.


2000 ◽  
Vol 6 (S2) ◽  
pp. 808-809
Author(s):  
F. J. Kao ◽  
B. L. Lin ◽  
P. C. Cheng

Considering its non-linear nature, two-photon excitation may generate very different spectral response in samples when compared with single photon excitation. It is thus necessary to measure the two-photon spectra of samples, so that the two-photon fluorescence microscopic images can be properly interpreted. Fluorescence spectra obtained from bulk samples may not provide useful information for microscopy. For instance, due to the relatively small contribution to the total fluorescence intensity, a small number of fluorescent particles in a generally fluorescing specimen may escape detection when the spectrum of the specimen as a whole is obtained. Under two-photon excitation, the background noise can be greatly reduced due to the naturally limited excitation volume of focused laser beam. In addition, signals resulted from second harmonic generation (SHG) may be mixed with low level broad-band background autofluorescence which is commonly found in biological specimen. Therefore, measuring fluorescence spectrum from a micro-focused volume is essential for the proper interpretation of multi-photon fluorescence images.


2021 ◽  
Vol 18 (10) ◽  
pp. 106003
Author(s):  
Jun Dai ◽  
Zhengguo Li ◽  
Yi Zhang ◽  
Yongzhu Chen ◽  
Xing Zhu ◽  
...  

2000 ◽  
Vol 6 (2) ◽  
pp. 156-160 ◽  
Author(s):  
S. P. Schilders ◽  
M. Gu

The effect of multiple scattering in a turbid medium on single-photon and two-photon fluorescence microscopy is experimentally investigated for different scattering characteristics including scattering anisotrophy and optical thickness of a turbid medium. It is demonstrated that two-photon excitation can provide significant improvement in penetration depth through turbid media, due to reduced scattering experienced by the excitation beam. It is also shown that the limiting factor in obtaining high-quality images under singlephoton excitation is the fast degradation of image resolution caused by multiple scattering, while for twophoton excitation it is limited by the degradation of image contrast due to the reduction in fluorescence strength.


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