One-Photon and Two-Photon Excitation of Fluorescent Proteins

Author(s):  
R. Nifosì ◽  
V. Tozzini
2018 ◽  
Vol 114 (3) ◽  
pp. 171a-172a
Author(s):  
Olga Rybakova ◽  
Stepan Timr ◽  
Josef Lazar

2010 ◽  
Vol 49 (17) ◽  
pp. 3323 ◽  
Author(s):  
Hiroshi Hashimoto ◽  
Keisuke Isobe ◽  
Akira Suda ◽  
Fumihiko Kannari ◽  
Hiroyuki Kawano ◽  
...  

2016 ◽  
Vol 110 (3) ◽  
pp. 493a
Author(s):  
Josef Lazar ◽  
Prakash Shukla ◽  
Richard Chazal ◽  
Alexey Bondar ◽  
David von Stetten ◽  
...  

2020 ◽  
Vol 11 (12) ◽  
pp. 7192
Author(s):  
Rosana S. Molina ◽  
Jonathan King ◽  
Jacob Franklin ◽  
Nathan Clack ◽  
Christopher McRaven ◽  
...  

2020 ◽  
Author(s):  
Rosana S. Molina ◽  
Jonathan King ◽  
Jacob Franklin ◽  
Nathan Clack ◽  
Christopher McRaven ◽  
...  

AbstractTwo-photon microscopy together with fluorescent proteins and fluorescent protein-based biosensors are commonly used tools in neuroscience. To enhance their experimental scope, it is important to optimize fluorescent proteins for two-photon excitation. Directed evolution of fluorescent proteins under one-photon excitation is common, but many one-photon properties do not correlate with two-photon properties. A simple system for expressing fluorescent protein mutants is E. coli colonies on an agar plate. The small focal volume of two-photon excitation makes creating a high throughput screen in this system a challenge for a conventional point-scanning approach. We present an instrument and accompanying software that solves this challenge by selectively scanning each colony based on a colony map captured under one-photon excitation. This instrument, called the GIZMO, can measure the two-photon excited fluorescence of 10,000 E. coli colonies in 7 hours. We show that the GIZMO can be used to evolve a fluorescent protein under two-photon excitation.


Author(s):  
David W. Piston ◽  
Brian D. Bennett ◽  
Robert G. Summers

Two-photon excitation microscopy (TPEM) provides attractive advantages over confocal microscopy for three-dimensionally resolved fluorescence imaging and photochemistry. Two-photon excitation arises from the simultaneous absorption of two photons in a single quantitized event whose probability is proportional to the square of the instantaneous intensity. For example, two red photons can cause the transition to an excited electronic state normally reached by absorption in the ultraviolet. In practice, two-photon excitation is made possible by the very high local instantaneous intensity provided by a combination of diffraction-limited focusing of a single laser beam in the microscope and the temporal concentration of 100 femtosecond pulses generated by a mode-locked laser. Resultant peak excitation intensities are 106 times greater than the CW intensities used in confocal microscopy, but the pulse duty cycle of 10-5 maintains the average input power on the order of 10 mW, only slightly greater than the power normally used in confocal microscopy.


Author(s):  
David W. Piston

Two-photon excitation fluorescence microscopy provides attractive advantages over confocal microscopy for three-dimensionally resolved fluorescence imaging. Two-photon excitation arises from the simultaneous absorption of two photons in a single quantitized event whose probability is proportional to the square of the instantaneous intensity. For example, two red photons can cause the transition to an excited electronic state normally reached by absorption in the ultraviolet. In our fluorescence experiments, the final excited state is the same singlet state that is populated during a conventional fluorescence experiment. Thus, the fluorophore exhibits the same emission properties (e.g. wavelength shifts, environmental sensitivity) used in typical biological microscopy studies. In practice, two-photon excitation is made possible by the very high local instantaneous intensity provided by a combination of diffraction-limited focusing of a single laser beam in the microscope and the temporal concentration of 100 femtosecond pulses generated by a mode-locked laser. Resultant peak excitation intensities are 106 times greater than the CW intensities used in confocal microscopy, but the pulse duty cycle of 10−5 maintains the average input power on the order of 10 mW, only slightly greater than the power normally used in confocal microscopy.


Bioimaging ◽  
1995 ◽  
Vol 3 (2) ◽  
pp. 70-75 ◽  
Author(s):  
Pekka E Hänninen ◽  
Martin Schrader ◽  
Erkki Soini ◽  
Stefan W Hell

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