Nonlinear fluorescence imaging by photoinduced charge separation

Mochizuki, Kimihiro; Shi, Lamei; Mizukami, Shin; Yamanaka, Masahito; Tanabe, Mamoru; Gong, Wei; Palonpon, Almar F.; Kawano, Shohei; Kawata, Satoshi; Kikuchi, Kazuya; Fujita, Katsumasa

doi:10.7567/jjap.54.042403

Cited by 10 publications

(5 citation statements)

References 27 publications

(26 reference statements)

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“…These properties appear to contribute to the high oscillator strength through charge separation of a molecule because nitrogen atoms donate lone pair electrons. It is known that charge separation is closely correlated with light-induced electron transfer …”

Section: Resultsmentioning

confidence: 99%

Prediction of Molecular Electronic Transitions Using Random Forests

Kang

Seok

Lee

2020

J. Chem. Inf. Model.

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Fluorescent molecules, fluorophores, play essential roles in bioimaging. Attachment of fluorophores to proteins enables observation of the detailed structure and dynamics of biological reactions occurring in the cell. Effective bioimaging requires fluorophores with high quantum yields to detect weak signals. Besides, fluorophores with various emission frequencies are necessary to extract richer information. An essential computational component to discover novel functional molecules is to predict molecular properties. Here, we present statistical machines that predict excitation energies and associated oscillator strengths of a given molecule using a random forest algorithm. Excitation energies and oscillator strengths are directly related to the emission spectrum and the quantum yields of fluorophores, respectively. We discovered specific molecular substructures and fragments that determine the oscillator strengths of molecules from the feature importance analysis of our random forest machine. This discovery is expected to serve as a new design principle for novel fluorophores.

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Section: Resultsmentioning

confidence: 99%

Prediction of Molecular Electronic Transitions Using Random Forests

Kang

Seok

Lee

2020

J. Chem. Inf. Model.

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“…While UCNPs are a convenient choice for SEE microscopy, neither the SEE microscopy concept nor the developed theoretical framework within this paper, are restricted to this type of luminescent markers. Recent developments in material science bring hope that novel types of super-linear emitters, suitable for SEE microscopy, will emerge in the near future 23,24,43 . Our theoretical framework takes as an input the empirically measured excitation–emission profile of the super-linear emitters and accounts for the concrete confocal microscope used for the measurement.…”

Section: Discussionmentioning

confidence: 99%

“…So far, this simple idea has found limited practical realization, mainly due to the lack of suitable fluorophores. Luminescent molecules with sufficiently strong super-linear properties are restricted to visible wavelengths and turned out difficult to design, synthesize and apply in practice 18–23 . From the library of luminescent nanoparticles, nanodiamonds work only in the visible spectrum, and require complex conditions to enter the super-linear regime of operation, involving several different lasers and specific illumination sequence 24 .…”

Section: Introductionmentioning

confidence: 99%

3D sub-diffraction imaging in a conventional confocal configuration by exploiting super-linear emitters

et al. 2019

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Sub-diffraction microscopy enables bio-imaging with unprecedented clarity. However, most super-resolution methods require complex, costly purpose-built systems, involve image post-processing and struggle with sub-diffraction imaging in 3D. Here, we realize a conceptually different super-resolution approach which circumvents these limitations and enables 3D sub-diffraction imaging on conventional confocal microscopes. We refer to it as super-linear excitation-emission (SEE) microscopy, as it relies on markers with super-linear dependence of the emission on the excitation power. Super-linear markers proposed here are upconversion nanoparticles of NaYF 4 , doped with 20% Yb and unconventionally high 8% Tm, which are conveniently excited in the near-infrared biological window. We develop a computational framework calculating the 3D resolution for any viable scanning beam shape and excitation-emission probe profile. Imaging of colominic acid-coated upconversion nanoparticles endocytosed by neuronal cells, at resolutions twice better than the diffraction limit both in lateral and axial directions, illustrates the applicability of SEE microscopy for sub-cellular biology.

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“…8−11 The use of photoinduced charge separation between the two molecules was also proposed. 12 Another type of probe with on-and off-fluorescence states are reversibly photoswitchable fluorescent proteins (RSFPs). The nonlinear fluorescence response of RSFPs has been utilized in laser scanning microscopy where it improved spatial resolution.…”

mentioning

confidence: 99%

“…Such a fluorescent probe has been first realized by combining two fluorescent molecules. One of them acts as a donor and the other as an acceptor of Förster resonance energy transfer (FRET). − The use of photoinduced charge separation between the two molecules was also proposed . Another type of probe with on- and off- fluorescence states are reversibly photoswitchable fluorescent proteins (RSFPs).…”

mentioning

confidence: 99%

Visible-Wavelength Multiphoton Activation Confocal Microscopy

et al. 2021

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Nonlinear optical effects modify the point spread function (PSF) in laser scanning microscopy and have been utilized to enhance the spatial resolution in three dimensions. In this paper, we propose the use of visible-wavelength two-photon excitation to activate negatively switching reversibly photoswitchable fluorescent proteins (RSFPs) to introduce nonlinear relationships between the distribution of excitation light and the fluorescence emission. Single-photon excitation following the two-photon induced photoactivation provides a PSF corresponding to the cube of the excitation intensity distribution and achieves imaging properties equivalent to that using third-order nonlinear optical effects. We experimentally confirmed several species of negatively switching RSFPs can be activated by two-photon excitation in the wavelength range of 530–560 nm. We applied the cubic PSF imaging to the observation of HeLa cells stained by Skylan-NS to confirm the improvement of the spatial resolution and the image contrast in confocal scanning microscopy.

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Nonlinear fluorescence imaging by photoinduced charge separation

Cited by 10 publications

References 27 publications

Prediction of Molecular Electronic Transitions Using Random Forests

Prediction of Molecular Electronic Transitions Using Random Forests

3D sub-diffraction imaging in a conventional confocal configuration by exploiting super-linear emitters

Visible-Wavelength Multiphoton Activation Confocal Microscopy

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