Ultrafast Twisting Dynamics of Thioflavin‐T: Spectroscopy of the Twisted Intramolecular Charge‐Transfer State

Ghosh, Rajib; Palit, Dipak K.

doi:10.1002/cphc.201402317

Cited by 31 publications

(32 citation statements)

References 57 publications

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“…In other words, these three compounds are not prone to TICT formations and would exhibit strong background emissions. Moreover, even though previous studies have shown that ThT could form the TICT state upon photoexcitation 33 , based on our calculations, ThT possesses a weaker push-pull strength than our designed AH-2 probe.…”

Section: Resultscontrasting

confidence: 54%

High-fidelity imaging of amyloid-beta deposits with an ultrasensitive fluorescent probe facilitates the early diagnosis and treatment of Alzheimer's Disease

Tao¹,

Wang²,

Shen³

et al. 2022

Theranostics

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Background: Imaging amyloid-beta (Aβ) deposits with high fidelity in naturally aging brains is crucial for the early diagnosis of Alzheimer's disease (AD). However, this is impeded by the lack of highly sensitive probes. Methods: By conducting computational modelling to quantitatively fine-tune the twisted intramolecular charge transfer (TICT) tendency of Thioflavin T ( ThT ) analogues, we developed an ultrasensitive probe AH-2 . AH-2 retained the binding affinity and binding mode of ThT towards Aβ deposits, and exhibited ca 10-fold less background fluorescence and 5-10 folds of improved signal-to-background contrast upon binding Aβ deposits. These desirable features endowed AH-2 the sensitivity to detect Aβ deposition in naturally aging wild-type mice. Results: AH-2 imaging revealed that Aβ puncta signals appeared near the nuclei in young mice and spread through the intracellular and extracellular compartments in older mice. Moreover, Aβ deposits were observed to emerge earlier in mice cerebral cortex than in the hippocampus region. Given this desirable sensitivity and good spatiotemporal resolution, AH-2 was successfully applied in the preclinical evaluation of Aβ-targeted treatment by melatonin. Conclusions: We expect that AH-2 is promising for early diagnosis of AD and will serve as a sensitive tool for studying Aβ-related AD pathology.

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Section: Resultscontrasting

confidence: 54%

High-fidelity imaging of amyloid-beta deposits with an ultrasensitive fluorescent probe facilitates the early diagnosis and treatment of Alzheimer's Disease

Tao¹,

Wang²,

Shen³

et al. 2022

Theranostics

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“…From both theoretical and spectroscopic studies, the proposed behavior for the solvated dye is that the molecule is photoexcited to its lowest Franck–Condon locally excited (LE) state and then exhibits an ultrafast twisting to its excited state minimum, during which a CT to the benzothiazole group occurs. As shown in these previous studies, the excitation induces a large torsional relaxation combined with a significant bending: to quantify this distortion two angles are introduced, namely the twisting angle,

φ

and the bending angle, α (see Figure ).…”

Section: Resultsmentioning

confidence: 99%

Fluorescent dyes in the context of DNA‐binding: The case of Thioflavin T

Biancardi

Biver

Mennucci

2017

Int J of Quantum Chemistry

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Thioflavin T (ThT) is a dye characterized by a strong fluorescence light‐up on binding to biosubstrates. Although this effect is known to be related to the inhibition of intramolecular torsion on excitation, the binding modes and their role in affecting photoinduced processes are by no means adequately understood. Here, a combined molecular dynamics and quantum chemical modeling is used to study the tuning of the photophysical properties of ThT when moving from solution to DNA binding. The binding mechanism of ThT to B‐DNA was found to be very complex as a result of an uncommon interplay between different binding modes, for example, monomer intercalation and external binding but also groove binding of the dimer. The detailed analysis of the relation between the different binding modes and the structural and electronic properties of ThT can be used to better understand the interaction with other biosubstrates.

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“…Phosphorescence spectrum with maximum at 585 nm was observed by Huppert et al for ThT solution in 1-propanol at low temperatures. Ghosh and Palit demonstrated recently that intersystem crossing takes place for solutions of ThT in acetonitrile at room temperature (with low efficiency of triplet formation but readily detectable) and that triplet states population can be responsible for the fluorescence quantum yield Φ decrease. Phosphorescence and photosensitizing properties of ThT in complexes with polynucleotides were reported earlier. , Although intersystem crossing processes seem to be not very efficient for ThT in nonviscous solvents, it can be quite possible that photochemical reactions involving triplet states of ThT are responsible for ThT photodegradation and photoproducts formation observed by Hsu et al…”

Section: Introductionmentioning

confidence: 99%

Solvent Polarity Effect on Nonradiative Decay Rate of Thioflavin T

Stsiapura

Kuzmitsky²,

Bouganov

et al. 2016

J. Phys. Chem. A

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It has been established earlier that fluorescence quantum yield of thioflavin T (ThT)-a probe widely used for amyloid fibrils detection-is viscosity-dependent, and photophysical properties of ThT can be well-described by the fluorescent molecular rotor model, which associates twisted internal charge transfer (TICT) reaction with the main nonradiative decay process in the excited state of the dye. Solutions of ThT in a range of polar solvents were studied using steady-state fluorescence and sub-picosecond transient absorption spectroscopy methods, and we showed that solvent effect on nonradiative transition rate knr cannot be reduced to the dependence on viscosity only and that ∼3 times change of knr can be observed for ThT in aprotic solvents and water, which correlates with solvent polarity. Different behavior was observed in alcohol solutions, particularly in longer n-alcohols, where TICT rate was mainly determined by rotational diffusion of ThT fragments. Quantum-chemical calculations of S0 → S1 transition energy were performed to get insight of polar solvent contribution to the excited-state energy stabilization. Effect of polar solvent on electronic energy levels of ThT was simulated by applying homogeneous electric field according to the Onsager cavity model. Static solvent effect on the excited-state potential energy surface, where charge transfer reaction takes place, was not essential to account for experimentally observed TICT rate differences in water and aprotic solvents. From the other side, nonradiative decay rate of ThT in water, ethylene glycol, and aprotic solvents was found to follow dynamics of polar solvation knr ∼ τS(-1), which can explain dependence of the TICT rate on both polarity and viscosity of the solvents.

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Ultrafast Twisting Dynamics of Thioflavin‐T: Spectroscopy of the Twisted Intramolecular Charge‐Transfer State

Cited by 31 publications

References 57 publications

High-fidelity imaging of amyloid-beta deposits with an ultrasensitive fluorescent probe facilitates the early diagnosis and treatment of Alzheimer's Disease

High-fidelity imaging of amyloid-beta deposits with an ultrasensitive fluorescent probe facilitates the early diagnosis and treatment of Alzheimer's Disease

Fluorescent dyes in the context of DNA‐binding: The case of Thioflavin T

Solvent Polarity Effect on Nonradiative Decay Rate of Thioflavin T

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