Time-Domain Lifetime Measurements

doi:10.1007/978-0-387-46312-4_4

Cited by 40 publications

(6 citation statements)

References 174 publications

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“…The α and τ values can be used to determine the fractional contribution (f) of each decay time to the steady-state intensity. 48 Figure 7b shows that the three parameters (α, τ, and f) remain unchanged across the range of NaCl concentrations studied, indicating that ionic strength of the solution does not affect these parameters. Therefore, the conformational change of the polymer does not significantly affect the fluorescence emission when the polymer is protonated.…”

Section: ■ Results and Discussionmentioning

confidence: 96%

Enhancement of the Photosensitizing Properties of 6-Carboxypterin through Covalent Binding to the pH-Responsive and Biocompatible Poly(allylamine Hydrochloride)

Armijos-Capa,

Tuninetti,

Thomas

et al. 2023

ACS Appl. Mater. Interfaces

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A polymeric photosensitizer was synthesized through covalent attachment of the natural photosensitizer 6carboxypterin (Cap) to a poly(allylamine hydrochloride) (PAH) polymer. The optimization of the functionalization steps and purification procedure is described. The overall yield of the functionalization reaction was 67% to generate the modified polymer (PAH-Cap), featuring a Cap substitution degree of approximately 1% and advantageous spectroscopic properties. Photosensitizing properties of PAH-Cap were observed to occur via both photooxidation mechanisms, i.e., type I and type II. This feature was demonstrated using a biologically relevant target molecule, 2′-deoxyguanosine (dG). The spectroscopic, photophysical, and photochemical behaviors in aqueous environments were studied and compared to Cap. To explore possible further relevant biological applications, experiments with PAH-Cap and dG were carried out at physiological pH. PAH-Cap can generate singlet molecular oxygen and initiate an electron transfer process at pH 7 in air-saturated solutions upon UVA irradiation. Moreover, based on its spectroscopic features, visible light can be used to initiate the photooxidation of biological compounds in water, with many interesting advantages compared to free Cap and other related pteridines. These advantages include an enhancement of the photosensitizing effect at physiological pH and the potential of PAH-Cap for its use as a building block in supramolecular assemblies. The functionalization strategy hereby described can be employed for the preparation of robust photoactive polymers with great potential for its application in photodynamic therapy (PDT) and disinfection technologies.

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Section: ■ Results and Discussionmentioning

confidence: 96%

Enhancement of the Photosensitizing Properties of 6-Carboxypterin through Covalent Binding to the pH-Responsive and Biocompatible Poly(allylamine Hydrochloride)

Armijos-Capa,

Tuninetti,

Thomas

et al. 2023

ACS Appl. Mater. Interfaces

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“…Time-resolved absorption decays were collected at the maximum of the excited-state absorption (650 nm for CC10 (1 Me) and CC11 (2 Me) and 660 nm for CC12 (0 Me)) by the use of a Czerny–Turner monochromator and a photomultiplier tube and averaged over 3000 laser shots. The following equations were used to obtain kinetics: where ΔOD t =0 represents the signal amplitude at time zero, τ KWW is the stretched exponential lifetime, and β is the stretch parameter, which ranges in value from 0 to 1. − The observed lifetime is calculated from the fitting parameters using a gamma function distribution of β –1 (eqs and ). To better account for biphasic kinetics, with competing rates of regeneration and BET, in the devices fabricated with CDCA, TBP, LiTFSI, and the Co(bpy) 3 3+/2+ redox shuttle, the ΔOD versus t curves were fit with a biexponential decay function where A 1 and A 2 represent the weight of lifetimes τ 1 and τ 2 , respectively . From these lifetime values, an average lifetime τ avg was calculated by eq . …”

Section: Methodsmentioning

confidence: 99%

“…where A 1 and A 2 represent the weight of lifetimes τ 1 and τ 2 , respectively. 42 From these lifetime values, an average lifetime τ avg was calculated by eq 5.…”

Section: +mentioning

confidence: 99%

Increasing Photoinduced Interfacial Charge Separation Lifetime through Control of the Twist Angle in the Donor Region of Carbazole-Based Dyes

Curiac,

Lambert,

Hunt

et al. 2023

J. Phys. Chem. C

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Molecular-based optoelectronic devices and photocatalytic systems often rely on the photogeneration of charge-separated states. Increasing the longevity of charge-separated states allows for access to higher-functioning devices and systems by extending the length of time before subsequent events are required to occur. In dye-sensitized solar cells (DSC), back electron transfer (BET) from a reduced metal oxide to an oxidized dye is an unproductive electron transfer pathway that determines the charge-separated state lifetime. This study seeks to limit BET by lowering the electronic coupling of the donor and acceptor in the charge-separated excited state through the use of sterics. A series of three dyes with a varying number of methyl groups (0–2) on the donor were studied using nanosecond transient absorption spectroscopy (nsTAS) to compare rates of BET. Novel dye CC10 (1 Me), designed with one methyl group in the donor region connected to the acceptor, was found to lower back electron transfer rates by 22× compared to the control dye, CC12 (0 Me), with no methyl groups.

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“…For a precise lifetime determination with background and finite T , photon detection events are aggregated according to their arrival times, yielding the so-called TCSPC histogram, which is then fitted with a suitable model. Most fluorophores show a mono-exponential fluorescent decay behavior, so that one used a mono-exponential decay function with single decay time for fitting the TCSPC histogram ( Lakowicz, 2006 ). In that case, the probability p for a photon to be detected at the time t is given by

where b is the relative background amplitude (constant background).…”

Section: Theory Of Lifetime Determinationmentioning

confidence: 99%

Advanced Data Analysis for Fluorescence-Lifetime Single-Molecule Localization Microscopy

Thiele¹,

Nevskyi²,

Helmerich³

et al. 2021

Front. Bioinform.

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Fluorescence-lifetime single molecule localization microscopy (FL-SMLM) adds the lifetime dimension to the spatial super-resolution provided by SMLM. Independent of intensity and spectrum, this lifetime information can be used, for example, to quantify the energy transfer efficiency in Förster Resonance Energy Transfer (FRET) imaging, to probe the local environment with dyes that change their lifetime in an environment-sensitive manner, or to achieve image multiplexing by using dyes with different lifetimes. We present a thorough theoretical analysis of fluorescence-lifetime determination in the context of FL-SMLM and compare different lifetime-fitting approaches. In particular, we investigate the impact of background and noise, and give clear guidelines for procedures that are optimized for FL-SMLM. We do also present and discuss our public-domain software package “Fluorescence-Lifetime TrackNTrace,” which converts recorded fluorescence microscopy movies into super-resolved FL-SMLM images.

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Time-Domain Lifetime Measurements

Cited by 40 publications

References 174 publications

Enhancement of the Photosensitizing Properties of 6-Carboxypterin through Covalent Binding to the pH-Responsive and Biocompatible Poly(allylamine Hydrochloride)

Enhancement of the Photosensitizing Properties of 6-Carboxypterin through Covalent Binding to the pH-Responsive and Biocompatible Poly(allylamine Hydrochloride)

Increasing Photoinduced Interfacial Charge Separation Lifetime through Control of the Twist Angle in the Donor Region of Carbazole-Based Dyes

Advanced Data Analysis for Fluorescence-Lifetime Single-Molecule Localization Microscopy

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