A Molecular Rotor as Viscosity Sensor in Aqueous Colloid Solutions

2004 ◽  
Vol 126 (3) ◽  
pp. 340-345 ◽  
Author(s):  
W. Akers ◽  
M. A. Haidekker
Keyword(s):  
Quantum Yield ◽  
Power Law ◽  
Emission Intensity ◽  
Molecular Rotors ◽  
Solution Viscosity ◽  
Colloid Solution ◽  
Fluid Viscosity ◽  
Molecular Rotor ◽  
Average Precision

Background: Molecular rotors exhibit viscosity-dependent quantum yield, allowing non-mechanical determination of fluid viscosity. We analyzed fluorescence in the presence of viscosity-modulating macromolecules several orders of magnitude larger than the rotor molecule. Method of approach: Fluorescence of aqueous starch solutions with a molecular rotor in solution was related to viscosity obtained in a cone-and-plate viscometer. Results: In dextran solutions, emission intensity was found to follow a power-law relationship with viscosity. Fluorescence in hydroxyethylstarch solutions showed biexponential behavior with different exponents at viscosities above and below 1.5 mPa s. Quantum yield was generally higher in hydroxyethylstarch than in dextran solutions. The power-law relationship was used to backcalculate viscosity from intensity with an average precision of 2.2% (range of −5.5% to 5.1%). Conclusions: This study indicates that hydrophilic molecular rotors are suitable as colloid solution viscosity probes after colloid-dependent calibration.

Precision Assessment of Biofluid Viscosity Measurements Using Molecular Rotors

2005 ◽  
Vol 127 (3) ◽  
pp. 450-454 ◽  
Author(s):  
Walter J. Akers ◽  
Mark A. Haidekker
Keyword(s):  
Fluorescence Emission ◽  
High Viscosity ◽  
Plasma Viscosity ◽  
Molecular Rotors ◽  
Solution Viscosity ◽  
Human Blood Plasma ◽  
Fluid Viscosity ◽  
Molecular Rotor ◽  
Test Set ◽  
Precision Assessment

Blood viscosity changes with many pathologic conditions, but its importance has not been fully investigated because the current methods of measurement are poorly suited for clinical applications. The use of viscosity-sensitive fluorescent molecular rotors to determine fluid viscosity in a nonmechanical manner has been investigated recently, but it is unknown how the precision of the fluorescence-based method compares to established mechanical viscometry. Human blood plasma viscosity was modulated with high-viscosity plasma expanders, dextran, pentastarch, and hetastarch. The samples were divided into a calibration and a test set. The relationship between fluorescence emission and viscosity was established using the calibration set. Viscosity of the test set was determined by fluorescence and by cone-and-plate viscometer, and the precision of both methods compared. Molecular rotor fluorescence intensity showed a power law relationship with solution viscosity. Mechanical measurements deviated from the theoretical viscosity value by less than 7.6%, while fluorescence-based measurements deviated by less than 6%. The average coefficient of variation was 6.9% (mechanical measurement) and 3.4% to 3.8% (fluorescence-based measurement, depending on the molecular rotor used). Fluorescence-based viscometry exhibits comparable precision to mechanical viscometry. Fluorescence viscometry does not apply shear and is therefore more practical for biofluids which have apparent non-Newtonian properties. In addition, fluorescence instrumentation makes very fast serial measurements possible, thus promising new areas of application in laboratory and clinical settings.

scholarly journals Quantitative Determination of Dark Chromophore Population Explains the Apparent Low Quantum Yield of Red Fluorescent Proteins

2020 ◽  
Vol 124 (8) ◽  
pp. 1383-1391 ◽  
Author(s):  
Jord C. Prangsma ◽  
Robert Molenaar ◽  
Laura van Weeren ◽  
Daphne S. Bindels ◽  
Lindsay Haarbosch ◽  
...  
Keyword(s):  
Quantum Yield ◽  
Quantitative Determination ◽  
Fluorescent Proteins ◽  
Red Fluorescent Proteins

Determination of the quantum yield of singlet oxygen sensitized by halogenated boron difluoride dipyrromethenes

2017 ◽  
Vol 51 (3) ◽  
pp. 175-181 ◽  
Author(s):  
R. T. Kuznetsova ◽  
Iu. V. Aksenova ◽  
D. E. Bashkirtsev ◽  
A. S. Shulev ◽  
E. V. Antina ◽  
...  
Keyword(s):  
Quantum Yield ◽  
Singlet Oxygen ◽  
Boron Difluoride

Terminology, relative photonic efficiencies and quantum yields in heterogeneous photocatalysis. Part II: Experimental determination of quantum yields

1999 ◽  
Vol 71 (2) ◽  
pp. 321-335 ◽  
Author(s):  
Angela Salinaro ◽  
Alexei V. Emeline ◽  
Jincai Zhao ◽  
Hisao Hidaka ◽  
Vladimir K. Ryabchuk ◽  
...  
Keyword(s):  
Quantum Yield ◽  
Visible Region ◽  
Heterogeneous Photocatalysis ◽  
Quantum Yields ◽  
Yield Data ◽  
Normal Absorption ◽  
The One ◽  
Solid Liquid ◽  
Photonic Efficiency

In the preceding article [Serpone and Salinaro, Pure Appl. Chem., 71(2), 303-320 (1999)] we examined two principal features of heterogeneous photocatalysis that demanded scrutiny: (i) description of photocatalysis and (ii) description of process efficiencies. For the latter we proposed a protocol relative photonic efficiency which could subsequently be converted to quantum yields. A difficulty in expressing a quantum yield in heterogeneous photochemistry is the very nature of the system, either solid/liquid or solid/gas, which places severe restrictions on measurement of the photon flow absorbed by the light harvesting component, herein the photocatalyst TiO2, owing to non-negligible scattering by the particulates. It was imperative therefore to examine the extent of this problem. Extinction and absorption spectra of TiO2 dispersions were determined at low titania loadings by normal absorption spectroscopy and by an integrated sphere method, respectively, to assess the extent of light scattering. The method is compared to the one reported by Grela et al. [J. Phys. Chem., 100, 16940 (1996)] who used a polynomial extrapolation of the light scattered in the visible region into the UV region where TiO2 absorbs significantly. This extrapolation underestimates the scattering component present in the extinction spectra, and will no doubt affect the accuracy of the quantum yield data. Further, we report additional details in assessing limiting photonic efficiencies and quantum yields in heterogeneous photocatalysis.

Fluorescence Quantum Yield Determination of Propylparaben Using Flow Injection Spectroscopy

2018 ◽  
Vol 28 (6) ◽  
pp. 1275-1280
Author(s):  
Kadhim Kh. Hashim ◽  
Shatha Y. Yahyaa ◽  
Asmaa A. Mohmmed Al-Rashidy
Keyword(s):  
Quantum Yield ◽  
Flow Injection ◽  
Fluorescence Quantum Yield ◽  
Yield Determination

Molecular Rotors as Reporters for Viscosity of Solutions of Collagen Like Peptides

2021 ◽  
Author(s):  
Christopher McTiernan ◽  
Matias Zuñiga-Bustos ◽  
Roberto Rosales-Rojas ◽  
Pablo Barrias ◽  
May Griffith ◽  
...  
Keyword(s):  
Steady State ◽  
Fluorometric Assay ◽  
Molecular Rotors ◽  
Molecular Rotor

We have studied the suitability of using a molecular rotor-based steady-state fluorometric assay for evaluating changes in both the conformation and the viscosity of collagen-like peptide solutions. Our results indicate...

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