We report on the use of molecular diffusional motion over a range of length scales to characterize compositional heterogeneity in monolayer structures. This work focuses on the diffusional motion of perylene in two types of films supported on functionalized silica surfaces: single-component (stearic acid) and two-component (hydrocarbon/fluorocarbon) films. Langmuir-Blodgett (LB) monolayers were deposited directly on silica or were bound to surface-modified silica by means of metal ion complexation. The LB films were characterized by their π-A isotherms and by Brewster angle microscopy (BAM) during formation and deposition. Chromophore mobility and monolayer structural heterogeneity were evaluated by comparing rotational diffusion data (fluorescence anisotropy decay imaging) and translational diffusion data (fluorescence recovery after photobleaching) on the same LB films. Our results indicate that the mobility of the chromophore depends sensitively on both metal ion identity and film composition.
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http://dx.doi.org/10.1021/acs.langmuir.6b04341 | DOI Listing |
Biochim Biophys Acta Gen Subj
December 2024
Department of Chemistry, College of Science, Qassim University, Mulaidah 52571, Saudi Arabia. Electronic address:
Brownian dynamics (BD) simulations, a powerful computer simulation tool that has gained significant attraction in investigating the intricate dynamics of chemical and biological systems. By meticulously modeling the diffusive motion of molecules and their intricate interactions, BD simulations offer invaluable insights into a diverse array of phenomena, including reaction kinetics, molecular transport, and biomolecular association. This comprehensive review delves into the utility of BD simulations within the realms of chemistry and biology.
View Article and Find Full Text PDFBiomimetics (Basel)
November 2024
Department of Theoretical Physics, Kursk State University, Radishcheva St. 33, Kursk 305000, Russia.
Recent studies of the spread of substances penetrating the disrupted blood-brain barrier have revealed that the spread in the parenchyma surrounding a vessel has a complex character. In particular, a flow-like motion occurred for a short time that exhibits a smooth transition to diffusional spread. To address the possible physical background of such behavior, we created a system formed by a hydrogel medium with a channel filled by a marker solution, which can serve as a physical model mimicking the process of a substance passively spreading to the brain's parenchyma when the blood-brain barrier is disrupted.
View Article and Find Full Text PDFChem Sci
December 2024
Department of Chemistry, National Taiwan University Taipei 10617 Taiwan Republic of China
By strategic design and synthesis of a new series of phosphonium salts (compounds 1-7[OTf]), where [OTf] stands for the trifluoromethanesulfonate anion, we performed comprehensive spectroscopic and dynamic studies on the photoinduced anion migration in toluene. Our aim is to probe if the anion migration is associated with an intrinsic barrier or is barrier-free. After the occurrence of excited-state intramolecular charge transfer (ESICT) in 1-7, the charge redistribution of the cation triggers the translocation of the counter anion [OTf], resulting in emission spectral temporal evolution.
View Article and Find Full Text PDFJ Chem Phys
October 2024
Graduate School of Engineering, Nagoya Institute of Technology, Nagoya 466-8555, Japan.
In molecular simulations, efficient methods for investigating equilibration and slow relaxation in dense systems are crucial yet challenging. This study focuses on the diffusional characteristics of monodisperse hard disk systems at equilibrium, comparing novel methodologies of event-chain Monte Carlo variants, specifically the Newtonian event-chain and straight event-chain algorithms. We systematically analyze both event-based and CPU time-based efficiency in liquid and solid phases, aiming to elucidate the microscopic mechanisms underlying structural relaxation.
View Article and Find Full Text PDFFEBS Lett
November 2024
Laboratory of Systems Biology, Department of Cybernetics, Tallinn University of Technology, Estonia.
Intracellular molecules are transported by motor proteins or move by diffusion resulting from random molecular motion. Cardiomyocytes are packed with structures that are crucial for function, but also confine the diffusional spaces, providing cells with a means to control diffusion. They form compartments in which local concentrations are different from the overall, average concentrations.
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