Facilitated and Non-Gaussian Diffusion of Cholesterol in Liquid Ordered Phase Bilayers Depends on the Flip-Flop and Spatial Arrangement of Cholesterol

Oh, Young Hoon; Sung, Bong June

doi:10.1021/acs.jpclett.8b02982

Cited by 15 publications

(17 citation statements)

References 71 publications

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“…In this case of (σ np , ϕ, ϵ ij ) = (3σ, 6%, 1ϵ), the NP diffuses much longer distance during t = 100 than expected by the diffusion coefficient ( D ∥,np ). Such a non-Gaussian diffusion often indicates that the dynamics of NPs might be spatially heterogeneous. − …”

Section: Resultsmentioning

confidence: 99%

Spatial Dependence of Non-Gaussian Diffusion of Nanoparticles in Free-Standing Thin Polymer Films

Jung

Kwon

et al. 2019

J. Phys. Chem. B

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The addition of nanoparticles (NPs) to a free-standing polymer film affects the properties of the film such as viscosity and glass transition temperature. Recent experiments, for example, showed that the glass transition temperature of thin polymer films was dependent on how NPs were distributed within the polymer films. However, the spatial arrangement of NPs in free-standing polymer films and its effect on the diffusion of NPs and polymers remain elusive at a molecular level. In this study, we employ generic coarse-grained models for polymers and NPs and perform extensive molecular dynamics simulations to investigate the diffusion of polymers and NPs in free-standing thin polymer films. We find that small NPs are likely to stay at the interfacial region of the polymer film, while large NPs tend to stay at the center of the film. On the other hand, as the interaction between a NP and a monomer becomes more attractive, the NP is more likely to be placed at the film center. The diffusion of monomers slows down slightly as more NPs are added to the film. Interestingly, the NP diffusion is dependent strongly on the spatial arrangement of the NPs: NPs at the interfacial region diffuse faster and undergo more non-Gaussian diffusion than NPs at the film center, which implies that the interfacial region would be more mobile and dynamically heterogeneous than the film center. We also find that the mechanism for non-Gaussian diffusion of NPs at the film center differs from that at the interfacial region and that the NP diffusion would reflect the local viscosity of the polymer films.

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Section: Resultsmentioning

confidence: 99%

Spatial Dependence of Non-Gaussian Diffusion of Nanoparticles in Free-Standing Thin Polymer Films

Jung

Kwon

et al. 2019

J. Phys. Chem. B

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“…The short-time MSD of vesicle motion only marginally increases with time, because at this time scale, active motion of the MPM is negligible compared to the quasi-stationary thermal fluctuation of vesicle position with respect to the MPM. It is interesting to note that the short-time VDD has an exponential tail, a commonly observed feature of thermal motion in disordered fluids. − The VDD along the microtubule becomes a power-law distribution after 0.5 s where the MPM’s active motion is the major contributor to vesicle displacement (Figure f–h).…”

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confidence: 96%

Anomalous Dynamics of in Vivo Cargo Delivery by Motor Protein Multiplexes

Shin

Song

et al. 2019

J. Phys. Chem. Lett.

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Vesicle transport conducted by motor protein multiplexes (MPMs), which is ubiquitous among eukaryotes, shows anomalous and stochastic dynamics qualitatively different from the dynamics of thermal motion and artificial active matter; the relationship between in vivo vesicle-delivery dynamics and the underlying physicochemical processes is not yet quantitatively understood. Addressing this issue, we perform accurate tracking of individual vesicles, containing upconverting nanoparticles, transported by kinesin−dynein-multiplexes along axonal microtubules. The mean-square-displacement of vesicles along the microtubule exhibits unusual dynamic phase transitions that are seemingly inconsistent with the scaling behavior of the meanfirst-passage time over the travel length. These paradoxical results and the vesicle displacement distribution are quantitatively explained and predicted by a multimode MPM model, developed in the current work, where ATP-hydrolysis-coupled motion of MPM has both unidirectional and bidirectional modes.

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“…9−13 Coarse grain simulations suggested that cholesterol may enter the interleaflet space and produce domains by increasing membrane thickness that way. 13 This prediction, however, is not supported by any experimental evidence thus far. Hence, there is an impetus to perform ultrahigh spatial resolution morphological and spectroscopic mapping to identify the localization and distribution of cholesterol in lipid bilayers.…”

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confidence: 88%

“…Information on the spatial distribution of cholesterol within and between membrane domains is not accessible with bulk methods, and until recently, there have not been any microscopy methods to perform simultaneous morphological and chemical mapping on the nanometer scale. Computational studies were attempted to overcome this limitation. − Coarse grain simulations suggested that cholesterol may enter the interleaflet space and produce domains by increasing membrane thickness that way . This prediction, however, is not supported by any experimental evidence thus far.…”

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confidence: 99%

Nanoscale Probing of Cholesterol-Rich Domains in Single Bilayer Dimyristoyl-Phosphocholine Membranes Using Near-Field Spectroscopic Imaging

Siddiquee

Houri

Messalea

et al. 2020

J. Phys. Chem. Lett.

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Cholesterol is believed to induce the formation of membrane domains, “rafts”, which are implicated in a range of natural and pathologic membrane processes. Therefore, it is important to understand the role that cholesterol plays in the formation of these structures. Here, we use label-free spectroscopic imaging to investigate cholesterol fractioning in supported bilayer membranes at nanoscale. Scattering-type scanning near-field optical microscopy (s-SNOM) was used to visualize the formation of cholesterol-induced domains in 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) membranes. Our results revealed the coexistence of phase separated domains in DMPC lipids with 10 mol % cholesterol content, whereas a mostly homogeneous bilayer was found at low (5 mol %) and high (15 mol %) cholesterol content. Near-field nano-FTIR spectroscopy was used to identify the cholesterol-rich domains based on their qualitative chemical compositions. It was determined that cholesterol binds to phosphodiester and alkyl glycerol ester moieties, likely via hydrogen bonding of the alcohol to either of the ester oxygens. The results also confirm the existence of an ideal cholesterol-lipid mixture ratio (∼15:85) with a geometrically defined packing. At lower cholesterol content there is phase separation between liquid ordered and almost neat DMPC domains. Thus, the liquid ordered phase exists at an energy minimum at a given lipid–cholesterol ratio.

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Facilitated and Non-Gaussian Diffusion of Cholesterol in Liquid Ordered Phase Bilayers Depends on the Flip-Flop and Spatial Arrangement of Cholesterol

Cited by 15 publications

References 71 publications

Spatial Dependence of Non-Gaussian Diffusion of Nanoparticles in Free-Standing Thin Polymer Films

Spatial Dependence of Non-Gaussian Diffusion of Nanoparticles in Free-Standing Thin Polymer Films

Anomalous Dynamics of in Vivo Cargo Delivery by Motor Protein Multiplexes

Nanoscale Probing of Cholesterol-Rich Domains in Single Bilayer Dimyristoyl-Phosphocholine Membranes Using Near-Field Spectroscopic Imaging

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