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Mechanics of lipid bilayer junctions affecting the size of a connecting lipid nanotube.

Karlsson R, Kurczy M, Grzhibovskis R, Adams KL, Ewing AG, Cans AS, Voinova MV - Nanoscale Res Lett (2011)

Bottom Line: An electrochemical method monitoring diffusion of electroactive molecules through the nanotube has been used to determine the radius of the nanotube R as a function of nanotube length L for the two configurations.The data show that the LNT connected in the TVC constricts to a smaller radius in comparison to the tube-only mode and that tube radius shrinks at shorter tube lengths.In particular, this model allows us to estimate the surface tension coefficients from R(L) measurements.

View Article: PubMed Central - HTML - PubMed

Affiliation: BioNano Systems Laboratory, Institute for Microtechnology and Nanoscience, Chalmers University of Technology, 41296 Gothenburg, Sweden. marina.voinova@chalmers.se.

ABSTRACT
In this study we report a physical analysis of the membrane mechanics affecting the size of the highly curved region of a lipid nanotube (LNT) that is either connected between a lipid bilayer vesicle and the tip of a glass microinjection pipette (tube-only) or between a lipid bilayer vesicle and a vesicle that is attached to the tip of a glass microinjection pipette (two-vesicle). For the tube-only configuration (TOC), a micropipette is used to pull a LNT into the interior of a surface-immobilized vesicle, where the length of the tube L is determined by the distance of the micropipette to the vesicle wall. For the two-vesicle configuration (TVC), a small vesicle is inflated at the tip of the micropipette tip and the length of the tube L is in this case determined by the distance between the two interconnected vesicles. An electrochemical method monitoring diffusion of electroactive molecules through the nanotube has been used to determine the radius of the nanotube R as a function of nanotube length L for the two configurations. The data show that the LNT connected in the TVC constricts to a smaller radius in comparison to the tube-only mode and that tube radius shrinks at shorter tube lengths. To explain these electrochemical data, we developed a theoretical model taking into account the free energy of the membrane regions of the vesicles, the LNT and the high curvature junctions. In particular, this model allows us to estimate the surface tension coefficients from R(L) measurements.

No MeSH data available.


Related in: MedlinePlus

Comparison of experimental and model results (unified description). The measurement points (shown as markers) for both TVC and TOC plotted after dividing the TVC length by two. Parameters for the model predictions were chosen to minimize functionals (11) (red line) and (10) (blue line).
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Figure 4: Comparison of experimental and model results (unified description). The measurement points (shown as markers) for both TVC and TOC plotted after dividing the TVC length by two. Parameters for the model predictions were chosen to minimize functionals (11) (red line) and (10) (blue line).

Mentions: To explore this theoretical prediction, we divide the lengths obtained in the experiment with TVC by two and plot the resulting data set together with the measurements for TOC on Figure 4. The optimal parameters of the model for this, unified, data are σ/k ≈ 55 μm-2, r ≈ 1.2 nm and σ/k ≈ 71 μm -2, r ≈ 1.6 nm for functionals (10) and (11), respectively. These values are similar to ones for the TOC case since this portion of the data is more disperse and has much greater contributions to functionals (11) and (10) when compared to the data for the TVC case. Figure 4 also shows that the measurements are in agreement in the region, where they overlap, i.e., for values of R between 0.05 and 0.06 μm.


Mechanics of lipid bilayer junctions affecting the size of a connecting lipid nanotube.

Karlsson R, Kurczy M, Grzhibovskis R, Adams KL, Ewing AG, Cans AS, Voinova MV - Nanoscale Res Lett (2011)

Comparison of experimental and model results (unified description). The measurement points (shown as markers) for both TVC and TOC plotted after dividing the TVC length by two. Parameters for the model predictions were chosen to minimize functionals (11) (red line) and (10) (blue line).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211838&req=5

Figure 4: Comparison of experimental and model results (unified description). The measurement points (shown as markers) for both TVC and TOC plotted after dividing the TVC length by two. Parameters for the model predictions were chosen to minimize functionals (11) (red line) and (10) (blue line).
Mentions: To explore this theoretical prediction, we divide the lengths obtained in the experiment with TVC by two and plot the resulting data set together with the measurements for TOC on Figure 4. The optimal parameters of the model for this, unified, data are σ/k ≈ 55 μm-2, r ≈ 1.2 nm and σ/k ≈ 71 μm -2, r ≈ 1.6 nm for functionals (10) and (11), respectively. These values are similar to ones for the TOC case since this portion of the data is more disperse and has much greater contributions to functionals (11) and (10) when compared to the data for the TVC case. Figure 4 also shows that the measurements are in agreement in the region, where they overlap, i.e., for values of R between 0.05 and 0.06 μm.

Bottom Line: An electrochemical method monitoring diffusion of electroactive molecules through the nanotube has been used to determine the radius of the nanotube R as a function of nanotube length L for the two configurations.The data show that the LNT connected in the TVC constricts to a smaller radius in comparison to the tube-only mode and that tube radius shrinks at shorter tube lengths.In particular, this model allows us to estimate the surface tension coefficients from R(L) measurements.

View Article: PubMed Central - HTML - PubMed

Affiliation: BioNano Systems Laboratory, Institute for Microtechnology and Nanoscience, Chalmers University of Technology, 41296 Gothenburg, Sweden. marina.voinova@chalmers.se.

ABSTRACT
In this study we report a physical analysis of the membrane mechanics affecting the size of the highly curved region of a lipid nanotube (LNT) that is either connected between a lipid bilayer vesicle and the tip of a glass microinjection pipette (tube-only) or between a lipid bilayer vesicle and a vesicle that is attached to the tip of a glass microinjection pipette (two-vesicle). For the tube-only configuration (TOC), a micropipette is used to pull a LNT into the interior of a surface-immobilized vesicle, where the length of the tube L is determined by the distance of the micropipette to the vesicle wall. For the two-vesicle configuration (TVC), a small vesicle is inflated at the tip of the micropipette tip and the length of the tube L is in this case determined by the distance between the two interconnected vesicles. An electrochemical method monitoring diffusion of electroactive molecules through the nanotube has been used to determine the radius of the nanotube R as a function of nanotube length L for the two configurations. The data show that the LNT connected in the TVC constricts to a smaller radius in comparison to the tube-only mode and that tube radius shrinks at shorter tube lengths. To explain these electrochemical data, we developed a theoretical model taking into account the free energy of the membrane regions of the vesicles, the LNT and the high curvature junctions. In particular, this model allows us to estimate the surface tension coefficients from R(L) measurements.

No MeSH data available.


Related in: MedlinePlus