Tag: 高速AFMプローブ

Carbon nanotube porin diffusion in mixed composition supported lipid bilayers

Lipid membranes play a key role in living systems by providing a structural barrier that separates cellular compartments. Bilayer fluidity in the lateral plane is a key property of lipid membranes, that allows the membrane to have sufficient flexibility to accommodate dynamic stresses, shape changes and rearrangements accompanying the cellular lifecycle.*

In the article “Carbon nanotube porin diffusion in mixed composition supported lipid bilayers” Kylee Sullivan, Yuliang Zhang, Joseph Lopez, Mary Lowe and Aleksandr Noy describe how they used high-speed atomic force microscopy (HS-AFM) and all-atom molecular dynamics (MD) simulations to study the behavior of CNTPs in a mixed lipid membrane consisting of DOPC lipid with a variable percentage of DMPC lipid added to it. HS-AFM data reveal that the CNTPs undergo diffusive motion in the bilayer plane.*

Motion trajectories extracted from the HS-AFM movies indicate that CNTPs exhibit diffusion coefficient values broadly similar to values reported for membrane proteins in supported lipid bilayers. The data also indicate that increasing the percentage of DMPC leads to a marked slowing of CNTP diffusion. MD simulations reveal a CNTP-lipid assembly that diffuses in the membrane and show trends that are consistent with the experimental observations. *

The above-mentioned study confirms that CNTPs mimic the major features of the diffusive movement of biological pores in lipid membranes and shows how the increase in bilayer viscosity leads to a corresponding slowdown in protein motion. It should be possible to extend this approach to studies of other membrane protein dynamics in supported lipid bilayers. The authors note that those studies, however, will need to be mindful of the challenge of unambiguous visualization of the membrane components, especially in systems that incorporate smaller proteins, such as antimicrobial peptides. Another challenge that could complicate these studies would be microscopic phase separation of the lipid matrix that could lead to complicated pore dynamics in the membrane. *

NanoWorld Ultra-Short AFM cantilevers with high-density carbon/diamond-like carbon (HDC/DLC) AFM tips of the USC-F1.2-k0.15 type were used for the high-speed atomic force microscopy described in the article. *

Figure 2 from “Carbon nanotube porin diffusion in mixed composition supported lipid bilayers” by Kylee Sullivan et al.: CNTP motion in supported lipid bilayers. (a) Representative frames (with times in seconds indicated on each image) from an HS-AFM movie showing a CNTP diffusing in a supported lipid bilayer with 80:20 DOPC-DMPC ratio (see also Supplementary Movie 2). (b) A representative trajectory for CNTP diffusion in the bilayer. The time step between each datapoint is 0.5 s. NanoWorld Ultra-Short AFM Cantilvers USC-F1.2-k0.15 were used for the HS-AFM imaging
Figure 2 a and b from “Carbon nanotube porin diffusion in mixed composition supported lipid bilayers” by Kylee Sullivan et al.:

CNTP motion in supported lipid bilayers. (a) Representative frames (with times in seconds indicated on each image) from an HS-AFM movie showing a CNTP diffusing in a supported lipid bilayer with 80:20 DOPC-DMPC ratio (see also Supplementary Movie 2). (b) A representative trajectory for CNTP diffusion in the bilayer. The time step between each datapoint is 0.5 s.
Please refer to the full article cited below for the full figure.

*Kylee Sullivan, Yuliang Zhang, Joseph Lopez, Mary Lowe and Aleksandr Noy
Carbon nanotube porin diffusion in mixed composition supported lipid bilayers
Nature Scientific Reports volume 10, Article number: 11908 (2020)
DOI: https://doi.org/10.1038/s41598-020-68059-2

Please follow this external link to read the full article: https://rdcu.be/b69wj

Open Access : The article “Carbon nanotube porin diffusion in mixed composition supported lipid bilayers” by Kylee Sullivan, Yuliang Zhang, Joseph Lopez, Mary Lowe and Aleksandr Noy is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit https://creativecommons.org/licenses/by/4.0/.

Photoresponsive Photoacid-Macroion Nano-Assemblies

In mother nature, the concept of self-assembly is vital for life, as it generates much of the functionality of living cells. It also bears great synthetic potential for the formation of versatile, switchable, and functional nanostructures.*

Noncovalent interactions can be triggered by external influences, such as the change of pH, light irradiation, thermal activation, introduction of a magnetic field, moisture, or redox response. Of high interest are light-responsive systems, for example in the fields of sensors or therapy, and, thus, it is desirable to explore novel concepts toward light-triggerable self-assembly.*

In the article “Photoresponsive Photoacid-Macroion Nano-Assemblies” Alexander Zika, Sarah Bernhardt and Franziska Gröhn present light-responsive nano-assemblies with light-switchable size based on photoacids.*

Anionic disulfonated napthol derivates and cationic dendrimer macroions are used as building blocks for electrostatic self-assembly. Nanoparticles are already formed under the exclusion of light as a result of electrostatic interactions. Upon photoexcitation, an excited-state dissociation of the photoacidic hydroxyl group takes place, which leads to a more highly charged linker molecule and, subsequently, to a change in size and structure of the nano-assemblies. The effects of the charge ratio and the concentration on the stability have been examined with absorption spectroscopy and -potential measurements.*

The influence of the chemical structure of three isomeric photoacids on the size and shape of the nanoscale aggregates has been studied by dynamic light scattering and atomic force microscopy, revealing a direct correlation of the strength of the photoacid with the changes of the assemblies upon irradiation.*

NanoWorld Ultra-Short AFM Cantilevers of the USC-F0.3-k0.3 type ( typical force constant 0.3 N/m ) were operated in tapping mode for the Atomic Force Microscopy (AFM) images presented in the article.*

Figure 1 a from “Photoresponsive Photoacid-Macroion Nano-Assemblies” by Alexander Zika et al: Assembly formation and photoresponse of the dendrimer–photoacid system at a charge ratio of r = 0.25: (a) AFM height images before (right) and after (left) irradiation. Figure 1 a from “Photoresponsive Photoacid-Macroion Nano-Assemblies” by Alexander Zika et al: Assembly formation and photoresponse of the dendrimer–photoacid system at a charge ratio of r = 0.25: (a) AFM height images before (right) and after (left) irradiation.
Figure 1 a from “Photoresponsive Photoacid-Macroion Nano-Assemblies” by Alexander Zika  et al:
Assembly formation and photoresponse of the dendrimer–photoacid system at a charge ratio of r = 0.25: (a) AFM height images before (right) and after (left) irradiation. Please refer to the full article for the full figure https://www.mdpi.com/2073-4360/12/8/1746

*Alexander Zika, Sarah Bernhardt and Franziska Gröhn
Photoresponsive Photoacid-Macroion Nano-Assemblies
Polymers 2020, 12, 1746
DOI: 10.3390/polym12081746

Please follow this external link to read the full article: https://www.mdpi.com/2073-4360/12/8/1746

Open Access : The article “Photoresponsive Photoacid-Macroion Nano-Assemblies” by Alexander Zika, Sarah Bernhardt and Franziska Gröhn is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.

NanoWorld Screencast on Ultra-Short Cantilevers (USC) for High-Speed AFM (HS-AFM) and video rate Atomic Force Microscopy passes 1000 views mark

The screencast on Ultra-Short Cantilevers (USC) for High Speed AFM (HS-AFM)  and video rate Atomic Force Microscopy held by Mathieu Burri  has just reached the 1000 views mark. Congratulations Mathieu!

The Ultra-Short Cantilevers series combines very small cantilevers capable of resonating in the MHz regime and a very sharp and wear resistant tip and is dedicated to High-Speed AFM (HS-AFM). The Ultra-Short Cantilevers series consists of six different types of probes which cover the complete range of high speed scanning applications, from non-contact mode to contact mode, from measurements in air to measurements in liquid.

More information such as high speed videos, an image gallery and a regularly updated reference list of scientific articles on high speed AFM can be found on the dedicated website: https://www.highspeedscanning.com/ . You can also find references to scientific articles mentioning the use of NanoWorld USC AFM probes on the NanoWorld blog.

If you haven’t seen the USC screencast yet have a look at:

NanoWorld ULTRA-SHORT CANTILEVERS for High-Speed AFM

A Chinese Version of this screencast is also available: