Tag: non-contact AFM

Self-assembled PCBM bilayers on graphene and HOPG examined by AFM and STM

In the article «Self-assembled PCBM bilayers on graphene and HOPG examined by AFM and STM” Yanlong Li, Chuanhui Chen, John Burton, Kyungwha Park, James R Heflin and Chenggang Tao demonstrate that PCBM molecules self-assemble into bilayer structures on graphene and HOPG substrates. They used Atomic Force Microscopy (AFM) and Scanning Tunneling Microscopy (STM), and analyzed the observed morphology by comparison to molecular models.*

The AFM measurements were carried out in a dark environment. NanoWorld™ Pointprobe® NCST AFM probes were used in soft tapping mode and simultaneous height and phase images were acquired and reproduced across multiple samples.*

The results of this study shed light on improvement of the energy efficiency in solar cells containing graphene and organic molecules, by increasing the donor–acceptor interface area and could provide valuable insight into fabrication of new hybrid, ordered structures for applications to organic solar cells.*

Figure 5. from “Self-assembled PCBM bilayers on graphene and HOPG examined by AFM and STM” by Yanlong Li et al.: AFM images of PCBM bilayer and size distributions of holes at different conditions. (a) AFM image of a PCBM bilayer before annealing. (b) AFM image of a PCBM bilayer after annealing at 140 °C. (c) AFM image of a PCBM bilayer after annealing at 160 °C. (d) Area distribution histogram of holes (without PCBM area) obtained from measurements of the area of holes in AFM images of before (green) and after annealing at 140 °C (dark red) and 160 °C (dark blue). Monolithic silicon cantilevers (NCST, NANO WORLD) with a spring constant of 7.4 N m−1, first longitudinal resonance frequencies between 120 and 205 kHz, and nominal tip radius of 8 nm were employed in soft tapping mode. Simultaneous height and phase images were acquired and reproduced across multiple samples.
Figure 5. from “Self-assembled PCBM bilayers on graphene and HOPG examined by AFM and STM” by Yanlong Li et al.: AFM images of PCBM bilayer and size distributions of holes at different conditions. (a) AFM image of a PCBM bilayer before annealing. (b) AFM image of a PCBM bilayer after annealing at 140 °C. (c) AFM image of a PCBM bilayer after annealing at 160 °C. (d) Area distribution histogram of holes (without PCBM area) obtained from measurements of the area of holes in AFM images of before (green) and after annealing at 140 °C (dark red) and 160 °C (dark blue).

*Yanlong Li, Chuanhui Chen, John Burton, Kyungwha Park, James R Heflin, Chenggang Tao
Self-assembled PCBM bilayers on graphene and HOPG examined by AFM and STM
Nanotechnology, Volume 29, Number 18 (2018)
DOI: https://doi.org/10.1088/1361-6528/aab00a

Open Access The article “Self-assembled PCBM bilayers on graphene and HOPG examined by AFM and STM” by Yanlong Li et al. is licensed under a Creative Commons Attribution 3.0 International License. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. To view a copy of this license, visit https://creativecommons.org/licenses/by/3.0/

Effective gamma-ray sterilization and characterization of conductive polypyrrole biomaterials

“Conductive polymers, including polypyrrole (PPy), have been extensively explored to fabricate electrically conductive biomaterials for bioelectrodes and tissue engineering scaffolds. For their in vivo uses, a sterilization method without severe impairment of original material properties and performance is necessary. Gamma-ray radiation has been commonly applied for sterilization of medical products because of its simple and uniform sterilization without heat generation.[…]”*

In the article “Effective gamma-ray sterilization and characterization of conductive polypyrrole biomaterials” by Semin Kim et. al cited here, the authors describe the first study on gamma-ray sterilization of PPy bioelectrodes and its effects on their characteristics.

The surface topography and roughness of the PPy and γ-PPy electrodes were analyzed by atomic force microscopy. The experiments were performed using a NanoWorld Pointprobe® NCHR AFM probe. All images were acquired at a 0.3 Hz scan rate in tapping mode.

Figure 2 from “Effective gamma-ray sterilization and characterization of conductive polypyrrole biomaterials”: (a) Atomic force micrographs of PPy and γ-PPy samples irradiated with different doses of gamma-ray. (b) Average roughness (root mean square) of PPy and γ-PPy samples. NanoWorld Pointprobe NCHR AFM probes were used for the imaging.
Figure 2 from “Effective gamma-ray sterilization and characterization of conductive polypyrrole biomaterials”: (a) Atomic force micrographs of PPy and γ-PPy samples irradiated with different doses of gamma-ray. (b) Average roughness (root mean square) of PPy and γ-PPy samples.

*Semin Kim, Jin-Oh Jeong, Sanghun Lee, Jong-Seok Park, Hui-Jeong Gwon, Sung In Jeong, John George Hardy, Youn-Mook Lim, Jae Young Lee
Effective gamma-ray sterilization and characterization of conductive polypyrrole biomaterials
Nature Scientific Reports, volume 8, Article number: 3721 (2018)
DOI: https://doi.org/10.1038/s41598-018-22066-6

Please follow this external link for the full article: https://rdcu.be/bariF

Open Access: The article “Effective gamma-ray sterilization and characterization of conductive polypyrrole biomaterials” by Semin Kim et. al 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/.

 

Mussel adhesion is dictated by time-regulated secretion and molecular conformation of mussel adhesive proteins

We have a month with “R” again and the shellfish season has started in the Northern Hemisphere. So we’d like to share the Nature Communications article by Petrone et. al “Mussel adhesion is dictated by time-regulated secretion and molecular conformation of mussel adhesive proteins” with you.
A NanoWorld Pointprobe® NCSTR AFM probe was used for the AFM images in this paper. This AFM probe is designed to give extra stability and accuracy during soft tapping mode imaging in order to produce higher quality AFM images while minimizing sample damage.

Supplementary Figure 16 from Petrone et. al "Mussel adhesion is dictated by time-regulated secretion and molecular conformation of mussel adhesive proteins": Atomic Force Microscopy (AFM) of mussel adhesive proteins on mica. AFM images of dry Pvfp-3α and Pvfp-5β adsorbed from 0.02 mg ml-1 solution in 5% acetic acid and 0.25 MO3 on mica. After 20 min adsorption, the mica surfaces were washed with protein -free buffer, and the AFM images show the homogenous distribution of the resulting adsorbed proteins. The height profiles for both proteins are shown in the graphs below, corresponding to the dotted red and blue lines in the respective AFM images (see black arrows).
Supplementary Figure 16 from Petrone et. al “Mussel adhesion is dictated by time-regulated
secretion and molecular conformation of mussel adhesive proteins”:
Atomic Force Microscopy (AFM) of mussel adhesive proteins on mica. AFM images of dry Pvfp-3α and Pvfp-5β adsorbed from 0.02 mg ml-1 solution in 5% acetic acid and 0.25 MO3 on mica. After 20 min adsorption, the mica surfaces were washed with protein -free buffer, and the AFM images show the homogenous distribution of the resulting adsorbed proteins. The height profiles for both proteins are shown in the graphs below, corresponding to the dotted red and blue lines in the respective AFM images (see black arrows).

Luigi Petrone, Akshita Kumar, Clarinda N. Sutanto, Navinkumar J. Patil, Srinivasaraghavan Kannan, Alagappan Palaniappan, Shahrouz Amini, Bruno Zappone, Chandra Verma, Ali Miserez
Mussel adhesion is dictated by time-regulated secretion and molecular conformation of mussel adhesive proteins
Nature Communications volume 6, Article number: 8737 (2015)
DOI https://doi.org/10.1038/ncomms9737

Please follow this external link for the full article: https://rdcu.be/5vcI

The article by Petrone, L.et al. “Mussel adhesion is dictated by time-regulated secretion and molecular conformation of mussel adhesive proteins” is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/