Tag Archives: PointProbe Plus

articles on the PointProbe Plus AFM probe series

Temperature effects on the nano-friction across exposed atomic step edges

In the article “Temperature effects on the nano-friction across exposed atomic step edges” Wen Wang, Ashu Wang and Lingyan Zeng describe how they used friction force microscopy ( FFM ) under ultrahigh vacuum ( UHV) conditions to study the temperature dependence of nanoscale friction between a silicon AFM tip ( NANOSENSORS™ PointProbe® Plus PPP-LFMR AFM probe for lateral/friction force microscopy ) and a freshly cleaved HOPG surface with exposed single- and double-layer step edges.*

They present experimental measurements as well as theoretical calculations of the temperature effects on atomic friction across HOPG surface step edges.*

Among other things the authors found that the resistive force for the double-layer step edge was twice as large as that of the single-step edge, and simultaneously, the assistive force that resulted from the horizontal component of the total force acting on the AFM tip seemed to be less influenced by the height of the step edges.*

Their experimental results also showed that temperature had very little effect on the friction coefficients at the step edges, which is inconsistent with the thermal activated friction where friction should decrease with temperature.*

Based on the theoretical studies, this observation can be explained by a process where the temperature effect is very small compared with the edge Schwoebel–Ehrlich barrier.*

The authors hope that their findings will contribute to understanding the temperature effects on macroscopic friction having a lot of step edges at the interface.*

Figure 1 from “Temperature effects on the nano-friction across exposed atomic step edges” by Wen Wang et al.:
 Experimental setup and the topographic image of the HOPG surface with step edges used in our measurements. (a) Illustration of the experimental setup. All experiments have been performed using a conventional friction force microscope on a freshly cleaved HOPG sample which was in contact with the temperature control stage under UHV conditions. (b) The typical topographic image of the HOPG surface with a single- and double-layer step edge obtained at T = 297.7 K using the contact mode operation with an applied normal force of 13.1 nN and a scan velocity of 1.25 μm/s. (c) The cross-section height profile across the step edges highlighted in (b). The black arrows in (b) and (c) indicate the scanning direction.  NANOSENSORS PointProbe Plus PPP-LFMR AFM probes for lateral force microscopy and friction force microscopy were used.
Figure 1 from “Temperature effects on the nano-friction across exposed atomic step edges” by Wen Wang et al.:
 Experimental setup and the topographic image of the HOPG surface with step edges used in our measurements. (a) Illustration of the experimental setup. All experiments have been performed using a conventional friction force microscope on a freshly cleaved HOPG sample which was in contact with the temperature control stage under UHV conditions. (b) The typical topographic image of the HOPG surface with a single- and double-layer step edge obtained at T = 297.7 K using the contact mode operation with an applied normal force of 13.1 nN and a scan velocity of 1.25 μm/s. (c) The cross-section height profile across the step edges highlighted in (b). The black arrows in (b) and (c) indicate the scanning direction.

*Wen Wang, Ashu Wang and Lingyan Zeng
Temperature effects on the nano-friction across exposed atomic step edges
AIP Advances 10, 085322 (2020)
DOI: https://doi.org/10.1063/5.0019196

Please follow this external link to read the full article: https://aip.scitation.org/doi/10.1063/5.0019196

Open Access The article “Temperature effects on the nano-friction across exposed atomic step edges” by Wen Wang, Ashu Wang and Lingyan Zeng 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/.

Development of a Lidocaine-Loaded Alginate/CMC/PEO Electrospun Nanofiber Film and Application as an Anti-Adhesion Barrier

Surgery, particularly open surgery, is known to cause tissue/organ adhesion during healing. These adhesions occur through contact between the surgical treatment site and other organ, bone, or abdominal sites. Fibrous bands can form in unnecessary contact areas and cause various complications. Consequently, film- and gel-type anti-adhesion agents have been developed. The development of sustained drug delivery systems is very important for disease treatment and prevention.*

In “Development of a Lidocaine-Loaded Alginate/CMC/PEO Electrospun Nanofiber Film and Application as an Anti-Adhesion Barrier” Seungho Baek, Heekyung Park, Youngah Park, Hyun Kang and Donghyun Lee describe how the drug release behavior was controlled by crosslinking lidocaine-loaded alginate/carboxymethyl cellulose (CMC)/polyethylene oxide (PEO) nanofiber films prepared by electrospinning.*

Lidocaine is mainly used as an anesthetic and is known to have anti-adhesion effects.*

Based on the results presented in the article, this study shows that the drug release behavior can be controlled by using CaCl2 as a nontoxic crosslinking agent to produce a good anti-adhesion barrier that can prevent unnecessary tissue adhesion at a surgical site.*

The authors selected atomic force microscopy (AFM) using NANOSENSORS™ PointProbe® Plus PPP-NCHR AFM cantilevers to analyze the electrospun films.*

Figure 3 from “Development of a Lidocaine-Loaded Alginate/CMC/PEO Electrospun Nanofiber Film and Application as an Anti-Adhesion Barrier” by Seungho Baek et al.:
Morphological and surface characterization of the 9% (w/v) alginate/CMC/PEO nanofiber film. Analyses used the noncontact mode of atomic microscopy. (a–c) are the same films at different scales (scale bars 40 µm, 15 µm, and 5 µm).
Figure 3 from “Development of a Lidocaine-Loaded Alginate/CMC/PEO Electrospun Nanofiber Film and Application as an Anti-Adhesion Barrier” by Seungho Baek et al.:
Morphological and surface characterization of the 9% (w/v) alginate/CMC/PEO nanofiber film. Analyses used the noncontact mode of atomic microscopy. (a–c) are the same films at different scales (scale bars 40 µm, 15 µm, and 5 µm).

*Seungho Baek, Heekyung Park, Youngah Park, Hyun Kang and Donghyun Lee
Development of a Lidocaine-Loaded Alginate/CMC/PEO Electrospun Nanofiber Film and Application as an Anti-Adhesion Barrier
Polymers 2020, 12(3), 618
DOI: https://doi.org/10.3390/polym12030618

Please follow this external link to read the full article: https://www.mdpi.com/2073-4360/12/3/618/htm

Open Access: The article “Development of a Lidocaine-Loaded Alginate/CMC/PEO Electrospun Nanofiber Film and Application as an Anti-Adhesion Barrier” by Seungho Baek, Heekyung Park, Youngah Park, Hyun Kang and Donghyun Lee 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/.

Selective oxidation of B800 bacteriochlorophyll a in photosynthetic light-harvesting protein LH2

Engineering chlorophyll (Chl) pigments that are bound to photosynthetic light-harvesting proteins is one promising strategy to regulate spectral coverage for photon capture and to improve the photosynthetic efficiency of these proteins.*

The in situ oxidation of BChl a in light-harvesting protein LH2 from a purple bacterium Rhodoblastus acidophilus by 2,3-dichloro-5,6-dicyano-1,4-benzoquinone demonstrated in the article “Selective oxidation of B800 bacteriochlorophyll a in photosynthetic light-harvesting protein LH2” by Yoshitaka Saga et al. will be useful for engineering photofunctions in natural light-harvesting proteins and for understanding the alteration from BChl pigments in anoxygenic photosynthetic bacteria to Chl pigments in oxygenic organisms in the evolution of photosynthesis.*

The authors observed their sample in 20 mM Tris buffer containing 150 mM NaCl (pH 8.0) using a  home-built frequency modulation AFM ( FM-AFM ) with NANOSENSORS™ PPP-NCHAuD AFM probes.*

Figure 6 from «Selective oxidation of B800 bacteriochlorophyll a in photosynthetic light-harvesting protein LH2” by Y. Saga et al.: FM-AFM images of native LH2 (A) and oxidized LH2 (B) adsorbed on mica taken in 20 mM Tris buffer containing 150 mM NaCl (pH 8.0). Left: wide images. Middle: locally enlarged images of single LH2 proteins. Right: overlapped height-profiles of ten proteins. NANOSENSORS PPP-NCHAuD AFM probes were used.
Figure 6 from «Selective oxidation of B800 bacteriochlorophyll a in photosynthetic light-harvesting protein LH2” by Y. Saga et al.: FM-AFM images of native LH2 (A) and oxidized LH2 (B) adsorbed on mica taken in 20 mM Tris buffer containing 150 mM NaCl (pH 8.0). Left: wide images. Middle: locally enlarged images of single LH2 proteins. Right: overlapped height-profiles of ten proteins.

*Yoshitaka Saga, Kiyoshiro Kawano, Yuji Otsuka, Michie Imanishi, Yukihiro Kimura, Sayaka Matsui & Hitoshi Asakawa
Selective oxidation of B800 bacteriochlorophyll a in photosynthetic light-harvesting protein LH2
Nature, Scientific Reports, volume 9, Article number: 3636 (2019)
DOI: https://doi.org/10.1038/s41598-019-40082-y

Please follow this external link to read the full article: https://www.nature.com/articles/s41598-019-40082-y

Open Access The article “Selective oxidation of B800 bacteriochlorophyll a in photosynthetic light-harvesting protein LH2” by Yoshitaka Saga, Kiyoshiro Kawano, Yuji Otsuka, Michie Imanishi, Yukihiro Kimura, Sayaka Matsui & Hitoshi Asakawa 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/.