Tag Archives: biomaterials

Efficient long-range conduction in cable bacteria through nickel protein wires

Bio-materials typically have an intrinsically low electrical conductivity, and so the availability of a bio-material with extraordinary electrical properties has great potential for new applications in bio-electronics. This prospect of technological application however requires a deeper understanding of the mechanism of electron transport as well as the structure and composition of the conductive fibers in cable bacteria.*

Filamentous cable bacteria display long-range electron transport, generating electrical currents over centimeter distances through a highly ordered network of fibers embedded in their cell envelope. The conductivity of these periplasmic wires is exceptionally high for a biological material, but their chemical structure and underlying electron transport mechanism remain unresolved.*

In their article “Efficient long-range conduction in cable bacteria through nickel protein wires”  Henricus T. S. Boschker, Perran L. M. Cook, Lubos Polerecky, Raghavendran Thiruvallur Eachambadi, Helena Lozano, Silvia Hidalgo-Martinez, Dmitry Khalenkow, Valentina Spampinato, Nathalie Claes, Paromita Kundu, Da Wang, Sara Bals, Karina K. Sand, Francesca Cavezza, Tom Hauffman, Jesper Tataru Bjerg, Andre G. Skirtach, Kamila Kochan, Merrilyn McKee, Bayden Wood, Diana Bedolla, Alessandra Gianoncelli, Nicole M. J. Geerlings, Nani Van Gerven, Han Remaut, Jeanine S. Geelhoed, Ruben Millan-Solsona, Laura Fumagalli, Lars Peter Nielsen, Alexis Franquet, Jean V. Manca, Gabriel Gomila and Filip J. R. Meysman combine high-resolution microscopy, spectroscopy, and chemical imaging on individual cable bacterium filaments to demonstrate that the periplasmic wires consist of a conductive protein core surrounded by an insulating protein shell layer.*

The core proteins contain a sulfur-ligated nickel cofactor, and conductivity decreases when nickel is oxidized or selectively removed. The involvement of nickel as the active metal in biological conduction is remarkable, and suggests a hitherto unknown form of electron transport that enables efficient conduction in centimeter-long protein structures.*

NANOSENSORS wear-resistant conductive Platinum Silicide AFM probes of the PtSi-CONT type were used for the Scanning dielectric microscopy (SDM) described in the article.

Figure 5 from Henricus T. S. Boschker et al. “Efficient long-range conduction in cable bacteria through nickel protein wires” A Compositional model of the conductive fiber sheath in cable bacteria based on the present findings. Cross-sections through a filament in the middle of a cell are drawn and the number of fibers has been reduced for clarity—a 4 μm diameter cable bacterium has typically ~60 fibers5. In its native state (right panel), the fiber sheath is embedded periplasm between the cell and outer membrane and adopts a circular shape. After extraction, which removes the membranes and most of the cytoplasm and after drying upon a surface for analysis, the fiber sheath flattens, leading to two mirrored sheaths on top of each other (middle panel). The enlargement shows a section of the top sheath, which is the sample section probed by ToF-SIMS depth profiles and NanoSIMS images. Fibers are made of protein with a conductive Ni/S rich core and a non-conductive outer shell, and are embedded in a basal layer enriched in polysaccharide. B Topographic AFM image of a fiber sheath with a single isolated fiber detaching. The insert shows a detailed AFM image of this single fiber. C SDM amplitude image (right insert) and cross-sectional profile. D Corresponding SDM phase image (insert) and cross-sectional profile. Constant height (z = 66 nm) cross-section profiles are measured along the dashed lines shown in the left inserts. The red dotted lines in C and D represent model fits assuming the a fiber has a conductive core and an insulating outer shell. The right insert in C shows a vertical cross-section of the electric potential distribution as predicted by the model. Model parameters: shell thickness, d = 12 nm; fiber height, h = 42 nm; fiber width w = 87 nm; relative dielectric constants of the shell and core, εs = ω εc = 3; conductivity of the shell σs = 0 S/cm (insulating); conductivity of the core σc = 20 S/cm7 (see Supplementary Note 2 for treatment of SDM results and models tested). SDM analysis on a single fiber is available only from one samples as this is a rare event, but results from a double fiber and fiber sheaths are in agreement (see Supplementary Note 2). NANOSENSORS wear-resistant conductive Platinum Silicide AFM probes of the PtSi-CONT type were used for the Scanning dielectric microscopy (SDM).
Figure 5 from Henricus T. S. Boschker et al. “Efficient long-range conduction in cable bacteria through nickel protein wires”
A Compositional model of the conductive fiber sheath in cable bacteria based on the present findings. Cross-sections through a filament in the middle of a cell are drawn and the number of fibers has been reduced for clarity—a 4 μm diameter cable bacterium has typically ~60 fibers5. In its native state (right panel), the fiber sheath is embedded periplasm between the cell and outer membrane and adopts a circular shape. After extraction, which removes the membranes and most of the cytoplasm and after drying upon a surface for analysis, the fiber sheath flattens, leading to two mirrored sheaths on top of each other (middle panel). The enlargement shows a section of the top sheath, which is the sample section probed by ToF-SIMS depth profiles and NanoSIMS images. Fibers are made of protein with a conductive Ni/S rich core and a non-conductive outer shell, and are embedded in a basal layer enriched in polysaccharide. B Topographic AFM image of a fiber sheath with a single isolated fiber detaching. The insert shows a detailed AFM image of this single fiber. C SDM amplitude image (right insert) and cross-sectional profile. D Corresponding SDM phase image (insert) and cross-sectional profile. Constant height (z = 66 nm) cross-section profiles are measured along the dashed lines shown in the left inserts. The red dotted lines in C and D represent model fits assuming the a fiber has a conductive core and an insulating outer shell. The right insert in C shows a vertical cross-section of the electric potential distribution as predicted by the model. Model parameters: shell thickness, d = 12 nm; fiber height, h = 42 nm; fiber width w = 87 nm; relative dielectric constants of the shell and core, εs = ω εc = 3; conductivity of the shell σs = 0 S/cm (insulating); conductivity of the core σc = 20 S/cm7 (see Supplementary Note 2 for treatment of SDM results and models tested). SDM analysis on a single fiber is available only from one samples as this is a rare event, but results from a double fiber and fiber sheaths are in agreement (see Supplementary Note 2).

*Henricus T. S. Boschker, Perran L. M. Cook, Lubos Polerecky, Raghavendran Thiruvallur Eachambadi, Helena Lozano, Silvia Hidalgo-Martinez, Dmitry Khalenkow, Valentina Spampinato, Nathalie Claes, Paromita Kundu, Da Wang, Sara Bals, Karina K. Sand, Francesca Cavezza, Tom Hauffman, Jesper Tataru Bjerg, Andre G. Skirtach, Kamila Kochan, Merrilyn McKee, Bayden Wood, Diana Bedolla, Alessandra Gianoncelli, Nicole M. J. Geerlings, Nani Van Gerven, Han Remaut, Jeanine S. Geelhoed, Ruben Millan-Solsona, Laura Fumagalli, Lars Peter Nielsen, Alexis Franquet, Jean V. Manca, Gabriel Gomila and Filip J. R. Meysman
Efficient long-range conduction in cable bacteria through nickel protein wires
Nature Communications volume 12, Article number: 3996 (2021)
DOI: https://doi.org/10.1038/s41467-021-24312-4

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https://rdcu.be/cP0I1

Open Access: The article “Efficient long-range conduction in cable bacteria through nickel protein wires” by Henricus T. S. Boschker, Perran L. M. Cook, Lubos Polerecky, Raghavendran Thiruvallur Eachambadi, Helena Lozano, Silvia Hidalgo-Martinez, Dmitry Khalenkow, Valentina Spampinato, Nathalie Claes, Paromita Kundu, Da Wang, Sara Bals, Karina K. Sand, Francesca Cavezza, Tom Hauffman, Jesper Tataru Bjerg, Andre G. Skirtach, Kamila Kochan, Merrilyn McKee, Bayden Wood, Diana Bedolla, Alessandra Gianoncelli, Nicole M. J. Geerlings, Nani Van Gerven, Han Remaut, Jeanine S. Geelhoed, Ruben Millan-Solsona, Laura Fumagalli, Lars Peter Nielsen, Alexis Franquet, Jean V. Manca, Gabriel Gomila & Filip J. R. Meysman 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 licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence 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 licence, visit http://creativecommons.org/licenses/by/4.0/.

Supercritical carbon dioxide decellularization of plant material to generate 3D biocompatible scaffolds

Biocompatible scaffolds that can be repopulated with human cells have many uses such serving as replacement organs and tissues. Therefore there is an increasing interest in plant-based biomaterials for tissue engineering.*

As the above mentioned scaffolds should mimic the in vivo tissue environment closely they need to provide a fitting structural and biomechanical support to the cells while at the same time promoting cell behaviour and tissue development. *

Currently the standard method to prepare plant tissue to serve as a biocompatible scaffold is to decellularize it with serial chemical treatment.*

In their article “Supercritical carbon dioxide decellularization of plant material to generate 3D biocompatible scaffolds” Ashlee F. Harris, Jerome Lacombe, Sumedha Liyanage, Margaret Y. Han, Emily Wallace, Sophia Karsunky, Noureddine Abidi and Frederic Zenhausern explore another method to produce biocompatible scaffolds.*

They use supercritical carbon dioxide (scCO2) together with 2% peracetic acid to decellularize plant material.*

Their subsequent investigations show that the process of decellularization, scaffold structure preservation and recellularization with human cells is less time consuming than with the standard chemical method.

In a further step the authors of the article describe how they use various scientific methods to evaluate the scaffolds they decellularized by the described scCO2 method.*

Ashlee F. Harris et al. use Atomic Force Microscopy (AFM) in order to find out if the scCO2 treatment had an impact on the mechanical properties of the scaffolds produced with this method.*

With AFM topography measurements they are able to establish that structures such as plant vasculature were preserved.*

The following determination of the Young’s Modulus calculated from multiple force curves of a homogeneous surface section of the produced scaffold shows it to be slightly lower than the one from a chemically decellularized scaffold.*

NANOSENSORS™ uniqprobe qp-BioAC AFM probes ( CB3 nominal values: 80 μm length, 30 μm mean width, 400 nm thickness, force constant 0.06 N/m, resonance frequency 30 kHz) were used for the scaffold measurements with Atomic Force Microscopy.

Figure 3 from “Supercritical carbon dioxide decellularization of plant material to generate 3D biocompatible scaffolds AFM imaging and spectrometry measurement” by Ashlee F. Harris et al.: 
They used AFM surface topography measurements to confirm that the structures such as plant vasculature were preserved after the scSO2 process and used  AFM force curves to calculate the  Young’s Modulus (YM) of the scCO2 decellularized scaffold. NANOSENSORS uniqprobe qp-BioAC AFM probes were used for the described AFM measurments. 
(a) Representative false colored three-dimensional surface mapping images and (b) Young’s modulus of scCO2 and chemically decellularized scaffolds (data as mean ± SEM; n = 5).
Figure 3 from “Supercritical carbon dioxide decellularization of plant material to generate 3D biocompatible scaffolds AFM imaging and spectrometry measurement” by Ashlee F. Harris et al.: (a) Representative false colored three-dimensional surface mapping images and (b) Young’s modulus of scCO2 and chemically decellularized scaffolds (data as mean ± SEM; n = 5).

While the scCo2 method promises to be a faster way to decellularize plant material and produce sterile and biocompatible scaffolds further research will be necessary to determine whether the differences the authors detected between the scaffolds produced with the scCO2 approach and the scaffolds produced with the chemical approach have a major influence on how repopulated cells behave in the achieved scaffolds.*

*Ashlee F. Harris, Jerome Lacombe, Sumedha Liyanage, Margaret Y. Han, Emily Wallace, Sophia Karsunky, Noureddine Abidi and Frederic Zenhausern
Supercritical carbon dioxide decellularization of plant material to generate 3D biocompatible scaffolds
Nature Scientific Reports 11, 3643 (2021)
DOI: https://doi.org/10.1038/s41598-021-83250-9

Please follow this external link to read the full article: https://rdcu.be/cAqW3

Open Access The article “Supercritical carbon dioxide decellularization of plant material to generate 3D biocompatible scaffolds” by Ashlee F. Harris, Jerome Lacombe, Sumedha Liyanage, Margaret Y. Han, Emily Wallace, Sophia Karsunky, Noureddine Abidi and Frederic Zenhausern 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 licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence 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 licence, visit http://creativecommons.org/licenses/by/4.0/.

Plant-Based Scaffolds Modify Cellular Response to Drug and Radiation Exposure Compared to Standard Cell Culture Models

Plant-based scaffolds present many advantages over a variety of biomaterials.*

Recent studies explored their potential to be repopulated with human cells and thus highlight a growing interest for their use in tissue engineering or for biomedical applications. However, it is still unclear if these in vitro plant-based scaffolds can modify cell phenotype or affect cellular response to external stimuli.

In the research article “Plant-Based Scaffolds Modify Cellular Response to Drug and Radiation Exposure Compared to Standard Cell Culture Models “ Jerome Lacombe, Ashlee F. Harris, Ryan Zenhausern, Sophia Karsunsky and Frederic Zenhausern report the characterization of the mechano-regulation of melanoma SK-MEL-28 and prostate PC3 cells seeded on decellularized spinach leaves scaffolds, compared to cells deposited on standard rigid cell culture substrate, as well as their response to drug and radiation treatment.*

In their study the authors show that plant decellularization provide soft scaffolds that match the stiffness range of most of the human tissue and modify cell behavior, including drug and radiation response, compared to standard cell culture models. Because of their distinguished features (natural vasculature, low immunogenicity, low cost, relative ease, etc.) and their wide variations in the shape and structures, these scaffolds offer a multi-controllable model with multiple biochemical and biophysical interactions. However, additional studies are required to determine if they could address important architectural and physical challenges of the in vivo tissue environment.

For force measurement, the Young’s Modulus (YM) of the leaf scaffolds were determined using force spectroscopy mode at liquid interface with NANOSENSORS uniqprobe qp-BioAC AFM probes for leaves measurement.*

NANOSENSORS uniqprobe qp-BioAC AFM probe top view (SEM image
NANOSENSORS uniqprobe qp-BioAC AFM probe top view (SEM image)

*Jerome Lacombe, Ashlee F. Harris, Ryan Zenhausern, Sophia Karsunsky and Frederic Zenhausern
Plant-Based Scaffolds Modify Cellular Response to Drug and Radiation Exposure Compared to Standard Cell Culture Models
Frontiers in Bioengineering and Biotechnology (2020) 8:932.
DOI: 10.3389/fbioe.2020.00932

Please follow this external link to read the full article: https://www.frontiersin.org/articles/10.3389/fbioe.2020.00932/full#B27

Open Access: The article “Plant-Based Scaffolds Modify Cellular Response to Drug and Radiation Exposure Compared to Standard Cell Culture Models” by Jerome Lacombe, Ashlee F. Harris, Ryan Zenhausern, Sophia Karsunsky and Frederic Zenhausern 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/.