Preis, I. ; Abramson, M. ; Shoseyov, O. .
The Modification Of Cell Wall Properties By Expression Of Recombinant Resilin In Transgenic Plants.
2018,
60, 310 - 318.
Publisher's VersionAbstractPlant tissue is composed of many different types of cells. Plant cells required to withstand mechanical pressure, such as vessel elements and fibers, have a secondary cell wall consisting of polysaccharides and lignin, which strengthen the cell wall structure and stabilize the cell shape. Previous attempts to alter the properties of the cell wall have mainly focused on reducing the amount of lignin or altering its structure in order to ease its extraction from raw woody materials for the pulp and paper and biorefinery industries. In this work, we propose the in vivo modification of the cell wall structure and mechanical properties by the introduction of resilin, an elastic protein that is able to crosslink with lignin monomers during cell wall synthesis. The effects of resilin were studied in transgenic eucalyptus plants. The protein was detected within the cell wall and its expression led to an increase in the elastic modulus of transgenic stems. In addition, transgenic stems displayed a higher yield point and toughness, indicating that they were able to absorb more energy before breaking.
Abitbol, T. ; Kam, D. ; Levi-Kalisman, Y. ; Gray, D. G. ; Shoseyov, O. .
Surface Charge Influence On The Phase Separation And Viscosity Of Cellulose Nanocrystals.
LangmuirLangmuir 2018,
34, 3925 - 3933.
Publisher's VersionAbstractA series of four cellulose nanocrystal (CNC) suspensions were prepared from bleached softwood kraft pulp using different conditions of sulfuric acid hydrolysis. The CNCs were identical in size (95 nm in length × 5 nm in width) but had different surface charges corresponding to the harshness of the hydrolysis conditions. Consequently, it was possible to isolate the effects of surface charge on the self-assembly and viscosity of the CNC suspensions across surface charges ranging from 0.27%S to 0.89%S. The four suspensions (never-dried, free of added electrolyte) all underwent liquid crystalline phase separation, but the concentration onset for the emergence of the chiral nematic phase shifted to higher values with increasing surface charge. Similarly, suspension viscosity was also influenced by surface charge, with suspensions of lower surface charge CNCs more viscous and tending to gel at lower concentrations. The properties of the suspensions were interpreted in terms of the increase in effective diameter of the nanocrystals due to the surface electrostatic repulsion of the negative sulfate half-esters, as modified by the screening effects of the H+ counterions in the suspensions. The results suggest that there is a threshold surface charge density (∼0.3%S) above which effective volume considerations are dominant across the concentration range relevant to liquid crystalline phase formation. Above this threshold value, phase separation occurs at the same effective volume fraction of CNCs (∼10 vol %), with a corresponding increase in critical concentration due to the decrease in effective diameter that occurs with increasing surface charge. Below or near this threshold value, the formation of end-to-end aggregates may favor gelation and interfere with ordered phase formation.A series of four cellulose nanocrystal (CNC) suspensions were prepared from bleached softwood kraft pulp using different conditions of sulfuric acid hydrolysis. The CNCs were identical in size (95 nm in length × 5 nm in width) but had different surface charges corresponding to the harshness of the hydrolysis conditions. Consequently, it was possible to isolate the effects of surface charge on the self-assembly and viscosity of the CNC suspensions across surface charges ranging from 0.27%S to 0.89%S. The four suspensions (never-dried, free of added electrolyte) all underwent liquid crystalline phase separation, but the concentration onset for the emergence of the chiral nematic phase shifted to higher values with increasing surface charge. Similarly, suspension viscosity was also influenced by surface charge, with suspensions of lower surface charge CNCs more viscous and tending to gel at lower concentrations. The properties of the suspensions were interpreted in terms of the increase in effective diameter of the nanocrystals due to the surface electrostatic repulsion of the negative sulfate half-esters, as modified by the screening effects of the H+ counterions in the suspensions. The results suggest that there is a threshold surface charge density (∼0.3%S) above which effective volume considerations are dominant across the concentration range relevant to liquid crystalline phase formation. Above this threshold value, phase separation occurs at the same effective volume fraction of CNCs (∼10 vol %), with a corresponding increase in critical concentration due to the decrease in effective diameter that occurs with increasing surface charge. Below or near this threshold value, the formation of end-to-end aggregates may favor gelation and interfere with ordered phase formation.
Gotta, J. ; Ben Shalom, T. ; Aslanoglou, S. ; Cifuentes-Rius, A. ; Voelcker, N. H. ; Elnathan, R. ; Shoseyov, O. ; Richter, S. .
Stable White Light-Emitting Biocomposite Films.
Advanced Functional Materials 2018,
28, 1706967.
Publisher's VersionAbstractAbstract The demonstration of reliable and stable white light-emitting diodes (LEDs) is one of the main technological challenges of the LED industry. This is usually accomplished by incorporation of light-emitting rare-earth elements (REEs) compounds within an external polymeric coating of a blue LED allowing the generation of white light. However, due to both environmental and cost issues, the development of low-cost REE-free coatings, which exhibit competitive performance compared to conventional white LED is of great importance. In this work, the formation of an REE-free white LED coating is demonstrated. This biocomposite material, composed of biological (crystalline nanocellulose and porcine gastric mucin) and organic (light-emitting dyes) compounds, exhibits excellent optical and mechanical properties as well as resistance to heat, humidity, and UV radiation. The coating is further used to demonstrate a working white LED by incorporating it within a commercial blue LED.
Gdor, E. ; Levy, D. ; Aharon, L. ; Shoseyov, O. ; Mandler, D. .
Sp1 Based Self-Assembled Selective Molecular Nanochannels.
Journal of Electroanalytical Chemistry 2018,
819, 220 - 225.
Publisher's VersionAbstractControlling the permeability and porosity of an inorganic layer using biomolecule building blocks has raised interest for nanotechnological applications. The challenge lies mostly in the fabrication, usually a long, expensive and tedious process, involving many steps. Using biomaterials for this purpose is highly appealing; due to both ease of fabrication and the final output, that contains a bioelement. The biomolecule, specifically, stable protein 1 (SP1), serving as the scaffold for our pattern, is of great stability and durability, and presents size, charge and structural selectivity towards electroactive species. Here, we demonstrate the ability of SP1 to form a rigid template within a sol-gel matrix, allowing selective electron transfer to the gold electrode. Specifically, a thiolated SP1 was first adsorbed on a gold surface followed by filling the non-occupied areas by sol-gel. The latter was electrochemically deposited. The various steps were carefully characterized. Finally, we studied the electrochemistry of numerous redox couple at the Au/SP1/sol-gel interface and found that the nanochannel array shows charge and structural selectivity, which is based on the interactions between the redox species and the functionalities of SP1. The resulted surface shows promise towards electrochemical sensing applications.
Zvirin, T. ; Magrisso, L. ; Yaari, A. ; Shoseyov, O. .
Stable Expression Of Adalimumab In Nicotiana Tabacum. Mol Biotechnol 2018,
60, 387-395.
AbstractProduction of monoclonal antibodies and pharmaceutical proteins in transgenic plants has been the focus of many research efforts for close to 30 years. Use of plants as bioreactors reduces large-scale production costs and minimizes risk for human pathogens contamination. Stable nuclear transformation of the plant genome offers a clear advantage in agricultural protein production platforms, limited only by the number of hectares that can be cultivated. We report here, for the first time, successful and stable expression of adalimumab in transgenic Nicotiana tabacum plants. The plant-derived adalimumab proved fully active and was shown to rescue L929 cells from the in vitro lethal effect of rhTNFα just as effectively as commercially available CHO-derived adalimumab (Humira). These results indicate that agricultural biopharming is an efficient alternative to mammalian cell-based expression platforms for the large-scale production of recombinant antibodies.
Calahorra, Y. ; Datta, A. ; Famelton, J. ; Kam, D. ; Shoseyov, O. ; Kar-Narayan, S. .
Nanoscale Electromechanical Properties Of Template-Assisted Hierarchical Self-Assembled Cellulose Nanofibers. Nanoscale 2018,
10, 16812-16821.
Cellulose, a major constituent of our natural environment and a structured biodegradable biopolymer, has been shown to exhibit shear piezoelectricity with potential applications in energy harvesters, biomedical sensors, electro-active displays and actuators. In this regard, a high-aspect ratio nanofiber geometry is particularly attractive as flexing or bending will likely produce a larger piezoelectric response as compared to axial deformation in this material. Here we report self-assembled cellulose nanofibers (SA-CNFs) fabricated using a template-wetting process, whereby parent cellulose nanocrystals (CNCs) introduced into a nanoporous template assemble to form rod-like cellulose clusters, which then assemble into SA-CNFs. Annealed SA-CNFs were found to exhibit an anisotropic shear piezoelectric response as directly measured using non-destructive piezo-response force microscopy (ND-PFM). We interpret these results in light of the distinct hierarchical structure in our template-grown SA-CNFs as revealed by scanning electron microscopy (SEM) and high resolution transmission electron microscopy (TEM).