Drying-Induced Self-Similar Assembly of Megamolecular Polysaccharides through Nano and Submicron Layering

Okeyoshi, Kosuke; Joshi, Gargi; Rawat, Sakshi; Sornkamnerd, Saranyoo; Amornwachirabodee, Kittima; Okajima, Maiko K.; Ito, Mayumi; Kobayashi, Shoko; Higashimine, Koichi; Oshima, Yoshifumi; Kaneko, Tatsuo

doi:10.1021/acs.langmuir.7b00107

Cited by 19 publications

(17 citation statements)

References 32 publications

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“…The cast films formed a layer structure which was driven by LC domains . During the drying process, nanoplatelets of sacran were formed as a result of self‐assembly . The nanoplatelets oriented along the in‐plane direction during condensation of the sacran solution to produce a layered arrangement in the cast films .…”

Section: Extraction and Properties Of Cyanobacterial Polysaccharidesmentioning

confidence: 99%

Development of Functional Bionanocomposites Using Cyanobacterial Polysaccharides

Okajima

Sornkamnerd

Kaneko

2018

The Chemical Record

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Cyanobacteria are regarded as very eco-friendly microreactors for the production of various biomolecules such as polysaccharides by fixing not only carbon but also nitrogen in water. Cyanobacterial polysaccharides having various functional groups such as hydroxyls, carboxyls, sulfates, etc. have the ability to interact with metals or inorganics, to create bionanocomposites. Sacran, a supergiant cyanobacterial anionic polysaccharide extracted from the extracellular matrix of Aphanothece sacrum which is mass-cultivated in freshwater, is mainly used to create functional bionanocomposites. Gel-type bionanocomposites of sacran with various metal cations are formed and showed photoresponsive functions. Metal recovery is performed from the sacran bionanocomposite gels. Sacran chains are complexed with multi-wall carbon nanotubes (MWCNT) to give viscose dispersion from which MWCNT bionanocomposites can be collected by electrophoresis. The MWCNT/sacran dispersion retains the capability of adsorbing various metal ions to form hardened hydrogel beads. Finally, natural inorganic sepiolite can be used for sacran bionanocomposites which show an efficient neodymium ion adsorption ability. Thus, cyanobacterial polysaccharides are useful for preparing eco-friendly and functional bionanocomposites with various hard materials.

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Section: Extraction and Properties Of Cyanobacterial Polysaccharidesmentioning

confidence: 99%

Development of Functional Bionanocomposites Using Cyanobacterial Polysaccharides

Okajima

Sornkamnerd

Kaneko

2018

The Chemical Record

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“…Here we choose the cyanobacterial polysaccharide, sacran which forms a giant rod or fiber as the self‐assembled structures with 1 µm diameter and >20 µm length, showing lyotropic liquid crystallinity (LC). By drying the sacran solution from the top‐side‐open cell with a narrow gap, the deposited polymer bridges the substrate walls to form membranes with uniaxial orientation of the rods . In order to investigate the reorientation during the drying, we have observed the interfacial atmosphere by polarized light microscopy in detail.…”

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confidence: 99%

“…Figure A shows the schematic illustration of the membrane formation vertical to meniscus by evaporating the solution from a top‐side‐open cell. The microrods are directed parallel to the air–LC interface along the contact line . The initial concentration of the polymer, C 0 was 0.5 wt%, higher than the critical concentration of LC formation (≈0.2 wt%) .…”

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Formation of Polysaccharide Membranes by Splitting of Evaporative Air–LC Interface

Okeyoshi

Joshi

Okajima

et al. 2017

Adv Materials Inter

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loss moduli, G′′ ≈ 2 Pa), [13] the polymer around the air-liquid interface deposits through a drastic increase of the polymer concentration from 0.5 to 100 wt%. This partitioning is a result of vertical membrane formation in a top-side-open cell accompanied by parallel orientation of the micrometer scale, rod-like domains with the three-phase contact line. [10,14] During the drying of polymer solution in the cell, the air-liquid interface is in a similar state as the skin layers of a deswelling gel with buckling patterns. [15,16] The deposited polymer on the air-liquid interface behaves like a lid and the evaporation is restricted. By drying in limited space with a narrow gap, the nonequilibrium state between deposition and hydration near the interface causes accumulation of small depositions at several specific points (pinning). Here, the split meniscus should make the area of the evaporative interface larger. This state continuously achieves both deposition and the evaporation. As a result, the deposited polymer bridges the two parallel substrates and the vertical membrane grows. This is unpredicted heterogeneous condensation of the microrods resulting macrospace partitioning in centimeter scale. However, toward generalization of this simple method to other polymeric materials, the role of interfacial curves and necessary conditions for the membrane formation are still required to be clarified.Here we choose the cyanobacterial polysaccharide, sacran [17][18][19][20] which forms a giant rod or fiber as the self-assembled structures with 1 µm diameter and >20 µm length, [14] showing lyotropic liquid crystallinity (LC). By drying the sacran solution from the top-side-open cell with a narrow gap, the deposited polymer bridges the substrate walls to form membranes with uniaxial orientation of the rods. [20] In order to investigate the reorientation during the drying, we have observed the interfacial atmosphere by polarized light microscopy in detail. In this study, to describe the correlation between the interfacial curve and the partitioning, the geometric effects of the evaporation front are discussed. Ideally, the air-liquid interface shows exponential curves that are mostly determined by the distance from the walls of cells. By controlling the evaporation front three-dimensionally, the necessary conditions for the vertical membrane formation are verified multilaterally.To demonstrate the effect of the interfacial geometry, we use an aqueous sacran solution composed of the self-assembled microrods or microfibers. They stably maintain their shape and Self-assembly methods for colloidal crystals are widely developed by using the evaporative interface and capillary forces. Recently, a distinct phenomenon is discovered of macrospace partitioning by a polysaccharide membrane formed in a limited space by drying its aqueous liquid crystalline solution. Differing from typical fingering patterns, here, the viscous solution is in a nonequilibrium process between the polymer deposition and hydration during drying. By drying...

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“…Sacran shows various unique phenomena such as high swelling [2,4,5] and anisotropic swelling behaviors [4], liquid crystalline (LC) behavior [6,7], ion adsorption behavior [8][9][10], and anisotropic diffusion behavior in highly ordered sacran films [3,[11][12][13][14]. The retention capacity for uncross-linked sacran exceeds higher than 6000 mL/g for pure water and 2700 mL/g for NaCl aqueous solution [2].…”

Section: Introductionmentioning

confidence: 99%

Rheopectic Behavior for Aqueous Solutions of Megamolecular Polysaccharide Sacran

Amat Yusof,

Yamaki,

Kawai

et al. 2020

Biomolecules

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The rheopectic behavior of sacran aqueous solutions, a natural giant molecular polysaccharide with a molecular weight of 1.6 × 107 g/mol, was investigated. When a low shear was applied to 1.0 wt.% sacran solution, the shear viscosity increased from 7.2 to 34 Pa·s. The increment in the viscosity was enhanced as the shear rate decreased. The shear viscosity was independent of the time at a shear rate of 0.8 s−1; simultaneously, thixotropic behavior was observed at shear rates higher than 1.0 s−1. A crossover was observed at 0.15 wt.% for the concentration dependence of both the viscosity increase and zeta potential, which was the vicinity of the helix transition concentration or gelation concentration. It was clear that the molecular mechanism for the rheopexy was different at lower and higher regions of the crossover concentration.

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Drying-Induced Self-Similar Assembly of Megamolecular Polysaccharides through Nano and Submicron Layering

Cited by 19 publications

References 32 publications

Development of Functional Bionanocomposites Using Cyanobacterial Polysaccharides

Development of Functional Bionanocomposites Using Cyanobacterial Polysaccharides

Formation of Polysaccharide Membranes by Splitting of Evaporative Air–LC Interface

Rheopectic Behavior for Aqueous Solutions of Megamolecular Polysaccharide Sacran

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