scholarly journals Tunable and switchable nanoparticle separation with thermo-responsive track-etched membranes prepared by controlled surface-initiated polymerization of poly(N-isopropylacrylamide)

RSC Advances ◽  
2020 ◽  
Vol 10 (36) ◽  
pp. 21028-21038
Author(s):  
Kevin Daumann ◽  
Sven Frost ◽  
Mathias Ulbricht
Keyword(s):  
Pore Size ◽  
Chain Length ◽  
Membrane Pores ◽  
Surface Initiated Polymerization ◽  
Nanoparticle Separation ◽  
Grafting Density ◽  
Responsive Polymer

This work describes how the control of grafting density and grafted chain length of a thermo-responsive polymer in membrane pores can be utilized to tune the pore size and the switchability of size-based selectivity in the ultrafiltration range.

scholarly journals Effects of Amino Acid Side-Chain Length and Chemical Structure on Anionic Polyglutamic and Polyaspartic Acid Cellulose-Based Polyelectrolyte Brushes

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1789
Author(s):  
Dmitry Tolmachev ◽  
George Mamistvalov ◽  
Natalia Lukasheva ◽  
Sergey Larin ◽  
Mikko Karttunen
Keyword(s):  
Glutamic Acid ◽  
Chain Length ◽  
Chemical Structure ◽  
Side Chain ◽  
Side Chains ◽  
Side Chain Length ◽  
Polyelectrolyte Brushes ◽  
Grafting Density ◽  
The Difference ◽  
Cellulose Surface

We used atomistic molecular dynamics (MD) simulations to study polyelectrolyte brushes based on anionic α,L-glutamic acid and α,L-aspartic acid grafted on cellulose in the presence of divalent CaCl2 salt at different concentrations. The motivation is to search for ways to control properties such as sorption capacity and the structural response of the brush to multivalent salts. For this detailed understanding of the role of side-chain length, the chemical structure and their interplay are required. It was found that in the case of glutamic acid oligomers, the longer side chains facilitate attractive interactions with the cellulose surface, which forces the grafted chains to lie down on the surface. The additional methylene group in the side chain enables side-chain rotation, enhancing this effect. On the other hand, the shorter and more restricted side chains of aspartic acid oligomers prevent attractive interactions to a large degree and push the grafted chains away from the surface. The difference in side-chain length also leads to differences in other properties of the brush in divalent salt solutions. At a low grafting density, the longer side chains of glutamic acid allow the adsorbed cations to be spatially distributed inside the brush resulting in a charge inversion. With an increase in grafting density, the difference in the total charge of the aspartic and glutamine brushes disappears, but new structural features appear. The longer sides allow for ion bridging between the grafted chains and the cellulose surface without a significant change in main-chain conformation. This leads to the brush structure being less sensitive to changes in salt concentration.

scholarly journals Effect of Inflammation on Gingival Mesenchymal Stem/Progenitor Cells’ Proliferation and Migration through Microperforated Membranes: An In Vitro Study

2020 ◽  
Vol 2020 ◽  
pp. 1-10 ◽  
Author(s):  
M. Al Bahrawy ◽  
K. Ghaffar ◽  
A. Gamal ◽  
K. El-Sayed ◽  
V. Iacono
Keyword(s):  
Pore Size ◽  
Progenitor Cells ◽  
Cellular Migration ◽  
Gingival Tissue ◽  
Population Doubling ◽  
Population Doubling Time ◽  
Electron Microscopic ◽  
Healthy Human ◽  
Membrane Pores ◽  
Scanning Electron

Background. In the field of periodontal guided tissue regeneration, microperforated membranes have recently proved to be very promising periodontal regenerative tissue engineering tools. Regenerative periodontal approaches, employing gingival mesenchymal stem/progenitor cells in combination with these novel membranes, would occur mostly in inflamed microenvironmental conditions intraorally. This in turn entails the investigation into how inflammation would affect the proliferation as well as the migration dynamics of gingival mesenchymal stem/progenitor cells. Materials and Methods. Clones of human gingival mesenchymal stem/progenitor cells (GMSCs) from inflamed gingival tissues were characterized for stem/progenitor cells’ characteristics and compared to clones of healthy human GMSCs (n=3), to be subsequently seeded on perforated collagen-coated poly-tetra-floro-ethylene (PTFE) membranes with a pore size 0.4 and 3 microns and polycarbonic acid membranes of 8 microns pore size in Transwell systems. The population doubling time and the MTT test of both populations were determined. Fetal bovine serum (FBS) was used as a chemoattractant in the culturing systems, and both groups were compared to their negative controls without FBS. Following 24 hours of incubation period, migrating cells were determined on the undersurface of microperforated membranes and the membrane-seeded cells were examined by scanning electron microscopy. Results. GMSCs demonstrated all predefined stem/progenitor cell characteristics. GMSCs from inflamed gingival tissues showed significantly shorter population doubling times. GMSCs of inflamed and healthy tissues did not show significant differences in their migration abilities towards the chemoattractant, with no cellular migration observed in the absence of FBS. GMSCs from healthy gingival tissue migrated significantly better through larger micropores (8 microns). Scanning electron microscopic images proved the migratory activity of the cells through the membrane pores. Conclusions. Inflammation appears to boost the proliferative abilities of GMSCs. In terms of migration through membrane pores, GMSCs from healthy as well as inflamed gingival tissues do not demonstrate a difference in their migration abilities through smaller pore sizes, whereas GMSCs from healthy gingival tissues appear to migrate significantly better through larger micropores.

scholarly journals Grafting of a Stimuli Responsive Polymer on Nanolayered Coextruded PS/PCL Films by Surface Initiated Polymerization

2016 ◽  
Vol 301 (7) ◽  
pp. 870-875 ◽  
Author(s):  
Katrina D. Pangilinan ◽  
Al Christopher C. de Leon ◽  
Joey Dacula Mangadlao ◽  
Eric Baer ◽  
Rigoberto C. Advincula
Keyword(s):  
Stimuli Responsive ◽  
Surface Initiated Polymerization ◽  
Responsive Polymer ◽  
Stimuli Responsive Polymer

Lattice self-consistent field calculations of ring polymer brushes

Soft Matter ◽  
2018 ◽  
Vol 14 (10) ◽  
pp. 1887-1896 ◽  
Author(s):  
Wenjuan Qiu ◽  
Baohui Li ◽  
Qiang Wang
Keyword(s):  
Chain Length ◽  
Polymer Brushes ◽  
Grafting Density ◽  
Consistent Field ◽  
Equivalent Linear ◽  
Self Consistent ◽  
Self Consistent Field ◽  
Ring Polymer

Ring brushes are slightly less stretched than, thus nearly but not completely identical to, the “equivalent” linear brushes having half the chain length and double the grafting density.

Tailored (Bio)Interfaces via Surface Initiated Polymerization: Control of Grafting Density and New Responsive Diblock Copolymer Brushes

2013 ◽  
Vol 328 (1) ◽  
pp. 64-72 ◽  
Author(s):  
Inga Lilge ◽  
Marc Steuber ◽  
Davide Tranchida ◽  
Elena Sperotto ◽  
Holger Schönherr
Keyword(s):  
Diblock Copolymer ◽  
Surface Initiated Polymerization ◽  
Grafting Density ◽  
Copolymer Brushes

scholarly journals Effects of Amino Acid Side Chain Length and Chemical Structure on Anionic Polyglutamic and Polyaspartic Acid Cellulose-Based Polyelectrolyte Brushes

2021 ◽  
Author(s):  
Dmitry Tolmachev ◽  
George Mamistvalov ◽  
Natalia Lukasheva ◽  
Sergey Larin ◽  
Mikko Karttunen
Keyword(s):  
Glutamic Acid ◽  
Chain Length ◽  
Chemical Structure ◽  
Side Chain ◽  
Side Chains ◽  
Side Chain Length ◽  
Polyelectrolyte Brushes ◽  
Grafting Density ◽  
The Difference ◽  
Cellulose Surface

We used atomistic molecular dynamics (MD) simulations to study polyelectrolyte brushes based on anionic α-L-glutamic acid and α-L-aspartic acid grafted on cellulose in the presence of divalent CaCl2 salt at different concentrations. The motivation is the search of the ways to control properties such as sorption capacity and the structural response of the brush to multivalent salts. For this detailed understanding of the role of side chain length, chemical structure and their interplay is required. It was found that in the case of glutamic acid oligomers, the longer side chains facilitate attractive interactions with the cellulose surface, which forces the grafted chains to lie down on the surface. The additional methylene group in the side chain enables side chain rotation enhancing this effect. On the other hand, the shorter and more restricted side chains of aspartic acid oligomers prevent attractive interactions to a large degree and push the grafted chains away from the surface. The difference in side chain length also leads to differences in other properties of the brush in divalent salt solutions. At a low grafting density, the longer side chains of glutamic acid allow the adsorbed cations to be spatially distributed inside the brush resulting in a charge inversion. With an increase in grafting density, the difference in the total charge of the aspartic and glutamine brushes disappears, but new structural features appear. The longer sides allow for ion bridging between the grafted chains and the cellulose surface without a significant change in main chain conformation. This leads to the brush structure being less sensitive to changes in salt concentration.

Sign in / Sign up

Export Citation Format

Share Document