TY - JOUR

T1 - Effects of Amino Acid Side-Chain Length and Chemical Structure on Anionic Polyglutamic and Polyaspartic Acid Cellulose-Based Polyelectrolyte Brushes

AU - Толмачев, Дмитрий Алексеевич

AU - Мамиствалов, Георгий Зазаевич

AU - Лукашева, Наталья Вячеславовна

AU - Ларин, Сергей Владимирович

AU - Karttunen, Mikko

N1 - Publisher Copyright: © 2021 by the authors.

PY - 2021/6/1

Y1 - 2021/6/1

N2 - 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 theadsorbed 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.

AB - 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 theadsorbed 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.

KW - Cellulose

KW - L-aspartic acid)

KW - L-glutamic acid)

KW - Mineralization

KW - Molecular dynamics simulation

KW - Poly(amino acids)

KW - Poly-(α

KW - Polyelectrolyte brushes

KW - SINGLE

KW - NANOCRYSTALS

KW - molecular dynamics simulation

KW - poly-(alpha,L-glutamic acid)

KW - ADSORPTION

KW - MIMICKING

KW - CALCIUM

KW - SIMULATIONS

KW - METADYNAMICS

KW - MEMBRANES

KW - poly(amino acids)

KW - polyelectrolyte brushes

KW - mineralization

KW - poly-(alpha,L-aspartic acid)

KW - cellulose

KW - DYNAMICS

KW - BINDING

UR - http://www.scopus.com/inward/record.url?scp=85107325792&partnerID=8YFLogxK

UR - https://www.mendeley.com/catalogue/4abc1136-29db-33a6-a29d-598959aac0d3/

U2 - 10.3390/polym13111789

DO - 10.3390/polym13111789

M3 - Article

C2 - 34071693

VL - 13

JO - Polymers

JF - Polymers

SN - 2073-4360

IS - 11

M1 - 1789

ER -