TY - JOUR
T1 - Salt Destabilization of Cationic Colistin Complexation within Polyanionic Microgels
AU - Xiao, Xixi
AU - Ji, Jingjing
AU - Zhao, Wenhan
AU - Nangia, Shikha
AU - Libera, Matthew
N1 - Publisher Copyright:
© 2022 American Chemical Society. All rights reserved.
PY - 2022/3/8
Y1 - 2022/3/8
N2 - Polyelectrolyte complexation, with and without additional salts such as NaCl, has been of long-standing interest across such areas as polyelectrolyte blends, layer-by-layer (LbL) thin films, and coacervates. To better understand how to control complexation strength, we study polyanionic microgels involving sulfonic or carboxylic acids that interact with colistin, a small multivalent cationic (+5) macroion. Complexation causes microgel deswelling, which can be followed by in situ optical microscopy. The release of complexed colistin causes microgel swelling and is triggered by threshold levels of NaCl in the surrounding buffer. Differences in these thresholds together with differences in the Na+doping of complexed microgels indicate that colistin complexation is stronger with poly(styrene sulfonate) (PSS) than it is with poly(acrylic acid) (PAA). Coarse-grained molecular dynamics simulations show that the free-energy decrease accompanying colistin-PSS complexation is significantly greater than that for colistin-PAA complexation. These simulations furthermore indicate that pendant aromatic groups in PSS play an important steric role as a spacer that creates polyanion conformations that maximize opportunities for both Coulombic and nonbonded Lennard-Jones interactions with colistin.
AB - Polyelectrolyte complexation, with and without additional salts such as NaCl, has been of long-standing interest across such areas as polyelectrolyte blends, layer-by-layer (LbL) thin films, and coacervates. To better understand how to control complexation strength, we study polyanionic microgels involving sulfonic or carboxylic acids that interact with colistin, a small multivalent cationic (+5) macroion. Complexation causes microgel deswelling, which can be followed by in situ optical microscopy. The release of complexed colistin causes microgel swelling and is triggered by threshold levels of NaCl in the surrounding buffer. Differences in these thresholds together with differences in the Na+doping of complexed microgels indicate that colistin complexation is stronger with poly(styrene sulfonate) (PSS) than it is with poly(acrylic acid) (PAA). Coarse-grained molecular dynamics simulations show that the free-energy decrease accompanying colistin-PSS complexation is significantly greater than that for colistin-PAA complexation. These simulations furthermore indicate that pendant aromatic groups in PSS play an important steric role as a spacer that creates polyanion conformations that maximize opportunities for both Coulombic and nonbonded Lennard-Jones interactions with colistin.
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U2 - 10.1021/acs.macromol.1c02157
DO - 10.1021/acs.macromol.1c02157
M3 - Article
AN - SCOPUS:85125114091
SN - 0024-9297
VL - 55
SP - 1736
EP - 1746
JO - Macromolecules
JF - Macromolecules
IS - 5
ER -