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Direct visualization of changes in deacylated Na + gellan polymer morphology during the sol–gel transition
Author(s) -
Atkin Neil,
Abeysekera Rukmal M.,
KronestedtRobards Eva C.,
Robards Anthony W.
Publication year - 2000
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/1097-0282(200009)54:3<195::aid-bip60>3.0.co;2-#
Subject(s) - chemistry , polymer , morphology (biology) , endothermic process , crystallography , helix (gastropod) , chemical engineering , polymer chemistry , chemical physics , biophysics , organic chemistry , genetics , engineering , biology , ecology , adsorption , snail
Changes in gellan polymer morphology during the sol–gel transition were directly visualized by transmission electron microscopy and a model incorporating these changes and existing physical data is proposed. Our observations suggest that the most thermodynamically stable conformations of gellan polymers in solution, in the absence of added cations, are the double helix and double‐helical duplexes. We have demonstrated two forms of lateral aggregation of gellan helices in the presence of Ca 2+ and K + ions. One type forms junction zones that lead to network formation and gelation, while the second type leads to the formation of isolated fibers of aggregated helices and inhibition of gelation. The proposed model of gellan gelation is based on these observations where thermoreversibility, gel strength, and endothermic transitions of gellan gels can be explained. © 2000 John Wiley & Sons, Inc. Biopoly 54: 195–210, 2000