TY - JOUR
T1 - Polysaccharide effects on calcite growth
T2 - the influence of composition and branching
AU - Nielsen, Jonas Willum
AU - Sand, Karina Krarup
AU - Pedersen, Christian Schack
AU - Lakshtanov, L. Z.
AU - Winther, Jakob R.
AU - Willemoës, Martin
AU - Stipp, Susan Louise Svane
PY - 2012/10/3
Y1 - 2012/10/3
N2 - Polysaccharides play a key role in the biomineralization of the elaborate and species specific calcite platelets, known as coccoliths. Coccoliths cover some species of algae and the polysaccharides serve as controlling agents, directing crystal growth. We conducted experiments of calcite growth in the presence of five well described polysaccharides to test the influence of composition and structural properties. Alginate and polygalacturonate contain a carboxylate group for every glycosyl unit, whereas the unbranched amylose and the progressively branched polysaccharides, ß-limit dextrin and amylopectin, contain only glucosyl units. Calcite growth was monitored by the consumption of Ca 2+ and CO 3 2- in a constant composition setup. Langmuir isotherms effectively describe the uptake data from experiments where polysaccharide concentration was varied. Our results demonstrate that polysaccharides containing acidic glycosyl units strongly inhibit calcite growth, compared to neutral polysaccharides, but fine structure, i.e., the anomeric configuration and/or the position of functional groups in the polymer, also plays a role, as illustrated by the difference in inhibitory properties of the acidic polysaccharides, alginate, and polygalacturonate. Of the neutral polysaccharides, the branched molecules were stronger inhibitors than the linear molecule and the longer the branches, the stronger the inhibition. Thus, amylopectin was 2 orders of magnitude more effective than ß-limit dextrin and amylose was inactive.
AB - Polysaccharides play a key role in the biomineralization of the elaborate and species specific calcite platelets, known as coccoliths. Coccoliths cover some species of algae and the polysaccharides serve as controlling agents, directing crystal growth. We conducted experiments of calcite growth in the presence of five well described polysaccharides to test the influence of composition and structural properties. Alginate and polygalacturonate contain a carboxylate group for every glycosyl unit, whereas the unbranched amylose and the progressively branched polysaccharides, ß-limit dextrin and amylopectin, contain only glucosyl units. Calcite growth was monitored by the consumption of Ca 2+ and CO 3 2- in a constant composition setup. Langmuir isotherms effectively describe the uptake data from experiments where polysaccharide concentration was varied. Our results demonstrate that polysaccharides containing acidic glycosyl units strongly inhibit calcite growth, compared to neutral polysaccharides, but fine structure, i.e., the anomeric configuration and/or the position of functional groups in the polymer, also plays a role, as illustrated by the difference in inhibitory properties of the acidic polysaccharides, alginate, and polygalacturonate. Of the neutral polysaccharides, the branched molecules were stronger inhibitors than the linear molecule and the longer the branches, the stronger the inhibition. Thus, amylopectin was 2 orders of magnitude more effective than ß-limit dextrin and amylose was inactive.
U2 - 10.1021/cg300772h
DO - 10.1021/cg300772h
M3 - Journal article
SN - 1528-7483
VL - 12
SP - 4906
EP - 4910
JO - Crystal Growth & Design
JF - Crystal Growth & Design
IS - 10
ER -