Conformational changes of cationic potato amylopectin; influence by salt, influence by nanosized silica particles

Static light scattering was used to follow the change in conformation of a moderately charged cationic potato amylopectin. It was found that the volume of the amylopectin decreased at an increased electrolyte concentration. However, the segment density (fractal dimension) was unaffected by the change in electrolyte concentration. Furthermore, increasing the salt content increased the degree of aggregation between amylopectin molecules. Mixing the cationic amylopectin starch with nanosized silica particles did not change the globular volume of the formed polyelectrolyte complex. However, the segment density decreased at an increased concentration of silica due to an increased binding of silica particles to each amylopectin molecule. Since the silica particles are highly charged at pH 8 they try to maximize the distance between themselves causing the amylopectin molecule to follow passively, thus decreasing the segment density. (C) 1998 Elsevier Science B.V. All rights reserved.