Salt-induced release of lipase from polyelectrolyte complex micelles

Abstract

With the aim to gain insight into the possible applicability of protein-filled polyelectrolyte complex micelles under physiological salt conditions, we studied the behavior of these micelles as a function of salt concentration. The micelles form by electrostatically driven co-assembly from strong cationic block copolymers poly(2-methyl vinyl pyridinium) 41 -block-poly(ethylene oxide) 205 , weak anionic homopolymers poly(acrylic acid) 139 , and negatively charged lipase molecules. The formation and disintegration of these micelles were studied with dynamic light scattering (DLS), by means of composition and salt titrations, respectively. The latter measurements revealed differences between disintegration of lipase-filled and normal polyelectrolyte complex micelles. These data, together with small angle neutron scattering (SANS) measurements provide indications that lipase is gradually released with increasing salt concentration. From the SANS data a linear relation between the intensity at q ¼ 0 and the volume of the cores of the micelles at different salt concentrations was derived, indicating a loss of volume of the micelles due to the release of lipase molecules. It was estimated that beyond 0.12 M NaCl all lipase molecules are released.

Hydrogel with cubic-packed giant concentric domains of semi-rigid polyion complex

“…The increase in the birefringence and the appearance of the ordered Maltese crosses structure by the swelling process in water possibly results from the enhancement of the polyion interaction due to the diffusion of the small counter ions and added NaCl out of the gel. [35][36][37] That is, the ordered structure should be developed during the polymerization and the swelling makes it visible under POM.…”

The Effect of Salt on the Complex Coacervation of Vinyl Polyelectrolytes

“…While the effects of salt on complex coacervation have been well studied in model systems, the majority of these studies have focused only on the impact of NaCl as a simple monovalent salt [1,2,[4][5][6][8][9][10]33,34,36,[46][47][48][49][50][51]. Those studies which have examined the impact of multivalent salts on polyelectrolyte complexation have either investigated systems which form solid complexes rather than liquid coacervates [39], or have utilized biologically-derived polymers and/or proteins [22,52,53].…”

Interaction between lysozyme and colloidal poly(NIPAM-co-acrylic acid) microgels

“…The shells, as they appear on confocal microscopy images, are strikingly similar to the protein layers forming in non-responsive chromatography beads [43,44], but the relationship remains to be clarified. In addition to the vast literature on linear polyelectrolyte-protein interactions (see [45][46][47] and references therein) there are studies of protein binding to polyelectrolyte brushes [48][49][50] and polyelectrolyte complex micelles [51][52][53] of relevance to the present work, as well as theoretical work on model networks interacting with oppositely charged macroions [54,55]. Of special interest are recent theoretical results pointing to the importance of charge regulation and charge anisotropy for protein-polyelectrolyte and protein-protein interactions [49,[56][57][58][59][60][61][62].…”