The Interaction between SDS and Lysozyme at the Hydrophilic Solid−Water Interface

Abstract

The interaction between sodium dodecyl sulfate (SDS) and preadsorbed lysozyme at the hydrophilic silicon oxide-water interface has been studied using specular neutron reflection. Measurements were carried out using two different solution concentrations of lysozyme and a range of SDS solution concentrations between 0.2 and 2 mM. The surface composition and the adsorbed layer structure were determined by varying H/D labeling of SDS. Initially, a uniform layer or bilayer of protein was formed at the interface by adsorption from either 0.03 or 1 g/L lysozyme solution concentrations. The SDS was then added to the system and the neutron reflectivity measured. It was found that this method of studying the SDS/lysozyme system produced highly repeatable neutron reflectivity profiles. On addition of intermediate SDS concentrations, cooperative binding of the SDS to the protein layer was observed, without any evidence of removal of the preadsorbed protein layer. On increasing the SDS concentration, to above 0.5 mM SDS, partial removal of the protein layer occurred. A concentration of 2 mM SDS was required to completely remove all traces of adsorbed material from the interface. These results suggest that the mechanism for protein elution from the interface is via the coadsorption of SDS to the protein layer and the formation of a SDS/protein complex whose surface activity varies with the extent of SDS binding.

Surfactant induced aggregation behavior of Merocyanine-540 adsorbed on polymer coated positively charged gold nanoparticles

“…Control experiments performed without using nanoparticles suggests that the nature of polymer-surfactant interaction at a water-solid interface is different from that in bulk. For a particular charged polymer coated surface, the determining factors which controls the polymer-surfactant interaction are electrostatic in nature which is consistent with earlier studies [1,2,[13][14][15][16].…”

“…Interactions of polymers with surfactants are a subject of several studies [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. These interactions are expected to be stronger when the polymer and surfactant are oppositely charged.…”

“…These interactions are expected to be stronger when the polymer and surfactant are oppositely charged. It has been observed that polymer-surfactant interaction is different in bulk solution and at an interface [1,2,[13][14][15][16]. For example, at an air-water interface this interaction readily occurs at low concentrations of the oppositely charged surfactant and polymer On the other hand, the interaction occurring at a solid-water interface is more complex as it now depends on the specific interactions between surfactants, polymers and the surface.…”

Comparison of positional surfactant isomers for displacement of rubisco protein from the air–water interface

“…Previous interfacial studies on protein-surfactant systems have focussed on models using proteins including lysozyme, b-lactoglobulin and BSA with non-ionic and ionic surfactants [5][6][7][8][9]. The reason for the selection of such systems is perhaps, in part, because detailed knowledge of each component is well documented and these proteins are commercially available.…”

Food Emulsifiers and Their Applications

“…Green et al studied the interaction between sodium dodecyl sulfate (SDS) and preadsorbed lysozyme at the hydrophilic silicon oxide-water interface by neutron reflectivity measurements (Green et al, 2001). SDS binds cooperatively to the preadsorbed protein layer at intermediate surfactant concentrations, with no desorption of lysozyme from the interface.…”