Ultrasonic Spectrometry of Aqueous Solutions of Alkyl Maltosides: Kinetics of Micelle Formation and Head‐Group Isomerization

Abstract

At frequencies between 100 kHz and 400 MHz, ultrasonic attenuation spectra are measured at 25 degrees C for aqueous solutions of hexyl-, heptyl-, octyl-, nonyl-, and decyl-beta-D-maltopyranoside as well as of decyl-alpha-D-maltopyranoside. The spectra with surfactant concentration c above the relevant critical micelle concentration (cmc) display three relaxation terms with discrete relaxation times. That with a relaxation time between 0.1 and 1.2 micros is due to exchange of monomers between micelles and the suspending phase. It is discussed in the light of the Teubner-Kahlweit-Aniansson-Wall model of the formation/decay kinetics of systems with Gaussian size distribution of micelles. The relaxation parameters are compared to those for solutions of other non-ionic surfactants, such as alkyl monoglycosides and poly(ethylene glycol) monoalkyl ethers. At c < cmc this low-frequency relaxation term is missing and at c approximately = cmc it is broadened, as is characteristic of solutions of oligomeric molecular structures rather than proper micelles. The relaxation terms with relaxation times between 6 and 15 ns and 0.7 and 2.3 ns reveal head-group rotations around glycosidic angles and isomerization of the exocyclic hydroxymethyl group, respectively. These unimolecular reactions are also examined with a view to solutions of alkyl monoglycosides as well as of glucose and maltose.

Exploring the affinity binding of alkylmaltoside surfactants to bovine serum albumin and their effect on the protein stability: A spectroscopic approach

“…Because of their mildness and solubilizing power, APG surfactants are receiving considerable attention as feasible alternatives to conventional nonionic ethoxylated surfactants in applications such as the solubilization and purification of membrane proteins [3,54], and drug delivery [55,56]. Consequently, understanding how these surfactants interact with a model protein, and how this interaction affects the protein conformation is essential in order to preserve protein stability and functionality in the aforementioned technical applications.…”

Analysis of the Photophysical Behavior and Rotational-Relaxation Dynamics of Coumarin 6 in Nonionic Micellar Environments: The Effect of Temperature

“…However, alkylpolyglycoside (APG) surfactants, characterized mainly by having one or more glucose molecules in their polar moiety, are attracting increasing interest due to their advantages in terms of biodegradability, consumer health, low toxicity and performance compared to nonionic ethoxylated surfactants [16,17,18,19]. In addition, due to their mildness and high solubilizing power, APG surfactants are being considered as possible alternatives to conventional nonionic surfactants in applications in the membrane protein field [20,21] and drug delivery [22,23].…”

Acoustical Spectroscopy of Carbohydrate Aqueous Solutions: Saccharides; Alkyl Glycosides; Cyclodextrins. Part I. Conformer Variations

“…On the one hand, it is capable to monitor the conformational variations of the saccharide head groups on the surface of micellar aggregates and to thus reveal differences with respect to non-associated molecules. On the other hand, it provides the opportunity to study the monomer exchange kinetics with a view to a comparison to other nonionic micelle solutions (Haller, Kaatze, 2009a;2009b).…”