Alkyl melibioside and alkyl cellobioside surfactants: effect of sugar headgroup and alkyl chain length on performance

Abstract

The potential of glycolipid surfactants, composed of a sugar headgroup and lipid tail, as highly biodegradable and less toxic alternatives to commonly used surfactants motivates the systematic study of structure-function relationships of various glycolipid surfactants. Advances in the efficient synthesis of high purity amphipathic glycolipid surfactants enable the analysis of a diverse set of glycolipids. The solution phase properties of two suites of glycolipid surfactants, nalkyl-O-melibiosides and n-alkyl-O-cellobiosides, with varying straight-chain alkyl tails of 8, 10 and 12 carbons are investigated in this work. This study substantiates their efficient surfactant performance and reveals their aggregate structure and microenvironment as it relates to molecular structure. Surface tensiometry demonstrates critical micelle concentrations of 0.2-40 mM with minimum surface tension values of 36-40 mN/m. Time resolved fluorescence quenching(TRFQ) spectroscopy is used to calculate micelle aggregation number (12-70 molecules/micelle) and assess relative micropolarity and microfluidity within the aggregates. The average aggregation numbers determined by TRFQ and apparent hydrodynamic radii determined by dynamic light scattering vary with alkyl chain length and headgroup size, but these properties are relatively insensitive to changes in concentration. The aggregates form nearly spherical, tightly-packed micelles with a small population of vesicles and polydispersity present at low concentrations or with short alkyl chain length.

Dodecyl-β-melibioside Detergent Micelles as a Medium for Membrane Proteins

“…This is higher than for β-DDM (0.2 mM 12 ) and matches the value previously determined for an unresolved mixture of α and β mixtures of DDMB. 13 Dynamic light scattering (DLS) was employed to assess the size and aggregation number of β-DDMB micelles based on the assumption that they are spherical. Our DLS measurements for micelles of pure β-DDMB at 25°C and at concentrations <100 mM (Figure 1) indicate that the radius of hydration (Rh) for β-DDMB micelles is 2.9 nm and the aggregation number is roughly 84, corresponding to an aggregate molecular weight of 42 kDa.…”

“…These results are similar to those previously reported for an α + β anomeric mixture of DDMB in the 20–40 mM concentration range. 13 Multi-angle light scattering (MALS) was used to confirm the DLS result. MALS determines the molecular weight of particles without needing a shape factor or modeling.…”

Biodegradability and Toxicity of Cellobiosides and Melibiosides

“…Technical applications generally use a complex mixture of glycosides (often referred to as alkyl polyglucosides or polyglycosides) composed of alkyl mono-, di-, tri-, and oligoglycosides. Further, these mixtures are typically an uncontrolled mixture of α-and β-anomers because the cost of "neighboring group" protecting groups and low temperature methods to produce pure anomers precludes their use in large scale production (Hill and LeHen-Ferrenbach, 2008;Kegel et al, 2016;Luder, 2000). A relatively efficient method for synthesis for the high purity glycoside surfactants has been reported (Coss et al, 2012;Lefever et al, 2012;Szabó et al, 2016), and may offer opportunities to complement or replace current commercially available surfactants for technical applications (e.g., drug delivery) (Faivre and Rosilio, 2010).…”

Alkyl Xylosides: Physico‐Chemical Properties and Influence on Environmental Bacteria Cells

“…The change of the surface properties depends on the alkyl length and the hydrophilic carbohydrate headgroup size among n -alkyl- O -melibiosides and n -alkyl- O -cellobiosides [27]. Similarly, the properties of alkyl maltosides and glucosides have also been described in the literature [28, 29].…”