NMR investigation of counterion binding to undecyl LL-leucinevalanate micelles

Fletcher, Jessica L.; Mahant, Grant; Witzleb, Tyler; Busche, Riley; Mauro, Garcia; Fang, Yayin; Billiot, Eugene; Billiot, Fereshteh; Morris, Kevin

doi:10.1080/01932691.2022.2145303

Cited by 4 publications

(5 citation statements)

References 46 publications

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“…Fletcher, et al investigated the binding of trans-1,4-cyclohexanediamine to amino acid-based undecyl-LL-Leucinevalanate micelles. This study showed that trans-1,4-cyclohexanediamine bound to the micelles in a perpendicular fashion with one amine functional group interacting with the anionic micelle surface and the rest of the molecule extending out into free solution [26]. This binding model is shown in Figure 4b.…”

Section: Micelle Radii and Counterion Bindingmentioning

confidence: 82%

“…Finally, in Figure 6, 1,4-diaminobutane and 1,6-diaminohexane are shown to bind parallel to the micelle surface with both amine functional groups interacting with different surfactant monomers. These counterions have been shown to bind to micelles formed by other amino acid-based surfactants in an analogous manner [17,26]. The results plotted in Figure 5a suggest that 1,4-diaminobutane also binds to tridecanoic-Glu micelles in a parallel fashion.…”

Section: Micelle Radii and Counterion Bindingmentioning

confidence: 84%

“…These MD simulations are underway. Finally, since R h includes both the micelle and counterions, comparing R h values at pHs where the mole fraction of bound counterions is high to pHs where these values are low provides insight into the structure of the micelle-counterion complex [15][16][17]26]. This method will be employed below to interpret the results shown in Figure 5.…”

Section: Micelle Radii and Counterion Bindingmentioning

confidence: 99%

“…pHs where these values are low provides insight into the structure of the micelleterion complex [15][16][17]26]. This method will be employed below to interpret the r shown in Figure 5.…”

Section: Micelle Radii and Counterion Bindingmentioning

confidence: 99%

“…In this study, the association of organic diamine counterions with tridecanoic-Glu micelles was investigated. Micelle-counterion interactions are of interest because counterions mediate the repulsion of the charged surfactant headgroups at the micelle surface and thus affect the physical properties of the micellar aggregates [26][27][28][29][30]. Commercial surfactant formulations containing diamine additives have also been reported [31,32].…”

Section: Introductionmentioning

confidence: 99%

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An Investigation of the Effect of pH on Micelle Formation by a Glutamic Acid-Based Biosurfactant

Mayer,

Rauscher,

Fritz

et al. 2024

Colloids and Interfaces

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NMR spectroscopy, molecular modeling, and conductivity experiments were used to investigate micelle formation by the amino acid-based surfactant tridecanoic L-glutamic acid. Amino acid-based biosurfactants are green alternatives to surfactants derived from petroleum. NMR titrations were used to measure the monomeric surfactant’s primary and gamma (γ) carboxylic acid pKa values. Intramolecular hydrogen bonding within the surfactant’s headgroup caused the primary carboxylic acid to be less acidic than the corresponding functional group in free L-glutamic acid. Likewise, intermolecular hydrogen bonding caused the micellar surfactant’s γ carboxylic functional group to be less acidic than the corresponding monomer value. The binding of four positive counterions to the anionic micelles was also investigated. At pH levels below 7.0 when the surfactant headgroup charge was −1, the micelle hydrodynamic radii were larger (~30 Å) and the mole fraction of micelle-bound counterions was in the 0.4–0.7 range. In the pH range of 7.0–10.5, the micelle radii decreased with increasing pH and the mole fraction of micelle bound counterions increased. These observations were attributed to changes in the surfactant headgroup charge with pH. Above pH 10.5, the counterions deprotonated and the mole fraction of micelle-bound counterions decreased further. Finally, critical micelle concentration measurements showed that the micelles formed at lower concentrations at pH 6 when the headgroup charge was predominately −1 and at higher concentrations at pH 7 where headgroups had a mixture of −1 and −2 charges in solution.

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Section: Micelle Radii and Counterion Bindingmentioning

confidence: 82%

Section: Micelle Radii and Counterion Bindingmentioning

confidence: 84%

Section: Micelle Radii and Counterion Bindingmentioning

confidence: 99%

“…pHs where these values are low provides insight into the structure of the micelleterion complex [15][16][17]26]. This method will be employed below to interpret the r shown in Figure 5.…”

Section: Micelle Radii and Counterion Bindingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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An Investigation of the Effect of pH on Micelle Formation by a Glutamic Acid-Based Biosurfactant

Mayer,

Rauscher,

Fritz

et al. 2024

Colloids and Interfaces

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Development of Amino Acid-Based Surfactants: From Synthesis to Applications

Holmberg,

Bilén,

Bordes

2024

Current Opinion in Colloid & Interface Science

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Characterization of Micelle Formation by the Single Amino Acid-Based Surfactants Undecanoic L-Isoleucine and Undecanoic L-Norleucine in the Presence of Diamine Counterions with Varying Chain Lengths

Maynard-Benson

Alekisch

Wall

et al. 2023

Colloids and Interfaces

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The binding of linear diamine counterions with different methylene chain lengths to the amino-acid-based surfactants undecanoic L-isoleucine (und-IL) and undecanoic L-norleucine (und-NL) was investigated with NMR spectroscopy. The counterions studied were 1,2-ethylenediamine, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, and 1,6-diaminohexane. These counterions were all linear diamines with varying spacer chain lengths between the two amine functional groups. The sodium counterion was studied as well. Results showed that when the length of the counterion methylene chain was increased, the surfactants’ critical micelle concentrations (CMC) decreased. This decrease was attributed to diamines with longer methylene chains binding to multiple surfactant monomers below the CMC and thus acting as templating agents for the formation of micelles. The entropic hydrophobic effect and differences in diamine counterion charge also contributed to the size of the micelles and the surfactants’ CMCs in the solution. NMR diffusion measurements showed that the micelles formed by both surfactants were largest when 1,4-diaminobutane counterions were present in the solution. This amine also had the largest mole fraction of micelle-bound counterions. Finally, the und-NL micelles were larger than the und-IL micelles when 1,4-diaminobutane counterions were bound to the micelle surface. A model was proposed in which this surfactant formed non-spherical aggregates with both the surfactant molecules’ hydrocarbon chains and n-butyl amino acid side chains pointing toward the micelle core. The und-IL micelles, in contrast, were smaller and likely spherically shaped.

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NMR investigation of counterion binding to undecyl LL-leucinevalanate micelles

Cited by 4 publications

References 46 publications

An Investigation of the Effect of pH on Micelle Formation by a Glutamic Acid-Based Biosurfactant

An Investigation of the Effect of pH on Micelle Formation by a Glutamic Acid-Based Biosurfactant

Development of Amino Acid-Based Surfactants: From Synthesis to Applications

Characterization of Micelle Formation by the Single Amino Acid-Based Surfactants Undecanoic L-Isoleucine and Undecanoic L-Norleucine in the Presence of Diamine Counterions with Varying Chain Lengths

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