Johan Larsson1, Adrian Sanchez-Fernandez2, Anna E Leung3, Ralf Schweins4, Baohu Wu5, Tommy Nylander6, Stefan Ulvenlund7, Marie Wahlgren7. 1. Physical Chemistry, Department of Chemistry, Lund University, Box 124, 221 00 Lund, Sweden. Electronic address: johan.larsson@fkem1.lu.se. 2. Food Technology, Nutrition and Engineering, Lund University, Box 124, 221 00 Lund, Sweden. 3. European Spallation Source, Box 176, 221 00 Lund, Sweden. 4. Institut Laue-Langevin, DS / LSS, 71 Avenue des Martyrs, 38000 Grenoble, France. 5. Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungszentrum Jülich GmbH, Lichtenbergstr. 1, 85748 Garching, Germany. 6. Physical Chemistry, Department of Chemistry, Lund University, Box 124, 221 00 Lund, Sweden; NanoLund, Lund University, Lund, Sweden. 7. Food Technology, Nutrition and Engineering, Lund University, Box 124, 221 00 Lund, Sweden; Enza Biotech AB, Scheelevägen 22, 22363 Lund, Sweden.
Abstract
HYPOTHESIS: The anomeric configuration (α or β) of n-hexadecyl-d-maltopyranoside (C16G2) has been shown to affect the morphology of the micelle, from elongated for α-C16G2 to worm-like micelles for β-C16G2. The entanglement of worm-like micelles often leads to strong modifications of the rheological behavior of the system and, as such, the anomeric configuration of C16G2 could also provide the possibility of controlling this. Furthermore, mixing these surfactants are hypothesized to result in mixed micelles allowing to finely tune the rheology of a system containing these sustainable surfactants. EXPERIMENTS: The rheology of α- and β-C16G2, and mixtures of those, was determined by rotational and oscillatory rheology at different temperatures and surfactant concentrations. Micelle structure and composition for these systems were characterized using contrast variation small-angle neutron scattering and small-angle X-ray scattering. The results from these were connected in order to elaborate a molecular understanding of the rheological response of the system. FINDINGS: The self-assembly of these surfactants have been found to result in different rheological properties. β-C16G2 show a high viscosity with a non-Newtonian viscoelastic behavior, which was linked to the formation of worm-like micelles. In contrast, α-C16G2 self-assembled into short cylindrical micelles, resulting in a Newtonian fluid with low viscosity. Furthermore, mixtures of these two surfactants lead to systems with intermediate rheological properties as a result of the formation of micelles with intermediate morphology to those of the pure anomers. These results also show that the rheological properties of the system can be tuned to change the micelle morphology, which in turn depends on the anomeric configuration of the surfactant. Also, surfactant concentration, temperature of the system, and micelle composition for surfactant mixtures provide control over the rheological properties of the system in a wide temperature range. Therefore, these results open new possibilities in the development of sustainable excipients for formulation technology, where the characteristics of the system can be easily tailored through geometric variations in the monomer structure whilst maintaining the chemical composition of the system.
HYPOTHESIS: The anomeric configuration (α or β) of n-hexadecyl-d-maltopyranoside (C16G2) has been shown to affect the morphology of the micelle, from elongated for α-C16G2 to worm-like micelles for β-C16G2. The entanglement of worm-like micelles often leads to strong modifications of the rheological behavior of the system and, as such, the anomeric configuration of C16G2 could also provide the possibility of controlling this. Furthermore, mixing these surfactants are hypothesized to result in mixed micelles allowing to finely tune the rheology of a system containing these sustainable surfactants. EXPERIMENTS: The rheology of α- and β-C16G2, and mixtures of those, was determined by rotational and oscillatory rheology at different temperatures and surfactant concentrations. Micelle structure and composition for these systems were characterized using contrast variation small-angle neutron scattering and small-angle X-ray scattering. The results from these were connected in order to elaborate a molecular understanding of the rheological response of the system. FINDINGS: The self-assembly of these surfactants have been found to result in different rheological properties. β-C16G2 show a high viscosity with a non-Newtonian viscoelastic behavior, which was linked to the formation of worm-like micelles. In contrast, α-C16G2 self-assembled into short cylindrical micelles, resulting in a Newtonian fluid with low viscosity. Furthermore, mixtures of these two surfactants lead to systems with intermediate rheological properties as a result of the formation of micelles with intermediate morphology to those of the pure anomers. These results also show that the rheological properties of the system can be tuned to change the micelle morphology, which in turn depends on the anomeric configuration of the surfactant. Also, surfactant concentration, temperature of the system, and micelle composition for surfactant mixtures provide control over the rheological properties of the system in a wide temperature range. Therefore, these results open new possibilities in the development of sustainable excipients for formulation technology, where the characteristics of the system can be easily tailored through geometric variations in the monomer structure whilst maintaining the chemical composition of the system.
Authors: Adrian Sanchez-Fernandez; Johan Larsson; Anna E Leung; Peter Holmqvist; Orsolya Czakkel; Tommy Nylander; Stefan Ulvenlund; Marie Wahlgren Journal: Langmuir Date: 2022-08-01 Impact factor: 4.331