Continuous Paranematic Ordering of Rigid and Semiflexible Amyloid-Fe3O4 Hybrid Fibrils in an External Magnetic Field.
External magnetic field is a powerful approach to induce orientational order in originally disordered suspensions of magneto-responsive anisotropic particles. By small angle neutron scattering and optical birefringence measurement technology, we investigated the effect of magnetic field on the spatial ordering of hybrid amyloid fibrils with different aspect ratios (length-to-diameter) and flexibilities decorated by spherical Fe3O4 nanoparticles. A continuous paranematic ordering from an initially isotropic suspension was observed upon increasing magnetic field strength, with spatial orientation increasing with colloidal volume fraction. At constant dimensionless concentration, stiff hybrid fibrils with varying aspect ratios and volume fractions, fall on the same master curve, with equivalent degrees of ordering at identical magnetic fields. However, the semiflexible hybrid fibrils with contour length close to persistence length exhibit a lower degree of alignment. This is consistent with Khokhlov-Semenov theoretical predictions. These findings sharpen the experimental toolbox to design colloidal systems with controllable degree of orientational ordering.
Laboratory of Food and Soft Materials, Department of Health Sciences and Technology, ETH Zurich , 8092 Zurich, Switzerland.
Jianguo
J
Zhao
Laboratory of Food and Soft Materials, Department of Health Sciences and Technology, ETH Zurich , 8092 Zurich, Switzerland.
Sreenath
S
Bolisetty
Laboratory of Food Process Engineering, Department of Health Sciences and Technology, ETH Zurich , 8092 Zurich, Switzerland.
Stéphane
S
Isabettini
Laboratory of Neutron Scattering and Imaging, Paul Scherrer Institute , 5232 Villigen, Switzerland.
Joachim
J
Kohlbrecher
Laboratory of Food and Soft Materials, Department of Health Sciences and Technology, ETH Zurich , 8092 Zurich, Switzerland.
Jozef
J
Adamcik
Laboratory of Food Process Engineering, Department of Health Sciences and Technology, ETH Zurich , 8092 Zurich, Switzerland.
Peter
P
Fischer
Laboratory of Food and Soft Materials, Department of Health Sciences and Technology, ETH Zurich , 8092 Zurich, Switzerland.
Raffaele
R
Mezzenga
D000682:Amyloid / Q000737:chemistry*; D016880:Anisotropy; D005290:Ferric Compounds / Q000737:chemistry*; D060526:Magnetic Fields; D053768:Metal Nanoparticles / Q000737:chemistry*; D053838:Scattering, Small Angle
D000682:Amyloid; D005290:Ferric Compounds; C000499:ferric oxide