Accelerated insulin aggregation under alternating current electric fields: Relevance to amyloid kinetics.
The time-dependent nucleation phase is critical to amyloid fibrillation and related to many pathologies, in which the conversion from natively folded amyloidogenic proteins to oligomers via nucleation is often hypothesized as a possible underlying mechanism. In this work, non-uniform AC-electric fields across two asymmetric electrodes were explored to control and examine the aggregation of insulin, a model amyloid protein, in aqueous buffer solution at constant temperature (20 °C) by fluorescence correlation spectroscopy and fluorescence microscopy. Insulin was rapidly concentrated in a strong AC-field by imposed AC-electroosmosis flow over an optimal frequency range of 0.5-2 kHz. In the presence of an AC-field, direct fibrillation from insulin monomers without the formation of oligomer precursors was observed. Once the insulin concentration had nearly doubled its initial concentration, insulin aggregates were observed in solution. The measured lag time for the onset of insulin aggregation, determined from the abrupt reduction in insulin concentration in solution, was significantly shortened from months or years in the absence of AC-fields to 1 min-3 h under AC-fields. The ability of external fields to alter amyloid nucleation kinetics provides insights into the onset of amyloid fibrillation.
Department of Chemical and Biomolecular Engineering, University of Notre Dame , Notre Dame, Indiana 46556, USA.
Zhongli
Z
Zheng
Department of Chemical and Biomolecular Engineering, University of Notre Dame , Notre Dame, Indiana 46556, USA.
Benxin
B
Jing
Howard P. Isermann Department of Chemical and Biological Engineering and The Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute , Troy, New York 12180, USA.
Mirco
M
Sorci
Howard P. Isermann Department of Chemical and Biological Engineering and The Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute , Troy, New York 12180, USA.
Georges
G
Belfort
Department of Chemical and Biomolecular Engineering, University of Notre Dame , Notre Dame, Indiana 46556, USA.
Yingxi
Y
Zhu