Insulin Aggregation at a Dynamic Solid–Liquid–Air Triple Interface

To optimize its fluidic processes, EVEON has collaborated for several years with the laboratory LMGP to understand the causes of the aggregation during the manipulation of proteins. Work on this subject has been published in the magazine Langmuir.

Abstract : Therapeutic proteins are privileged in drug development because of their exquisite specificity, which is due to their three-dimensional conformation in solution. During their manufacture, storage, and delivery, interactions with material surfaces and air interfaces are known to affect their stability. The growing use of automated devices for handling and injection of therapeutics increases their exposure to protocols involving intermittent wetting, during which the solid–liquid and liquid–air interfaces meet at a triple contact line, which is often dynamic. Using a microfluidic setup, we analyze the effect of a moving triple interface on insulin aggregation in real time over a hydrophobic surface. We combine thioflavin T fluorescence and reflection interference microscopy to concomitantly monitor insulin aggregation and the morphology of the liquid as it dewets the surface. We demonstrate that insulin aggregates in the region of a moving triple interface and not in regions submitted to hydrodynamic shear stress alone, induced by the moving liquid. During dewetting, liquid droplets form on the surface anchored by adsorbed proteins, and the accumulation of amyloid aggregates is observed exclusively as fluorescent rings growing eccentrically around these droplets. The fluorescent rings expand until the entire channel surface sweeped by the triple interface is covered by amyloid fibers. On the basis of our experimental results, we propose a model describing the growth mechanism of insulin amyloid fibers at a moving triple contact line, where proteins adsorbed at a hydrophobic surface are exposed to the liquid–air interface.

Thibaut Frachon†‡, Franz Bruckert†, Quentin Le Masne‡, Emmanuel Monnin‡, and Marianne Weidenhaupt*†
† LMGP, University Grenoble Alpes, CNRS, F-38000 Grenoble, France
‡ Eveon S.A.S., Inovallée, F-38330 Montbonnot Saint Martin, France
Langmuir, 2016, 32 (49), pp 13009–13019
DOI: 10.1021/acs.langmuir.6b03314
Publication Date (Web): November 16, 2016
Copyright © 2016 American Chemical Society

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