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Issue 8, 2013
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Separation of chiral colloidal particles in a helical flow field

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Stereoisomeric molecules with opposite chirality, so-called enantiomers, often vary regarding their sensory, pharmacological and toxicological properties. Such enantiomer specific effects play a central role in the development, testing and evaluation of drugs, pesticides and food related products. Accordingly, efficient techniques for separation of chiral mixtures into enantiopure compounds are of enormous practical relevance. Most current enantiomer separation methods are based on enantioselective interactions with an auxiliary substance which has to be developed and optimized for different chiral molecules in an elaborate and costly process. Here, we experimentally demonstrate the separation of micron-sized chiral particles in a helical fluid flow which is created inside a microfluidic device patterned with slanted grooves. We observe that the retention time of particles in a helical flow field strongly depends on their chirality which leads to an effective chiral separation within the channel. Our experimental results are confirmed by numerical calculations which demonstrate how the coupling of rotational and translational degrees of freedom leads to differences in the trajectories of particles with opposite chirality. Since our separation mechanism does not rely on material specific interactions, this offers considerable advantages over existing methods. We expect that our approach can be also applied at nanometre length scales by using channels with smaller diameters and with an optimized geometry.

Graphical abstract: Separation of chiral colloidal particles in a helical flow field

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Publication details

The article was received on 23 Oct 2012, accepted on 20 Dec 2012 and first published on 17 Jan 2013

Article type: Paper
DOI: 10.1039/C2SM27441H
Soft Matter, 2013,9, 2525-2530

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    Separation of chiral colloidal particles in a helical flow field

    M. Aristov, R. Eichhorn and C. Bechinger, Soft Matter, 2013, 9, 2525
    DOI: 10.1039/C2SM27441H

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