Biphasic Janus particles with nanoscale anisotropy

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Advances in the field of nanotechnology have fuelled the vision of future devices spawned from tiny functional components that are able to assemble according to a master blueprint1. In this concept, the controlled distribution of matter or ‘patchiness’2 is important for creating anisotropic building blocks and introduces an extra design parameter — beyond size and shape3,4. Although the reliable and efficient fabrication of building blocks with controllable material distributions will be of interest for many applications in research and technology, their synthesis has been addressed only in a few specialized cases5,6. Here we show the design and synthesis of polymer-based particles with two distinct phases. The biphasic geometry of these Janus particles is induced by the simultaneous electrohydrodynamic jetting7,8,9 of parallel polymer solutions under the influence of an electrical field. The individual phases can be independently loaded with biomolecules or selectively modified with model ligands, as confirmed by confocal microscopy and transmission electron microscopy. The fact that the spatial distribution of matter can be controlled at such small length scales will provide access to unknown anisotropic materials. This type of nanocolloid may enable the design of multicomponent carriers for drug delivery, molecular imaging or guided self-assembly.

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Figure 1: Biphasic electrified jetting using side-by-side dual capillaries.
Figure 2: Biphasic anisotropy examined by TEM and modelling.
Figure 3: Encapsulation of biomolecules in a dipolar fashion.
Figure 4: Selective chemical modification.


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We thank Solomon, University of Michigan, for use of the confocal laser scanning microscope and Manke, Wayne State University, for use of the viscometer. D.C.M. acknowledges partial support from the National Science Foundation through grant DMR-0084304.

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Correspondence to Joerg Lahann.

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Roh, K., Martin, D. & Lahann, J. Biphasic Janus particles with nanoscale anisotropy. Nature Mater 4, 759–763 (2005) doi:10.1038/nmat1486

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