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Manipulation of liquid droplets using amphiphilic, magnetic one-dimensional photonic crystal chaperones

Nature Materials volume 3, pages 896–899 (2004)Cite this article

Abstract

The controlled manipulation of small volumes of liquids is a challenging problem in microfluidics1,2,3,4, and it is a key requirement for many high-throughput analyses and microassays5,6. One-dimensional photonic crystals made from porous silicon have been constructed with amphiphilic properties7. When prepared in the form of micrometre-sized particles and placed in a two-phase liquid such as dichloromethane/water, these materials will accumulate and spontaneously align at the interface. Here we show that superparamagnetic nanoparticles of Fe3O4 can be incorporated into the porous nanostructure, allowing the materials to chaperone microlitre-scale liquid droplets when an external magnetic field is applied. The optical reflectivity spectrum of the photonic crystal displays a peak that serves to identify the droplet. Two simple microfluidics applications are demonstrated: filling and draining a chaperoned droplet, and combining two different droplets to perform a chemical reaction. The method provides a general means for manipulating and monitoring small volumes of liquids without the use of pumps, valves or a microfluidic container.

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Figure 1: Schematic diagram of the synthesis of bifunctional magnetic particles.
Figure 2: Optical microscope images of bifunctional magnetic porous Si particles.
Figure 3: Reflectivity spectra of the bifunctional porous Si particle assembly before and after delivery of payload.
Figure 4: Reflectivity spectra of two sets of porous Si chaperones involved in mixing two chemicals to perform a reaction.

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Acknowledgements

We thank Erkki Ruoslahti of the Burnham Institute for discussions, and Evelyn York of the Scripps Institute of Oceanography, Analytical Instrument Facility, for assistance with the electron microscopy measurements. This project has been funded in part by the Air Force Office of Scientific Research under grant no. F49620-02-1-0288 and by the National Cancer Institute, National Institutes of Health, under contract no. N01-CO-37117. J.D. thanks the UCSD California Institute of Telecommunications and Information Technology for a fellowship.

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  1. Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, Department 0358, La Jolla, 92093-0358, California, USA

    Jason R. Dorvee & Michael J. Sailor

  2. Department of Bioengineering, University of California, San Diego, 9500 Gilman Drive, Department 0412, La Jolla, 92093-0412, California, USA

    Austin M. Derfus & Sangeeta N. Bhatia

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  1. Jason R. Dorvee
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Correspondence to Michael J. Sailor.

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Dorvee, J., Derfus, A., Bhatia, S. et al. Manipulation of liquid droplets using amphiphilic, magnetic one-dimensional photonic crystal chaperones. Nature Mater 3, 896–899 (2004). https://doi.org/10.1038/nmat1253

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