Delivering More Than Charge

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Science  14 Nov 2008:
Vol. 322, Issue 5904, pp. 1027
DOI: 10.1126/science.322.5904.1027c

A small platinum or carbon wire inserted into a solution environment can yield substantial chemical insight through charge exchange with local compounds. One limitation of such electrode sensing, however, is that only electrons can be shuttled back and forth. Chen et al. have engineered a microfluidic apparatus, which they term a chemistrode, that can deliver or remove complex molecules from specific sites with a spatial resolution of 15 μm. The system relies on a fluorocarbon carrier fluid that pulls well-separated aqueous droplets through a channel that briefly opens to contact a substrate surface for molecular exchange. Analytes absorbed from the substrate can then be subjected to a wide range of traditional spectrometric probing techniques. The authors demonstrate the device through a measurement of insulin secretion kinetics by murine islet of Langerhans cells. — JSY

Proc. Natl. Acad. Sci. U.S.A. 105, 16843 (2008).

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