Attosyringe Delivers Via Electrochemistry

Talk about your tiny needles. Michael V. Mirkin and coworkers at Queens College of the City University of New York have developed a syringe just nanometers in diameter that's capable of sampling and dispensing fluid in attoliter to picoliter (10^-18 to 10^-12 L) volumes (Proc. Natl. Acad. Sci. USA 2007, 104, 11895). The device could be useful in fields such as cell biology, microfluidics, and nanolithography, which rely on the ability to transport minuscule volumes of fluid from one place to another. To create the tiny needle, Mirkin's group heats and pulls a glass capillary tube until it breaks in two. The resulting attosyringes are filled with an organic solution and immersed in an aqueous solution. When a voltage is applied across the liquid-liquid interface, liquid is either withdrawn or dispensed, depending on whether the potential is positive or negative. Mirkin and colleagues found they could use the precision syringe to deliver miniscule volumes of solution into mammalian cells.