Chad Mirkin is developing a new DNA detection method. The Northwestern University professor and director of the school's Institute of NanoTechnology pairs microelectrodes and nanoprobes for detecting Anthrax, small pox, and other biohazards. He asserts that nanotechnology offers better results in all categories of detection, including sensitivity, selectivity, cost, ease of use, and speed. The new detection method eliminates the need to heat the gene chip. Mirkin says that companies in the gene chip technology business currently use a polymerase chain reaction (PCR) for detection. Gene chips are read using a confocal microscope, a complex instrument costing more than $60,000. Mirkin's electrical DNA detection method eliminates the PCR. It also allows testing of thousands of biological targets on a single chip. Various DNA tests are placed on a glass slide, each made up of single strands of synthesized DNA that bind with targeted DNA. The bound strands are placed between a pair of electrodes, one test for each pair. When the slide is placed in a solution containing the target, perfect and partial matches bind to gold probes. The probe accumulations are then amplified using modified photographic developing solution. Each gold nanoparticle becomes covered with silver and grows in size, closing the gap between the electrodes and thus carrying a current. For more information, go to www.northwestern.edu.
An in-depth survey of 700 current and future users of 3D printing holds few surprises, but results emphasize some major trends already in progress. Two standouts are the big growth in end-use parts and metal additive manufacturing (AM) most respondents expect.
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