Much like the checkout clerk uses a machine that scans the barcodes on packages to identify what customers bought at the store, scientists use powerful microscopes and their own kinds of barcodes to help them identify various parts of a cell, or types of molecules at a disease site. But their barcodes only come in a handful of "styles," limiting the number of objects scientists can study in a cell sample at any one time. Researchers at the Wyss Institute for Biologically Inspired Engineering at Harvard University have created a new kind of barcode that could come in an almost limitless array of styles -- with the potential to enable scientists to gather vastly more vital information, at one given time, than ever before. The method harnesses the natural ability of DNA to self-assemble, and was reported on September 24, 2012 in the online issue of Nature Chemistry and in the October 2012 print issue of the same journal. "We hope this new method will provide much-needed molecular tools for using fluorescence microscopy to study complex biological problems," says Dr. Peng Yin, Wyss core faculty member and study co-author who has been instrumental in the DNA origami technology at the heart of the new method. Fluorescence microscopy has been a tour de force in biomedical imaging for the last several decades. In short, scientists couple fluorescent elements -- the barcodes -- to molecules they know will attach to the part of the cells they wanted to investigate. Illuminating the sample triggers each kind of barcode to fluoresce at a particular wavelength of light, such as red, blue, or green -- indicating where the molecules of interest are. However, the method is limited by the number of colors available -- three or four -- and sometimes the colors get blurry.
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