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It's no coincidence that nanotech has developed in tandem with increasingly powerful microscopes that allow scientists to see objects that were once invisible to the world's strongest lenses. But even with the latest technology, it has always been assumed that optical microscopes could never zoom down to the level of an individual molecule.
Fortunately, that assumption has just been proven to be wrong. According to a research paper in the journal Nature, science has surpassed the previous limits. In the process, it has debunked a law of physics known as the "diffraction limit," which holds that the smallest image that an optical system can resolve is about half the wavelength of the light used to produce that image.
For conventional optics, this corresponds to about 200 nanometers. By comparison, a DNA molecule measures about 2.5 nanometers in width.
Now, a team led by Steven Chu - the Secretary of Energy, Nobel laureate, and former director of the Lawrence Berkeley National Laboratory - invented a technique that enables the use of optical microscopy to detect objects, or the distance between them, with resolutions as small as 0.5 nanometers. This is one-half of one billionth of a meter, or an order of magnitude smaller than the previous best. This has wide-ranging implications for a variety of research disciplines, including the following five examples:
- It could revolutionize structural biology because it could be used to measure distances between proteins that form multi-domain, highly complex structures, such as the protein assembly that forms the human RNA polymerase II system,which initiates DNA transcription.
- Chu's team is using it to determine the structure of the Epithelialcadherin molecules that are responsible for the cell-to-cell adhesion that holds tissue and other biological materials together.
- Other members of the team are also using this technique to create 3D measurements of the molecular organization inside brain cells. The goal is to determine the structure and dynamics of the vesicle fusion process that releases the neurotransmitter molecules used by neurons to communicate with one another.
- Working with Berkeley cancer researcher Joe Gray, still other members of the team are using the super-resolution technique to study the attachment of signaling molecules on the RAS protein, which has been linked to a number of cancers, including those of the breast, pancreas, lung,and colon. This research could help explain why cancer therapies that perform well on some patients are ineffective on others.
- The super-resolution technique should also prove valuable to characterize and design precision photometric imaging systems in atomic physics orastronomy, and allow for new tools in optical lithography and nanometrology.
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