Fluorescence microscopes use technology that enables them to accomplish tasks not easy to achieve with normal light microscopes, including imaging DNA molecules to detect and diagnose cancer, nervous system disorders such as Alzheimer’s disease, and drug resistance in infectious diseases. These microscopes work by labeling the samples with fluorescent molecules that are “excited” with a laser. This process gives off differently colored light that the microscope detects and uses to build images of fluorescently labeled samples, visualizing objects that are 100 to 1,000 times smaller than the diameter of human hair. These fluorescent microscopes are expensive, bulky, and relatively complicated, typically making them available only in high-tech laboratories. Now, researchers from UCLA’s California NanoSystems Institute have reported the first demonstration of imaging and measuring the size of individual DNA molecules using a lightweight and compact device that converts an ordinary smartphone into an advanced fluorescence microscope. Led by Dr. Aydogan Ozcan, Associate Director of the UCLA California NanoSystems Institute and Chancellor’s Professor of Electrical Engineering and Bioengineering at the UCLA Henry Samueli School of Engineering and Applied Science, the research team published its results online on December 10, 2014 in ACS Nano. The mobile microscopy unit is an inexpensive, 3-D-printed optical device that uses the phone’s camera to visualize and measure the length of single-molecule DNA strands. The device includes an attachment that creates a high-contrast, dark-field imaging set-up using an inexpensive external lens, thin-film interference filters, a miniature dovetail stage, and a laser diode that excites the fluorescently labeled DNA molecules.
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