Imaging is one of the most important tools in biology. However, observing biological structures and processes in living cells at a resolution below the diffraction limit of light microscopy (~200 nm) remains extremely challenging. Recently, several super-resolution techniques have been introduced to improve the resolution of optical fluorescence, with reported static and dynamic resolutions reaching ~20 nm and ~60 nm, respectively. However, these techniques have yet to be translated to the live cell because of difficulties caused by limitations of fluorescent probes and optical aberrations and light scattering in tissues. Thus researchers must extrapolate information from images of fixed specimens to the living state. This project proposes a new super-resolution imaging technology: QSTORM, which combines user-controlled, switchable quantum dots (QDs) with specialized computer-based algorithms (STORM) and adaptive optics to enhance images. QSTORM will, for the first time, enable imaging in living cells with a resolution superior or comparable to other super-resolution techniques. QSTORM will be evaluated in two models systems: the structure and function of muscle myofilaments in zebrafish and the intracellular transport of vesicles in fruit fly neurons. Normal muscle function depends on the highly organized multi-scale architecture of muscle tissue. QSTORM will enable simultaneous imaging of functioning myofilaments, sarcomeres, and whole muscle cells within the same sample. Similarly, axonal transport of cargo by vesicles is critical to the survival and function of neuronal cells. QSTORM will permit observation of the movements of individual vesicles and the mapping of the underlying cytoskeletal structures that enable this transport. Additionally, the QSTORM team will collaborate with the Museum of Science in Boston to share the results of this research broadly through science education programs, museum demonstrations, and Web-based multimedia projects.
Intellectual merit. If fully successful, QSTORM will harness the superior imaging capabilities of quantum dots and adaptive optics for live cell imaging at a super-resolution of less than 50 nm. QSTORM will transform imaging of biological processes, particularly those involving the cytoskeleton and motor proteins. In the models to be studied, QSTORM will permit three-dimensional high resolution imaging of intact live muscle without the destructive processing required for transmission electron microscopy (TEM), thus potentially leading to new hypotheses of how muscle proteins such as actin, myosin, and associated proteins interact. Similarly, QSTORM will permit, for the first time, imaging the movements of neuronal vesicles over complete transport cycles along the entire length of the axon at single nanometer resolution, thus potentially transforming current understanding of the fundamental molecular mechanisms of transport and its regulation.
Broader impacts. QSTORM will contribute a powerful new microscopy tool to the scientific community. Not only will this research produce extraordinary images that offer visual insight into fundamental biological processes, but also the broader dissemination of results and educational activities will widely advance subcellular biological research and training. Researchers, students, educators, and public audiences will benefit from the potentially extraordinary visualizations produced by QSTORM. This research will be incorporated into graduate and undergraduate courses in a wide-range of disciplines. Collaboration with the Museum of Science will provide broadly accessible and nationally disseminated educational materials. A QSTORM Web site will present these extraordinary images as part of a lively multimedia story of high-risk, interdisciplinary scientific and technical collaboration in pursuit of a grand challenge.
The Q-STORM project was initiated with two primary goals in mind: (1) To develop new optical microscopy tools that can image objects smaller than what can currently be imaged, ideally by an order of magnitude, inside whole organisms. This is crucially important because most biological process occur via the actions of proteins or other molecules that are smaller than 200 nm in diameter, which makes them impossible to see with most optical microscopes. Recently, several new technologies have been proposed or piloted to permit imaging of these very small molecules. This project focused on the idea of combining a new type of microscopy: Stochastic Optical Reconstruction Microscopy, or STORM, with a new type of tag, known as a Quantum Dot, (i.e., QSTORM) to identify the protein of interest. This new type of tag is a semiconductor-based nanoparticle whose light signal could be turned on or off by the investigator to allow imaging of very small objects individually rather than having signals from multiple objects bleeding together. In this project, we investigated two mechanisms for turning the tag on and off, one based on degrading the particle with intense light and another based on transferring the light energy from the tag to another nanoparticle made of gold. We had initial success with both methods, which suggests that further investigation is merited. Technologies, such as these, will enable deeper understanding of biological processes in whole organisms, which not only increases fundamental biological knowledge, but could translate into improvements in medicine and agriculture. For example, results from this research were crucial to the founding and advancement of 1 company, Core Quantum Technologies, which is developing nanoparticle imaging reagents for diagnostic testing in cancer. (2) To foster and study the practice of interdisciplinary research. This research team consisted of a biomedical engineer, a chemical engineer, a biologist, a biophysicist, and an expert in science communication and visualization to the general public who had not previously met or worked together before. This team was formed through a special National Science Foundation workshop to tackle the challenges of biological microscopy. Although we had not previously worked together, the team was exceptionally functional, yielding joint conference presentations and publications. Most notably, the team participated in several museum outreach events to the general public organized by the Museum of Science (MOS), Boston, and shown at MOS, COSI (Columbus, OH), and the Carnegie Science Center. These events allowed researchers to explain their work to the general public, and also to explain the life of an interdisciplinary scientist or engineer, potentially enhancing understanding of the STEM (Science, Technology, Engineering, and Math) disciplines and STEM careers. This team will be highlighted at the American Association for the Advancement of Science (AAAS) meeting in February 2015.
