MRI-R^2: Development of STIM and DATS for Protein and Nanosystem Characterization
Markelz, Andrea Principal Investigator
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This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). Support from the MRI-R2 program has been awarded to SUNY at Buffalo to develop two complimentary instruments: Spectral Terahertz Imaging Microscopy (STIM) and Dynamic Alignment Terahertz Spectroscopy (DATS). This pair of instruments is essential to address a fundamental question: what is the role of collective motions in protein function? Answering this question has an immediate impact on biological physics, and bioengineering. STIM enables terahertz imaging of protein crystals and solid state samples with < 1 micron resolution, 0.2-7.0 THz bandwidth, 4.2 K - 300 K and in fields up to 10 T. DATS enables terahertz spectroscopy of electrostatically aligned molecular systems and structural measurements of non-crystallizing molecular systems. Proteins and RNA-systems lay at the intersection between highly structured and amorphous systems. Traditional approaches to studying these systems are limited by background from the relaxational contribution of surface side chains and solvent, and by the broad spectrum of overlapping modes. STIM and DATS address these limitations through molecular alignment and polarization modulation and thereby establish the functional importance of structural vibrational motion. This instrumentation significantly improves our understanding of protein dynamics. Also, magnetic excitations, phonon frequencies and carrier transport times for technologically emerging materials lie in the terahertz frequency range. As device size shrinks, one cannot assume bulk material properties and local characterization is essential. Further, emerging materials often do not have sufficient sample size or uniformity for bulk characterization. To probe nonuniformity, localized states and phase transitions require terahertz microscopy. STIM is a high resolution, high quality spectroscopy system for measurement of nanosystems. The development of STIM and DATS enables critical measurements in fields as diverse as structural biology and condensed matter research. The instrumentation directly addresses needs that other current terahertz instrumentation does not: 1) need to discriminate structural motion from diffusive surface motion in proteins; 2) need for spatially resolved conductivity tensor and spin spectroscopy of electronic materials 3) need for structural determination for non-crystallizing molecules. This MRI-R2 project fosters interdisciplinary work among multiple departments, schools and agencies. The system development offers unique training opportunities for graduate and undergraduate researchers. This MRI-R2 activity also includes a new microscopy exhibit for our GGEMS on the GO program for 7-12 graders and an undergraduate Discovery Seminar Series: Bringing Science and Engineering to Life. Results of the development effort, and of the research enabled by the new instruments, will be published in peer-reviewed journals and disseminated through student and faculty presentations at regional and national meetings.