Recent work by Associate Professor David Masiello and colleagues was highlighted in an article in Nature Photonics, published November 7th. The research was also highlighted in Chemical & Engineering News as well as in a News & Views feature article in Nature Photonics.
Measurement of the two distinct components—scattering and absorption—of a single nanoscale object’s optical extinction provides fundamentally important and complementary information on how that object processes light: either scattering it back to the far-field or converting it into internal excitation. Today, various techniques exist to measure the scattering from individual nanoscale objects, all relying on the detection of scattered photons in regions of zero background. Measuring their absorption, however, is much more complicated due to the fundamental inability to detect extremely small reductions in transmission over statistical fluctuations in the number of photons. This means that the spectroscopic signature of the vast majority of molecules—specifically, those that are transformed into dark states through photoreactions—is difficult to access.
To overcome this challenge, researchers in the Masiello and Goldsmith groups at UW and UW, Madison (WI) devised a new experimental route to measure the absorption spectra of individual, nonemissive nanoscale objects by photothermal contrast in an optical microresonator cavity.
Photothermal spectroscopies function by inferring an object’s absorption from the localized temperature increase and resulting refractive index inhomogeneity produced by the excited object’s nonradiative decay. In their work, the team coupled individual plasmonic nanorods to an ultrahigh-quality optical microresonator cavity and succeeded in determining the nanorod’s absorption spectrum by monitoring the temperature-dependent attometer shifts in the resonance frequency of microresonator’s whispering gallery modes. These exceedingly small but detectable resonance shifts correspond to temperature increases of ~100 nK (measured at room temperature!), making their absorption spectrometer simultaneously one of the world’s best thermometers. Suprisingly, the nanorod’s absorption spectrum revealed a dense array of sharp Fano interferences arising from its interaction with the whispering gallery modes of the microresonator, allowing the team to deeply explore the hybridization of plasmonic and photonic cavity modes.
The collaborative effort, involving both theorists and experimentalists, brought together the creativity and talents of several graduate students and postdocs in multiple departments between the two institutions and took years of hard work to accomplish. Future directions will explore the feasibility of this system to serve as a platform for studying quantum physics at room temperature.
To learn more about Prof. Masiello and his research, visit his website.
Congratulations to Assistant Professor Joshua Vaughan and his UW co-workers, whose recent work was featured on the cover of Nature Methods. Their report details the development of a simplified method to “inflate” cellular structures for use in an imaging technique known as expansion microscopy.
Efforts to improve the resolution of cellular structures typically focus on addressing the limitations of microscope hardware. With expansion microscopy, higher resolution is achieved through physical alteration of the specimen. By linking swellable polymers to customized fluorophores, researchers can physically expand the specimen to enable super-resolution microscopy with a conventional laboratory microscope.
As noted in the journal, Vaughan and co-workers have “developed and characterized new methods for linking fluorophores to the polymer that now enable expansion microscopy with conventional fluorescently labeled antibodies and fluorescent proteins.” By simplifying the procedure and expanding fluorophore options, they came up with separate approaches to provide high resolution imaging of individual cells and of tissue slices. In addition to facilitating a range of biological studies, these refinements broadly expand access to the technique, enabling researchers to use a variety of conventional fluorophores and ordinary laboratory microscopes to achieve high resolution cellular imaging.
More information about this work can be found in Nature Methods and in the UW News press release.
For more information about Professor Vaughan and his research, please visit his faculty page and research group website.
Assistant Professor Jesse Zalatan and co-workers at the UCSF have developed a method to encode complex, synthetic transcriptional regulatory programs using the CRISPR-Cas system. Natural biological systems can switch between different functional or developmental states depending on the particular set of genes being expressed, and the ability to synthetically control gene expression has important implications as both a research tool and as a means to engineer novel cell-based therapeutics and devices.
Zalatan and coworkers designed CRISPR-Cas RNA scaffold molecules that specify both a DNA target and the function to execute at the target, so that sets of RNA scaffolds can be used to generate a synthetic, multigene transcriptional program in eukaryotic cells in which some genes are activated and others are repressed. These types of programs can be used to reprogram complex reaction networks in biological systems, such as metabolic pathways or signaling cascades.
For more information about Professor Zalatan and his research, please visit his faculty page and research group website.
Research by Assistant Professor AJ Boydston and his group has been featured in two recent articles in the American Chemical Society’s Chemical & Engineering News. An article in the December 18, 2014 issue highlights his research on polymers that change color when stretched (http://cen.acs.org/articles/92/web/2014/12/3-D-Printed-Polymer-Devices.html). Just one month later, an article in the January 19, 2015 issue summarized the Boydston group’s research on a metal-free route to prepare polymers (http://cen.acs.org/articles/93/i3/Radical-Polymer-Approach.html).
For more information about Professor Boydston and his research program, please visit his faculty page and research group website.
Assistant Professor Stefan Stoll (Chemistry), Professor William Zagotta (Physiology & Biophysics), and co-workers have used double electron-electron resonance (DEER) spectroscopy to determine the structural origins of the regulatory function of cyclic adenosine monophosphate (cAMP) on an important ion channel. Their work reveals that binding of the cAMP induces a large structural change in the intracellular part of the channel. The ion channel studied, a hyperpolarization-activated cyclic nucleotide-gated (HCN) ion channel, is critical to the function of heart, as it is part of the heart’s natural pacemaker. The HCN channel is crucial in regulating the heartbeat: binding of cAMP to HCN increases of the heart rate. This work, reported in the Proceedings of the National Academy of Sciences, could form the basis for better drug design for disorders of electrical signaling in the heart. (A movie showing a model of the structural change can be downloaded in Quicktime format from: http://felix.chem.washington.edu/HCN_DEER_movie.mov.)
To learn more about Professor Stoll and his research, please visit his faculty page and research group website.
To learn more about Professor Zagotta and his research, please visit his faculty page.
One measure of the scale and strength of chemistry research programs is success in the allocation of competitively awarded grant and contract funds in support of research. The Department of Chemistry at the University of Washington has in recent years been among the leaders nationally by this measure. According to the most recent (2012) National Science Foundation Survey of Higher Education Research and Development, the University of Washington Department of Chemistry is ranked 10th nationally for overall research and development spending in chemistry, appearing just below the Department of Chemistry at the Massachusetts Institute of Technology for total expenditures. In terms of federally-funded research and development spending, the Department of Chemistry ranks 8th nationally.
Date related to the survey can be found at http://www.nsf.gov/statistics/herd/.
Research Associate Professor Werner Kaminsky contributed to a research project recently highlighted in Nature. With the catch phrase “BOTOX paralyses zebrafish muscles and blocks fin regeneration”, Nature highlighted a publication on the effect of Botulinum toxin on bone regeneration,[i] tested on small fish, whose fins were cut-off (under sedation), then regrown while testing different amounts of medications administrated to the fish’s dorsolateral trunk and the base of the tail fin prior to surgery.[ii] Nature summed up the findings with “muscle paralysis (was) similar to that seen in mammals and humans in that it was focal, dose-dependent and short-lasting.” and “BTx treatment had a negative impact on bone formation during fin regeneration.” The work involved a truly diverse multi-discipline co-operation between members of three departments on the UW campus: Orthopaedics and Sports Medicine, Pharmacology, and Chemistry. The regenerating zebrafish tail fin often provides a compelling model for therapeutic studies. However, a major hurdle to such efforts is the lack of quantitative modalities for bone mineralization analysis. Kaminsky contributed his patented microscopy technology to determine bone mineralization with a custom built automated polarized light microscope to sequentially acquire images under a stepwise rotating polarizer. This enabled birefringence to be decoupled from transmittance and orientation, allowing for quantitative analysis.
A new University of Washington institute to develop efficient, cost-effective solar power and better energy storage systems launched December 12 with an event attended by UW President Michael K. Young, Gov. Jay Inslee and researchers, industry experts and policy leaders in renewable energy.
The Clean Energy Institute formed when Washington’s governor and state legislators last summer allocated $6 million to create a research center at the university that will advance solar energy and electrical energy storage capacities. The institute will better connect and boost existing energy research at the UW as well as attract new partnerships and talent, including new faculty members.
The opening of the Clean Energy Institute was covered by KIRO 7 News, the Seattle Times, and UW News. Chemistry Professor David Ginger, Raymon E. and Rosellen M. Lawton Distinguished Scholar in Chemistry, is the Associate Director of the Clean Energy Institute. Daniel Gamelin, Harry and Catherine Jaynne Boand Endowed Professor of Chemistry, serves on the Faculty Advisory Board.
A vial holds a solution that contains the UW-developed polymer “ink” that can be printed to make solar cells.
David Ginger, Professor and Raymon E. and Rosellen M. Lawton Distinguished Scholar in Chemistry, and Alex Jen, Boeing/Johnson Chair Professor of Materials Science & Engineering, along with other researchers, have recently reported on the role of electron spin in creating efficient organic solar cells. Their findings were recently published in the journal Nature.
Organic solar cells that convert light to electricity using carbon-based molecules have shown promise as a versatile energy source but have not been able to match the efficiency of their silicon-based counterparts. These researchers have discovered a synthetic, high-performance polymer that behaves differently from other tested materials and could make inexpensive, highly efficient organic solar panels a reality. The polymer, created at the University of Washington and tested at the University of Cambridge in England, appears to improve efficiency by wringing electrical current from pathways that, in other materials, cause a loss of electrical charge.
More information can be found at Nature and in the UW News press release.
To learn more about Professor Ginger and Professor Jen, please visit their research group websites.
Ginger Research Group: http://depts.washington.edu/gingerlb/
Jen Research Group: http://depts.washington.edu/jengroup/
Sarah Keller, working with Roy Black, affiliate professor of bioengineering, has helped to unravel some of the mystery surrounding the origin of cells in Earth’s ancient oceans. The work, recently published in the Proceedings of the National Academy of Sciences, describes the unexpected interaction of the chemical components of RNA and fatty acids and their role in stabilizing the precursors to cellular membranes.
The chemical components crucial to the start of life on Earth may have primed and protected each other in never-before-realized ways. That could mean a simpler scenario for how that first spark of life on the planet came about. Scientists have long thought that life started when the right combination of bases and sugars produced self-replicating ribonucleic acid, or RNA, inside a rudimentary ‘cell’ composed of fatty acids. Under the right conditions, fatty acids naturally form into bag-like structures similar to today’s cell membranes. In testing one of the fatty acids representative of those found before life began – decanoic acid – Keller and Black discovered that the four bases in RNA bound more readily to the decanoic acid than did the other seven bases tested. By concentrating more of the bases and sugar that are the building blocks of RNA, the system would have been primed for the next steps, reactions that led to RNA inside a bag.
Descriptions of the published research can be found on the UW News website and on Babbage, the science and technology blog of The Economist.
To learn more about Professor Keller, visit her faculty page and research group website.