From PNNL: “Geologic CO2 Sequestration Inhibits Microbial Growth”

January 2015
Tom Rickey

Microbes’ response to injected CO2 has implications for microbial ecology, engineering processes

Results: A recent study used a novel combination of techniques to reveal how carbon dioxide (CO2) injections—a process that could reduce greenhouse gas emissions to the atmosphere—could affect sulfate-reducing bacteria that catalyze a key biogeochemical process in the deep subsurface. Ultimately, these findings offer an insight into the effects of CO2 sequestration on indigenous microbial populations, and could lead to new strategies for improving the success of CO2 sequestration, thereby helping to reduce climate change.

Scientists at PNNL used a novel combination of techniques to reveal how carbon dioxide (CO2) injections that could reduce greenhouse gas emissions could affect sulfate-reducing bacteria catalyzing a key biogeochemical process in the deep subsurface. Ultimately, these findings offer an insight into the effects of CO2 sequestration on indigenous microbial populations, and could lead to new strategies for improving the success of CO2 sequestration, thereby helping to reduce climate change. No image credit.

Combining novel high-pressure nuclear magnetic resonance spectroscopy and transcriptomic measurements, researchers from The Ohio State University and Pacific Northwest National Laboratory (PNNL) tracked the response of a model sulfate-reducing bacterium, Desulfovibrio vulgaris, to CO2 exposure under a range of pressures.

Their findings suggest geologic sequestration of CO2 may significantly inhibit sulfate reduction in deep subsurface environments where this metabolism is a key respiratory process. This effect may help limit harmful subsurface processes such as sulfide-induced corrosion, mineral precipitation, and injection-well blockage, thereby improving the overall efficiency of CO2 sequestration.

“Although pressure itself had no negative effect on the health of the microbes, some microbial activity was significantly impacted by CO2 exposure, even at relatively low pressures,” said Dr. Michael Wilkins, Ohio State University, who led the study while at PNNL. “In particular, cell growth was limited and respiration ceased under all conditions of pressurized CO2 exposure, which disrupted the integrity of the cell membrane. However, the cells initially remained viable and continued to transcribe genes at all CO2 pressures.”

Why It Matters: CO2 sequestration in deep subsurface environments has received significant attention and investment as a way to reduce greenhouse gas emissions to the atmosphere. However, relatively little is known about the effect of CO2 on the microbial community in the deep biosphere—the largest biosphere on earth.

The research team’s findings suggest CO2 injected in subsurface systems likely acts as a driving force for shifts in microbial community structure, which in turn could influence efficiency of the CO2 sequestration process.

What’s Next? The study paves the way for future research aimed at further examining mechanisms that inhibit the activity of microbial populations to improve CO2 sequestration. Moreover, this work could be a foundation for understanding how some indigenous microorganisms survive in conditions of high pressure levels and CO2 in deep subsurface environments.

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Pacific Northwest National Laboratory (PNNL) is one of the United States Department of Energy National Laboratories, managed by the Department of Energy’s Office of Science. The main campus of the laboratory is in Richland, Washington.

PNNL scientists conduct basic and applied research and development to strengthen U.S. scientific foundations for fundamental research and innovation; prevent and counter acts of terrorism through applied research in information analysis, cyber security, and the nonproliferation of weapons of mass destruction; increase the U.S. energy capacity and reduce dependence on imported oil; and reduce the effects of human activity on the environment. PNNL has been operated by Battelle Memorial Institute since 1965.

From PNNL: “Duets by Molecules and Plasmons”

PNNL Lab

January 2015
No Writer Credit

Scientists examine the information content in nanoscale chemical images

Frequency resolved TERS images of the laser-irradiated region, reconstructed using four different Raman-allowed vibrations of DMS. The representative images are obtained from the same pass of the AFM probe through the laser-illuminated region of the substrate. Namely, this is the same image, reconstructed at four different energies. The 2D contours have a color bar starting at white (brightest signals), passing through yellow to black (lowest signals). Copyright 2014: American Chemical Society. Enlarge/expand Image.

Results: Light waves trapped on a metal’s surface can interrogate the nearby molecules about their chemical identity through the molecule’s characteristic vibrations, which act as fingerprints. Scientists at Pacific Northwest National Laboratory (PNNL) “saw” the interaction between the molecules and the trapped light waves or surface plasmons. Their fundamental endeavor could lead to breakthroughs in interpreting ultrasensitive chemical images for characterizing new materials with potential uses in catalysis and energy conversion.

The article is featured in the American Chemical Society (ACS) Editors’ Choice collection. The decision was made by the journal editors, who select one article a day from across the 55 ACS journals to appear in this special collection. As such, it was made freely available to the public. The article was the editors’ choice for November 12, 2014.

Why It Matters: To detect only a few molecules, researchers using ultrasensitive spectroscopic and microscopic techniques rely on localized surface plasmons. This is particularly the case when the molecular identity must be determined. These plasmons are essentially light waves trapped at the surface of nanoscale noble metal structures. In surface plasmon-enhanced vibrational spectroscopy, the recorded optical signals result from the interaction between molecular and plasmonic states. This was revealed by PNNL scientists, who set out to understand the information content encoded in nanoscale chemical images, recorded by taking advantage of the unique properties of localized surface plasmons. They found that each pixel in their recorded images reports on the distinct local environments in which each probed molecule resides.

“This is really fundamental science that takes us a step closer to understanding what one actually measures with this type of spectroscopy,” said Dr. Patrick El-Khoury, a PNNL chemical physicist who carried out the measurements.

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From PNNL Lab “Particle’s Warming Impact Brought to Light”

PNNL Lab

January 2015

Results: When dust, soot and other black or dark-colored particles emitted through pollution are deposited in snow and ice, they increase melting. Pacific Northwest National Laboratory led a comprehensive, state-of-the-science review of light-absorbing particles. Their findings offer a better understanding of these complex climate-changers, underscoring the particles’ far-reaching influence, affecting freshwater supplies and sea-level rise, as well as atmospheric heat and cloud formation. The team summarized the range of methods used to measure these particles in snow and ice, especially in regions that are most sensitive to changes in the Earth’s ability to reflect sunlight. The review also covered modeling progress and suggested ways to advance understanding the particles’ impact on the global climate.

Dark particles on the surface of the Greenland ice sheet creates “dirty ice” which absorbs sunlight and accelerates the melting process, especially at the edges of a melt-water stream. © Henrik Egede Lassen/Alpha Film. Photo courtesy of The Arctic Monitoring and Assessment Programme, a working group of the Arctic Council.

Why It Matters: True to their name, light-absorbing particles attract sunlight and become a major factor in increasing snow and ice melt. They also influence Earth’s temperature, the ability of the surface to reflect sunlight, the amount of freshwater, and the rise of sea levels. Thus, these particles were identified as formidable climate-changing agents in the fourth and fifth assessment reports of the Intergovernmental Panel on Climate Change. To understand how changes in biomass- and fuel-burning —a large source of these particles —might help mitigate glacier melting, scientists must disentangle the influences of the particles’ natural and human-caused sources. The goal is to quantify the effects and simulate possible future changes to better understand changing climate.

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From PNNL: “Decoding Microbial Interactions”

PNNL Lab

December 2014
Web Publishing Services

Deep sequencing gives insights into mechanisms of microbial interactions

Results: As scientists strive to gain a systems-level understanding of microbial communities, their task grows increasingly more complex. Yet the benefits of doing this work can lead to new ways to engineer these amazing biological systems with significant implications for bioenergy, carbon sequestration, and bioremediation.

In ongoing work to integrate field investigations with well-controlled laboratory studies, scientists at Pacific Northwest National Laboratory grew two bacteria in a co-culture and applied deep transcriptome sequencing to study the physiological and genetic underpinnings driving interspecies interactions. They investigated the effect of co-cultivation and carbon flux directions on interactions between a salt-tolerant cyanobacterium, Synechococcus sp. PCC 7002 and a marine heterotroph, Shewanella putrefaciens W3-18-1. The results of this study, which appeared in The ISME Journal, provide novel and relevant insights into the physiological basis of microbial interactions.

Representative micrograph of Synechococcus sp. PCC7002 (red) and Shewanella sp. W3-18-1 (green) cell aggregates formed in a co-culture grown under carbon-limited aerobic chemostat conditions using lactate as the sole source of carbon.

Why It Matters: Phototrophs use energy from light to carry out various cellular metabolic processes, while heterotrophs use organic carbon for growth. In aquatic environments, an important class of interactions is based on cross-feeding and metabolite exchange, whereby photosynthetically fixed dissolved organic carbon (DOC) can elicit chemotactic responses that lead to spatial associations. This study provides initial insight into the complexity of photoautotrophic-heterotrophic interactions and brings new perspectives regarding their role in the robustness and stability of the association.

“Our experiments suggest that material and energy flows in microbial communities strongly affect the nature and direction of interactions between primary producers and heterotrophic consumers,” said Dr. Alex Beliaev, a microbiologist at PNNL and lead author of the publication. “Knowing the fundamental rules that govern the functioning of complex biological systems will inform science and policy challenges associated with environmental stewardship and climate change. It will also guide development of technical programs, including biodesign of stable microbial communities for bioenergy and environmental applications.”

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From PNNL Lab: “The Quality of Light”

PNNL Lab

December 2014

Optimizing production rates of cyanobacteria that have a “bright” future in biofuel synthesis

Results: Rapidly growing bacteria that live in the ocean and can manufacture their own food hold promise as host organisms for producing chemicals, biofuels, and medicine. Researchers at Pacific Northwest National Laboratory (PNNL) and The Pennsylvania State University are closely studying one of these photosynthetic species of fast-growing cyanobacteria using advanced tools developed at PNNL to determine the optimum environment that contributes to record growth and productivity. Their work on how the cyanobacteria respond to different wavelengths of light, as critical resources, recently was featured in Frontiers in Microbiology.

PNNL and The Pennsylvania State University are studying Synechococcus, a promising cyanobacterium (the yellow-orange cells) that could be used to determine optimum growing conditions for biofuels.
No image credit

Why It Matters: Using biofuels based on cyanobacteria on an industrial scale could lower pollution levels from fossil fuels, provide a sustainable source of energy, and curb energy dependence. The challenge has been to find the right organism that can be cost-effectively grown quickly enough to meet industrial demand. The strain of cyanobacteria researchers studied, Synechococcus sp. PCC 7002, grows at rates that rank among the fastest reported for photosynthetic microorganisms. With a better understanding of how the cyanobacterium adapts to changing environmental conditions, researchers are able to optimize growth and productivity.

Scientists at PNNL compare culturing conditions in samples generated from a novel cultivation approach: binary cultivation in photobioreactors. The approach uses binary cultivation inside photobioreactors to facilitate growth by creating a closed system where the metabolic by-products of one organism are used to fuel metabolism in the other.

“Understanding the fundamental underpinnings that determine growth rates of cyanobacteria provides an insight into the biological blueprint of photosynthetic organisms,” said PNNL’s Dr. Alex Beliaev, the lead scientist on the project.

Dr. Hans Bernstein, a Linus Pauling Postdoctoral Fellow at PNNL who helped lead the study, added, “A deeper understanding of the basic biology for this organism is helping us develop solutions for efficient renewable energy production and will ultimately help us develop novel technologies based on microbial communities.”

See the full article here.

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From PNNL: “New Assay Platform Detects Largest Number of Known Biotoxins Simultaneously”

PNNL Lab

October 2014
No Writer Credit

New Assay Platform Detects Largest Number of Known Biotoxins Simultaneously

Rapid, inexpensive microarray increases ability to identify, treat toxin exposure

Results: The largest panel of biotoxins to be simultaneously detected to date has been achieved using an assay platform developed by scientists at Pacific Northwest National Laboratory. The enzyme-linked immunosorbent assay (ELISA) microarray simultaneously detected 10 plant and microbial toxins in buffer and clinical and environmental samples. These included ricin, botulinum neurotoxins (BoNT), shiga (STX), and staphylococcal enterotoxin B (SEB). Previously, the largest number of toxins to be simultaneously detected has been six.

ricin
A molecule of ricin, one of the most deadly and common toxins discovered to date. An assay developed at Pacific Northwest National Laboratory can detect ricin and nine other biotoxins simultaneously, the largest panel to date.

“Most assays to detect toxins target one or two toxins at a time, at best. In the event of a bioterrorist attack, it may not be obvious which agent was released, although this knowledge is critical for delivering appropriate medical treatment,” said Dr. Susan Varnum, a biologist at PNNL who led the study, which appears in Analyst.

“There’s a pressing need for assays that analyze multiple toxins simultaneously so that in case of exposure, differentiation of multiple biothreat toxins can occur early enough for appropriate care to be given,” Varnum added.

ELISAs are widely used to detect the presence of a single antigen-or biomarker-in biological samples. This new microarray ELISA platform allows the highly sensitive detection of up to 50 antigens simultaneously. Typically, commercially available antibodies are used in the development of these assays. However, to differentiate among six closely related BoNT serotypes, the scientists used high-affinity reagents generated in the laboratory of Dr. James Marks, University of California, San Francisco School of Medicine. The new, highly sensitive assay design developed by PNNL is rapid, specific, and simple enough for easy adoption by other research groups.

Why It Matters: Protein toxins are considered to be potential biological threat agents because of their extreme toxicity, widespread availability, and ease of use. Biothreat toxins have been stockpiled for bioweapon use and even used in previous bioterrorism events. To treat exposure to these toxins, sensitive and specific detection systems that can quickly identify multiple biothreat toxins are needed. The new assay platform affords simultaneous detection of 10 biothreat toxins simultaneously in a diverse range of clinical and environmental samples, including blood, saliva, urine, stool, milk, and apple juice.

Methods: The research team based their diagnostic assay on the antibody microarray approach. Antibody protein microarrays are miniaturized, solid-phase analytical assays for the detection of many proteins in parallel. This approach uses an array of high-affinity capture reagents, or antibodies, immobilized on a glass slide. These spatially arrayed antibodies bind a specific antigen from a sample added to the array. A second, labeled antibody that recognizes the same antigen as the first antibody then is used for detection to form a “sandwich” assay. This sandwich approach favors specificity in analyte detection.

A Venn diagram outlining and contrasting some aspects of the fields of bio-MEMS, lab-on-a-chip, μTAS.

The assay not only sensitively detected the biotoxins in buffer but also in complex clinical and environmental matrices at levels in the low picogram per mL-1 range and with a minimal sample volume of 20 microliters. The multiplex ELISA-based protein antibody microarray developed at PNNL demonstrates an excellent assay that can achieve some of the lowest detection limits and maintain sensitivity below the reported median lethal dose (LD50) in a wide range of biological fluids.

Acknowledgments

Sponsors: This research was supported by the National Institute of Allergy and Infectious Diseases.

Research Team: Kathryn Jenko, Yanfang Zhang, Yulia Kostenko, and Susan Varnum (PNNL); Yongfeng Fan, Consuelo Garcia-Rodriguez, Jianlong Lou, and James Marks (UCSF).

Research Area: Biological Systems Science

Reference: Jenko K, Y Zhang, Y Kostenko, Y Fan, C Garcia-Rodriguez, J Lou, JD Marks, and SM Varnum. 2014. Development of an ELISA Microarray Assay for the Sensitive and Simultaneous Detection of Ten Biodefense Toxins. Analyst 139(20):5093-5102. DOI: 10.1039/c4an01270d.

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From PNNL: “Off-shore Power Potential Floating in the Wind”

PNNL Lab

September 2014
Web Publishing Services

Results: Two bright yellow buoys – each worth $1.3 million – are being deployed by Pacific Northwest National Laboratory in Washington State’s Sequim Bay. The massive, 20,000-pound buoys are decked out with the latest in meteorological and oceanographic equipment to enable more accurate predictions of the power-producing potential of winds that blow off U.S. shores. Starting in November, they will be commissioned for up to a year at two offshore wind demonstration projects: one near Coos Bay, Oregon, and another near Virginia Beach, Virginia.

off
PNNL staff conduct tests in Sequim Bay, Washington, while aboard one of two new research buoys being commissioned to more accurately predict offshore wind’s power-producing potential.

“We know offshore winds are powerful, but these buoys will allow us to better understand exactly how strong they really are at the heights of wind turbines,” said PNNL atmospheric scientist Dr. William J. Shaw. “Data provided by the buoys will give us a much clearer picture of how much power can be generated at specific sites along the American coastline – and enable us to generate that clean, renewable power sooner.”

Why It Matters: Offshore wind is a new frontier for U.S. renewable energy developers. There’s tremendous power-producing potential, but limited information is available about ocean-based wind resources. A recent report estimated the U.S. could power nearly 17 million homes by generating more than 54 gigawatts of offshore wind energy, but more information is needed.

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From PNNL: “As Light Dims and Food Sources Are Limited, Key Changes in Proteins Occur in Cyanobacteria”

PNNL Lab

September 2014
Web Publishing Services

As Light Dims and Food Sources Are Limited, Key Changes in Proteins Occur in Cyanobacteria
Identification of redox-sensitive enzymes can enrich biofuel production research

Results: Using a chemical biology approach, scientists at Pacific Northwest National Laboratory (PNNL) identified more than 300 proteins in a bacterium adept at converting carbon dioxide into other molecules of interest to energy researchers. These proteins are involved in generating macromolecule synthesis and carbon flux through central metabolic pathways and may also be involved in cell signaling and response mechanisms.

The team’s research also suggests that dynamic redox changes in response to specific nutrient limitations, including carbon and nitrogen limitations, contribute to the regulatory changes driven by a shift from light to dark.

They also observed that the number of labeled proteins under nitrogen or carbon limitation was ~50 percent greater than in nutrient-replete cultures, suggesting that nitrogen or carbon limitation results in increased probe labeling of proteins, indicative of a more reduced cellular environment.

“Together, our results contribute to a high-level understanding of post-translational mechanisms that regulate flux distributions and suggest potential metabolic engineering targets for redirecting carbon toward biofuel precursors,” said Dr. Charles Ansong, PNNL scientist and co-first author of the research publication that appears in Frontiers in Microbiology. “Our identification of redox-sensitive enzymes involved in these processes can potentially enrich the experimental design of research in biofuel production.”

Overview of the chemical biology technique used by PNNL scientists to determine Synechococcus sp. PCC 7002 cells’ protein redox status in real time and identify redox-sensitive proteins as they occurred under induced nutrient perturbations including C and N limitation and transition from light to dark environments. Cell-permeable chemical probes derived from iodoacetamide (IAM-RP) and n-ethylmaleimide (Mal-RP) (top right) were applied to living cells. Once applied, the chemical probes irreversibly labeled proteins with reduced cysteines (bottom middle). The probe-labeled proteins were subsequently isolated for identification by high-resolution LC-MS (bottom right).

Why It Matters: Plants or organisms that use sunlight to convert inorganic materials to organic ones for chemical compound production and respiration, among other functions, are called phototrophs. Scientists are interested in them because their conversion properties could translate into research experiments for biofuel production. But a key step toward such research is understanding protein redox chemistry-a reaction that can alter protein structure thereby regulating function. The lack of such understanding is a major void in knowledge about photoautotrophic system regulation and signaling processes.

To decrease that void, the PNNL team analyzed redox-sensitive proteins in live Synechococcus sp. PCC 7002 cells in both light and dark periods, and to understand how cellular redox balance is disrupted during nutrient perturbation.

Research Team: Charles Ansong, Natalie C. Sadler, Eric A. Hill, Michael P. Lewis, Erika M. Zink, Richard D. Smith, Alexander S. Beliaev, Allan E. Konopka, and Aaron T. Wright, all PNNL.

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From PNNL: “Birth of a mineral”

PNNL Lab

September 04, 2014
Mary Beckman, PNNL, (509) 375-3688

One of the most important molecules on earth, calcium carbonate crystallizes into chalk, shells and minerals the world over. In a study led by the Department of Energy’s Pacific Northwest National Laboratory, researchers used a powerful microscope that allows them to see the birth of crystals in real time, giving them a peek at how different calcium carbonate crystals form, they report September 5 in Science.

The results might help scientists understand how to lock carbon dioxide out of the atmosphere as well as how to better reconstruct ancient climates.

“Carbonates are most important for what they represent, interactions between biology and Earth,” said lead researcher James De Yoreo, a materials scientist at PNNL. “For a decade, we’ve been studying the formation pathways of carbonates using high-powered microscopes, but we hadn’t had the tools to watch the crystals form in real time. Now we know the pathways are far more complicated than envisioned in the models established in the twentieth century.”

Earth’s Reserve

Calcium carbonate is the largest reservoir of carbon on the planet. It is found in rocks the world over, shells of both land- and water-dwelling creatures, and pearls, coral, marble and limestone. When carbon resides within calcium carbonate, it is not hanging out in the atmosphere as carbon dioxide, warming the world. Understanding how calcium carbonate turns into various minerals could help scientists control its formation to keep carbon dioxide from getting into the atmosphere.

Calcium carbonate deposits also contain a record of Earth’s history. Researchers reconstructing ancient climates delve into the mineral for a record of temperature and atmospheric composition, environmental conditions and the state of the ocean at the time those minerals formed. A better understanding of its formation pathways will likely provide insights into those events.

To get a handle on mineral formation, researchers at PNNL, the University of California, Berkeley, and Lawrence Berkeley National Laboratory [LBNL] examined the earliest step to becoming a mineral, called nucleation. In nucleation, molecules assemble into a tiny crystal that then grows with great speed. Nucleation has been difficult to study because it happens suddenly and unpredictably, so the scientists needed a microscope that could watch the process in real time.

Come to Order

In the 20th century, researchers established a theory that crystals formed in an orderly fashion. Once the ordered nucleus formed, more molecules added to the crystal, growing the mineral but not changing its structure. Recently, however, scientists have wondered if the process might be more complicated, with other things contributing to mineral formation. For example, in previous experiments they’ve seen forms of calcium carbonate that appear to be dense liquids that could be sources for minerals.

Researchers have also wondered if calcite forms from less stable varieties or directly from calcium and carbonate dissolved in the liquid. Aragonite and vaterite are calcium carbonate minerals with slightly different crystal architectures than calcite and could represent a step in calcite’s formation. The fourth form called amorphous calcium carbonate — or ACC, which could be liquid or solid, might also be a reservoir for sprouting minerals.

To find out, the team created a miniature lab under a transmission electron microscope at the Molecular Foundry, a DOE Office of Science User Facility at LBNL. In this miniature lab, they mixed sodium bicarbonate (used to make club soda) and calcium chloride (similar to table salt) in water. At high enough concentrations, crystals grew. Videos of nucleating and growing crystals recorded what happened:

tem
transmission electron microscope at LBNL

Morphing Minerals

The videos revealed that mineral growth took many pathways. Some crystals formed through a two-step process. For example, droplet-like particles of ACC formed, then crystals of aragonite or vaterite appeared on the surface of the droplets. As the new crystals formed, they consumed the calcium carbonate within the drop on which they nucleated.

Other crystals formed directly from the solution, appearing by themselves far away from any ACC particles. Multiple forms often nucleated in a single experiment — at least one calcite crystal formed on top of an aragonite crystal while vaterite crystals grew nearby.

What the team didn’t see in and among the many options, however, was calcite forming from ACC even though researchers widely expect it to happen. Whether that means it never does, De Yoreo can’t say for certain. But after looking at hundreds of nucleation events, he said it is a very unlikely event.

“This is the first time we have directly visualized the formation process,” said De Yoreo. “We observed many pathways happening simultaneously. And they happened randomly. We were never able to predict what was going to come up next. In order to control the process, we’d need to introduce some kind of template that can direct which crystal forms and where.”

In future work, De Yoreo and colleagues plan to investigate how living organisms control the nucleation process to build their shells and pearls. Biological organisms keep a store of mineral components in their cells and have evolved ways to make nucleation happen when and where needed. The team is curious to know how they use cellular molecules to achieve this control.

This work was supported by the Department of Energy Office of Science.

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From PNNL Lab: “Playing Twenty Questions with Molecules at Plasmonic Junctions”

PNNL Lab

August 2014
Toward engineering ultrasensitive probes of nanoscale physical and chemical processes

Results: Sometimes, it seems as if molecules struggle to communicate with scientists. When it comes to junction plasmons, essentially light waves trapped at tiny gaps between noble metals, what the molecules have to say could radically change the design of detectors used for science and security. Single molecule detection sensitivity is feasible through Raman scattering from molecules coaxed into plasmonic junctions. Scientists at Pacific Northwest National Laboratory (PNNL) found that sequences of Raman spectra recorded at a plasmonic junction, formed by a gold tip and a silver surface, exhibit dramatic intensity fluctuations, accompanied by switching from familiar vibrational line spectra of a molecule to broad band spectra of the same origin. The fluctuations confirm the team’s earlier model that assigns enhanced band spectra in Raman scattering from plasmonic nanojunctions to shorting of the junction plasmon through intervening molecular bridges.

“It’s all about asking it the right questions and listening to what it has to say,” said Dr. Patrick El-Khoury, who has been working on this project for 2 years.

charts
“This is a paradigm shift in molecular spectroscopy, as we are no longer after molecular properties. Rather, we use those properties — in this study the symmetry of the observable vibrational modes — to tell us about the rich environments in which molecules reside,” said Dr. Patrick El-Khoury. (A) Time evolution of contact mode spectra of DMS on a 15 nm silver film. (B) Cross-correlation map of the individually normalized spectra shown in the image on the top. Copyright 2014: American Chemical Society

Why It Matters: A host of emerging state-of-the-art devices and instruments rely on molecule-plasmon interactions. Recent works demonstrated yoctomolar detection sensitivity in Raman scattering from plasmonic nanojunctions, or the ability to detect 1 molecule in 602,214,000,000,000,000,000,000. Plasmonic sensors operating at this detection limit are able to determine the chemical identity of minute quantities of radioactive and environmental hazards. The development of single molecule chemical nanoscopes could answer fundamental questions about physical and chemical processes taking place over nanometer length scales. The fundamentals gained from this study could impact the design of ultrasensitive plasmonic sensors and chemical nanoscopes used to understand the fundamental chemistry behind energy storage and production, as well as the blueprints of extremely tiny electronic devices.

“Before you can engineer the devices you need, you need to know how molecules behave over length scales comparable to their characteristic dimensions. Our research is fundamental, providing novel insights into how molecules interact with junction plasmons,” said Dr. Wayne Hess, a chemical physicist at PNNL

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