Edible carbon dioxide sponge: All-natural nanostructures could address pressing environmental problem

ScienceDaily (Sep. 25, 2011) — A year ago Northwestern University chemists published their recipe for a new class of nanostructures made of sugar, salt and alcohol. Now, the same team has discovered the edible compounds can efficiently detect, capture and store carbon dioxide. And the compounds themselves are carbon-neutral.

The porous crystals -- known as metal-organic frameworks (MOFs) -- are made from all-natural ingredients and are simple to prepare, giving them a huge advantage over other MOFs. Conventional MOFs, which also are effective at adsorbing carbon dioxide, are usually prepared from materials derived from crude oil and often incorporate toxic heavy metals.

Other features of the Northwestern MOFs are they turn red when completely full of carbon dioxide, and the carbon capture process is reversible.

The findings, made by scientists working in the laboratory of Sir Fraser Stoddart, Board of Trustees Professor of Chemistry in the Weinberg College of Arts and Sciences, are published in the Journal of the American Chemical Society (JACS).

"We are able to take molecules that are themselves sourced from atmospheric carbon, through photosynthesis, and use them to capture even more carbon dioxide," said Ross S. Forgan, a co-author of the study and a postdoctoral fellow in Stoddart's laboratory. "By preparing our MOFs from naturally derived ingredients, we are not only making materials that are entirely nontoxic, but we are also cutting down on the carbon dioxide emissions associated with their manufacture."

The main component, gamma-cyclodextrin, is a naturally occurring biorenewable sugar molecule that is derived from cornstarch.

The sugar molecules are held in place by metals taken from salts such as potassium benzoate or rubidium hydroxide, and it is the precise arrangement of the sugars in the crystals that is vital to their successful capture of carbon dioxide.

"It turns out that a fairly unexpected event occurs when you put that many sugars next to each other in an alkaline environment -- they start reacting with carbon dioxide in a process akin to carbon fixation, which is how sugars are made in the first place," said Jeremiah J. Gassensmith, lead author of the paper and also a postdoctoral fellow in Stoddart's laboratory. "The reaction leads to the carbon dioxide being tightly bound inside the crystals, but we can still recover it at a later date very simply."

The fact that the carbon dioxide reacts with the MOF, an unusual occurrence, led to a simple method of detecting when the crystals have reached full capacity. The researchers place an indicator molecule, which detects changes in pH by changing its color, inside each crystal. When the yellow crystals of the MOFs are full of carbon dioxide they turn red.

The simplicity of the new MOFs, allied with their low cost and green credentials, have marked them as candidates for further commercialization. Ronald A. Smaldone, also a postdoctoral fellow in Stoddart's group and a co-author of the paper, added, "I think this is a remarkable demonstration of how simple chemistry can be successfully applied to relevant problems like carbon capture and sensor technology."

The National Science Foundation, the U.S. Department of Energy, the Engineering and Physical Sciences Research Council in the U.K., the King Abdulaziz City of Science and Technology (KACST) in Saudi Arabia and the Korea Advanced Institute of Science and Technology (KAIST) in Korea supported the research.

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Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Northwestern University. The original article was written by Megan Fellman.

Journal Reference:

Jeremiah J. Gassensmith, Hiroyasu Furukawa, Ronald A. Smaldone, Ross S. Forgan, Youssry Y. Botros, Omar M. Yaghi, J. Fraser Stoddart. Strong and Reversible Binding of Carbon Dioxide in a Green Metal–Organic Framework. Journal of the American Chemical Society, 2011; 110913144109022 DOI: 10.1021/ja206525x

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Edible carbon dioxide sponge: All-natural nanostructures could address pressing environmental problem

ScienceDaily (Sep. 25, 2011) — A year ago Northwestern University chemists published their recipe for a new class of nanostructures made of sugar, salt and alcohol. Now, the same team has discovered the edible compounds can efficiently detect, capture and store carbon dioxide. And the compounds themselves are carbon-neutral.

The porous crystals -- known as metal-organic frameworks (MOFs) -- are made from all-natural ingredients and are simple to prepare, giving them a huge advantage over other MOFs. Conventional MOFs, which also are effective at adsorbing carbon dioxide, are usually prepared from materials derived from crude oil and often incorporate toxic heavy metals.

Other features of the Northwestern MOFs are they turn red when completely full of carbon dioxide, and the carbon capture process is reversible.

The findings, made by scientists working in the laboratory of Sir Fraser Stoddart, Board of Trustees Professor of Chemistry in the Weinberg College of Arts and Sciences, are published in the Journal of the American Chemical Society (JACS).

"We are able to take molecules that are themselves sourced from atmospheric carbon, through photosynthesis, and use them to capture even more carbon dioxide," said Ross S. Forgan, a co-author of the study and a postdoctoral fellow in Stoddart's laboratory. "By preparing our MOFs from naturally derived ingredients, we are not only making materials that are entirely nontoxic, but we are also cutting down on the carbon dioxide emissions associated with their manufacture."

The main component, gamma-cyclodextrin, is a naturally occurring biorenewable sugar molecule that is derived from cornstarch.

The sugar molecules are held in place by metals taken from salts such as potassium benzoate or rubidium hydroxide, and it is the precise arrangement of the sugars in the crystals that is vital to their successful capture of carbon dioxide.

"It turns out that a fairly unexpected event occurs when you put that many sugars next to each other in an alkaline environment -- they start reacting with carbon dioxide in a process akin to carbon fixation, which is how sugars are made in the first place," said Jeremiah J. Gassensmith, lead author of the paper and also a postdoctoral fellow in Stoddart's laboratory. "The reaction leads to the carbon dioxide being tightly bound inside the crystals, but we can still recover it at a later date very simply."

The fact that the carbon dioxide reacts with the MOF, an unusual occurrence, led to a simple method of detecting when the crystals have reached full capacity. The researchers place an indicator molecule, which detects changes in pH by changing its color, inside each crystal. When the yellow crystals of the MOFs are full of carbon dioxide they turn red.

The simplicity of the new MOFs, allied with their low cost and green credentials, have marked them as candidates for further commercialization. Ronald A. Smaldone, also a postdoctoral fellow in Stoddart's group and a co-author of the paper, added, "I think this is a remarkable demonstration of how simple chemistry can be successfully applied to relevant problems like carbon capture and sensor technology."

The National Science Foundation, the U.S. Department of Energy, the Engineering and Physical Sciences Research Council in the U.K., the King Abdulaziz City of Science and Technology (KACST) in Saudi Arabia and the Korea Advanced Institute of Science and Technology (KAIST) in Korea supported the research.

Recommend this story on Facebook, Twitter,
and Google +1:

Other bookmarking and sharing tools:

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Northwestern University. The original article was written by Megan Fellman.

Journal Reference:

Jeremiah J. Gassensmith, Hiroyasu Furukawa, Ronald A. Smaldone, Ross S. Forgan, Youssry Y. Botros, Omar M. Yaghi, J. Fraser Stoddart. Strong and Reversible Binding of Carbon Dioxide in a Green Metal–Organic Framework. Journal of the American Chemical Society, 2011; 110913144109022 DOI: 10.1021/ja206525x

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Antibody-based biosensor can guide environmental clean-ups, provide early warning system for spills

ScienceDaily (May 9, 2011) — Tests of a new antibody-based "biosensor" developed by researchers at the Virginia Institute of Marine Science show that it can detect marine pollutants like oil much faster and more cheaply than current technologies. The device is small and sturdy enough to be used from a boat.

Testing of the biosensor in the Elizabeth River and Yorktown Creek, which both drain into lower Chesapeake Bay, shows that the instrument can process samples in less than 10 minutes, detect pollutants at levels as low as just a few parts per billion, and do so at a cost of just pennies per sample. Current technology requires hours of lab work, with a per-sample cost of up to $1,000.

"Our biosensor combines the power of the immune system with the sensitivity of cutting-edge electronics," says Dr. Mike Unger of VIMS. "It holds great promise for real-time detection and monitoring of oil spills and other releases of contaminants into the marine environment."

The biosensor was developed and tested by Unger, fellow VIMS professor Steve Kaattari, and their doctoral student Candace Spier, with assistance from marine scientist George Vadas. The team's report of field tests with the sensor appears in this month's issue of Environmental Toxicology and Chemistry.

The instrument was developed in conjunction with Sapidyne Instruments, Inc., with funding from the state of Virginia, the Office of Naval Research, and the Cooperative Institute for Coastal and Estuarine Environmental Technology, a partnership between NOAA and the University of New Hampshire.

The tests in the Elizabeth River took place during clean up of a site contaminated by polycyclic aromatic hydrocarbons (PAHs), byproducts of decades of industrial use of creosote to treat marine pilings. The U.S. Environmental Protection Agency considers PAHs highly toxic and lists 17 as suspected carcinogens.

The biosensor allowed the researchers to quantify PAH concentrations while the Elizabeth River remediation was taking place, gaining on-site knowledge about water quality surrounding the remediation site. Spier says the test was "the first use of an antibody-based biosensor to guide sampling efforts through near real-time evaluation of environmental contamination."

In the Yorktown Creek study, the researchers used the biosensor to track the runoff of PAHs from roadways and soils during a rainstorm.

Biosensor development

Kaattari says "Our basic idea was to fuse two different kinds of technologies -- monoclonal antibodies and electronic sensors -- in order to detect contaminants."

Antibodies are proteins produced by the immune system of humans and other mammals. They are particularly well suited for detecting contaminants because they have, as Kaattari puts it, an "almost an infinite power to recognize the 3-dimensional shape of any molecule."

Mammals produce antibodies that recognize and bind with large organic molecules such as proteins or with viruses. The VIMS team took this process one step further, linking proteins to PAHs and other contaminants, then exposing mice to these paired compounds in a manner very similar to a regular vaccination.

"Just like you get vaccinated against the flu, we in essence are vaccinating our mice against contaminants," says Kaattari. "The mouse's lymphatic system then produces antibodies to PAHs, TNT, tributyl tin [TBT, the active ingredient in anti-fouling paints for boats], or other compounds."

Once a mouse has produced an antibody to a particular contaminant, the VIMS team applies standard clinical techniques to produce "monoclonal antibodies" in sufficiently large quantities for use in a biosensor.

"This technology allows you to immortalize a lymphocyte that produces only a very specific antibody," says Kaattari. "You grow the lymphocytes in culture and can produce large quantities of antibodies within a couple of weeks. You can preserve the antibody-producing lymphocyte forever, which means you don't have to go to a new animal every time you need to produce new antibodies."

From antibody to electrical signal

The team's next step was to develop a sensor that can recognize when an antibody binds with a contaminant and translate that recognition into an electrical signal. The Sapidyne® sensor used by the VIMS team works via what Kaattari calls a "fluorescence-inhibitory, spectroscopic kind of assay."

In the sensor used on the Elizabeth River and Yorktown Creek, antibodies designed to recognize a specific class of PAHs were joined with a dye that glows when exposed to fluorescent light. The intensity of that light is in turn recorded as a voltage. The sensor also houses tiny plastic beads that are coated with what Spier calls a "PAH surrogate" -- a PAH derivative that retains the shape that the antibody recognizes as a PAH molecule.

When water samples with low PAH levels are added to the sensor chamber (which is already flooded with a solution of anti-PAH antibodies), the antibodies have little to bind with and are thus free to attach to the surrogate-coated beads, providing a strong fluorescent glow and electric signal. In water samples with high PAH concentrations, on the other hand, a large fraction of the antibodies bind with the environmental contaminants. That leaves fewer to attach to the surrogate-coated beads, which consequently provides a fainter glow and a weaker electric signal.

During the Elizabeth River study, the biosensor measured PAH concentrations that ranged from 0.3 to 3.2 parts per billion, with higher PAH levels closer to the dredge site. In Yorktown Creek, the biosensor showed that PAH levels in runoff peaked 1 to 2 hours after the rain started, with peak concentration of 4.4 parts per billion.

Comparison of the biosensor's field readings with later readings from a mass spectrometer at VIMS showed that the biosensor is just as accurate as the more expensive, slower, and laboratory-bound machine.

A valuable field tool

Spier says "Using the biosensor allowed us to quickly survey an area of almost 900 acres around the Elizabeth River dredge, and to provide information about the size and intensity of the contaminant plume to engineers monitoring the dredging from shore. If our results had shown elevated concentrations, they could have halted dredging and put remedial actions in place."

Unger adds "measuring data in real-time also allowed us to guide the collection of large-volume water samples right from the boat. We used these samples for later analysis of specific PAH compounds in the lab. This saved time, effort, and money by keeping us from having to analyze samples that might contain PAHs at levels below our detection limit."

"Biosensors have their constraints and optimal operating conditions," says Kaattari, "but their promise far outweighs any limitations. The primary advantages of our biosensor are its sensitivity, speed, and portability. These instruments are sure to have a myriad of uses in future environmental monitoring and management."

One promising use of the biosensor is for early detection and tracking of oil spills. "If biosensors were placed near an oil facility and there was a spill, we would know immediately," says Kaattari. "And because we could see concentrations increasing or decreasing in a certain pattern, we could also monitor the dispersal over real time."

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Virginia Institute of Marine Science. The original article was written by David Malmquist.

Journal Reference:

Candace R. Spier, George G. Vadas, Stephen L. Kaattari, Michael A. Unger. Near real-time, on-site, quantitative analysis of PAHs in the aqueous environment using an antibody-based biosensor. Environmental Toxicology and Chemistry, 2011; DOI: 10.1002/etc.546

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Antibody-based biosensor can guide environmental clean-ups, provide early warning system for spills

ScienceDaily (May 9, 2011) — Tests of a new antibody-based "biosensor" developed by researchers at the Virginia Institute of Marine Science show that it can detect marine pollutants like oil much faster and more cheaply than current technologies. The device is small and sturdy enough to be used from a boat.

Testing of the biosensor in the Elizabeth River and Yorktown Creek, which both drain into lower Chesapeake Bay, shows that the instrument can process samples in less than 10 minutes, detect pollutants at levels as low as just a few parts per billion, and do so at a cost of just pennies per sample. Current technology requires hours of lab work, with a per-sample cost of up to $1,000.

"Our biosensor combines the power of the immune system with the sensitivity of cutting-edge electronics," says Dr. Mike Unger of VIMS. "It holds great promise for real-time detection and monitoring of oil spills and other releases of contaminants into the marine environment."

The biosensor was developed and tested by Unger, fellow VIMS professor Steve Kaattari, and their doctoral student Candace Spier, with assistance from marine scientist George Vadas. The team's report of field tests with the sensor appears in this month's issue of Environmental Toxicology and Chemistry.

The instrument was developed in conjunction with Sapidyne Instruments, Inc., with funding from the state of Virginia, the Office of Naval Research, and the Cooperative Institute for Coastal and Estuarine Environmental Technology, a partnership between NOAA and the University of New Hampshire.

The tests in the Elizabeth River took place during clean up of a site contaminated by polycyclic aromatic hydrocarbons (PAHs), byproducts of decades of industrial use of creosote to treat marine pilings. The U.S. Environmental Protection Agency considers PAHs highly toxic and lists 17 as suspected carcinogens.

The biosensor allowed the researchers to quantify PAH concentrations while the Elizabeth River remediation was taking place, gaining on-site knowledge about water quality surrounding the remediation site. Spier says the test was "the first use of an antibody-based biosensor to guide sampling efforts through near real-time evaluation of environmental contamination."

In the Yorktown Creek study, the researchers used the biosensor to track the runoff of PAHs from roadways and soils during a rainstorm.

Biosensor development

Kaattari says "Our basic idea was to fuse two different kinds of technologies -- monoclonal antibodies and electronic sensors -- in order to detect contaminants."

Antibodies are proteins produced by the immune system of humans and other mammals. They are particularly well suited for detecting contaminants because they have, as Kaattari puts it, an "almost an infinite power to recognize the 3-dimensional shape of any molecule."

Mammals produce antibodies that recognize and bind with large organic molecules such as proteins or with viruses. The VIMS team took this process one step further, linking proteins to PAHs and other contaminants, then exposing mice to these paired compounds in a manner very similar to a regular vaccination.

"Just like you get vaccinated against the flu, we in essence are vaccinating our mice against contaminants," says Kaattari. "The mouse's lymphatic system then produces antibodies to PAHs, TNT, tributyl tin [TBT, the active ingredient in anti-fouling paints for boats], or other compounds."

Once a mouse has produced an antibody to a particular contaminant, the VIMS team applies standard clinical techniques to produce "monoclonal antibodies" in sufficiently large quantities for use in a biosensor.

"This technology allows you to immortalize a lymphocyte that produces only a very specific antibody," says Kaattari. "You grow the lymphocytes in culture and can produce large quantities of antibodies within a couple of weeks. You can preserve the antibody-producing lymphocyte forever, which means you don't have to go to a new animal every time you need to produce new antibodies."

From antibody to electrical signal

The team's next step was to develop a sensor that can recognize when an antibody binds with a contaminant and translate that recognition into an electrical signal. The Sapidyne® sensor used by the VIMS team works via what Kaattari calls a "fluorescence-inhibitory, spectroscopic kind of assay."

In the sensor used on the Elizabeth River and Yorktown Creek, antibodies designed to recognize a specific class of PAHs were joined with a dye that glows when exposed to fluorescent light. The intensity of that light is in turn recorded as a voltage. The sensor also houses tiny plastic beads that are coated with what Spier calls a "PAH surrogate" -- a PAH derivative that retains the shape that the antibody recognizes as a PAH molecule.

When water samples with low PAH levels are added to the sensor chamber (which is already flooded with a solution of anti-PAH antibodies), the antibodies have little to bind with and are thus free to attach to the surrogate-coated beads, providing a strong fluorescent glow and electric signal. In water samples with high PAH concentrations, on the other hand, a large fraction of the antibodies bind with the environmental contaminants. That leaves fewer to attach to the surrogate-coated beads, which consequently provides a fainter glow and a weaker electric signal.

During the Elizabeth River study, the biosensor measured PAH concentrations that ranged from 0.3 to 3.2 parts per billion, with higher PAH levels closer to the dredge site. In Yorktown Creek, the biosensor showed that PAH levels in runoff peaked 1 to 2 hours after the rain started, with peak concentration of 4.4 parts per billion.

Comparison of the biosensor's field readings with later readings from a mass spectrometer at VIMS showed that the biosensor is just as accurate as the more expensive, slower, and laboratory-bound machine.

A valuable field tool

Spier says "Using the biosensor allowed us to quickly survey an area of almost 900 acres around the Elizabeth River dredge, and to provide information about the size and intensity of the contaminant plume to engineers monitoring the dredging from shore. If our results had shown elevated concentrations, they could have halted dredging and put remedial actions in place."

Unger adds "measuring data in real-time also allowed us to guide the collection of large-volume water samples right from the boat. We used these samples for later analysis of specific PAH compounds in the lab. This saved time, effort, and money by keeping us from having to analyze samples that might contain PAHs at levels below our detection limit."

"Biosensors have their constraints and optimal operating conditions," says Kaattari, "but their promise far outweighs any limitations. The primary advantages of our biosensor are its sensitivity, speed, and portability. These instruments are sure to have a myriad of uses in future environmental monitoring and management."

One promising use of the biosensor is for early detection and tracking of oil spills. "If biosensors were placed near an oil facility and there was a spill, we would know immediately," says Kaattari. "And because we could see concentrations increasing or decreasing in a certain pattern, we could also monitor the dispersal over real time."

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Virginia Institute of Marine Science. The original article was written by David Malmquist.

Journal Reference:

Candace R. Spier, George G. Vadas, Stephen L. Kaattari, Michael A. Unger. Near real-time, on-site, quantitative analysis of PAHs in the aqueous environment using an antibody-based biosensor. Environmental Toxicology and Chemistry, 2011; DOI: 10.1002/etc.546

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here