Edible carbon dioxide sponge

 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."

More information: http://pubs.acs.or … 21/ja206525x

 

Built like the Dreamliner: 2013 debut of carbon composite cars

The revolutionary material used to build the Boeing 787 Dreamliner, the Airbus A350 super-jumbo jet, and the military's stealth jet fighter planes is coming down to Earth in a new generation of energy-saving automobiles expected to hit the roads during the next few years. That ultra-strong carbon fiber composite material — 50% lighter than steel and 30% lighter than aluminum — is the topic of the cover story in the current edition of Chemical & Engineering News, ACS's weekly newsmagazine.

In the story, C&EN Senior Correspondent Marc S. Reisch describes how carmakers such as BMW, Mercedes, and Audi are turning to carbon fiber composites to reduce the weight and improve the mileage of their next-generation of electric and hybrid vehicles. Carbon fiber composites are plastics containing fine strands of carbon that are spun into fibers and woven into a fabric. Manufacturers lay the fabric into a mold with the shape of the final part, and soak it with epoxy or other resin to produce parts for aircraft and other products.

Despite concerns about the high cost of carbon fiber composites, automakers are embracing this energy-saving material, even though it may increase the cost of small electric or hybrid cars by $5,000 or more, the article notes. It describes major auto manufacturers' plans for marketing vehicles made with carbon fiber composites, and research underway to reduce the cost of the material.

More information: “Getting the Steel Out” http://pubs.acs.or … 39cover.html

Provided by American Chemical Society (news : web)

Scientists model the pathways of pain-blocking meds

Benzocaine, a commonly used local anesthetic, may more easily wiggle into a cell's membrane when the membrane is made up of compounds that carry a negative charge, a new study shows. The finding could help scientists piece together a more complete understanding of the molecular-level mechanisms behind pain-blocking medicines, possibly leading to their safer and more effective use.

Most scientists believe that local anesthetics prevent pain signals from propagating to the central nervous system by blocking nerve cells' sodium channels, but exactly how the medicines accomplish this feat remains vague. Since the solubility of anesthetics in the cell membrane can affect the medicine's potency, some scientists have hypothesized that certain anesthetics may block the action of sodium channels indirectly, by entering the cell membrane and jostling the channels into a new shape that prevents ion flow.

With the aim of further investigating such complex processes, scientists from the Universidad Politecnica de Cartagena in Spain and the Universidad Nacional de San Luis in Argentina have created a computer model that calculates the probability of molecules of benzocaine entering a cell's membrane, based on the composition of the membrane.

As reported in the AIP's Journal of Chemical Physics, the model predicts that membranes made of a large percentage of DPPS, a negatively charged phospholipid component of cells, present less of a barrier to benzocaine molecules than membranes made mostly of DPPC, a neutral phospholipid. DPPS is normally found as one of the main components of cell membranes in the central nervous system, as well as a component of the inner side of membranes in other humans cells.

More information: "Thermodynamic study of benzocaine insertion into different lipid bilayers" is accepted for publication in the Journal of Chemical Physics.

Provided by American Institute of Physics

New research promises better collection of prostate cancer cells

At the Oct. 2-6 microTAS 2011 conference, the premier international event for reporting research in microfluidics, nanotechnology and detection technologies for life science and chemistry, University of Cincinnati researchers will present a simple, low-cost, method for separating and safely collecting concentrated volumes of fragile prostate cancer cells.

The research results resolve the critical technical challenge of isolating and collecting fragile cells, specifically rare circulating tumor cells (CTCs) that are present in the blood in very low concentrations – as low as one cell in 100,000.

Normally, the isolation and collection of such cells is complicated and relies on the availability of biological markers on the cells; whereas, the method developed at UC – using inertial microfluidic lab-on-a-chip technology – is simple, relying only on cell size for separation. UC has already obtained a provisional patent for the new inertial microfluidics device and is in the process of obtaining a full patent.

At the Fifteenth International Conference on Miniaturized Systems for Chemistry and Life Sciences (microTAS) to be held Oct. 2-6, in Seattle, Wash., the research will be presented in papers titled "Extraction and Enrichment of Rare Cells in a Simple Inertial Microfluidic Device" and "Sorting Human Prostate Epithelial (HPET) Cells in an Inertial Microfluidic Device."

This video is not supported by your browser at this time.

In this video, see how polystyrene particles are affected by hydrodynamic forces in a straight microchannel. At the end of the 20-second video, lift and shear forces have separated the particles into three distinct bands. Credit: Ian Papautsky, University of Cincinnati

The first paper is by UC researchers Jian Zhou, engineering doctoral student, Premkumar Vummidi Giridhar, environmental health postdoctoral fellow; Susan Kasper, associate professor of environmental health; and Ian Papautsky, associate professor of engineering and director of both the BioMicroSystems Lab and the Micro/Nano Fabrication Engineering Research Center at UC. The second paper is presented by Nivedita Nivedita, doctoral student in engineering, and by Giridhar, Kasper and Papautsky.

Kasper has been investigating the cancer stem cell properties of HPET cells and began collaborating with Papautsky to characterize prostate cancer stem cells and determine the manner in which these cells survive in the circulation and metastasize to their target organs such as bone. "Prostate cancer cells are a challenge to collect because they appear quite fragile and are present in very small numbers in the blood. If we damage them in the collection process, they are not viable for experimentation and the development of more effective strategies to combat this disease," Kasper adds.

GENERAL BACKGROUND ON INERTIAL MICROFLUIDICS: SPIRAL AND STRAIGHT CHANNELS

Inertial microfluidic lab-on-a-chip devices – whether based on a straight or a spiral channel – take advantage of hydrodynamic (liquid in motion) forces acting on cells or particles within laminar flow (fluid flows in parallel layers). These forces cause cells to equilibrate in streams near channel walls. The equilibrium positions of focused cells are strongly dependent on cell size, as well as flow properties and channel geometry. In spiral microchannels, these inertial forces can be influenced by centrifugal forces, adding additional control over the position of the focused streams of cells.

UC's work with inertial microfluidics – both spiral and straight channel – is unusual because, up until now, it has proven difficult to separate cells without the introduction of external electric or magnetic forces or using immunoselection.

Enlarge

This image shows the size dependence of particle trapping using fluorescent particles. The superimposed fluorescent image indicates trapping of larger particles (blue rings) while smaller particles (yellow rings) pass through. Credit: Ian Papautsky, University of Cincinnati

HOW INERTIAL MICROFLUIDIC CHIPS WORK

In spiral-channel lab-on-chips, a sample is introduced at the center of the spiral channel. Before the cells reach the end of the spiral, the cells focus into individual steams and are separated. Papautsky previously developed these chips for separating blood and other cell types at high throughput.

However, while successful, spiral chips are not able to separate out cells present in blood in extremely low concentrations, as is the case with prostate cells. This led him to explore inertial chips with straight channel geometries.

In a straight-channel inertial chip, a sample is introduced into a channel (with the diameter of a human hair) by means of a syringe. Before the cells reach the "crossroads" or "expansion" in the channel, lift and shear forces balance and focus cells into distinct groups near the sidewalls. This balance is disrupted at the "expansion" or "crossroads" and the larger cells, prostate cancer cells in this case, experience lateral velocity – in other words, move sideways into the expansions where they are trapped for later use in experimentation.

This straight-channel method can be used to effectively isolate and collect cells and particles with a concentration as low as one cell per milliliter of blood.

According to UC's Papautsky, "The flow rate and channel geometry are critical to the method. We need to get the flow rate right so that the cells will separate out. We want to control the lift and shear forces that stem from the flow rate – enough to cull out and collect the cancer cells but to avoid damaging them."

METHOD HAS BROAD APPLICATIONS TO OTHER CELL TYPES

While UC's experiments with inertial microfluidics focused on separating and concentrating prostate cancer cells, the approach is broadly applicable to other cell types and sizes. Working closely with Kasper, the Papautsky's group has already tested a number of other cell lines in these inertial microfluidic devices, including DU-145 cells (derived from brain metastasis) and LNCaP cells (derived from left supraclavicular lymph node). The simple planar structure of the devices and the passive mechanism of separation make them an easy-to-use tool for cell biologists, and affords integration with existing lab-on-a-chip systems.

Provided by University of Cincinnati (news : web)