One of science’s greatest challenges is learning about the origin of life and its precursor molecules. Formamide (NH2CHO) is an excellent candidate for helping to search for answers as it contains four essential elements (nitrogen, hydrogen, carbon and oxygen), and can synthesise amino acids, carbohydrates, nucleic acids and other key compounds for living organisms.
However, this molecule is also abundant in space, mainly in molecular clouds or the concentrations of gas and dust where stars are born. This has been confirmed by an international team of researchers, including Spanish investigators, after searching for formamide in ten star-forming regions.
“We have detected formamide in five protosuns, which proves that this molecule (in all probability also true for our Solar System) is relatively abundant in molecular clouds and is formed in the very early stages of evolution towards a star and its planets,” explains Ana López Sepulcre, lead author of the study and researcher at the University of Tokyo (Japan), to SINC.
The other five objects where formamide has not been detected are less evolved and colder, “which indicates that a minimum temperature is needed for it to be detected in the gas,” adds the scientist.
The study, which has just been published in the ‘Monthly Notices of the Royal Astronomical Society’, also offers clues on how formamide could be created in interstellar conditions. “We propose that it is formed on the surface of the dust grains of the molecular clouds from isocyanic acid (HNCO), by a process of hydrogenation or addition of hydrogen atoms,” says López Sepulcre.
“Formamide formed in this way remains attached to the dust grain until the temperature is high enough (in other words, until the protostar evolves) to cause its sublimation,” she argues. “And that is when we can detect it with radio telescopes”.
The researchers have achieved this thanks to a telescope measuring 30 m in diameter at the Institut de Radioastronomie Millimétrique (IRAM), located in the Sierra Nevada, as part of the framework of the international project Astrochemical Surveys At IRAM (ASAI). Its principal investigators are Bertrand Lefloch from the Institut de Planétologie et d’Astrophysique de Grenoble (CNRS, France) and Rafael Bachiller from the Observatorio Astronómico Nacional (IGN, Spain).
More organic molecules in space
Yet formamide is not the only potentially prebiotic organic molecule analysed in space. Just this month the detection of methyl cyanide (CH3CN) around the young star MWC 480, already in a protoplanetary stage, has been published in the journal ‘Nature’.
“This other study demonstrates that complex molecules survive until the later stages of stellar formation, and even continue forming afterwards,” López Sepulcre notes, but formamide does have some advantages: “It contains oxygen (another essential element for life) and is a strong candidate as a precursor of prebiotic material, as not only amino acids can be formed from it (which could also be synthesised from CH3CN), but also nucleic acids and bases, or rather genetic material”.
“This proves the significance of our study,” emphasises the researcher, who sums it up as: “formamide, a significant biomolecule, is already formed in regions where stars like our Sun are born in the very early stages and in relatively high amounts”.
The above story is based on materials provided by Plataforma SINC. Note: Materials may be edited for content and length.
In what is believed to be the largest epigenetic analysis to date of cell-signaling molecules in early-stage melanoma, researchers at NYU Langone Medical Center and its Laura and Isaac Perlmutter Cancer Center have identified two tiny bits of non-coding genetic material in primary tumors that appear critical to stalling the cancer’s spread — and essentially setting the biological fate of the disease.
Reporting in the Journal of the National Cancer Institute online Feb. 11, researchers say that pinpointing these so-called “microRNAs” — known as miR-382 and miR-516b — could provide the basis for future medical tests that identify those melanoma most likely to spread and kill. In fact, the NYU Langone team that led this study has already begun a follow-up clinical study to see if any microRNAs have a similar prognostic value in identifying melanoma patients whose cancer is more likely to spread to the brain. Nearly half of people who die from melanoma succumb from its spread to the brain, they note.
MicroRNAs are epigenetic factors, chemical cousins of DNA that help regulate gene function. But unlike other kinds of RNA, microRNAs do not get translated into specific proteins.
Detection of the suppressor microRNAs emerged from the analysis of more than 800 of them found in tumor tissue samples from 92 men and women with melanoma. Some 48 of the patients had aggressive cancer, while the rest did not. Tumor tissue samples were provided by patients who agreed to donate their specimens to a research database maintained at NYU Langone.
“Our study results show the suppressive effects of two specific microRNAs in melanoma that are less active in aggressive, primary tumors,” says cell biologist and senior study investigator Eva Hernando, PhD. “Going forward, our goal is to show how we can use this information to identify patients more at risk of aggressive disease, and see whether early, more intense therapy improves survival from melanoma,” says Hernando, an associate professor at NYU Langone and its Perlmutter Cancer Center.
The American Cancer Society estimates that in 2015, some 73,870 new cases of melanoma will be diagnosed in the United States, resulting in close to 9,940 deaths.
According to oncologist and study co-investigator, Iman Osman, MD, a professor in the Ronald O. Perelman Department of Dermatology at NYU Langone and an associate director of the Perlmutter Cancer Center, “Now that we know that the fate of these melanoma tumors is set and predetermined by these microRNAs, we can investigate whether the same principle applies in other tumors and what interventions are possible to prevent or stall their predestined spread.”
As part of the study, researchers focused their analysis on 40 microRNAs found active or inactive in early-stage tumors, which had also grown deeper than 2 millimeters and were, as a result, already known most likely to spread. Further experiments were designed to show which, if any, of the microRNAs hindered or helped cancer spread among cells grown in the lab. This helped narrow the search to just a few microRNAs. When the scientific team compared their microRNA results to active or inactive microRNAs in an additional set of tissue samples from 119 people with early-stage melanoma, only the two microRNAs stood out as less abundant in localized cancers that did not spread.
Dwayne Miller’s team constructed movies from patterns produced by firing a bench-top ‘electron gun’ at organic superconductors. Miller, who splits his time between the University of Toronto, Canada, and University of Hamburg, Germany, emphasises the significance of capturing organic molecular changes. ‘You can watch the very essence of organic chemistry and biology,’ he tells Chemistry World.
Femtosecond electron diffraction has already produced atomic scale movies of changes in inorganic lattices. However, small atoms in organic materials scatter electrons weakly, meaning many passes would previously have been needed to gather enough data. And with processes usually triggered by laser pulses, repeated exposure to heat from the laser degrades the molecules before enough data are collected. But Miller’s team’s gun overcomes this by firing bunches of roughly a million electrons in 30 femtosecond flashes that each produce enough data for an image. ‘Electrons scatter a million times more brightly than x-rays, making this source comparable to a million, million x-rays per pulse, which is extremely bright,’ Miller says.
After starting the organic superconductor candidate EDO-TTF2PF6’s insulator-to-metal phase transition with a laser, the scientists used electron flashes to take 10 snapshots per second. In different experiments they progressively increased the time between laser photoexcitation and the first flash in very fine steps. The increasing delay creates still frames of stages in the transition’s progress separated by as little as a few hundred femtoseconds. By combining diffraction pattern frames Miller’s team could reconstruct a movie tracking changes over a nanosecond. That revealed the transition comprised just three key movements: bending and sliding of the organic chain, and movement of its counter-ion.
Eindhoven University of Technology’s Jom Luiten, who invented the electron bunching approach, says this study confirms the leading role Miller’s team plays in this area. ‘This is beautiful work, state-of-the-art in the new field of femtosecond electron diffraction,’ he says.
For Miller, watching this conversion proceed beyond its transition point puts chemistry into context. ‘At this critical point of no return the system converts from reactants to products, and chemistry reduces to a few key motions,’ he says. ‘If it wasn’t for that, chemistry couldn’t be transferable. Chemists are taught to push arrows and memorise these reactions, and you forget this is really a bit of magic.’
A family of nanoporous materials well known for their gas separation properties can sort molecules with much more sophistication than previously thought. Researchers in Australia have discovered that certain zeolites don’t act as simple molecular sieves, but rather separate molecules according to their ability to open ‘molecular trapdoors’ within the zeolite structure. Carbon dioxide molecules are particularly adept at slipping through these trapdoors, making it a promising discovery for industrial gas separation technologies such as carbon capture.
The trapdoor mechanism was discovered by Paul Webley at the University of Melbourne, Jefferson Liu at Monash University and their colleagues. The researchers were investigating new zeolite structures as part of their work for the Cooperative Research Centre for Greenhouse Gas Technologies (CO2CRC) when they noticed some unusual behaviour. The particular zeolite they were studying, a chabazite, wasn’t just taking up carbon dioxide in preference to larger molecules – expected behaviour for a molecular sieve – it was also taking up carbon dioxide in preference to smaller ones.
Key to this behaviour, the researchers found, was the behaviour of free metal ions in their chabazite structure. These cations balance the negative charge of the zeolite framework and sit within the oxygen-rich nanopores that act as doorways through which gases enter the structure. ‘It’s a bit like when you want to go into a bar and there’s a bouncer at the door,’ says Webley. ‘If you sweet-talk the bouncer then he’ll move aside and let you through – and that’s what the CO2 molecule is able to do.’
Carbon dioxide can slip past the cation bouncers because of its electron-rich oxygen atoms. By interacting with the cation and partly stabilising it, the cation becomes less tightly bound within the doorway, moving aside enough for the carbon dioxide molecule to slip past. The cation then snaps back into place, preventing other gases from riding on the carbon dioxide’s coat tails. Webley suspects that other, known zeolites might also work in the same way.
The material’s behaviour is promising for two key industrial gas separation processes: separating carbon dioxide from nitrogen in flue gases and removing carbon dioxide from natural gas. ‘We see a nice take-up of CO2 and almost no take-up at all of nitrogen or methane,’ says Webley. ‘Those selectivities are right in the ballpark for what we are looking for.’
Randy Snurr, who researches nanoporous materials for gas separation at Northwestern University, US, is impressed by the research. ‘It provides a new insight into what people thought they had understood for a long time, this old idea of molecular sieving,’ he says. ‘They have used a whole array of techniques to back up this picture, but then they do the very practical thing and pass gas mixtures through the material and they see this very nice selectivity.’
While the zeolite’s selectivity is high, its CO2 uptake capacity is modest, admits Webley. However, the team’s future work will include efforts to grow the zeolites in the form of membranes through which only CO2 can pass, circumventing the capacity issue.
J Shang et al, J. Am. Chem. Soc., 2012, DOI: 10.1021/ja309274y
Editors note: Original article can be found here.
Ice crystals must contain at least 275 water molecules, say German chemists. This size limit has implications for any process that involves ice particles, from cloud formation to making the perfect gin and tonic.
To determine the smallest possible ice crystal, the German chemists, jointly led by Thomas Zeuch at the University of Göttingen and Udo Buck at the Max Planck Institute for Dynamics and Self-Organization in Göttingen, analysed various different size water clusters using mass spectrometry and infrared (IR) spectroscopy. They used mass spectrometry to determine the number of water molecules in each cluster, which ranged from 85 to 475, and IR spectroscopy to determine the structure of the water clusters.
Previous groups have struggled to perform both mass spectrometry and IR spectroscopy on such small clusters of water molecules. Zeuch and Buck managed it by doping the surface of the clusters with sodium atoms. These helped to ionise the water clusters for analysis by mass spectrometry, but because they were only present on the surface they didn’t alter the structure of the clusters, which could still be probed by IR spectroscopy.
IR spectroscopy records the specific IR frequencies absorbed by the chemical bonds in a molecule: the bonds in liquid water absorb at one frequency, while those in ice absorb at a slightly different one. So Zeuch and Buck simply looked for the smallest cluster that absorbed at the IR frequency characteristic of ice, finding the first evidence of ice-like absorption for clusters containing 275 molecules. This represents the start of the crystallisation process, which is more or less complete by the time you reach clusters with 475 water molecules.
‘We have determined the onset of crystallisation, which is the size where the inner core of the cluster becomes crystalline,’ explains Zeuch. ‘This is around 275 molecules. [By] adding more molecules the crystalline part of the cluster grows. For around 475 molecules, the cluster has become a nanocrystal showing the spectral features of ice. Thus, we have obtained a fully size-resolved picture of the gradual change between amorphous and crystalline ice.’
Smaller clusters are unable to crystallise into ice because there is simply not enough room for their water molecules to adopt the ice configuration, which is based around a central ring of six hydrogen-bonded water molecules. ‘The hexagonal ice crystal needs, because of the underlying hydrogen bonds, a lot of space and, therefore, a minimum number of molecules is required to form it,’ Zeuch tells Chemistry World.
‘This study is of major scientific importance, but it’s also a significant development from an experimental point of view,’ says Christoph Salzmann, a physical chemist who studies crystalline materials, such as ice, at University College London. ‘The experiments the authors have done are not easy; it’s a real achievement.’
Zeuch and Buck say that the same approach could be used to investigate the crystallisation process in other substances, such as alcohols. All of which bodes well for making the perfect gin and tonic.
C C Pradzynski et al, Science, 2012, 337, 1529 (DOI: 10.1126/science.1225468)