Freezing the action in living things

A fast, high-resolution infrared imaging technique that can ‘freeze’ living specimens has been designed by UK scientists and tested on human ovarian cancer cells. The technique could lead to a better understanding of how cancer drugs work.

Infrared spectroscopy of cell images can be used in a number of fields including forensic science and cancer research. However, taking pictures of samples can take up to 12 hours. Chris Phillips and his team at Imperial College London have developed a technique to produce 2D images that takes a fraction of a second. By combining a purpose-built pulsed IR laser source with a charge-coupled device camera, rather like a digital camera, they were able to generate pictures 1011 times faster than current IR spectroscopic imaging methods. The IR source generates very short pulses (~100 psec) that keep the illumination levels below cell phototoxicity limits and allow moving specimens to be frozen in a way that mimics conventional flash photography.

Previous attempts to image cells in this way have required long illumination times, which causes the cells to move away from the light source or can kill them. ‘Because you can do it so quickly, you can freeze the action in living things, and because you have so much more light signal, you can get right inside the cells to take chemical maps,’ says Phillips.

The sharpest focus cell images are visually selected for the cell-level spectroscopy analysis

Link to journal article
Ultrafast infrared chemical imaging of live cells
Hemmel Amrania, Andrew P. McCrow, Mary R. Matthews, Sergei G. Kazarian, Marina K. Kuimova and Chris C. Phillips
Chem. Sci., 2011, DOI: 10.1039/c0sc00409j

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Editor’s diary

A round up of the latest activities in the RSC General Chemistry Editorial Office

Over the past week or two we’ve been writing the editorials for Chemical Science, ChemComm and Chem Soc Rev issue 1s, 2011. It seems strange to be wishing people a Happy New Year in October but the issues will be sent to the printers next month so we need to plan in advance. It has been great to reflect on all the success of 2010 – we’ve launched a new journal, published more articles than ever before…but I’ll stop there before I give too much away. All will be revealed in issue 1.

We’ve also been planning our conference attendance for next year. There are so many great events to choose from so it has been really difficult to narrow them down to a manageable and affordable number. We’ll of course be at the ISACS meetings in July and September but if you have any suggestions of where else we should be, please do let us know.

Particularly exciting during the past month has been a short Chemical Science information film we’ve been working on with Anne from the RSC communications team. Thankfully I was behind the scenes only but Robert (the Editor) gave a stellar performance on camera – Anne described him as “a natural”. The film will be screened at the RSC general assembly in November.

Please keep sending us your feedback and suggestions for Chemical Science, ChemComm and Chem Soc Rev. You can leave comments below or email me.

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Chemical Science issue 6 now online

The final issue for 2010 is now online and free to access.

Following the trend set by issues 1-5, issue 6 is jam-packed with the highest quality research from across the chemical science spectrum.

The issue contains a Perspective on the future perspectives of nonadiabatic chemical dynamics (Hiroki Nakamura et al) and a Mini review on continuous flow multi-step organic synthesis (Damien Webb and Timothy Jamison). It also features a couple of attractive covers highlighting two exciting Edge articles.

Outside front cover

Inside front cover

Sign up for the Chemical Science e-alert to be notified when issue 1, 2011, is available online.

Let your work shine in 2011 – submit to Chemical Science and be seen with the best.

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Catalytic capsids: the art of confinement

Confining enzymes in a small container increases overall reaction rates but the increase is independent of the number of enzymes encapsulated, claim scientists in the Netherlands. 

Jeroen Cornelissen, at the University of Twente, and colleagues used the capsid of the Cowpea Chlorotic Mottle virus to encapsulate enzymes, mimicking the crowded environment enzymes experience in a cell. They found that encapsulated enzymes have a higher activity than free enzymes, which they say is caused by the high confinement molarity of the enzyme and the increased collision rate with its substrate. 

Graphical abstract: Catalytic capsids: the art of confinement
Encapsulation of enzymes in the confined space of a virus capsid influences reaction rates

But increasing the number of enzymes inside the capsid does not increase the reaction rate, says Cornelissen. A capsid rarely contains more than one substrate molecule so one enzyme is sufficient to convert the substrate, he explains.

Want to learn more about the art of confinement? Read the Edge article for free online.

Do you feel confined by the page and colour restrictions placed on you by other journals? Experience the freedom of publishing with Chemical Science by submitting today.

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Building complex oxides layer-by-layer

The Ruddlesden-Popper structure is an archetypal structure in solid state chemistry, consisting of slabs of perovskite units separated by rock salt layers. But conventional high temperature oxide synthesis methods can’t be used to make these structures when the perovskite blocks are greater than three octahedral thick.

Now Matthew Rosseinsky, at the University of Liverpool, UK, and colleagues have exploited the capabilities of modern thin film deposition to grow an artificial metastable oxide where the perovskite block is six octahedral thick and is made of two distinct perovskite units.

Graphical abstract: Cation ordering within the perovskite block of a six-layer Ruddlesden-Popper oxide from layer-by-layer growth – artificial interfaces in complex unit cells

Find out more in their Chemical Science Edge article and let us know your comments on the work below.

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A system that mimics the human nose

Scientists from Switzerland have created a system that mimics the way the human nose recognises scents.

Stefan Matile and colleagues from the University of Geneva made an artificial membrane that can distinguish between a range of odour molecules. Their ‘nose’ uses differential sensing, a form of molecular recognition, to recognise subtle structural differences between the molecules. ‘Our nose works by differential sensing in the membrane and differential sensing has been done almost everywhere except in the membrane,’ says Matile.

The human nose can distinguish over 10,000 different smells using 350 receptors. Smell molecules, known as an odorants, interact with the receptors to create an overall ‘fingerprint’ that is recognised by the brain. Matile’s system works by moving odorants across a lipid bilayer, an artificial cell membrane, using electrostatic interactions. Once across the membrane, this creates a fluorescent response, which is then measured to build up an electronic fingerprint of the smell. The team say they can distinguish a range of commercial perfumes using their nose.

Odour molecule

The artificial nose builds up a fingerprint of odour molecules

‘This highlights just how closely related this system is to the human system,’ says Jon Steed, an expert in supramolecular sensing at the University of Durham, Durham, UK, who adds: ‘You can adapt the chemistry to sense whatever you want.’

‘The applications are broad and very promising,’ says Matile. Steed adds that detection of low levels of molecules is important in many areas, for example in the detection of explosives or pollutants. Matile is now studying different forms of membrane transport in the system and how this affects its sensing capability.

Will Dennis

Read the full Edge article for free in Chemical Science.

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Top ten most accessed articles in September

This month sees the following articles in Chemical Science that are in the top ten most accessed:-

Dialkylbiaryl phosphines in Pd-catalyzed amination: a user’s guide 
David S. Surry and Stephen L. Buchwald 
Chem. Sci., 2010, Advance Article, DOI: 10.1039/C0SC00331J , Perspective 

DNA fluorocode: A single molecule, optical map of DNA with nanometre resolution 
Robert K. Neely, Peter Dedecker, Jun-ichi Hotta, Giedrė Urbanavičiūtė, Saulius Klimašauskas and Johan Hofkens 
Chem. Sci., 2010, 453-460, DOI: 10.1039/C0SC00277A , Edge Article 

Total synthesis of all (−)-agelastatin alkaloids 
Mohammad Movassaghi, Dustin S. Siegel and Sunkyu Han 
Chem. Sci., 2010, 561-566, DOI: 10.1039/C0SC00351D , Edge Article 

The organocatalytic three-step total synthesis of (+)-frondosin B 
Maud Reiter, Staffan Torssell, Sandra Lee and David W. C. MacMillan 
Chem. Sci., 2010, 37-42, DOI: 10.1039/C0SC00204F , Edge Article 

Catalytic asymmetric allylic alkylation employing heteroatom nucleophiles: a powerful method for C–X bond formation  
Barry M. Trost, Ting Zhang and Joshua D. Sieber 
Chem. Sci., 2010, 427-440, DOI: 10.1039/C0SC00234H , Perspective 

Palladium-catalyzed coupling of functionalized primary and secondary amines with aryl and heteroaryl halides: two ligands suffice in most cases 
Debabrata Maiti, Brett P. Fors, Jaclyn L. Henderson, Yoshinori Nakamura and Stephen L. Buchwald 
Chem. Sci., 2010, Advance Article, DOI: 10.1039/C0SC00330A , Edge Article 

Asymmetric Brønsted acid catalysis in aqueous solution  
Magnus Rueping and Thomas Theissmann 
Chem. Sci., 2010, 473-476, DOI: 10.1039/C0SC00206B , Edge Article 

Supramolecular hydrogel capsule showing prostate specific antigen-responsive function for sensing and targeting prostate cancer cells 
Masato Ikeda, Rika Ochi, Atsuhiko Wada and Itaru Hamachi 
Chem. Sci., 2010, 491-498, DOI: 10.1039/C0SC00278J , Edge Article 

Diamine ligands in copper-catalyzed reactions 
David S. Surry and Stephen L. Buchwald 
Chem. Sci., 2010, 13-31, DOI: 10.1039/C0SC00107D , Perspective 

Unified synthesis of enantiopure β2h, β3h and β2,3-amino acids  
Shouyun Yu, Hiroshi Ishida, M. Elisa Juarez-Garcia and Jeffrey W. Bode 
Chem. Sci., 2010, 637-641, DOI: 10.1039/C0SC00317D , Edge Article 

Why not take a look at the articles today and blog your thoughts and comments below.

Fancy submitting an article to Chemical Science? Then why not submit to us today or alternatively email us your suggestions.
  

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Iron complex could prevent cardiovascular disease

Scientists in Israel have shown how an iron-based antioxidant could prevent damage in arteries that leads to cardiovascular disease.

Zeev Gross and team from the Israel Institute of Technology, Haifa, say that iron-corrole complex 1-Fe works by binding to the two types of cholesterol in the body to block the damaging effects of reactive oxygen and nitrogen species.

Reactive oxygen and nitrogen species are naturally present in the body. They modify the structures of cholesterol-delivering, or atherogenic, low-density lipoproteins and cholesterol-removing, or anti-atherogenic, high-density lipoproteins. This modification, known as oxidative stress, makes low-density lipoproteins (LDL, or bad cholesterol) more atherogenic and high-density lipoproteins (HDL, or good cholesterol) less anti-atherogenic.

1-FE

1-Fe binds tightly to lipoproteins and is carried to the arterial wall

Gross’ team found that 1-Fe decomposes the harmful species in a catalytic fashion and binds tightly to the lipoproteins implying that the antioxidant will be carried all the way to the arterial wall, where the oxidative environment prevails. This is in contrast to current dietary antioxidants that are not as efficient against some reactive species and can damage the lipoproteins and the arterial wall.

The team analysed the 1-Fe/LDL and 1-Fe/HDL complexes in human serum. ‘The bipolarity of the complex is responsible for the high affinity of the corrole to lipoproteins in general,’ says Gross, ‘while coordination of the chelated iron(III) ion in 1-Fe with specific amino acid residues is involved in the selectivity to HDL.’

‘These findings will have a major impact on future antioxidant design,’ says Claus Jacob, an expert on catalytic antioxidants from Saarland University, Germany. ‘It is now possible to attach catalytic antioxidants to the targets of oxidative stress, providing perfect protection against the damage caused by reactive species. This is a promising lead for the development of the next generation of multi-functional, smart antioxidants. Such antioxidants are of particular importance in the field of cardiovascular diseases.’

‘Demonstrating the effects and understanding the variables that determine efficiency of catalytic antioxidants may lead to the design of optimal new drug candidates for treating the most severe diseases affecting human health,’ says Gross. He intends to extend his study to look at macrophages (white blood cells), major contributors to the development of atherosclerotic plaques.

Jennifer Newton

For more details, read Gross’ Chemical Science Edge article.

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October hot article round-up

flameThat’s it. British summertime is officially over. So to help us through the cold, dark winter, I’ve collected together some of the hottest Edge articles published in October.

Bright results
Oligomeric tandem terpyridyl platinum(II) complexes display spectacular solvent dependent emission properties and self-aggregating behaviour. What factors govern this strong emissive property? Find out in Chi-Ming Che’s Edge Article.

Catalytic water oxidation
Robert Crabtree and colleagues report a new method for generating an amorphous electrodeposited material, principally consisting of iridium and oxygen, which is a robust and long-lived catalyst for water oxidation, when driven electrochemically.

Forming C-C bonds
A novel method for the direct, amine-catalysed, highly enantioselective α-alkylation of aldehydes has been discovered by Claudio Palomo and colleagues. Find out more about the reaction conditions and mechanism.

Extending cyclopropenium activation
Geminal dichlorocyclopropenes rapidly and efficiently convert oximes to amides at room temperature, with reactivity that far surpasses other organic-based promoters, report Tristan Lambert and colleagues in their Edge article.

Understanding aerobic oxidation
Experimental and computational data provide direct evidence for two parallel mechanistic pathways for O2 insertion into a Pd–H bond, claim Shannon Stahl and colleagues. Assess the evidence for yourself in their Edge Article.

Gauging electronic dissymmetry
What kinds of environments give rise to effective levels of electronic dissymmetry in metal complexes? Seth Brown and colleagues investigate the behaviour of a series of tetrasubstituted biphenolates with substituents of varying electronic and steric character and shed light on the origins of stereoselectivity in these complexes. Read more

Easy access to polycyclic ring systems
Daniel Seidel and colleagues report a new 1,6-annulation reaction for azomethine ylides which could find widespread use in alkaloid synthesis.

Catalytic nitrene transfer
Alan Heyduk and colleagues report on the catalytic formation of carbodiimide using zirconium(IV) bearing a redox-active ligand.

If you like the sound of these articles, subscribe to the Chemical Science e-alert to receive details of the latest issues. And if you have some hot science to report, submit to Chemical Science.

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Nanoparticles get the white light

White light emitting organic nanoparticles can be made simply by encapsulating an orange-red emitting dye within a scaffold of blue light emitting nanoparticles, say scientists in Japan. The material could be suitable for applications in optoelectronics and bio-imaging, they claim.

Masayuki Takeuchi and colleagues at the National Institute for Materials Science, Tsukuba, made an oligofluorene derivative that self-assembled in solution to form stable colloidal nanoparticles. They tuned the nanoparticles’ bright blue fluorescence to white through fluorescence resonance energy transfer by encapsulating DCM, an orange-red emitting dye, within the nanoparticle assembly.

Graphical abstract: Oligofluorene-based electrophoretic nanoparticles in aqueous medium as a donor scaffold for fluorescence resonance energy transfer and white-light emission

Download the Edge article and find out more about this work.

Do you have your own glowing research results? Submit them today to Chemical Science.

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