Archive for the ‘Physical’ Category

Fluorescently finding a specific disease marker needle in a biological haystack

The early detection and monitoring of disease is a somewhat recent advancement in healthcare that offers the significant advantage of being able to treat an illness in its initial stages, rather than once it has already manifested itself in the patient. Such a feat requires, however, the ability to see very specific and characteristic disease markers in situ, not unlike the search for a needle in a haystack.
 
Luckily, with the advent of fluorescence (and other) imaging techniques, methods have been developed whereby, in combination with contrast agents that are able to interact with specific molecules in the body, cell chemistry and function can be observed with high sensitivity, and, more importantly, abnormalities in these processes noticed in real time.
 
The art and ultimate success of this fluorescence imaging comes from the design of the contrast agent employed – the probe should be able to selectively recognise and target the relevant disease marker reversibly and under biological conditions. A number of approaches currently exist that meet these requirements, one of which is the boronic acid recognition motif that is able to act as a molecular receptor for the 1,2- and 1,3-diols commonly expressed in carbohydrates and complex glycoproteins. Tony James and his team from the University of Bath, whose own research focuses on such use of boronic acid receptors in the detection of carbohydrates, have summarised the recent and exciting advances in this particular field of selective biological imaging.
 
The well-known and strong affinity of boronic acids for carbohydrates offers a convenient means of detecting commonly expressed markers in diseases including some cancers, as well as Alzheimer’s, autoimmune, and heart diseases. As such, the attachment of this relatively simple chemical moiety to fluorescent small molecular, polymeric or benzoxaborale-based probes offers a diagnostic tool that is able to detect, monitor, and aid in the personalised treatment of such significant and life-changing diseases.
 
This Feature Article convincingly highlights the impact that boronic acid-based fluorescence imaging will ultimately have on a range of important clinical and theranostic practices and their successes.
  
Read this hot ChemComm article in full:
X. Sun, W. Zhai, J. S. Fossey and T. D. James
Chem. Commun., 2016, 52, 3456–3469
DOI: 10.1039/C5CC08633G

About the Writer:
Anthea Blackburn is a guest Web Writer for Chemical Communications. Anthea hails from New Zealand, carried out her graduate studies in mechanostereochemistry under the guidance of Prof. Fraser Stoddart in the US, and has recently relocated to live in London. She is a recent addition to the Econic Technologies team, where she is working on the development of new catalysts for the environmentally beneficial preparation of polycarbonates from CO2.
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ChemComm Emerging Investigator Lectureship: Marina Kuimova

Dr Marina Kuimova (Imperial College London) was a recipient of the 2013 ChemComm Emerging Investigator Lectureship.

Marina has just completed her lectureship tour which took place in three locations in Europe from 7 – 13 July:

Kuimova

ChemComm Lectureship recipient Marina Kuimova giving her lecture at the IUPAC Symposium on Photochemistry

Our annual lectureship recognises an emerging scientist in the early stages of their independent academic career.

Professor Louise Berben (University of California Davis, USA) was the other recipient of the lectureship last year and we have just announced the 2014 winners – look out for further details of their lectureship tours soon.

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Mind the gap – Enhancing intercalation of luminescent aggregates

Particular molecules, which are not luminescent in solution, can luminesce intensely upon molecular aggregation; this is known as aggregation-induced emission (AIE). AIE luminogens are used widely as efficient electroluminescent materials, sensitive chemosensors, and as bioprobes. The main cause of the AIE effect is the restriction of intramolecular rotation. Therefore it can be promoted by introducing the molecules into inorganic materials with a rigid skeleton such as α-zirconium phosphate layers.

Jihong Yu and colleagues from Jilin University in China have published a method describing the intercalation of a quaternary tetraphenylethene (TPEN) cation, an AIE chromophore, into α-zirconium phosphate. At first glance, this does not seem to be too difficult a task– after all, the TPEN has two permanent positive charges on either end suitable to interact with the negatively charged phosphate layers. But, in this case, size does matter. The chromophore is almost three times larger than the distance between phosphate layers, more than a tight fit!

Stretching the layers of α-zirconium phosphate by preintercalation of butylamine before introduction of the chromophore

To overcome this problem, Yu and colleagues carried out a preintercalation step with butylamine before performing a cation exchange step to place the TPEN chromophore within the phosphate layers. Ultimately, they stretched the layer before putting the final molecule inside, just like you would stretch a pair of shoes in an effort to make them fit before placing your sensitive feet inside.

The intercalated product was found to be highly emissive in the blue region of the electromagnetic spectrum and was readily internalized by cells. The system also showed good biocompatibility, suggesting that it would make an excellent base for fluorescent labels in future biomedical imaging applications.

To read the details, check out the HOT Chem Comm article in full:

AIE cation functionalized layered zirconium phosphate nanoplatelets: ion-exchange intercalation and cell imaging

Dongdong Li, Chuanlong Miao, Xiaodan Wang, Xianghui Yu, Jihong Yu and Ruren Xu
Chem. Commun., 2013, 49, Accepted Manuscript
DOI: 10.1039/C3CC45041D

Iain Larmour is a guest web writer for ChemComm.  He has researched a wide variety of topics during his years in the lab including nanostructured surfaces for water repellency and developing nanoparticle systems for bioanalysis by surface enhanced optical spectroscopies.  He currently works in science management with a focus on responses to climate change.  In his spare time he enjoys reading, photography and art.

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Mechanochemistry: ChemComm web theme and Faraday Discussion 170 abstracts deadline 12 August

ChemComm Mechanochemistry web collection

We are delighted to present our ChemComm web themed issue on Mechanochemistry: fundamentals and applications in synthesis, guest edited by Stuart James (Queen’s University Belfast, UK) and Tomislav Friščić (McGill University, Canada).  Check out this special online collection now!

C3CC90136J

Faraday Discussion 170 on Mechanochemistry– deadline for oral abstracts 12 August 2013

We also invite you to submit your oral abstract for Faraday Discussion 170– Mechanochemistry: From Functional Solids to Single Molecules by Monday, 12 August 2013.  Stuart and Tomislav co-chair the FD170 Scientific Committee; they are joined by Jon Steed, James Mack, Elena Boldyreva and Carsten Bolm.

FD170banner

Submit your abstract now and register to secure your place at this exciting event!

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A cloak of many carbons

Catalysts can be exceedingly useful in the real world, from treating our car’s exhaust fumes to creating fertilisers.  There are many ways to make catalysts and even multiple ways to make the same catalyst.  The path that you choose to a catalyst can have a significant impact on the quality of the end product.

Eloy del Rio and team from the Structure and Chemistry of Nanomaterials group at the University of Cadiz in Spain have investigated ceria-based oxide-supported gold catalysts for carbon monoxide oxidation.  The routine for depositing the metal phase onto the oxide support and the subsequent catalyst activation step can ultimately affect the activity of the catalyst.  Catalysts prepared by deposition-precipitation with urea followed by activation under oxidising conditions result in significantly more activity than those prepared under reducing conditions.

Variation in catalyst activity under oxidising and reducing activation protocols.

This had previously been observed by others, but the reason for the difference was never discussed.  The authors set out to find out why the activity differed.  They used a suite of nano-analytical and nano-structural techniques to probe the catalysts, finding that the catalyst prepared under reducing conditions had a coat of amorphous carbon which severely hampered the catalyst activity.  This could be removed by a re-oxidation treatment that burnt away the carbon layer and produced an active catalyst similar to the one produced under oxidising conditions.

The precipitating agent used in the synthesis can also influence the resulting activities of catalysts prepared via the deposition-precipitation method.  No difference between oxidising and reducing activations is observed when sodium carbonate is used in place of urea.

To read the details, check out the ChemComm article in full:

Dramatic effect of redox pre-treatments on the CO oxidation activity of Au/Ce0.50Tb0.12Zr0.38O2-x catalysts prepared by deposition-precipitation with urea: a nano-analytical and nano-structural study
E. del Rio, M. López-Haro, J.M. Cies, J.J. Delgado, J.J. Calvino, S. Trasobares, G. Blanco, M.A. Cauqui and S. Bernal
Chem. Commun., 2013, 49, Accepted Manuscript
DOI: 10.1039/C3CC42051e

Iain Larmour is a guest web writer for ChemComm.  He has researched a wide variety of topics during his years in the lab including nanostructured surfaces for water repellency and developing nanoparticle systems for bioanalysis by surface enhanced optical spectroscopies.  He currently works in science management with a focus on responses to climate change.  In his spare time he enjoys reading, photography and art.

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ChemComm Emerging Investigator Lectureship 2013: Winners Announced

louise

Louise Berben

On behalf of the ChemComm Editorial Board we are delighted to announce the winners of the ChemComm Emerging Investigator Lectureship 2013.

Marina Kuimova

Marina Kuimova

This year we received a high number of excellent nominations and therefore the Editorial Board have decided to award two Emerging Investigator Lectureships in 2013. The winners are Professor Louise A. Berben (University of California Davis, USA) and Dr Marina Kuimova (Imperial College London).

This annual lectureship recognises an emerging scientist in the early stages of their independent academic career.

The Editorial Board commended Louise’s contributions to the field of synthetic and physical inorganic chemistry, and Marina was awarded the lectureship for her excellent work within biophysical chemistry. Further details of the two Lectureships, including lecture locations, will be announced soon.

To find out more about the winners’ research, read some of their latest articles in ChemComm:

Redox active aluminium(III) complexes convert CO2 into MgCO3 or CaCO3 in a synthetic cycle using Mg or Ca metal
Thomas W. Myers and Louise A. Berben
Chem. Commun., 2013, DOI: 10.1039/C2CC37208H

Simple routes to bulky silyl-substituted acetylide ligands and examples of V(III), Fe(II), and Mn(II) complexes
Gereon M. Yee, Kristin Kowolik, Shuhei Manabe, James C. Fettinger and Louise A. Berben
Chem. Commun., 2011,47, 11680-11682, DOI: 10.1039/C1CC14758G

Reactive oxygen species in photochemistry of the red fluorescent protein “Killer Red”
Russell B. Vegh, Kyril M. Solntsev, Marina K. Kuimova, Soohee Cho, Yue Liang, Bernard L. W. Loo, Laren M. Tolbert and Andreas S. Bommarius
Chem. Commun., 2011,47, 4887-4889, DOI: 10.1039/C0CC05713D

Also of interest: You can now browse the 2013 Emerging Investigators Issue – which features research from outstanding up-and-coming scientists

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Nitrogen-containing graphene-like structures: Theory and experiment combine to reveal active sites

There is significant interest in nitrogen-containing electrocatalysts, driven by the need to find cost-effective and efficient material solutions for replacing platinum in polymer electrolyte membrane fuel cells.  However, the active sites of non-platinum group metal, oxygen reduction reaction electrocatalysts have been contentious for over 50 years.

Fortunately researchers are agreed that Metal(Me)-Nx centres may serve as possible active sites but whether it is Me-N2 or Me-N4 remains unresolved.  X-ray Photoelectron Spectroscopy (XPS) would be the ideal technique to answer this question if it didn’t rely on the use of reference spectra; none exist for the Me-N2 species which makes it less than ideal.

Fitting of DFT calculated curves to experimental results.

Kateryna Artyushkova, Plamen Atanassov and their team have overcome this problem by using density functional theory (DFT) to calculate the binding energy shifts of the species.  Calculating the binding energy shifts, rather than just the binding energies, allows the team to overcome the challenges associated with DFT calculations including; treatment of the core electrons and the poorly screened Coulomb potential near the nucleus.

Once validated, the DFT output can be used as input for XPS curve fitting.  This has revealed rearrangement around Cobalt-Nx centres in an oxidizing atmosphere and supports the understanding of these catalysts as vacancy-and-substitution defects in a graphene-like matrix.

This work demonstrates the synergy between experiment and theory which allows critical information to be extracted that might otherwise remain hidden.

For more, read this ChemComm article in full:

Density functional theory calculations of XPS binding energy shift for nitrogen-containing graphene-like structures
K. Artyushkova, B. Kiefer, B. Halevi, A. Knop-Gericke, R. Schlogl and P. Atanassov
Chem. Commun., 2013, 49, 2539-2541
DOI: 10.1039/C3CC40324F

Iain Larmour is a guest web-writer for ChemComm.  He has researched a wide variety of topics during his years in the lab including nanostructured surfaces for water repellency and developing nanoparticle systems for bioanalysis by surface enhanced optical spectroscopies.  He currently works in science management with a focus on responses to climate change.  In his spare time he enjoys reading and photography.

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Lewis acidity of metal ions investigated in the gas phase

In aqueous solutions metal ions can promote acidity via the hydrolysis reaction. This is measured by a hydrolysis constant, which has previously been correlated to the ratio of the ion’s charge to size. Unfortunately lead and tin stubbornly refuse to fit this correlation; additional factors must be at work.

Anthony Stace and team investigated further by studying the minimum number of water molecules needed to stabilise a dication complex in the gas phase against spontaneous hydrolysis (called Coulomb fission in the gas phase). They found an extraordinarily good correlation between the number of water molecules required and the metal ion’s hydrolysis constant in aqueous solution.

What about those stubborn dications, lead and tin? They fit within the trend, requiring a surprising 11 and 26 water molecules to stabilise them respectively. This work suggests that Lewis acidity of metal ions is determined, in part, by the requirement that the ions remain fully solvated.

Plot of acidity constant against minimum number of water molecules required to stabilise the complex against Coulomb fission.

To find out more, download the ChemComm article today.

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Highlights from themed issues on ionic liquids

Ionic liquids ChemComm web themed issueCrystal engineering with ionic liquids CrystEngComm CollectionInterfaces of ionic liquids PCCP Themed issue

The field of ionic liquids has seen phenomenal growth in recent years, with the topic spanning a variety of disciplines across the chemical sciences. The recent themed issues from ChemComm, PCCP and CrystEngComm showcase some of the latest developments from a range of scientific subjects utilising the unique properties of ionic liquids.

Highlights from these themed issues include the articles below, which are free to download until the 24th August. You can also access the full themed issues by clicking on the buttons above.

CrystEngComm journal cover imageIonic liquids as crystallisation media for inorganic materials Ejaz Ahmed, Joachim Breternitz, Matthias Friedrich Groh and Michael Ruck, CrystEngComm, 2012, 14, 4874-4885

Ionic liquids in confined geometries Susan Perkin, Phys. Chem. Chem. Phys., 2012, 14, 5052-5062

Fluorescence monitoring of ionic liquid-facilitated biopolymer mobilization and reorganization Luke M. Haverhals, Laura M. Nevin, Matthew P. Foley, E. Kathryn Brown, Hugh C. De Long and Paul C. Trulove, Chem. Commun., 2012, 48, 6417-6419

Hofmeister effects of ionic liquids in protein crystallization: Direct and water-mediated interactions Magdalena Kowacz, Abhik Mukhopadhyay, Ana Luísa Carvalho, José M. S. S. Esperança, Maria J. Romão and Luís Paulo N. Rebelo, CrystEngComm, 2012, 14, 4912-4921

Influence of the ionic liquid/gas surface on ionic liquid chemistry Kevin R. J. Lovelock, Phys. Chem. Chem. Phys., 2012, 14, 5071-5089

ChemComm cover imageOptically responsive switchable ionic liquid for internally-referenced fluorescence monitoring and visual determination of carbon dioxide Shubha Pandey, Sheila N. Baker, Siddharth Pandey and Gary A. Baker, Chem. Commun., 2012, 48, 7043-7045

Supramolecular architectures of symmetrical dicationic ionic liquid based systems Haregewine Tadesse, Alexander J. Blake, Neil R. Champness, John E. Warren, Pierre J. Rizkallah and Peter Licence, CrystEngComm, 2012, 14, 4886-4893

New insights into the interface between a single-crystalline metal electrode and an extremely pure ionic liquid: slow interfacial processes and the influence of temperature on interfacial dynamics Marcel Drüschler, Natalia Borisenko, Jens Wallauer, Christian Winter, Benedikt Huber, Frank Endres and Bernhard Roling, Phys. Chem. Chem. Phys., 2012, 14, 5090-5099

An elegant access to formation and vaporization enthalpies of ionic liquids by indirect DSC experiment and “in silico” calculations Sergey P. Verevkin, Dzmitry H. Zaitsau, Vladimir N. Emel’yanenko, Christoph Schick, Saivenkataraman Jayaraman and Edward J. Maginn, Chem. Commun., 2012, 48, 6915-6917

PCCP journal cover imageIonic liquid-mediated epitaxy of high-quality C60 crystallites in a vacuum Yoko Takeyama, Shingo Maruyama, Hiroki Taniguchi, Mitsuru Itoh, Keiji Ueno and Yuji Matsumoto, CrystEngComm, 2012, 14, 4939-4945

Proton transfer and polarity changes in ionic liquid–water mixtures: a perspective on hydrogen bonds from ab initio molecular dynamics at the example of 1-ethyl-3-methylimidazolium acetate–water mixtures—Part 1 Martin Brehm, Henry Weber, Alfonso S. Pensado, Annegret Stark and Barbara Kirchner, Phys. Chem. Chem. Phys., 2012, 14, 5030-5044

Direct visualization of solution morphology of cellulose in ionic liquids by conventional TEM at room temperature Nan Luo, Yuxia Lv, Dexiu Wang, Jinming Zhang, Jin Wu, Jiasong He and Jun Zhang, Chem. Commun., 2012, 48, 6283-6285

If you’re interested in ionic liquids, why not take a look at the recent cross-journal promotion Incredible ionic liquids: an article collection.

You can keep up to date with all the latest developments across the chemical sciences by signing up to your favourite journal e-alerts or following them on twitter!

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Luminogenic materials have a bright future

Luminogenic materials are a hot topic of research due to their potential applications in biotechnology and memory systems. But most luminogenic materials undergo aggregation-caused quenching (ACQ) in the solid state. This is when the dye molecules near each other aggregate and form species that weaken the material’s emission.

Ben Zhong Tang and his team have been researching materials that instead exhibit aggregation-induced emission (AIE). This makes the preparation of solid state luminogens much simpler as aggregation increases the activity. Unfortunately, there are few AIE-active emitters in the longer wavelength region, which is of interest for biotechnology applications.

Tang’s team have addressed this oversight by developing a novel luminogen which couples the AIE property of tetraphenylethene and the longer wavelength activity of a hemicyanine dye. The emission properties of the resultant crystals can be readily tuned by the solvent molecules in the solution they are grown from.

Crystochromism of the novel luminogen

Most interestingly, the prepared luminogen shows crystochromism: a strong yellow emission in its thermodynamically stable crystalline form and a red colour in its metastable amorphous form. These changes are fully reversible, with grinding, heating or fuming causing the change in the luminogen’s crystallinity.

To find out more, download the ChemComm article today.

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