Archive for the ‘Sensors’ Category

Elizabeth New: Winner of the 2017 ChemComm Emerging Investigator Lectureship

On behalf of the ChemComm Editorial Board, we are delighted to announce Elizabeth New from the University of Sydney, Australia, as the winner of the 2017 ChemComm Emerging Investigator Lectureship – congratulations, Liz!

Elizabeth New

Liz finished her BSc (Advanced, Hons 1 and Medal) and MSc in Chemistry at the University of Sydney before embarking on a PhD programme at Durham University, UK, working with Professor David Parker. After being awarded her PhD in Chemistry in January, 2010, she was a Royal Commission for the Exhibition of 1851 Postdoctoral Fellow at the University of California at Berkeley within the group of Professor Christopher Chang. She then returned to the University of Sydney as an ARC DECRA Fellow to start her independent research career in 2012, establishing herself at the cutting-edge of molecular imaging and developing novel chemical imaging tools to supplement existing imaging platforms.

She developed the first set of reversible sensors for cellular redox environment containing flavins as the sensing group, including the first examples of ratiometric reversible cytoplasmic sensing, reversible mitochondrial sensing, and ratiometric mitochondrial sensing. She has also developed the first fluorescent sensor for a platinum metabolite, enabling the unprecedented visualisation of cisplatin metabolism, and a subsequent sensor to study the metabolism of transplatin analogues. Her research group is one of the very few in the world to be investigating cobalt complexes as responsive magnetic resonance contrast agents, and she has developed new methods for ratiometric fluorescent sensing, as well as new strategies to control subcellular targeting. Her research excellence has been recognised by a number of awards, among them the NSW Early Career Researcher of the Year (2016) and the Asian Biological Inorganic Chemistry Early Career Researcher Award (2014).

Passionate about communicating science, she has spoken about her research to high school students (as the Royal Australian Chemical Institute (RACI) Nyholm Youth Lecturer, 2014-5, and the RACI Tasmanian Youth Lecturer, 2017), to the general public (as a NSW Young Tall Poppy Awardee, 2015), and to politicians and policy-makers (as elected executive member of the Australian Academy of Science’s Early-Mid Career Researcher Forum). She is currently a Senior Lecturer and Westpac Research Fellow in the School of Chemistry at the University of Sydney, where her group continues to focus on the development of molecular probes for the study of biological systems.

As part of the Lectureship, Elizabeth will present a lecture at three locations over the coming year, with at least one of these events taking place at an international conference, where she will be formally presented with her Emerging Investigator Lectureship certificate. Details of her lectures will be announced in due course – keep an eye on the blog for details.

Read these articles by Elizabeth New:

A cobalt(II) complex with unique paraSHIFT responses to anion
E. S. O’Neill, J. L. Kolanowski, P. D. Bonnitcha and E. J. New
Chem. Commun., 2017, 53, 3571-3574
DOI: 10.1039/C7CC00619E, Communication

On the outside looking in: redefining the role of analytical chemistry in the biosciences
Dominic J. Hare and Elizabeth J. New
Chem. Commun., 2016, 52, 8918-8934
DOI: 10.1039/C6CC00128A, Feature Article
From themed collection 2016 Emerging Investigators

Fluorescent sensing of monofunctional platinum species
Clara Shen, Benjamin D. W. Harris, Lucy J. Dawson, Kellie A. Charles, Trevor W. Hambley and Elizabeth J. New
Chem. Commun., 2015, 51, 6312-6314
DOI: 10.1039/C4CC08077G, Communication,  Open Access

Imaging metals in biology: balancing sensitivity, selectivity and spatial resolution
Dominic J. Hare, Elizabeth J. New, Martin D. de Jonge and Gawain McColl
Chem. Soc. Rev., 2015, 44, 5941-5958
DOI: 10.1039/C5CS00055F, Tutorial Review,  Open Access

A FRET-based ratiometric redox probe for detecting oxidative stress by confocal microscopy, FLIM and flow cytometry
Amandeep Kaur, Mohammad A. Haghighatbin, Conor F. Hogan and Elizabeth J. New
Chem. Commun., 2015, 51, 10510-10513
DOI: 10.1039/C5CC03394B, Communication

The annual ChemComm Emerging Investigator Lectureship recognises emerging scientists in the early stages of their independent academic career. Nominations for the 2018 Emerging Investigator Lectureship will open later in the year – keep an eye on the blog for details, and read more about our previous winners.

2016:    Ang Li from the Shanghai Institute of Organic Chemistry, China

2015:    Deanne D’Alessandro from the University of Sydney, Australia

    Yong Sheng Zhao from the Beijing National Laboratory for Molecular Sciences, China

2014:    Xinliang Feng from the Max Planck Institute for Polymer Research, Germany

2014:    Tomislav Friščić from McGill University, Canada

2014:    Simon M. Humphrey from the University of Texas at Austin, USA

2013:    Louise A. Berben from the University of California at Davis, USA

2013:    Marina Kuimova from Imperial College London, UK

2012:    Hiromitsu Maeda from Ritsumeikan University, Japan

2011:    Scott Dalgarno from Heriot-Watt University, Edinburgh, UK

Also of interest: You can read the 2016 ChemComm Emerging Investigators Issue which highlights research from outstanding up-and-coming scientists and watch out for our 2017 Emerging Investigators issue – coming very soon. You can also take a look at our previous Emerging Investigator issues in 2011, 2012, 2013, 2014 and 2015.

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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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Catalysis and Sensing for our Environment (CASE) Network

The Catalysis and Sensing for our Environment (CASE) network is a group of friends keen to pool their parallel interests to develop novel molecular sensors and catalysts exploiting common underlying interests. Now key members of the CASE network (including Fossey, James, Qian, Jiang and Deng) publish two papers in the current edition of Chemical Communications that take pride of place on the front and back cover.

The front cover article (doi: 10.1039/c3cc43265c) describes catalytic de-borylation in a peroxide sensing regime (model for biological reactive oxygen species), the cover image pays homage to Joseph Priestly, who discovered oxygen in Birmingham, by including the RSC medal bearing his image as a centre piece. The back cover article (doi:10.1039/c3cc43083a) cleverly uses a molecule previously reported in nucleophilic catalysis (Chem. Commun., 2011,47, 10632) and uses it as a sensor for chiral secondary alcohols.

The metallocene containing sensor exists as two diastereoisomers and a surprising finding of this dual catalyst/sensor approach is that the non-catalytically active diastereoisomer is an equally efficient sensor as the catalytically active diastereoisomer. The research described in these papers derives from the close knit CASE collaboration and so the authors have used visual keys linking the front and back cover images, just as the research teams are linked via the CASE Network.

CASE network’s, free to attend, symposia have been held at the University of Bath (UK, 2008), ECUST (China, 2009), the University of Birmingham (UK, 2011), SIOC (Shanghai, 2012), University of Texas at Austin (USA, 2013) and future meetings are planned for Xiamen and Dublin. The CASE symposia have proven to be hot beds for collaborative discussion with numerous papers and successful funding applications resulting from the interactions initiated through the networking opportunities provided by these meetings. The authors gratefully acknowledge the support offered by RSC Journals who have actively supported these meetings, thus fostering the research presented in these two papers.

These two papers embody the ethos and importance of the CASE concept, since they include international collaboration and ideas that are underpinned by the complimentary combination catalysis and sensing.

Both these papers are Open Access and can be read and downloaded for free – find out more about the Royal Society of Chemistry’s Open Access policy:

Front Cover:

“Integrated” and “insulated” boronate-based fluorescent probes for the detection of hydrogen peroxide
Xiaolong Sun, Su-Ying Xu, Stephen E. Flower, John S. Fossey, Xuhong Qian and Tony D. James*
Chem. Commun., 2013, DOI: 10.1039/C3CC43265C

Back Cover:
Colorimetric enantioselective recognition of chiral secondary alcohols via hydrogen bonding to a chiral metallocene containing chemosensor
Su-Ying Xu, Bin Hu, Stephen E. Flower, Yun-Bao Jiang, John S. Fossey, Wei-Ping Deng and Tony D. James*
Chem. Commun., 2013, DOI: 10.1039/C3CC43083A

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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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‘Breathprint’ analysis as a real-time, non-invasive diagnostic tool

Scientists, led by Renato Zenobi of the Swiss Federal Institute of Technology (ETH) in Zurich, have been investigating metabolites in exhaled breath, showing that each person’s breath holds a unique, characteristic molecular ‘breathprint,’ as recently featured on the BBC website.  This means that high-precision chemical analysis of a patient’s breath can potentially provide an instant, pain-free and non-invasive medical diagnosis, and may even provide an early warning for healthy persons at risk for certain diseases.  In the future, it may also be used to calculate safe dosages of anaesthesia tailored to each patient’s metabolism and tolerance, or as a fast and convenient doping check for athletes.

Using mass spectrometry, Zenobi and his team regularly measured and analysed the exhaled breath of eleven volunteers for eleven days, finding that each individual’s metabolic ‘breathprint’ showed a unique core pattern and remained stable enough to be useful for medical purposes.  Their mass spectra of exhaled breath have shown peaks or signals representing around a hundred compounds, most of which they are just beginning to identify and assign.

Their findings represent a significant step towards ‘personalised medicine,’ and show great potential for other applications, such as in forensics or metabolomics.

Zenobi and his co-workers first published their early work in chemical breath analysis in a 2011 ChemComm article, in which they used their novel method to identify valproic acid, a medication for epilepsy, in exhaled breath.

C1CC10343A

Read the ChemComm article where it all began!

Real-time, in vivo monitoring and pharmacokinetics of valproic acid via a novel biomarker in exhaled breath
Gerardo Gamez, Liang Zhu, Andreas Disko, Huanwen Chen, Vladimir Azov, Konstantin Chingin, Günter Krämer and Renato Zenobi
Chem. Commun., 2011, 47, 4884-4886
DOI: 10.1039/C1CC10343A

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If you like it, then you should put two rings on it

Microring resonators are pretty amazing things, offering label-free biosensing by coupling with light and then circulating the photons inside the cavity of the ring, enhancing the interaction between the light and the analytes.

However, I like to think of traditional microring resonators as tents: difficult to construct. They require a submicrometer gap between the input waveguide and the resonator ring structure to allow the coupling of light and before you can even get to that stage, you need to make the microring resonator, which requires a series of complex fabrication steps (FIG 1a).  In this Communication, which is part of ChemComm‘s Microfluidics themed web collection, Professor Jonathan Cooper and his colleagues at Glasgow University and at the International Islamic University Malaysia’s CTS Department have made (what I think of as) the double pop-up tent equivalent– or as they call it, the dual disk resonator (DDR). Made from SU8, an epoxy-based polymer used in microfluidics chips, it can be patterned in a single lithographic step. Not only that, but the DDR uses a gapless design and two rings, increasing the sensitivity of the device (FIG 1b).

FIG 1: The hard way or the easy way (a) the traditional microring resonator with submicrometer gap (b) gapless dual disk resonator

Once they had constructed the DDR, the team characterised the optical sensitivity of the device using sucrose solutions to vary the refractive index of the sample above the waveguide. They then went on to show that the sensor could be used to evaluate the dynamics of antibody interactions on surfaces, exploring avidin-biotin-based immobilisations; sharp resonance shifts confirmed the assembly and disassembly of constructs.

The simpler fabrication shows great promise, as the authors suggest that the sensitivity of the device could be greatly improved by coupling more disks to it– in which case Beyoncé might soon be singing ‘if you like it, then you should put a chain on it.’

Read this ‘HOT’ ChemComm article today:

Polymer dual ring resonators for label-free optical biosensing using microfluidics

Muhammad H. M. Salleh, Andrew Glidle, Marc Sorel, Julien Reboud and Jonathan M. Cooper

Chem. Commun., 2013, Advance Article

DOI: 10.1039/C3CC38228A

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