Analytical – Chemical Communications Blog

Archive for the ‘Analytical’ Category

Marbles, Microreactions and Magic Tricks

03 Aug 2018

The reaction vessel is a fixed variable behind every innovative chemical synthesis, material or catalyst. It may be as simple as a round bottom flask or as complex as a single cell, as large as an industrial batch reactor or as small as a test tube.

Yujun Feng and co-workers, at Sichuan University in China, study a different kind of reaction vessel: water droplets. The droplets are ‘liquid marbles’, composed of microlitre volumes of water with fine hydrophobic particles covering their surface. Liquid marbles can be used as reaction vessels to manipulate small liquid volumes, avoiding the use of specialised microfluidics equipment. In this communication the authors show that carbon dioxide can trigger coalescence of droplets containing multiple reagents, in order to perform microscale chemistry. This research could be useful for developing high-throughput assays for procedures that would benefit from remotely controlled induction such as very fast or hazardous reactions.

The authors synthesised CO₂-responsive particles composed of a mixture of polystyrene and PDEA: a methacrylate polymer bearing tertiary amine ancillary groups. The amine is vital to the properties of the polymer: when deprotonated the powder is hydrophobic, but exposure to carbon dioxide renders the polymer hydrophilic by transforming the amine into an ammonium bicarbonate salt. Liquid marbles were synthesised with a patch of CO₂-responsive polymer powder. The rest of the marble was coated in lycopodium, a moss spore with hydrophobic properties that is not CO₂-responsive (trivia: the high fat content of lycopdoium makes it a great flash powder, used by magicians since the middle ages).

A) Liquid marbles with white hydrophobic/hydrophilic CO2-responsive patches and pink (dyed) lycopodium powder. B) Coalescence of two liquid marbles upon CO2 carbon dioxide exposure within one minute. C) Coalescence schematic

A) Liquid marbles with white CO₂-responsive patches and pink (dyed) lycopodium powder. B) & C) Photos and schematic of coalescence between two liquid marbles upon CO₂ exposure

To realise CO₂-induced chemistry, two liquid marbles containing different chemical reagents are placed side by side with the CO₂-responsive powder positioned at the interface of the two marbles. Upon exposure to CO₂ the responsive powder becomes hydrophilic and disperses into the aqueous solution within the two marbles, causing them to coalesce and the reagents to react within a single vessel. The authors performed several reactions using this method, all with distinct colour changes for rapid analysis: redox (persulfate and iodide, permanganate and persulfate), complexation (starch and iodine), substitution (bromine water and phenol) and chemiluminescence (luminol, peroxide and ferricyanide).

The authors show in this paper that innovations in chemistry needn’t be limited to reactions themselves; the vessel we choose can broaden what is possible on a practical level. On a completely impractical note, remotely controlled microreactions in liquid marbles sounds like a magic trick, resonant with the lycopodium flash powder covering their surface.

To find out more please read:

CO₂-triggered microreactions in liquid marbles

Xinjie Luo, Hongyao Yin, Xian’e Li, Xin Su, Yujun Feng.
Chem. Commun., 2018, Advance Article
DOI: 10.1039/c8cc01786g

About the author

Zoë Hearne is a PhD candidate in chemistry at McGill University in Montréal, Canada, under the supervision of Professor Chao-Jun Li. She hails from Canberra, Australia, where she completed her undergraduate degree. Her current research focuses on transition metal catalysis to effect novel transformations, and out of the lab she is an enthusiastic chemistry tutor and science communicator.

Comments Off on Marbles, Microreactions and Magic Tricks

Elizabeth New: Winner of the 2017 ChemComm Emerging Investigator Lectureship

09 Jun 2017

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.

Comments Off on Elizabeth New: Winner of the 2017 ChemComm Emerging Investigator Lectureship

Sharpening up super-resolution images by getting heavy

04 Nov 2015

Single molecule super-resolution microscopy is the technique which takes advantage of the photoconversion of fluorescent probes and single molecule dyes to image cellular ultrastructures beyond the diffraction limit of light. The most common approach for this technique is to genetically fuse photoactivatable fluorescent proteins (PA-FPs) to the biomolecules of interest. However, PA-FPs do not emit as much light as organic dyes, which poses a problem since this technique relies heavily on the number of photons that are collected. If you can increase the amount of photons emitted, you can increase the amount collected, which leads to higher localization and ultimately a higher resolution image.

Bo Huang and colleagues from the Department of Pharmaceutical Chemistry at the University of California, San Francisco set out to investigate ways to make the PA-FPs brighter. It was previously shown that heavy water (D2O) increased the photon count from popular small molecule dyes¹; would the same effect be seen in the PA-FPs? The answer was yes: as the heavy water component increased, the photon count also increased.

Photon counts seen from 8 fluorescent proteins in PBS and D2O PBS

One possible concern is that heavy water in live cells can slow down cell growth and even cause cell death. However, in real life this happens on significantly longer time-scales than it does in an experimental environment, therefore, any adverse effects on live cells would be minimal.

If you use PA-FPs in your work and you want to sharpen up your images then this paper is worth a read.

To find out the details, read the ChemComm article in full:
Heavy Water: A Simple Solution to Increasing Brightness of Fluorescence Proteins in Super-resolution Imaging
Wei Qiang Ong, Y. Rose Citron, Joerg Schnitzbauer, Daichi Kamiyama and Bo Huang
Chem. Commun., 2015, 51, Advance Article
DOI: 10.1039/C5CC04575D

¹S. van de Linde, A. Loschberger, T. Klein, M. Heidbreder, S. Wolter, M. Heilemann and M. Sauer, Nat. Protoc., 2011, 6, 991

Comments Off on Sharpening up super-resolution images by getting heavy

Incorporating DNA hydrogels into enzymatic biofuel cells

12 Oct 2015

I remember a time when mobile phones weren’t so power hungry, and when my phone could go a week on one charge. Admittedly, that was before it had a colour screen, internet connectivity and a hundred other bells and whistles. Increased device connectivity, in particular, has led to a huge increase in power demands and the need for better battery technology.

Wouldn’t it be marvellous if your phone battery generated its power from a wide selection of renewable sources? Khiem Van Nguyen and Shelly Minteer from the University of Utah look toward this possibility in their most recent ChemComm, which describes the use of DNA hydrogels in the production of an enzymatic biofuel cell.

The authors describe how they used the self-assembly of DNA monomers under physiological conditions to form a DNA hydrogel capable of trapping glucose oxidase, the most widely used enzyme in enzymatic biofuel cells. This DNA hydrogel remains permeable to small molecules, such as the battery fuel, whilst successfully trapping the enzyme close to the electrode surface. Enzyme immobilization on the electrode surface is critical to achieve an effective enzymatic biofuel cell, and this model biobattery was shown to have a similar performance to previously reported^ⱡglucose oxidase biofuel cells.

Entrapment of glucose oxidase in DNA hydrogel

With enzymes capable of oxidising a wide range of fuels, from alcohols and carbohydrates to amino acids, it may not be too long until a multi-enzyme biobattery is created that can be powered by the sweat from your skin. Then you’ll be able to browse the internet wherever and whenever you want…provided you have signal, of course.

To read the details, check out the ChemComm article in full:
Investigating DNA hydrogels as a new biomaterial for enzyme immobilization in biobatteries
Khiem Van Nguyen and Shelley D Minteer
Chem. Commun., 2015, 51, Advance Article
DOI: 10.1039/C5CC04810A

^ⱡFor example: S. Aquino Neto et al., Power Sources, 2015, 285, 493–498

Comments Off on Incorporating DNA hydrogels into enzymatic biofuel cells

Hierarchical 3D immunoassays – higher loading, lower fouling

08 May 2015

If you are producing an immunoassay there are two key parameters you need to understand and optimise: surface structure and surface chemistry. Get these two parameters right and you will optimise the sensitivity of your immunoassay.

Although there have been a multitude of 3D surface generation routes reported, they are generally complicated and require a lot of additional steps. Although these 3D surfaces lead to high probe loading levels they also often lead to high levels of non-specific protein absorption, undoing any good the surface structure would have led to.

Jinghua Yin and team from the State Key Laboratory of Polymer Physics and Chemistry at the Changchun Institute of Applied Chemistry have focussed on both properties to generate a much improved immunoassay.

Firstly they generated a 3D surface using UV irradiation of polystyrene spheres onto a substrate; they then grafted polymer brushes to the sphere surface. The polymer brushes not only further increased the surface area (more than doubling it from the bare sphere surface) but also acted as an anti-fouling agent, reducing the amount of non-specific binding observed by up to 90%.

Antibody loading on different surface types showing increasing loading levels

The commonality of the functional groups on the polymer brushes mean that any antibody can be attached to the prepared surface. To find out the details of how to make these surfaces and try them out on your own immunoassays, read the paper today!

To read the details, check out the ChemComm article in full:
Facile fabrication of microsphere-polymer brush hierarchically three-dimensional (3D) substrates for immunoassays
Jiao Ma, Shifang Luan, Lingjie Song, Shuaishuai Yuan, Shunjie Yan, Jing Jin and Jinghua Yin
Chem. Commun., 2015, 51, 6749-6752
DOI: 10.1039/C5CC01250C

Comments Off on Hierarchical 3D immunoassays – higher loading, lower fouling

Optimising multi-enzyme reactions – enabling enzymatic encoding

10 Sep 2014

The ability to mimic cascade and linked enzyme reactions has potential applications for disease diagnosis and pharmaceutical manufacturing, to name just two. However, the optimisation of the ratios of the interacting enzymes can be a time consuming step when carried out using standard solution based enzyme assays. With the problem becoming exponentially more difficult with the number of enzymes in the system, Jun Ge and Zheng Liu of the Department of Chemical Engineering at Tsinghua University, with colleagues, have looked to overcome this hurdle by developing a simple, fast and high throughput method based on ink-jet printing.

The team replaced the colour inks in a standard inkjet printer with enzyme and substrate solutions. The ratio of these solutions could be controlled by varying the overall colour that was printed. Optimisation of cascade and coupled enzymatic reactions could be carried out rapidly and inexpensively compared to the standard solution based method.

Enzymatic encryption, decoding and deletion of information

Precise two-dimensional control of enzyme placement via ink-jet printing also raises the possibility of creating 2D codes with enzymatic encryption built in, as the figure demonstrates. I don’t want to give the secret of this encryption technique away so you’ll have to read the paper today.

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

Ink-jet printing an optimal multi-enzyme system
Yifei Zhang, Fengjiao Lyu, Jun Ge, Zheng Liu
Chem. Commun., 2014, Accepted Article
DOI: 10.1039/C4CC06158F

Comments Off on Optimising multi-enzyme reactions – enabling enzymatic encoding

A cloak of many carbons

28 Jun 2013

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/Ce_0.50Tb_0.12Zr_0.38O_2-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.

Comments Off on A cloak of many carbons

‘The next generation of SEC/GPC Analysis’ free webinar on 30 April 2013– register now!

17 Apr 2013

Join Chemistry World and Waters for this free webinar on ‘The Next Generation of SEC/GPC Analysis’ in order to…

Identify the requirements for an advanced chromatographic system to meet the needs for determination of molecular weight distributions

Understand the benefits of a complete system approach to molecular weight characterization

See how the new paradigm in molecular size characterization will reduce test cycle time and consumption of operating chemicals while providing improved test precision with statistically enhanced data sets

See where the innovative separation approach can allow for a deeper understanding of polymeric properties and their variation

Register today at http://rsc.li/waters-acquity

Comments Off on ‘The next generation of SEC/GPC Analysis’ free webinar on 30 April 2013– register now!

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

09 Apr 2013

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)-N_x 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-N_x 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.

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

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

05 Apr 2013

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

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

Chemical Communications Blog