Category Archives: Chemistry

A chocolate chemistry session, how could I refuse? Not only that, but when I got there I realised that there were also free samples.

Happily, from the talks I saw, ‘eat chocolate, it’s good for you’ seems to be the message. A lot of the science focused on the antioxidant in chocolate and the individual studies were compelling, although everyone was sure to highlight that cutting out other risk factors, such as smoking, is even more important. Not only were there individual studies, but Eric Ding from Harvard Medical School presented a meta analysis that suggested those conclusions were part of a larger pantheon of evidence.

But the really interesting talk for me, was one from Francisco Villarreal of UCSD that suggested that as well as chemical actions, the antioxidant chemicals epicatechin and catechin also have biological mechanisms. That they seem to affect signalling pathways and receptors, and even act as antagonists to each other. And how much chocolate do you need for this affect? Villareal says less is more: about 5g of dark chocolate. A paper is apparently in the pipeline with pretty big results, so stay tuned!

Villareal is, however, a big proponent of chocolate. From it’s mystical health and strength giving importance in Mesoamerica to its benefits brought back to Europe, and essentially being described as the first super food, Villareal says he believes that that’s all down to the flavanols and minerals in the chocolate. And who am I to argue with Casanova, who consumed chocolate before ‘entertaining’ – perhaps he needed a pick me up to boost his stamina!

So for both antioxidant benefits, and the more biological effects, the advice is the more cocoa solids the better, but how much of it you eat is, as always, probably more to do with appetite rather than intention.

Laura Howes

                  

Source:
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Pealeontology, archaeology and chemistry – if I say those words you’re probably thinking isotopic rations, and chemical analysis. But what about peeling back the layers of biological history?

Loren Williams of Georgia Tech has been doing just that with the ribosome, specifically, the large subunit (LSU) ‘where all the chemistry happens.’ X-ray chromatography of the ribozome, that thing some people won the nobel prize in chemistry a few years ago, shows that the core of the LSU is conserved across the tree of life, implying not just a common ancestor but, says Williams, that the core is what the LSU began it’s life as. Peeling back the layers to the core as molecular time travel.

So Williams is working on making a testable model of what the core was, and to establish what the LSU did before it grew up and joined with the small sub unit and started making protein chains. However, it was a throw-away comment in Williams’ talk that really got me thinking. He said that as we look out of the window, or watch a nature documentary, that impression of such wide diversity is an illusion. If you break the ribozyme, meddle with the core of the LSU, life cannot continue. Once that core functionality was achieved, it stayed and at the core of all life, the structure and sequence is almost identical.

Now maybe it’s the long days, but I find that such an interesting concept and relevant to this entire meeting. The convention centre and the hotels are filled with disparate groups of chemists. Different sections that can spend their entire time in a couple of rooms, their niches. Looking at the programme, the science covered seems so diverse but ultimately, at the core the science is the same.

Laura Howes

                  

Source:
http://prospect.rsc.org/blogs/cw/?feed=rss2

It was made to save fuel by stopping tyre wear but now saves lives by stopping bullets. And it’s useful for much more besides. David Lindsay looks at the wonder material, Kevlar, in this week’s Chemistry in its element podcast.

                  

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The ACS Award for Creative Innovation Symposium in honour of Chad Mirkin was a who’s who of clever nano chemistry with bio applications.

John Rogers presented his flexible circuits and you can read my story here. But the flexible circuits are also being used in a way I didn’t mention in the story – for imaging the brain during epileptic fits. With patients with extreme epilepsy, surgery is sometimes used. Surgeons open up the skull, cover the brain in electrodes and then provoke a seizure to see where to cut. Rogers’ group has developed their circuits for this as well, and he showed an amazing video of the repeating waves that pulse through the brain during a fit. So what looks like very applications based science has now given new insights into epilepsy:

I luckily got to chat to David Walt after the session about creative innovation and how spin outs can amplify the impact of science. Obviously, being the founder of Illumina, Walt has an interesting perspective. ‘A lot of scientists don’t realise that the real impact is when you grow a technology to when it’s commercially successful,’ he says. He urged people not to focus on the ‘quick buck’ but focus on creating a lasting, long-term company. Of course, that’s easier said than done, but Walt does believe that the entrepreneurial side of science then pushes you to do better fundamental research. At the symposium today, that was a heady and enticing prospect.

Laura Howes

                  

Source:
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Static electricity usually conjures up images of Van de Graaff generators, crazy hair, sticking balloons to walls and the odd shock from an inappropriate clothing choice.

But when Classic Kit columnist Andrea Sella happened to mention a couple of months ago that the cause of static charging is still far from understood, my interest was piqued.

I had assumed from schooldays that it was all sorted out – you rub stuff and it gets charged. But when you think about it, what’s actually causing that charge buildup? Is it really electrons? Surely the work function – the energy required to displace an electron from the surface – of those materials is far higher than simply placing them in contact with another material? What about ions? Or both?  Or even bits of the materials themselves transferring over – as I found out researching my latest news piece?

So what’s really going on? The short answer is we really don’t know. That came across talking to Dan Lacks at Case Western Reserve University, US. Lacks told me that he’d originally got into looking at tribocharging when he was approached by a company with a project. ‘I thought it would be easy – I’d just read in the literature how it works and be able to simply solve their problem.’

Static charge on a Teflon surface touched repeatedly with an inflated and deflated rubber balloon © Wiley-VCH

It turns out to be significantly more complex, and seven years later Lacks is still pondering the issue. In a recent paper of his own, Lacks has shown that touching a rubber balloon to a Teflon surface charges it oppositely depending on whether it’s inflated or deflated, so straining a material changes how it charges.

Not only that, with the advent of modern microscopy techniques, it’s now possible to see what’s happening to charged surfaces at the nanoscale. Last year, Bartosz Grzybowski from Northwestern University, US, showed that – rather than one surface charging positively and the other negatively when 2 materials are rubbed together – both surfaces are covered with tiny mosaic patches of positive and negative charge, and a tiny imbalance of one over the other is responsible for the overall charge.

When you combine that result with his latest work on how nanoscale fragments of the materials are transferred between surfaces on contact, taking their charge with them, it becomes easier to see how material transfer can flip the polarity of the charge on two materials.

But it gets even more interesting when you start to think how that material transfer happens. Grzybowski says that it involves ripping polymer chains off the surfaces, which involves breaking covalent bonds. The same happens when you deform polymers – some of the bonds break and, according to Grzybowski, this produces radicals. If you have the polymers under water when you deform them, then you can produce hydrogen peroxide or stimulate other radical chemistry processes.

To demonstrate how effective the process is, Grzybowski’s team injected a solution of a boronate protected umbelliferone into the sole cavity of some Nike Air trainers. Walking around in the trainers produced enough radicals and H₂O₂ to cleave the boronate group and release fluorescent umbelliferone.

Fluorescent trainers - the next fashion craze? © Wiley-VCH

I’m not sure the people at Nike will be taking it up as a marketing gimmick (especially since you need a UV lamp to see the fluorescence), but it certainly shows that the charge and electronic behaviour of polymers is  mind-bogglingly complex and a potential source of some really interesting chemistry – harnessing polymers as a convenient source of mechanically produced radicals could have huge potential when you consider how many industrial and academic processes involve radical pathways.

Phillip Broadwith

                  

Source:
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Well I’m here in San Diego for the Spring ACS meeting (even if my suitcase isn’t) and the packed schedule has already brought up some gems. Here’s my round up of day 1…

The San Diego skyline, a nice place for a conference!

Bassam Z Shakhashiri, the new ACS president, wearing his ‘Science is Fun’ pin badge, used the meeting to launch his priorities for his presidency. As ACS presidents only have a one year term to implement their vision, I often wonder how much can really be achieved in that year, but Shakhashiri does at least seem to be getting one thing done. He’s appointed a working group on the public understanding of the science of climate change, to develop a tool kit for ACS members. Public understanding of science is something Shakhashiri has been very involved in for many years, but he says that the kit is needed to make sure that the ACS membership is well versed in the science of climate change, as well as then using it to communicate the facts more widely.

‘In my visits with colleagues, graduate students, high school teachers, university professors, members of our profession and industry,’ he explained diplomatically. ‘I have discovered there is a need to refresh our knowledge of what a greenhouse gas is.’

Shakhashiri’s climate change group has also been asked to look at how to communicate the science of climate change to the wider public, from teachers to policy makers, to the people I walked past on my way to the convention centre. ‘There are the deniers, there are sceptics and there’s everyone else,’ he said. ‘I have deliberately chosen not to spend too much time engaging in conversation with the deniers … that will definitely elevate my blood pressure. I’m very much interested in conversing with sceptics and with everyone else – in science we make progress by being sceptical.’

If you’re interested in the toolkit, it will be web-based and, while it is only two-fifths completed, it should all be available by the time of the Fall meeting in Philadelphia.

Of course, with Shakhashiri’s interest in communicating science, there are some great talks at a more general level in the programme. I felt I had to go to the plenary session in the afternoon to listen to Roger Tsien and I’m so glad I did. Tsien, I’m sure, needs no introduction, but in his first slide introduced us all to the jelly fish that makes green fluorescent protein (GFP), which he says his should Nobel prize should go to. What followed was not a look back at the work that led to Tsien being awarded his Nobel Prize, but where that work has taken him since.

The spring ACS is dedicated to the chemistry of life

There’s something really neat about sitting in a packed room seeing how papers you gave as journal clubs back at university, now fit into something much larger. Tsien’s activatable cell penetrating proteins (CPPs) specifically target cancer cells, making them fluorescent so that during surgery, doctors can ensure that all of the tumour is removed. Or the cell penetrating proteins can be made specific for nerve cells, protecting the nerves from the scalpel during prostate surgery (something which, Tsien said, men are quite interested in!). That’s some low hanging fruit for Tsien’s spin out Avelas if ever I heard it.

Laura Howes

                  

Source:
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