Chemistry Blog

Apr 30

Reagent pencils, turning chemistry into child’s play





If you’ve ever sat opposite a doctor and wondered what she was scribbling on her notepad, the answer may soon not only be medical notes on your condition, but real-time chemical preparations for an instant diagnostic test.

Thanks to the work of a team of researchers from California Polytechnic State University, recently published in the journal Lab on a Chip, chemicals formed into pencils can be made to react with one another by simply drawing with them on paper. The team may have taken inspiration from colouring books for their take on a chemical toolkit, but their approach could make carrying out simple but common diagnostic tests based on chemical reactions – for example diabetes, HIV, or tests for environmental pollutants – much easier.

The project started with an established technique called paper-based microfluidics. This uses the capillary effect of paper to carefully mix together what are called reagents – those chemicals mixed to form a reaction, or to measure the presence or absence of a substance. The capillary effect in action is easily seen by dropping two inks of different colours onto a piece of tissue paper. As the liquid is absorbed by the paper the colour drops spread out until they merge with one another and form a colour blend. In the same way two or more reagents can be mixed with water on a strip of paper.



Colouring-in chemistry.
Lab on a Chip/RSC

In this case, the difference is that the reagents aren’t added to the paper via droplets. Instead they’re applied via pencils, meaning that without specialist equipment anyone can set about creating chemical reactions by simply using them on the paper.

The team made the reagent pencils by pulverising a mixture of graphite (just as you’d find in normal pencils), test reagents and polyethylene glycol, which helps to keep the reagent dispersed throughout the mixture, as is used for the same reason in toothpaste. They compressed the mixture into pellets and mounted them into mechanical pencil holders bought from the high street stores.

The reaction paper pad was created by using a waxy ink to print small connected enclosures onto filter paper. The reagent pencils could be used to colour in these areas within the enclosures – when water was added to the paper, the reagents dissolved and, confined by the waxy ink, were forced to diffuse towards one another and react.

Real world uses for real world problems

The team demonstrated a potential use of the reagent pencil technique by using it in place of a common test used by diabetics to check their blood glucose levels, which involves reacting a pinprick blood sample with a chemical solution and examining the result.

One pencil was constructed with a mixture of enzymes, one called horseradish peroxidase (HRP) and the other glucose oxidase (GOx). A second pencil contained a reagent called ABTS. When combined in the presence of glucose these react together to give a blue-coloured product. Comparing the results from their pencils on the pad with the more traditional dropper method used by diabetics the team found the results were identical.



An example of how chemical reactions using pencils can provide instant results.
Lab on a Chip/RSC

The image shows, on the left, the reagents applied via droplets of solution. On the right, the reagent pencils were used. The top row shows the paper at the beginning of the test, the bottom row the result. Applied to the left enclosure, the sample solution carries the two reagents together which react. The coloured product produced is, as shown on the graph, identical between the two methods.

This is of course extremely easy to set up. Traditional diagnostic tests require training, while this pad and pencil system requires no more than skill than required to colour within the lines. The reagents are extremely stable once made into pencils – usually they would degrade in a matter of days as liquids, limiting how and where the tests can be made. However the reagent pencils showed no sign of degrading after two months.

So this pencil tool kit has obvious advantages: a kit of reagent pencils, much like a box of colouring pencils, is easily transported, without the chemicals degrading. Kits could be designed with particular tests in mind – and the reaction mix can be adjusted by applying more or less, without the need or equipment to make-up complex solutions. There’s scope to monitor environmental pollutants, carry out diagnostic tests in remote locations – not to mention teach chemistry in primary schools.

The Conversation

This article was originally published on The Conversation.
Read the original article.

Apr 29

The Food Babe quiz. Can you tell Vani Hari quotes from other irrational nonsense?





By now I’m sure you’ve all seen the ravings of Vani Hari a.k.a. Food Babe. Her one women campaign to spread fear through nonsense has netted her (in)fame, fortune and influence. Not to mention a pretty strong back lash from the rational side of the internet.

So to test if you’ve been paying attention I thought I’d set a little quiz.

All you have to do is identify, in the list below, genuine Food Babe musings mixed with other random nonsense.

Answers at the bottom of the page.

So here goes, with a nice game of …

Food Babe or Not Food Babe.

1) There is just no acceptable level of any chemical to ingest, ever.

2) Chlorophyll is the first product of light and, therefore, contains more light energy than any other element.

3) Please consider removing this additive from your diet because artificial dyes…Are man-made in a lab with chemicals derived from petroleum (a crude oil product, which also happens to be used in gasoline, diesel fuel, asphalt, and tar).

4) Your brain uses more oxygen than any another organ. If you need to concentrate it is important to keep you oxygen levels high .… Green leaves produce oxygen so if you need to study eat plenty of leafy vegetables to keep that brain well oxygenated.

5) When you look at the ingredients, if you can’t spell it or pronounce it, you probably shouldn’t eat it.

6) With a name like 8-methyl-N-vannillyl-6-nonenamide it’s bound to be a baddie. If you want more evidence of its unpleasantness then you may like to know that it is used by the police to control rioters.

7) Mass produced bread contains Potassium Bromate. Its used to help make the bread light and fluffy. Bromates have been banned as fire retardants in furniture, so how come its still used in the food we eat!?

8) Wheatgrass … is more than 70% chlorophyll which is essential for improving blood sugar problems.

9) For the experiment pictured above, microwaved water produced a similar physical structure to when the words “satan” and “hitler” were repeatedly exposed to the water.

10) You all know that we breath out carbon dioxide. But did you know that it’s an acid? … Whenever I’ve been in a crowded place I cleanse myself of the effects of all that acid breath with a good dose of Spirulina.

11) North Americans deserve to truly eat fresh – not yoga mats.

Credit: Fraud Files

How did you think you did? Here’s the answers.

1) Genuine Food Babe. An easy one to start with. You can find this little gem in her book. Don’t go out and buy it now.

2) Food babe again. Apparently wheatgrass is a miracle.

3) Food babe. Those nasty men in labs.

4) Not Food babe. Just me trying to channel Gillian McKeith.  

5) Food babe. But how are my fellow dyslexics and I going to eat?

6) Not Food babe. That one was me, with tongue firmly in cheek.

7) Not Food babe. Just random nonsense I made up, but sounds good doesn’t it?

8) Not Food babe. This gem came from the menu of the health food cafe I dinned in recently.

9) Food babe! Honesty, has she no shame? We’ll actually she might, since she’s removed offending post from her blog. But luckily the internet forgets nothing.

10) Not Food babe, I just made it up. But Vani does have some odd ideas about Spiriulina.

11) Food babe. What about fresh yoga mats? 

How did you do? Tell use you scores in the comments. And play along on twitter with #FoodbabeOrNot

Apr 18

It’s time science reclaimed health food from the quacks



 

IMG_0189I’m not quite sure what came over me, I’d set out in search of a beer and a burger. But somehow ended up in a juice bar wolfing down falafel, quaffing a cucumber, celery, ginger smoothie and sprinkling sweet potato chips with some strange pink salt.

And it was good. Really, really good. Tasty, satisfying and altogether wholesome.

Whilst I mopped up the last of the beetroot ketchup with my rye bread and slurped the dregs of the green juice, I flicked through the menu, idly wondering why the salt was pink. Tucked away on the back page I found the info I’d been looking for.

Apparently it was Himalayan pink salt.

What I read next pretty much ruined the whole dining experience.

Himalayan Pink Salt

This is a natural salt not like white table salt, which is a drug. Pink salt is extracted from the Himalayan mountains. It is negatively charged helping to draw positive ions out the body.

I sat paralysed. And wondered if this was due to my dinner having been laced with this strange substance that had removed all the ions essential for nerve impulses.

I regained enough movement to flick on my phone and Google the credentials of Himalayan salt. My panicked state subsided. For it is 98%, good old, sodium chloride, 2% polyhalite and a smidgen of rust (hence the pink tinge).

Once my composure had returned, I continued to flick through the menu. It was laced with plenty more pseudo-scientific claptrap.

IMG_5084IMG_5083

 

At this point I was starting to wonder if the place was run by Food babe. I rapidly made my exit and went in search of a stiff drink.

In the pub down the road, over a nice glass of single malt I got to thinking. The food, service and atmosphere in the juice bar had been great. Their products really were healthy. There was no need for the pseudo-science. Especially since genuine science about their ingredients is actually really interesting.

So I say to you Juice bar (and I will write to them) “Why not redraft your material with real science? I’ll even help you do it.”.

And if that doesn’t work, how about someone out there starts a health food cafe which doesn’t shy away from hard science, where real evidence prevails, where they tell you why the salt is pink, what chlorophyll actually does and how to eat a healthily diet. Wouldn’t such a place be more credible?

Apr 14

A letter from a chemist to homeopaths



Dear Homeopaths,

Homeopathy awareness week is here again. And I’ve got some questions about this most popular of alternative therapies. The answers to which I’d very much like to be aware of.

Homeopathy, as I understand it (please correct me if I’m wrong), is based on a idea that ‘like cures like’. So if your hayfever causes runny eyes then onions may be be able to help (because onions cause similar symptoms). Or maybe you suffer from insomnia, in which case caffeine may be the solution. However a cup of strong coffee is likely to keep you wide awake. So you get around this through massive dilutions. This way, you claim, the beneficial effects are retained whilst the unpleasant side-effects are removed. 

Now before we go any further let’s make sure I understand the dilution process, again using the caffeine example. You might start with a solution of caffeine that’s about the same concentration as coffee. Then you perform a 1 in 100 dilution. The solution is shaken, often by hitting it against a leather bound surface (a process known as succussion). The result is known as a 1C solution. You perform another dilution, shake etc. resulting in a 2C solution. The process continues often 30 or more times. The net result is a solution that will not contain a single molecule of the original. In fact it might be the equivalent of diluting the cup of coffee in sphere of water the size of the solar system.

So far I hope we can agree. But it seems rather unlikely, to me, that this process might result in an effective remedy. Although you have explanations e.g. ‘water is capable of storing information relating to substances with which it has previously been in contact’. Or to put it another way the water can remember what was diluted in it.

There is no sound scientific evidence that water has any such memory storage capacity. However, homeopaths often tell scientist that we should be more open minded and not to be so wedded to the dogma that we have been taught. So here I am, putting my education and experience in chemistry to one side for a moment.

Nevertheless, even without everything that chemistry might tell me, I’m still left with what seems to be some logical holes in your therapy.  Hence my questions for you, and I really am interested in the answers.

How come the water remembers the starting substance (e.g. the caffeine) but not impurities?

The gold standard for water purity (used by analytical chemists, but not homeopaths) is just 10 parts impurity to 1 billion parts water. The concentration of these impurities is equivalent to a 4C solution. So in dilutions made beyond this point the impurities will outnumber the original substance. How then can the homeopathic solution know which molecules it is supposed to store information about?

How do you make an oxygen based homeopathic remedy?

There appear to be quite a few remedies based on oxygen. But oxygen from the air will continually dissolve in the water you use to dilute your solutions. So how do you actually manage to make a 30C dilution of oxygen, when at every step along the way you are just adding more of it to your remedy?  

How is the power of a remedy transferred from water to a dry pill?

You make pills by dropping a water remedy onto a sugar tablet and then drying it. How is the stored information (supposedly in the water) retained in the pill after the water has evaporated?

Why can’t I find a homeopathic contraceptive?

I looked and you don’t seem to make or sell any.

If the potency of a remedy increases the more it gets diluted why can this never be perceived as a strong taste?

If a remedy is to work then it must interact with our biology. Why does this never manifest to our sense of taste?

Why was homeopathy so ineffectual at combating infectious diseases before the advent of vaccines?

Your theme for this years homeopathy awareness week is infectious disease. Vaccinations have reduced the spread of infectious diseases to a tiny fraction of what they once were. Homeopathy was around long before most vaccinations were commonplace, so why did it fail to reduce the incidents of infectious diseases?

I hope by answering these you might be able to give me a greater awareness of how you believe your therapies work.

Yours sincerely,

Dr Mark Lorch

Creative Commons License
Feel free to republish this letter. This work is licensed under a Creative Commons Attribution-NoDerivatives 4.0 International License.

Mar 27

The Disney Periodic Table: Clever Hook or Abomination?


We’ve all seen the plethora of faux periodic tables. I’ve ranted written about them before.

And now Disney (not content with trying to taking ownership of every  story ever) has chipped in with its own version of the periodic table.

At least it resembles the original, all the symbols are their, numbered correctly and laid out in the familiar way. But no longer do the symbols represent elements. Instead manganese has become Mulan, neon has transmutated into Nemo, and lead has been replaced by Pooh Bear (at least they are both rather dense). The only element that survives intact is copper, all be it in dog form and where cobalt should be.

Now I’m in two minds about this one. On the one hand it might serve as a way to get a bit of chemistry onto the walls of Disney fans and maybe they’ll then graduate onto the real version. But on the other hand it just makes me feel a bit sick :-/

So what do you think? Is it a clever way to elicit an interest in chemistry in those that might otherwise be more interested in fairy tale princesses or is it just an abomination?

 

Mar 12

Sharing Science: Distilling Publications Into 5 Minute Videos


Aiming to make our research more accessible, the Hanson research group will post five minute videos recapping each of our papers after they are published. This probably sounds like a very time consuming undertaking, but our group is very lucky to have access to GEOSET studio, a creation of our local Nobelist Harry Kroto.

Harry, a 2006 Nobel Prize winner for the discovery of the Buckminster Fullerene and current faculty member at Florida State University, has been heavily involved in outreach activities encouraging children and public involvement in science. Global Educational Outreach for Science, Engineering and Technology (GEOSET) is one branch of this effort. GEOSET is a free, online service that allows users to upload and view science-related videos. GEOSET videos mirror what students see in a seminar or classroom. Its dual-window format shows side-by-side views of the presenter and his or her presentation slides (or you can click to expand one or the other).

The process for creating a video is very user-friendly. All I need to bring to the GEOSET studio are myself and my presentation slides (quick aside: I don’t mean to underplay what may be a stressful activity for those who are camera-shy. It takes a lot to be a comfortable presenter. Thankfully, GEOSET makes it as easy as possible). The studio camera has a teleprompter that shows your presentation slides as you present. It’s a wonderful set-up that makes it look like you are presenting off the top of your head. After giving your presentation, just like you would at any group meeting, the in-studio software couples the recording with the presentation file and then the GEOSET staff post the video online.

There are numerous partner institutions around the world that have dedicated studios for creating GEOSET videos. At FSU the GEOSET studio is located on campus in the Dirac Library. Any student/faculty/staff can schedule an appointment, bring their presentation file (Keynote, PowerPoint, etc.) and quickly record a video.

The first GEOSET video from our research group is presented by second year graduate student Jamie Wang. Jamie recently published her paper “Modulating Electron Transfer Dynamics at Dye–Semiconductor Interfaces via Self-Assembled Bilayers”, in the Journal of Physical Chemistry C. Her research is focused on controlling electron transfer events at dye-semiconductor interfaces particularly for application in dye-sensitized solar cells.

I want to send a special thanks to Jamie for being the first group member to pioneer this Hanson Research group practice. She did a wonderful job and will serve as a solid example for future videos – a few of which will be available soon.

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