The World of Chemistry

Labs on a chip and milk in tea,
14 January 2007

Interview with 

Dr Mark Peplow, editor of Chemistry World


Chris - Joining us now from Chemistry World is Mark Peplow. Welcome to the Naked Scientists. You gave us a rundown on why Alexander Litvinenko had a bit of a horrid time when you joined us in December. This month there's some very exciting news, so let's start at the top of the list: how researchers are using heart cells to pump things around labs on chips. Perhaps you'd better start off by describing what a lab on a chip is.

Mark - Chemists are very interested in trying to shrink their laboratories down until they're the size of the sort of chip you get in your computer; maybe just the size of a postage stamp. Now these can be used for chemical reactions on very small scales. Similar sorts of technologies could be used in medical implants as well and this particular breakthrough, which has come from some Japanese scientists, is that rather than using a battery-powered pump to move liquids around, they've actually managed to strap a couple of bundles of heart cells on either side of a plastic ball. Those heart cells will stay alive as long as you keep feeding them nutrients for up to five days actually. And they actually pump continuously as long as you keep them bathed in nutrients and actually pump fluids through this little ball of plastic. It's only about five millimetres wide, but it's a really nice proof of principle that you don't necessarily need batteries on these tiny pumps.

Chris - Is it actually worth doing though? Why not have tiny pumps? Why use heart cells? It sounds fiddly.

Mark - If you're actually constructing this on a lab, one of the difficulties could be that while technology in terms of moving liquids around and doing chemical reactions - that's shrinking all the time. Battery technology is developing quite a lot slower, so there's no point in having a tiny laboratory is you have to have a massive battery to power it inside. In a sense, the same is true if you're using medical implants. Batteries can only last so long so one can imagine that in the future if you can actually attach heart cells to a pump so it's actually going to work continuously, all you need to do is to keep feeding them nutrients and they will go on and on and on. So they could even beat Ever Ready batteries!

Kat - It is one of the most crazy things I've ever seen in science looking down a microscope at a petri dish full of cells and seeing them beating, because they were heart cells growing in the lab. So what's the deal with nanoparticles in exhaust fumes? Are nanoparticles dangerous? What's all that about?

Mark - If you look hard enough, you can find them pretty much anywhere. Nanoparticles are basically anything that you can measure in billionths of a metre, so they're maybe a thousand times smaller than the width of a human hair, something like that. We already know quite a lot about microparticles in exhaust; you can find them in diesel emissions and things like that. Now they're just about one fifth of the width of a hair, so we're talking about a completely different scale. So Justin Linguard and some of his colleagues at the University of Leeds have basically sat out on a roadside for a couple of months in Leeds and just sucked up particles from the air to find out what's in there. Interestingly they find that if you just count the number of particles, the vast majority, about 90% of them, are these nanoparticles. Although we don't know exactly what risks are associated with these, there's some suspicion that if you inhale them, they can potentially get into the lungs through tiny alveoli and through the walls because they're so small. They could then go into your blood stream. Again, we don't know what the effects of these might be once they're there, but one might suspect that it's not going to be ideal.

Dave - So what's this about milk and tea and it not being very helpful?

Mark - It's been around in the news quite a bit for the last week or two actually. Many people drink tea because of its antioxidant properties and it's stuffed full of these things called polyphenyls, which are supposed to have good effects for you. But some German researchers have found that if you add milk to your tea, it actually neutralises those health benefits. They suspect that what's going on is that once you put milk in, proteins called caseins actually wrap themselves round these beneficial polyphenyls that are good for helping your arteries expand and increasing your blood flow, and stop them from working in your blood stream. So effectively, if you put milk in your tea, it's no better for you than drinking hot water.

Kat - It's certainly interesting because that was a laboratory chemical study, but some of the studies done in huge populations of people have found beneficial effects of tea and green tea in things like cancer and heart disease, so it'll be interesting to kind of drill down into it.

Mark - One of the interesting things that our reporters found on the Chemistry World team was that when they spoke to some researchers in the States about this, they pointed out that yes, many studies had found benefits to drinking green and black tea in countries in Asia and things like that. But when you actually look at the UK and the epidemiology, there's no benefit from tea drinking at all even though we're a nation of tea drinkers.

Chris - I think we drink more tea than anyone else per capita.

Mark - Yeah, and the reason we don't get any benefit from that is maybe that we unusually choose to drink our tea with milk.


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