Glow worms, Spider Silk, Light, Raman Spectroscopy and Phototherapy

05 December 2004
Presented by Chris Smith, Helen Scales.

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This show is dedicated to the science of light. Professor Robin Clarke, from University College London, joins us to talk about the use of Raman spectroscopy to date paintings and manuscripts, to identify pigments, and spot forgeries. Also in the studio is Professor David Philips, from Imperial College London, who joins us to discuss the therapeutic applications of light including photodynamic therapy for the treatment of cancers, light-therapy for the treatment of neonatal jaundice, and a laser-toothbrush he is currently working on. Also joining us is Ephraim Emery from the New Zealand Waitomo Glow Worm Caves, to explain the science of glow worms, and spider silk expert Dr Uri Gat, from Israel.

In this episode

Free Blind Mice

Harvard scientists announced this week that they have successfully used stem cells to restore vision in mice with the rodent equivalent of macular degeneration, a leading cause of blindess in humans. The disease is characterised by the progressive loss of light-sensitive cells from the central part of the retina - the macula - which is responsible for high-acuity vision. Damage to this region leaves an affected person unable to see what is directly in front of them, meaning that they have difficulty reading, watching television, or even seeing peoples' faces. Wondering whether stem cells could help to repair the damage and restore sight, the Harvard scientists transplanted stem cells collected from mice engineered to glow green, into the eyes of a second group of mice with retinal disease. The glowing green colour made the transplanted cells easy to follow, and the researchers found that they made their way to damaged regions of the retina and turned into new retinal cells. At the same time, the rate of damage to the existing retinal tissue also appeared to slow down, leading the scientists to suggest that perhaps the transplanted cells were secreting protective growth factors capable of keeping the diseased retina alive. Next, the researchers tested the transplanted mice to find out whether they could see any better than control mice not given any stem cells. This was done by shining progressively dimmer lights at them. Normally-sighted mice are photophobic and stop what they are doing when a light shines their way. Encouragingly, the transplanted mice continued to respond in this way, even at the dimmest light levels, but the control (untransplanted mice) did not showing that the transplanted mice had better light perception compared with their control counterparts. The researchers are optimistic that this approach might also work in humans and are now testing the technique in pigs which have bigger eyes, more like people.

Suits You Sir

Housewives (and house-husbands !) may soon have empty laundry baskets and lower water bills to look forward to thanks to researchers at Clemson University, who have discovered how to make a dirt-resistant fabric coating. The new highly water-repellant coating is made from a polymer gel (polyglycidyl methacrylate) mixed with silver nanoparticles and promises to offer superior resistance to dirt, meaning it needs cleaning much less often. Treated-clothes can be made in any colour because the coating is added after the material has been dyed. Phil Brown, one of the researchers behind the new coating, likens the concept to a lotus plant, the leaves of which are known to 'self clean' by repelling dirt and water. When water does come along, dirt is carried away much more easily. In the same way, dirt can simply by sprayed or wiped from clothes made with the new coating which, unlike conventional water-repellant coatings, is permanently bonded to the fabric so it can't wash off. The team are now working on a way to engineer antimicrobial particles into the coating which would also help to cut down odours such as cigarette smoke, and even body odours (so presumably the wearer doesn't need to wash either !).

Closeup of spiral orb web

- Spider Man Becomes a Reality

The Naked Scientists spoke to Uri Gat, Hebrew University of Jerusalem

Spider Man Becomes a Reality
with Uri Gat, Hebrew University of Jerusalem

Scientists in Israel have artificially produced a form of spider silk which could be used commercially to make protective clothes such as bullet-proof vests, surgical thread, optical fibres and even fishing rods. Together with researchers from Oxford and Munich, the Jerusalem-based scientists isolated the genes that spiders use to make dragline silk, a form of web which is known for its strength and elasticity; the silk is 6 times stronger than similarly-sized steel or nylon fibres. Dr. Uri Gat, one of the scientists behind the discovery, joins us from his lab in the Hebrew University of Jerusalem to explain how it works...

Chris - What are the commercial uses of spider silk?

Uri - Spider silk can be made into many useful products. These include stronger and lighter bullet-proof vests; reinforced fishing lines; digestible sutures for surgery; and maybe even new textiles! The only problem with spider silk clothes is that washing them will cause dramatic shrinkage, meaning you'd need new clothes every two days! As spider silk is a natural material, you don't even have to throw it away - you could eat it like spiders do !

Chris - Seeing as spider silk has so many useful applications, why has it taken so long to make it ?

Uri - Artificial spider silk has been made before now by creating it in bacteria. However, the quality was poor and the fibres were not ideal. We have been making spider silk in insect cell cultures. Spider silk genes were put into a virus, which was then used to infect insect cells. This forced the cells to produce spider silk. The most amazing part of this was that the silk proteins arranged themselves into fibres automatically inside the cells. It was incredible to watch.

Chris - How do you get the silk out of the cells, and how is this purified to make it suitable for commercial use?

Uri - Getting the silk out of the cells is actually quite easy. Spider silk is extremely chemically resistant, so when we destroy the cells with detergent, the silk is the only thing left. As to making it suitable for commercial use, we still need to develop a suitable method. Our discovery is the first step, and there are more to go before spider silk can be used on a large scale.

- Why do newborn babies get jaundice?

Why do babies get jaundice when they are born, and why does a session on a sun bed help get rid of it?

Why do newborn babies get jaundice?

Babies are not actually born yellow; it develops when they are first born. Every minute we make lots of red blood cells to replace those that have worn out. When old red blood cells are broken down, a yellow-coloured waste product, called bilirubin, is produced. Bilirubin is insoluble in water until it is metabolised by enzymes in the liver which add sugars to the molecule to help it dissolve meaning that it can be excreted in bile, and in urine. However, a developing baby doesn't need this biochemical pathway for metabolising bilirubin until it is born, because the mother removes the bilirubin via the placenta. But when some babies are first born and can no longer rely on their mother to help remove bilirubin for them, particularly if they are premature or have liver problems, there can be a delay in switching on this metabolic pathway and a backlog of bilirubin builds up around the body, making the child yellow. Because , until it is metabolised, bilirubin is insoluble in water but dissolves very well in fats, it accumulates in the skin, where we store most of our body fats, explaining why the babies appear yellow. If it is allowed to continue for a long time, jaundice can cause permanent damage to the brain, but if the baby is put under a blue light, a photochemical reaction occurs, breaking up the bilirubin and making it water soluble. This allows the baby to excrete the excess bilirubin in its urine. The process was discovered accidentally by Judith Ward who used to take babies into sunlight because she thought it was good for them. Having returned them to the hospital, she found that a previously-jaundiced baby had normally-coloured skin on sun-exposed areas, but yellow skin where the nappy had been. As a result the method was quickly adopted for the treatment of neonatal jaundice.

- Why do I get hot sweats at night?

Why do I get hot sweats at night? I think I am going through the menopause.

Why do I get hot sweats at night?

This is a very common symptom of the menopause. Normally, your ovaries respond to a hormone signal from the brain by beginning to produce eggs, which produce oestrogen as they develop. In response to the oestrogen the brain switches off the hormone signal until the next cycle. Women are born with all the eggs they will ever have already in their ovaries and so as women age, they start to run out of eggs, meaning it cannot produce oestrogen. In response to this, the brain sends even higher levels of hormones to try to encourage the ovaries to produce eggs. It is this increase in hormones from the brain that can cause the symptoms of the menopause. Hormone replacement therapy (HRT) works by increasing oestrogen levels in the blood which, in turn, suppresses the release of the hormones produced by brain and preventing the symptoms. But the increased risk of breast cancer associated with HRT use means that it should probably not be used for longer than about 5 years.

- I have a blocked eustacian tube. How did this happen and how can I clear it?

I have a blocked eustacian tube. How did this happen and how can I clear it?

I have a blocked eustacian tube. How did this happen and how can I clear it?

The eustacian tube is a connection from the back of your throat to your middle ear. Without this tube, your middle ear would be like a closed box, so that if you took off in a plane, the air inside your ear would expand and cause pain. The eustacian tubes allow you to equalise the pressure in your ears by letting air in and out. Swallowing several times can cause the pressure to equalise, and you know this has happened when you hear a popping sound. Divers equalise pressure in their ears by holding their noses and blowing. The tubes can get blocked by mucus left over after having a bad cold. With mucus blocking the end of the tube, air can't get past and pressure starts to build up. This is also the reason why people can't always hear very well after having a bad cold. Eventually, the mucus should clea and your ears should return to normal.

- Can Raman Spectroscopy spot asbestos?

I am interested in finding asbestos in buildings. I was wondering whether Raman spectroscopy could be incorporated into a handheld gadget...

Can Raman Spectroscopy spot asbestos?

The chemicals in asbestos do have a distinct raman spectrum, so a handheld gadget would be a possibility. It could be a useful application.

- Can you use spectroscopy to spot whether ID cards are real, or faked on a home printer?

Can you use spectroscopy to spot whether ID cards are real, or faked on a home printer?

Can you use spectroscopy to spot whether ID cards are real, or faked on a home printer?

It is very difficult to fake identity cards properly. Using bank notes as an example, an immense number of security measures have been put into them. Many of these measures are very hard and expensive to fake. One security feature on bank notes is the use of phosphors that give off different colours under light. Therefore, despite concerns about ID cards, they shouldn't be easy to forge.

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