25 February 2009

Tattoo allows diabetics to monitor blood glucose

By
Cosmos Online
Scientists are developing unique tattoo ink for diabetics that changes colour depending on glucose concentrations in the body and would allow continuous monitoring of blood sugar levels.
Blood test

Painful prick: Diabetics currently have to monitor their glucose level by drawing blood and testing it manually, sometimes several times a day. A new tattoo could make this a thing of the past, say researchers. Credit: iStockphoto

SYDNEY: Scientists are developing unique tattoo ink for diabetics that changes colour depending on glucose concentrations in the body and would allow continuous monitoring of blood sugar levels.

Researchers at Charles Stark Draper Laboratories in Boston, USA, said that the ink could ultimately save lives and would mean that diabetics no longer need to painfully prick their fingers to draw blood and manually measure glucose levels.

Glucose detector

The glucose-sensitive ink would need to be injected into surface layers of the skin, but the tattoo would only need to be a few millimetres in size, said lead researcher behind the project, Heather Clarke. “The ink would need to be reapplied regularly, to avoid the problem – like with regular tattoos – where the ink fades or gets walled off from the body,” she said.

Originally conceived to monitor blood sodium levels for the treatment of heart problems and dehydration, the tattoo ink is made up of tiny porous nanoparticles, which are just 120 nanometres across. Each nanoparticle contains both molecules that detect glucose and a colour-changing dye.

Clarke said that when there is glucose present, the glucose-detecting molecules attach to it and the dye appears purple. When there is no glucose available, the molecules instead attach to the dye, turning it yellow. Normal glucose levels in the blood leave the ink an orange colour.

The interstitial fluid, which surrounds cells in the skin, contains as much glucose as levels found directly in the blood, said Clarke. However, her team is still unsure exactly how long it takes for skin glucose levels to respond and match to changes in the blood.

Human tests

“It will be interesting to measure the time correlation between change in blood glucose levels and the subsequent change in interstitial fluid glucose levels,” she said. “There may be a ‘lag time’ where it takes [up to several] minutes for the interstitial fluid to equilibrate.”

The tattoo has not yet been tested on human subjects and will take at least a number of years before it could be available commercially. Testing on mice is due to start in the next few weeks, though, and earlier tests on the version of the dye for monitoring sodium didn’t show any adverse side effects, Clarke said.

“I think it’s a very interesting and very innovative idea. If it works, it will probably benefit all diabetics,” commented Sof Adrikopoulos, head of the Islet Biology Research Group at the University of Melbourne in Australia. “[But] one needs to be careful that the colour of the ink actually reflects the blood sugar levels, and how sensitive the changes in the ink are,” he said.

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