The artificial organelle's membrane can be chemically tuned to control which chemicals can pass through it and regulate the reactions inside, according to Wolfgang Meier, one of the researchers. "We call it a 'nanoreactor'," he says...At 200 nanometres across, the organelles are 400 times smaller in width than a human hair.

...Artificial organelles might .. be able to treat conditions caused by a deficit of a particular enzyme. For example, someone with lactose intolerance could have their digestive cells given artificial organelles containing lactose-digesting enzymes.

In the far future, it might be possible to introduce non-human metabolic functions into human cells. "We could, in principle, bring in a nanoreactor that [lets] your skin do something like photosynthesis. So if you are hungry, you just lie in the Sun," says Meier. __ NS _via_Kurzweilai.net

He has created tiny sacks of the polymer polyethylene glycol just 8 micrometres across – in the range of human red blood cells – that are capable of deforming in a way that allows them to pass through the tiniest capillaries.

Polyethylene glycol is biologically benign, but binds easily with other substances, which makes it ideal for carrying cargo through the blood, says DeSimone.

For example, a haemoglobin-type molecule carried inside the bag could deliver oxygen to the body and carry away carbon dioxide. The bags could also deliver drugs instead, or help as contrast agents for scans such as magnetic resonance imaging, PET or ultrasound. __ NS _suggested by Will Brown