Which is better, a quick vertical jab on the buttock or the delicately soft entry of a blood sample? Waiting to find out "for what", some are already wondering "how" to use those tiny "molecular syringes" which are carbon nanotubes. With a diameter of less than one millionth of a millimetre (nanometre) and a maximum length of just a few millimetres, the first use that springs to mind when we think of this ethereal tubes - the smallest ever made by man - is as potential needles for injecting drugs or genes into sick cells. And if a syringe it is, we had better start thinking about how to use them. A group of researchers at the Ciamician department of the University of Bologna (Unibo, Italy) has no doubt about it. The easiest and most natural way of penetrating a cell membrane with a carbon nanotube, in its simplest form, is at an angle which is almost flat against the membrane surface. Just as a nurse does to "find" a vein.
Siegfried Hfinger (Unibo) explains: "A flat entry offers the most favourable energy balance." The entry of the nano-needle is in fact twice as easy than at an angle of, say, 45, and three times easier than vertical penetration. "We can even hypothesise that the nanotube takes on this position of its own free will when placed near the membrane," adds Tommaso Gallo, another of the young authors working on the study, which is in press in the scientific journal Biomaterials.
The scientists' doubts lie in the extreme difficulty in handling such small objects. "Probably no one is able to experimentally verify these phenomena yet," says Hfinger. The chemists from Bologna, part of Francesco Zerbetto's research group, have drawn their conclusions not from physical experiments but from theoretical simulations. Mathematical models which consider all the forces at stake and the physical and chemical properties of the elements involved, predicting their behaviour.
The encouraging aspect of the Unibo research, which also
|Contact: Luigi Valeri|
Universit di Bologna