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Artificial Blood Vessels Created On a 3D Printer
rallymatte writes "A team at Fraunhofer Institute in Germany has managed to create artificial blood vessels with a 3D printer that may come to be used for transplants of lab-created organs. From the article: 'To print something as small and complex as a blood vessel, the scientists combined the 3D printing technology with two-photon polymerisation — shining intense laser beams onto the material to stimulate the molecules in a very small focus point.'"
(person at the hospital) "What do you mean you don't have this type of blood? Why don't you just print some, I read it on the news."
Blood vessel != blood cell. Or is that the joke?
The headline doesn't exaggerate. They need to make artificial capillaries for synthetic tissue, and now they've come up with a way to make them. It'll be years before this will have progressed far enough to be an actual product (let alone one that is routinely used on human patients), but that's how all research works.
All of a sudden I had this image of printing kidneys, blood vessels and all, shooting out of a laser printer because someone clicked the wrong application.
"I said print out my organizer not organs!"
When my father was in for aortic valve replacement and bypass I asked the surgeon (Dr. Oz, the guy on TV a lot, did his surgery) and his cardiologist why there weren't artificial grafts. Instead they take vessels from the legs, adding another opportunity for infection and something else to heal, not to mention time to the procedure. They said that nobody had any success with it, they didn't know why. Venus grafts clog right back up pretty frequently; arterial grafts do much better, but you don't have a lot of arteries you can spare. TFA talks about capillaries, not coronary arteries. I'm not sure if the tissue needs would be any different.
You bring the light from a pulsed laser to a very tight focus inside a photoresist -- the same type of chemical used in standard photolithography. When this photoresist absorbs light with a wavelength of, say, 400nm, it cross-links to become a fairly solid plastic. In normal photolith, you'd illuminate a controlled area with 400nm light.
In two-photon polymerisation, you start with light of, say, 800nm, and you rely on two photons being absorbed at the same time, which together have enough energy to do what a single 400nm photon could. The key here is that, since the probability of this two-photon process depends on the square of the intensity, rather than linearly as in the case of normal one-photon processes, then you can localise it much better: with a tight focus, the chance of polymerising a ~100nm region near the focus is pretty much unity, while the chance of polymerising something away from the focus is pretty much zero. You then move that spot around inside the a blob of photoresist on a microscope slide.
Have a look at Nanoscribe GmbH for a commercial device, with images of some things they've made.