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« Live Blogging at MIT | Main | They say it can't happen that fast... »

September 25, 2006

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Tom Craver

Sounds promising - though I wonder if - should it become used for actually producing widespread products - there might be some risk of "free" DNA breaking off and dispersing. Outside UV would probably destroy it fairly fast, but indoors, getting breathed in - might it accidentally get embedded in lung cells, skin cells, etc and actually get expressed?

I'd feel better about it if it were using totally non-bio-compatible molecules that are merely analogous to DNA...e.g. something that uses bases not present in living creatures.

jim moore

Chris,
Instead of a micro-bead, start with a micro-cylinder (with handles) use dip-pen nano-lithography to add an anchoring groups to the surface of the cylinder at a particular locations. You make a series of dots (anchoring monomers) that spiral around the cylinder, with a ~30 nm gap between the anchoring groups.
Take the cylinder put it into a chamber with long strand DNA which binds to each anchoring group, then add the DNA staples to get it to fold into an nano-brick, Or you could use some modified version of Merrifield method to do step wise polymerization from the anchoring group out, to make your nano-brick.

By constraining the location of the nano-bricks, you make it much easier to transfer the bricks to some kind of placement mechanism, compared to having the bricks float around in solution.

Tom Craver

Totally off topic of DNA beads, but...

I wonder if you could build nanostructures out of salt. I think salt (NaCl) has only one common crystalline structure, as opposed to carbon's many forms - which should make it easier to work with and get expected results.

Salt isn't very strong, and obviously has issues with water - but maybe as a transitional stage it'd be interesting, and at least might demonstrate building structures at the nanoscale.

Chris Phoenix, CRN

Tom, I think DNA is too weak and floppy to make good human-usable (large, complete) products... it is, however, good for several things. It would be an important proof of concept, might be a very useful enabling technology, and might make some extremely useful stuff like diagnostic/sensing chips or computers (by templating other molecules).

Chris

Chris Phoenix, CRN

Salt... interesting! I'd be more likely to go for silica than salt. I don't know if there's a known way to attach covalent chemistry (molecules) to salt crystals. It's certainly not something life would have evolved, at least not for NaCl.

Chris

Andrew

Well, salt is ionically , not covalently bonded. This means that the chemical bonds between Na and Cl are not directional. In fact, the crystal structure of ionic solids is purely a function of the ratio of atomic radii of the atoms. This is a simplification of reality, as all ionic solids have a degree of covalency to them. Also, I think that salt might have more than one crystal structure, depending on temperature and pressure (I would have to look at the phase diagram to say for sure).

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