Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!swrinde!cs.utexas.edu!bcm!dimacs.rutgers.edu!aramis.rutgers.edu!athos.rutgers.edu!nanotech From: toms@fcs260c2.ncifcrf.gov (Tom Schneider) Newsgroups: sci.nanotech Subject: Diamonds? Keywords: diamonds, bones Message-ID: Date: 3 Apr 91 19:33:26 GMT Sender: nanotech@athos.rutgers.edu Organization: NCI Supercomputer Facility, Frederick, MD Lines: 47 Approved: nanotech@aramis.rutgers.edu I was reading one of Drexler's papers in the Nanocon 1989 proceedings, where he notes the possibility of creating diamond for structural components. So I began to think of a shark with diamond tipped teeth. Wouldn't that have an advantage over calcium? Wouldn't a diatom or shrimp encased in diamond be able to survive better? So why don't living things use diamond? Or do they? If they don't, is this telling us something about the limits of nanotechnology? That is, maybe diamond can ONLY be made at high pressures and/or temperatures, so a molecular machine couldn't do it, unless the machine operated under those conditions. It's clearly possible for cells to deal with crystals. We know of bacteria that make magnets, that trigger ice formation (!) and lots of other cases of mineral deposition, such as bone formation: @article{Mann1988, author = "S. Mann", title = "Molecular recognition in biomineralization", journal = "Nature", volume = "332", pages = "119-124", year = "1988"} Cells handle carbon structures all the time, so why are shells and structural components mostly silicon and calcuim? The person who figures out how to get a cell to grow a diamond may become rich! Tom Schneider National Cancer Institute Laboratory of Mathematical Biology Frederick, Maryland 21702-1201 toms@ncifcrf.gov [I don't know about sharks' teeth, but human teeth are continually redeposited from minerals in the saliva, in a process involving no molecular machinery at all. Maybe this puts limits on the materials that can work. More fundamentally, there are some limits to the capabilities of biomechanisms as they work inside cells. In particular, a design that calls for a specific reaction to happen at one place and not another is much more complicated than with a nanomechanism that works like a "pick and place" robot arm. The mechanisms that the cell has to use look a lot more like those of synthetic chemistry, and the assembly of a complex design can become exponential in the worst case. (Although I don't think this applies to diamond per se). --JoSH]