Yes, one could probably use weaker bonding (e.g. hydrogen bonding which is most common in biology) to hold a nanopart in place while forming new covalent bonds. It may be a question of how many hydrogen bonds you can establish and how many atoms you are attempting to add at the same time. But applying atoms (or small molecules) should not exert much force on the part, so the number of hydrogen bonds per atom being applied can probably be kept low. Alternatively, if one is using a biological model to add atoms or molecules (like the ribosome or DNA polymerase) the enzyme tends to be much larger and generally encases the molecules being dealt with. Perhaps the best example of the type of binding you are describing is the MHC proteins in the cells that bind sequences of amino acids (perhaps averaging 10 amino acids long) so they can be presented to T-cells for scanning (to recognize foreign substances within the cells). My immunology professor used a hotdog on a grill analogy to explain this — I've always thought that was good.

With regard to question 2, I believe that both Northwestern and Stanford have worked on parallel systems (NW with its dip-pen and Stanford with parallel AFM/STM). There are probably several other groups that I'm unaware of.

As far as I'm concerned its fine to ask such questions. You might however get a faster answer from Google. The trick is to know how to ask the question (for example to check my memory I just Googled on Northwestern and NanoInk).

Robert

I see that I'm only about 5 years behind the times on that particular idea…Amazing what you can find on Foresight.