There are reasons very little work is going into it—the concept makes very little sense compared to manipulating biological systems or making systems that work similar to biological systems. See http://www.sciencemag.org/content/347/6227/1221.short or this previous post of mine: http://lesswrong.com/lw/hs5/for_fai_is_molecular_nanotechnology_putting_our/97rl
There are reasons very little work is going into it—the concept makes very little sense compared to manipulating biological systems or making systems that work similar to biological systems. See http://www.sciencemag.org/content/347/6227/1221.short or this previous post of mine: http://lesswrong.com/lw/hs5/for_fai_is_molecular_nanotechnology_putting_our/97rl