Eric Drexler talks about the current state of self assembly and future possibilities in three recent articles.
1. Eric has been exploring some recent developments in chemical synthesis and self-assembly that suggest attractive possibilities for engineering robust self-assembling molecular systems. Boronate esters are involved in two ways.
Eric Drexler often think in terms of four levels of molecular assembly:
* Specialized covalent chemistry to synthesize monomers
* Modular covalent chemistry to link monomers to make oligomers
(~10 nm length)
* Intramolecular self-assembly (folding) to make 3D objects
(< 10 nm diameter) * Intermolecular self-assembly to make functional systems (~10–1000 nm) Recent developments are blurring the first level into the second, however, because new modular chemistries can make complex structures that can serve a monomers at the next level of assembly. Perhaps the most outstanding example comes from Marty Burke’s lab, which has pioneered a new, combinatorial methodology for piecing together small molecules of enormous diversity.
Regarding readiness to build extended, self assembling structures, yes, I think that the existing fabrication abilities (that is, the range of molecular structures that can be synthesized) are now more than adequate. The bottleneck is design software, including the development of rules that adequately (not perfectly) predict whether a given design satisfies a range of constraints. These include synthesis, stability, solubility, and sufficiently strong net binding interactions.
Chris Phoenix – of the Center for Responsible Nanotechnology also has been talking self assembly as well.
Chris Phoenix noted that the Foundations of Nanoscience FNANO10: Self-Assembled Architectures and Devices has many interesting topics.
Nanoplasmonics & Nanophotovoltaics
Self-Assembly Across Scales
Top-down Meets Bottom-up
Principles and Theory of Self-Assembly
DNA self-assembles very nicely into quite large structures – as big as 100 nanometers, almost bacteria-sized – almost big enough to see with an ordinary microscope.
Molecular manufacturing uses nanoscale tools to guide the fabrication of more tools. Once you can computer-control those tools to make a programmable range of shapes, you can make more tools (both in quantity and variety) than you started with.
Self-assembly is already using templates, and templated self-assembly is pretty darn close to molecular manufacturing. Once the templates become programmable and are built using the same processes and building blocks that they guide… then that is molecular manufacturing.
With so many advances on self-assembly, it seems pretty clear that just a few years from now, we’ll have primitive molecular manufacturing. More steps will be needed, of course, to design a full nanofactory and get it working. But the conceptual and practical hurdles are falling fast.