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According to the Project on Emerging Nanotechnologies, the number of nano products available to the public has topped the 1000 mark.
Of course, these are mostly conventional products that include some component created by a nanoscale technology: a nanomaterial, a sensor, or a chemical integrated into a much larger conventionally manufactured product.
Still, for those who like round numbers, this is a milestone worth noting.
The EU-funded NanoHand project has developed micro-scale manipulators that can fit inside an electron microscope and manipulate objects as small as carbon nanotubes - just tens of nanometers wide. The robots are mobile, "walking" on a glass plate. They have grippers that open and close. They can, with some difficulty, put down what they pick up - at that scale, things tend to stick together, but the researchers have worked out at least two techniques for unloading the gripped object.
The robots have already been used to build better atomic force microscope tips by attaching carbon nanotubes to the tips. The equipment is said to have a "high degree of automation."
This is a few steps away (no pun intended) from atomic-precision manufacturing, but it's one of a rapidly growing set of potential enabling technologies. It may not be long before these robots, or something similar, are being used to assemble engineered molecules into machines.
More precise robots would, of course, be able to do more precise work - for example, they might be better able to drop what they're holding. Something as simple as one robot adding an engineered molecular "pad" to the gripping surface of another robot might improve performance. Over time, more and more components of the robots might be built of molecules...
Access to the nanoscale is advancing extremely rapidly now. How long until we have nanoscale machines capable of building improved nanoscale machines?
(Hat tip to "nanoman.")
Chemists and biologists can build medium-sized molecules and structures in a variety of shapes and materials.
It's hard to build large (greater than micron scale) molecular structures, especially large strong structures.
There are ways of fastening together molecules more strongly than DNA binding, but there's no obvious chemical way of controlling what fastens to what. Dissolved in solution, anything could bond to anything.
If medium-sized molecules were held in constrained position and orientation relative to each other, so that only desired bond sites could get close enough, then bonds could be formed only where desired.
A few years ago, Drexler (IIRC) described two ways of fastening molecules together. One is a protein structure called a zinc finger, wherein several amino acids (cysteine and/or histidine) bind to a single zinc ion. Another is a pair of paired carbon atoms, which rearrange bonds when hit by light to form a link across the pair. There are many other ways of fastening molecules, as well.
So, if DNA-tagged molecular shapes (whether made of DNA with Rothemund staples, or Schafmeister polymers, or whatever) were allowed to self-assemble to a DNA framework, and then zinc or light (or whatever reagent) were added, then the shapes could bond quite strongly into a single large strong precise molecule. The molecule could be highly crosslinked, and thus stronger and stiffer than most protein, and certainly stronger and stiffer than just plain DNA.
How big could the molecule be? Well, let's not forget IBM's recent announcement of plans to template entire computer chips with surface-attached DNA. That implies that the molecule - a single, engineered molecule - could be centimeter-scale!
IBM has announced a method of self-assembling DNA-staple shapes to a surface in precisely-designed patterns. They say that in ten years, this could be a way to make computer chips - if the shapes are attached to buckytubes or silicon nanowires to make the circuits.
This is important.
Computer chips ten years from now will have well over a billion circuit elements. So this means that IBM is thinking that, in ten years, a structure of a billion DNA staple shapes, plus a billion buckytubes or silicon shapes, will be self-assembled with very low error rate in a commercially relevant process. (I suppose the initial chips may consist of a billion separate transistor structures self-assembled to very narrow lithographed wires. But adding self-assembled DNA bridges between the DNA transistor holders, to link the billions structures into one structure, would not add much additional difficulty.)
As I've studied molecular manufacturing over the past twenty years, I've gone back and forth every few years on whether the world will get there first via direct scanning probe chemistry, or by building biopolymer structures of sufficient functionality. It's not that either approach ever looked bad - just that they keep leapfrogging each other.
My money is now firmly on biopolymers. What IBM is proposing to do sounds substantially more difficult than building a basic nanofactory. Note that the DNA structures would have to be electrically connected, which means that any electrical actuators could be individually addressed, and controlled by local computer circuitry.
The distance between this picture and a nanofactory proposal comes down to two main gaps. First, there aren't any actuators in IBM's proposal. But any of several classes of actuator should be fairly straightforward to integrate with DNA. Second, it's not quite clear what products might be built with such a nanofactory. But I have some ideas...
(Hat tip to Sander Olson.)
Although Eric Drexler wrote in 1992 that smooth atomically precise surfaces should have extremely low friction, it wasn't until 2004 (as far as I know) that a demonstration of this was published. Martin Dienwiebel published "Superlubricity of Graphite" - he may have coined the word.
I just googled his work, and found that there's already a book with the title "Superlubricity" - it was published in 2007, just three years after the first demonstration. The book includes a chapter by Dienwiebel, as well as a dozen other chapters - not just on experimental demonstrations of a theory, but on surfaces with engineering applications.
Things happen fast these days, but it still impressed me - pure research to book in three years. It implies that other things predicted decades ago from basic physics and chemistry may also develop quickly once they are first demonstrated. Things like fabrication of covalent crystals by scanning probe microscope. Or engineered nanomachines building other nanomachines under computer control.
I just thought of a molecular manufacturing system that could probably be built today, and might be very useful, at least in the lab.
When building 100-nm structures out of DNA, the final self-assembly step may require a week. This is OK for a lab demo, but too long for a serious manufacturing process.
It might be possible to speed this up substantially, by keeping the sub-components of DNA in approximately the right orientation for self-assembly as they are being fabricated. How to do this? With a framework built of DNA, of course.
I assume the synthesis of large structures goes something like this: First, use Rothemund staples to build each of the components. Rothemund staples bind to a DNA backbone or "scaffold" (Rothemund's term), folding it up into a structure. This is a relatively fast process (~ 2 hours), since the staples are just a few dozen nucleotides and can diffuse quickly. Next, mix the components together, along with more staples to bind them to each other (the staples may have been built into the sides already). The components, being large (over ten thousand nucleotides), diffuse slowly, and it takes a long time for the correct components to find each other.
If the backbone/scaffolds could be bound to a framework before the staples are added, and the framework held them in proximity to each other, then once the staples folded the backbones into components, the components could self-assemble far more quickly. The position of the components would be mechanically controlled by the framework, greatly increasing their effective concentration.
The framework might be quite large - in fact, it could be too large to self-assemble rapidly. But with the help of another framework - even a smaller framework - a large framework could be built quickly, then used to guide the building of products. This would be true molecular manufacturing, including a nano-building-nano aspect.
If several different components are to be built in parallel on the same framework and then joined, the simplest approach is to use several different backbones. Each backbone will bind with its own staples and not with staples meant for another backbone, just as staples bind to the correct location on a single backbone and not to the many incorrect locations. The ability to use multiple backbones, each making a structure, and then quickly join the structures, implies that shorter backbone strands may be used which will diffuse more quickly to their proper place on the framework.
DNA can be made to unzip as well as zip, by the addition of additional DNA strands that bind to a dangling tail on the strand to be removed. This means that the framework can be physically reconfigured during the fabrication process, and the manufactured parts can be removed from the framework.
When it's time to build products consisting of hundreds or thousands of backbones, it may be difficult to find that many different backbones. But a few dozen backbones might be used in combinatorial pairs to build hundreds of different structures in parallel on the same framework. First, attach several copies of each backbone at various places on the framework (perhaps with multiple attachment points to each backbone), so that the framework holds them apart, and each spatially adjacent pair is different. Second, add staples that bond from one backbone to another; they will only be able to bond to physically adjacent backbones. As each structure takes shape, constraining the topology of each backbone strand, staples may be added that bond from one to another location on the same backbone. Even identical backbones, with different sets of staples attached to form different topologies, can have different dangling strands attached to staple them to different other structures. Thus, there is no obvious limit to how large a product can be built in parallel.
(A staple bonded only on one side, to one backbone, and unable to find an appropriate pair backbone, may be removed by adding an unzipping strand. However, it may be simpler to leave dangling staples in place until the correct staple displaces them by zipping to the backbone. It may also be possible to use staples short enough to float free by themselves unless bonded on both sides. If I understand correctly, the problem of unwanted half-staple attachment must already be solved for Rothemund staples to work at all.)
A sufficiently large framework may be accessible with an optical microscope and conventional cell-manipulation tools or optical tweezers. This would open up whole new vistas of rapid actuation and controlled manufacturing. As a simple example, if it's difficult to build a framework stiff enough to keep unwanted backbone pairs apart, the framework could be physically stretched between optical tweezer beads. Getting a bit more ambitious, a framework attached to several beads could be folded on itself in a variety of ways under computer control, perhaps allowing a single set of structures to be bonded to each other in any of several configurations after the structures are built.
The devil is, of course, in the details. But it seems likely that some variant of this basic framework idea could be developed right away. For starters, take several small backbones, staple them together, build structures by adding more staples, then show that the structures self-assemble into a product far more quickly than they would by mixing separate solutions of the structures. Next, show that the product can be removed (by DNA unzipping) from a previously-stapled framework and the framework (perhaps attached to beads) can be re-used. Then, use the framework to build a larger framework out of multiple backbones. Then, demonstrate that the rigidity of the framework can be controlled to keep identical backbones apart during structure creation but allow their structures to self-assemble once they're built. At that point, you can start imagining what one-micron or even ten-micron product you'd like to build out of DNA.
[Edit: Originally this post referred to a 100-nm box built of DNA taking a week for the final self-assembly step. The DNA box exists, but it's 40 nm, not 100, and it apparently didn't take so long to assemble. William Shih's honeycomb DNA structures do take a week for final assembly, and can reach 100 nm. Several paragraphs of this post have been edited to reflect this.]
CRN is pleased to bring Herman Salgado on board as our Global Outreach Strategist. One of his first projects will be to complete the launch of our re-designed website.
Herman Salgado, Jr. is a management professional with over 15 years of work experience and a proven track record of success in areas such as project management, marketing, sales, QA, security and training. He has assisted organizations in the US and overseas in creating, analyzing and redefining business processes, systems and policies which have yielded great increases for organizations in their bottom lines, personnel development, production streamlining, personnel commitment, fundraising, public awareness, cost-cutting, and many other aspects due to his unorthodox management and marketing tactics and highly analytical processes. He has also used his years of web and graphic design experience to assist companies in creating or redefining their image to the public via websites, company logos, signboards and other printed material.
Eric Drexler recently posted slides for a talk titled "Advanced Nanotechnology: Advanced Computing on the Critical Path" that he gave as the keynote at WORLDCOMP’09.
The title got me wondering: Is advanced computing actually on the critical path for developing molecular manufacturing? Does that imply that the computers we had a decade or two ago would not have been adequate to develop molecular manufacturing?
I remember back in 1988, when I first learned about molecular manufacturing (then called "nanotechnology"), those who studied it most deeply seemed to expect it to be developed pretty quickly. It was obvious that the computational tools were quite primitive, certainly not up to simulating millions of atoms working together in mechanical systems. But that wasn't seen as a show-stopper.
So I read Drexler's slides with some interest, wondering whether they would imply that, in hindsight, no amount of effort could have developed molecular manufacturing before, say, 2010... in which case we might have to question our predictive abilities, and perhaps wonder about 2020 or 2030 as well.
It turns out that what Drexler is calling for is not faster computers, but better software. Specifically, better simulation software. More specifically, "Multi-scale, multi-material physical simulation" software, with "Integration of specification, search, and modeling" and "Tools for manipulation and multiple visualizations."
Could we have run such software on 20-year-old computers? I think so. Not that we could have run today's simulation software on 20-year-old computers. But we couldn't even run today's word processors on 20-year-old computers - and, nevertheless, we had WYSIWYG word processors back in 1984.
A multi-scale simulation program back in 1989 would not have been as precise as today's systems could be. It would have had to use more experimental data. It would not have been general-purpose, in the sense of being usable for designing a wide range of nanostructures and testing them before they were built. In fact, we don't have that even today.
But an iterative design-and-test process is a time-honored approach for developing any new field. It's a bit harder at the nanoscale, because it's harder to tell what's happening. I certainly don't want to imply that it would have been easy to develop molecular manufacturing back in the previous century. It surely would have taken multiple billions of dollars and many years. But it would have been worth it - and many of us thought that would be enough to inspire it to be tried.
Ever since it was proposed, the cost of a molecular manufacturing development program has been falling steadily. We will only know the cost in hindsight, after a development program has been successful. And historians may argue over how rapidly the cost would have increased for an earlier delivery date.
We are now at the point where nanoscale technology development is driving tools, such as multiscale simulators, that are directly on the critical path for molecular manufacturing. We're not quite at the point where desire for more powerful nanoscale technology capabilities is driving molecular manufacturing research directly, but we are close.
Despite the obvious fact that molecular manufacturing is not putting products on shelves today, I continue to believe that it could have existed years ago, if sufficient effort had been spent on it - and that it is not too soon for someone to0 launch a development program (indeed, it may already have happened) - and that some form of molecular manufacturing will be developed surprisingly soon.
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