Invention: Self-replicating materials

"While nature teems with organisms that readily reproduce, no one has yet succeeded in making an artificial material that can repeatedly copy itself," say Paul Chaikin and colleagues at New York University, US. They want to change all that using micrometre-scale particles that, when in solution, self-organise into units able to reproduce.

Their idea, described in a new patent application, is based on the fact that sequences of DNA can be designed to recognise and bond with each other. By carefully designing these sequences, it is possible to build structures from them - for example, microscopic relief maps of the Americas.

Chaikin and colleagues point out that these techniques can be used to build with micrometre-sized particles of plastic, glass or metal, by coating them with DNA. Using the right sequences, they can induce such particles to assemble themselves into complex objects.

These assemblies can in turn self-replicate by corralling other DNA-tagged particles into more versions of the same thing. Heating and cooling the mixture can forge or break the DNA bonds, and chemicals can be used to modify the binding sequences in between each round of replication so as to produce very complex structures.

The ability to create new materials in this way could provide new routes to building regular structures like those used in microelectronics. Or it could produce entirely new materials, such as photonic crystal that control the movement of light through them in a way akin to how electricity flows through a semiconductor.

The team say the idea is particularly well suited to colloids - micrometre-sized particles suspended in a fluid. Experiments on colloids have proved that self-replication is possible, they say. By tagging colloid particles with a range of DNA coatings that fluoresce at different wavelengths, they were able to see how a mixture gradually turned into a collection of ordered lines of particles after a self-replicating "seed" structure was added.

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