DNA nanorobot releases drug cargoes on chemical command - A virus-sized self-assembling robot crafted from a strand of DNA has been engineered by scientists in America.
Writing in the journal Science, Harvard researcher Shawn Douglas and his colleagues have used "DNA origami" techniques to come up with a 7300 letter-long DNA sequence that folds itself up into a hollow hexagonal barrel-shaped structure measuring 35x35x45 nanometres.
This is roughly the same size as a small viral particle. Further clever engineering has endowed the structure with hinges and a pair of chemically-activated locks on each side.
Presenting the correct "key" molecules, which can even include structures sticking out from the surfaces of cells, causes the nanorobot, as the researchers are dubbing these entities, to spring open and discharge their contents.
In a proof-of-concept experiment, the Harvard team loaded their robots with a signalling molecule that stops certain types of cells from growing and endowed the particles with "locks" that would be opened only by chemicals expressed by a specific class of cancer cell.
In tests carried out in vitro, the DNA particles unloaded their growth-paralysing cargoes selectively onto the cultured cancer cells.
In further experiments the particles were even able to pick up other chemical signals and present them to T cells to trigger an immune response. This prototype "could inspire ne designs with different selectivities and biologically active payloads for cell targeting tasks," say the scientists.
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