My favorite character on Star Trek Voyager is “the Doctor” (pictured on the left and portrayed by the very talented Robert Picardo), who despite being “merely” a computer program was able to diagnose and treat nearly any medical ailment. The best part about him was that, because he was “merely” a hologram, he was portable and able to travel through the harshest environments and across any terrain.

While I’m pretty sure we still have years to go before we start being treated by medical holograms with Robert Picardo’s sense of style and humor, the portability of diagnosis is something which we may have just taken one large step closer towards. Christine Keating’s group at Pennsylvania State University has just developed what I’ve dubbed a “Doctor-on-a-Chip” (or DoC, after all system-on-a-chip’s are called SoCs by the semiconductor industry) which have the capability to detect any number of viral pathogens on a single computer chip.

Keating and her colleagues developed a means of coating a chip with nanowires (small wires 8 micrometers long and 300 nanometers in diameter) coated with DNA strands complementary to viral genomes (so that they will bind to viral DNA/RNA if given a chance). But, instead of haphazardly coating the chip, Keating’s group was able to develop a precise, targeted method, employing electrical fields to position the nanowires to exactly where the researchers wanted them (here’s a video showing how the method works).

The picture to the left is almost kind of eerie to me in its precision, much like one would expect on a chip fabbed by Intel or IBM (or Affymetrix) which uses photolithography rather than through electrophoresis.

Impressive to say the least, but the big question remained – does it work? To test this, Keating’s group incubated the chip with suspensions of fluorescently tagged viral DNA fragments complementary to the DNA strands on the nanowires, removed the suspension, and then subjected the chip to fluorescence. What would the result be? Would one see fluorescence organized neatly in the same rows that the nanowires were deposited? Or would there be diffuse or no fluorescence, suggesting nothing at all?

See for yourself:

So, do we have a DoC in the making? Jury’s still out – as we have yet to see if this method can be scaled up, or if its even applicable in a medical setting where time is short, accuracy needs to be very high, and the ability to run controlled samples (e.g. long DNA binding period with perfect fluorescently-labeled viral DNA fragments) is hindered. But, the Keating group is already hard at work creating electrical leads which will enable a faster (and potentially more quantitative) read process for detection.

And who knows, in a few years, this may end up looking like Robert Picardo.

(Image source – Doctor) (remainder of images come from Penn State University public image archive)

Morrow, T. Li, M. Kim, J. Mayer, T. Keating, C; Programmed Assembly of DNA-Coated Nanowire Devices; Science 16 January 2009: Vol. 323. no. 5912, p. 352 DOI: 10.1126/science.1165921