Bio-forklifts to help shrink lab-on-chip to dust particle size

January 19th, 2009 - 4:54 pm ICT by IANS  

Washington, Jan 19 (IANS) Scientists are trying to shrink chip-based labs to a dust sized particle, used in detection of bio-weapons, pollution, or to conduct on-the-spot blood tests.Although the existing versions may be small, they still require hand-held equipment or ones as large as a lab bench.

The extra equipment is needed because the assay, which uses pairs of antibodies to latch onto target contaminants and the markers that give away their presence, requires repeated flushing with water.

That requires pumps, which need power. To miniaturise the system, it’s necessary to build miniature pumps and batteries. But that’s a challenge, especially for miniaturisation to the level required for individual pieces of smart dust, said Henry Hess.

Hess is University of Florida (U-F) assistant professor of materials science and engineering and co-author of the paper. His team has tapped the working parts of cells to clear a major hurdle to creating such “smart dust”.

“Instead of just changing one part of an existing system, we have a new and different way of doing things,” said Henry Hess. “And we can do it this way because of building blocks from bionanotechnology, and that’s what makes it very exciting.”

“It’s like a computer,” Hess said. “The central processing unit is the really interesting thing, but you need all this other stuff to make it work.”

His research strips out all peripheral equipment by using an altogether unique and different approach: biologically powered molecular forklifts.

The forklifts are assembled from natural motor proteins that are active in cell division. Hess and his team’s main innovation is manipulating these tiny proteins to perform heavy lifting and transport tasks - tasks that lead to a successful assay. For a system rooted in biology, the process is uncannily mechanical.

Using standard lab methods, the researchers squirt the forklifts into the central zone of three-zone circular surface no larger than the period at the end of this sentence. They then attach the same antibodies used in traditional chip-based labs.

When the surface is exposed to a contaminant, the antibodies latch onto it, just as happens with traditional assays. But then, activated by a flash of light, molecular shuttles start pushing the forklifts into a second zone, where they load aboard fluorescent particles, or tags.

They move their cargo to the third zone, at the edge of the circle. There, over several hours, they crowd against each other, accumulating to the point where their combined loads form a line visible under magnification - and providing the telltale indicator of the contaminant, said an U-F release.

The process requires no rinsing. And instead of electricity, the naturally derived forklifts are powered by adenosine triphosphate, or ATP, the molecule that carries energy for cells.

These findings were published in Nature Nanotechnology Sunday.

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