Nanoslinky created
27 Mar 2012 by Evoluted New Media
American researchers have created the nanoslinky, a novel microfluidic technology for DNA manipulation and measurement.
The nanoslinky – developed by researchers at the National Institute of Standards and Technology (NIST) – is 10 million times smaller than the popular spring-shaped toy. The technology could be used for manipulating and measuring DNA and other nanoscale technologies.
Researchers showed that a staircase-shaped nanoscale fluidic channel can be used to control the otherwise random drift of DNA through a fluid. When squeezed into the shallow top step of the staircase, the DNA diffuses randomly across the step and increases its entropy by walking down to the next step, stopping only when it gets trapped on the bottom step.
Molecules of different sizes and shapes descend the staircase at different rates, which suggests the structure could be used to separate, concentrate and organise mixtures of nanoscale objects. The researchers have termed this entropophoresis – entropy-driven transport.
“Control over the behaviour of a DNA molecule is built into the staircase structure,” said Samuel Stavis. “After placing the molecule on the top step (by driving the DNA strand up the staircase with an electric field), no external forces are needed to make it move. The staircase is a passive nanofluidic technology that automates complex manipulations and measurements of DNA.”
This work tallies with a NIST innovation in measurement science, namely determining the size of a DNA molecule in nanofluidic slitlike confinement imposed by the narrow gap between the floor of each step and the ceiling of the channel. The coiled and folded DNA strand contracts progressively as it moves down the step.
“Because there are many steps, we can make more detailed measurements than previous studies,” said Elizabeth Strychalski.
Previous measurements of DNA dimensions in nanofluidic systems have been limited by errors from optical microscopes used to make the dimensions of DNA molecules labelled with fluorescent dye. To improve measurements, the researchers used models to approximate the effects of diffraction and pixilation.
The researchers say the staircase is a simple prototype of a new class of engineered nanofluidic structures with complex three-dimensional surfaces. With further refinements, it could be mass produced for measuring and manipulating DNA, biopolymers and nanoscale materials for healthcare and nanomanufacturing.
DNA molecules descending a nanofluidic staircase by entropophoresis
