such as "Introduction", "Conclusion"..etc
An array of magnetic traps designed for manipulating individual
biomolecules and measuring the ultrasmall forces that affect their
behavior has been demonstrated by scientists at the National Institute
of Standards and Technology (NIST).
Described in a recent issue of Applied Physics Letters, the chip-scale,
microfluidic device works in conjunction with a magnetic force
microscope. It's intended to serve as magnetic "tweezers" that can
stretch, twist and uncoil individual biomolecules such as strands of
DNA. The device should help scientists study folding patterns and other
biochemical details important in medical, forensic and other research
The new NIST device works like drawing toys that use a magnetized
stylus to pick up and drag magnetic particles. Magnetic particles 2 to
3 micrometers across are suspended in a fluid and injected into the
device. The surface of a thin membrane enclosing the fluid is dotted
with an array of thin film pads made of a nickel-iron alloy. When a
magnetic field is applied, each particle is attracted to the closest
So far, the research team has demonstrated that the traps attract
individual particles and that the microscope tip can gently drag
particles with piconewton forces. (One piconewton is about a trillionth
the force required to hold an apple against Earth's gravity.) The next
step is to attach particles to both ends of biomolecules such as DNA.
The trapping stations then can be used to hold one end of a molecule
while the microscope tip gently pulls on the other end. By applying
magnetic fields in different directions, the researchers hope to
ultimately rotate the magnetic particles to produce complex single
molecule motions for genomic studies.
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