Nanotechnology Now





Heifer International

Wikipedia Affiliate Button


DHgate

Home > Press > Not-so-precious: Stripping gold from AFM probes allows better measurement of picoscale forces

This is an artist's conception of JILA's advance in atomic force microscope (AFM) design. To measure picoscale forces in liquid, a AFM probe attaches to a molecule such as DNA and pulls, and the deflection of the probe is measured. JILA researchers found that probes with the gold coating removed (purple in the illustration) make measurements that are 10 times more stable and precise than those made with conventional gold-coated probes. Gold helps reflect the laser light but it can also potentially crack, age, and creep, which degrades its mechanical properties and reduces measurement precision.

Credit: Baxley/JILA
This is an artist's conception of JILA's advance in atomic force microscope (AFM) design. To measure picoscale forces in liquid, a AFM probe attaches to a molecule such as DNA and pulls, and the deflection of the probe is measured. JILA researchers found that probes with the gold coating removed (purple in the illustration) make measurements that are 10 times more stable and precise than those made with conventional gold-coated probes. Gold helps reflect the laser light but it can also potentially crack, age, and creep, which degrades its mechanical properties and reduces measurement precision.

Credit: Baxley/JILA

Abstract:
Gold is not necessarily precious—at least not as a coating on atomic force microscope (AFM) probes.

JILA researchers found that removing an AFM probe's gold coating—until now considered helpful—greatly improved force measurements performed in a liquid, the medium favored for biophysical studies such as stretching DNA or unfolding proteins. As described in Nano Letters,* stripping the gold from the diving-board-shaped probe, or cantilever, with a brief chemical bath improved the precision and stability of force measurements about 10-fold. The advance is expected to quickly and broadly benefit the fields of biophysics and nanoscience.

Not-so-precious: Stripping gold from AFM probes allows better measurement of picoscale forces

Boulder, CO | Posted on June 28th, 2012

JILA is a joint institute of the National Institute of Standards and Technology (NIST) and the University of Colorado Boulder.

"What I find interesting about this experiment is it's so incredibly simple. It takes a minute to strip the gold off a commercial cantilever and you get a 10-fold improvement in force precision," says NIST/JILA physicist Thomas Perkins.

To measure forces at the molecular scale, an AFM's cantilever attaches to a molecule with its pointed end and pulls; the resulting deflection of the cantilever is measured. The forces are in the realm of piconewtons (pN), or trillionths of a newton. A unit of force, one newton is roughly the weight of a small apple.

Cantilevers are typically made of silicon or silicon nitride and coated with gold on both sides to reflect light. Perkins discovered the gold coating was a problem while his research group was probing the folding and unfolding of protein molecules over time periods of seconds to minutes. The group previously improved AFM position stability** and holds a related patent,*** but then discovered that the force was drifting. "It's counterintuitive," says Perkins. "Everyone has assumed you needed gold for the enhanced reflectivity, when in fact, gold is clearly the dominant source of force drift on short and long time scales."

"Gold exhibits a sort of complex elastic property in high-precision measurements," Perkins explains. "When you bend gold, it creeps a little bit, like silly putty. Further, the lore in the field is that gold can crack, it can age, and molecules can bind to it—all of which may change its mechanical properties. This problem is even worse when you do biological experiments in liquid."

AFM force measurements in liquid typically have had precision (error range) of plus or minus 5 to 10 pN. By stripping the gold JILA researchers reduced the error by 10 times, to about 0.5 pN for measurements on both short and long timescales. Researchers can now precisely measure fast processes, such as proteins folding and unfolding 50 times per second, over long time periods of several minutes. Significantly, the results were achieved with commercially available microscopes and cantilevers, so the practical benefits can be applied quickly for any AFM force measurements and imaging. AFM can now compete with optical traps and magnetic tweezers in terms of sensitivity.

The research was supported by the National Science Foundation and NIST.

* A.B. Churnside, R.M.A. Sullan, D.M. Nguyen, S.O. Case, M.S. Bull, G.M. King and T.T. Perkins. Routine and timely sub-piconewton force stability and precision for biological applications of atomic force microscopy. Nano Letters. Published online June 13.

** See the Mar. 24, 2009, NIST Tech Beat article, "Making a Point: Picoscale Stability in a Room-Temperature AFM" at www.nist.gov/public_affairs/tech-beat/tb20090324.cfm#afm.

*** U.S. Patent 7,928,409, April 19, 2011, Real-time, active picometer-scale alignment, stabilization and registration in one or more dimensions, T.T. Perkins, G.M. King and A.R. Carter.

####

For more information, please click here

Contacts:
Laura Ost

303-497-4880

Copyright © National Institute of Standards and Technology (NIST)

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

Nanostructures Increase Corrosion Resistance in Metallic Body Implants May 24th, 2015

Iranian Scientists Use Magnetic Field to Transfer Anticancer Drug to Tumor Tissue May 24th, 2015

Basel physicists develop efficient method of signal transmission from nanocomponents May 23rd, 2015

This Slinky lookalike 'hyperlens' helps us see tiny objects: The photonics advancement could improve early cancer detection, nanoelectronics manufacturing and scientists' ability to observe single molecules May 23rd, 2015

Visualizing How Radiation Bombardment Boosts Superconductivity: Atomic-level flyovers show how impact sites of high-energy ions pin potentially disruptive vortices to keep high-current superconductivity flowing May 23rd, 2015

Imaging

This Slinky lookalike 'hyperlens' helps us see tiny objects: The photonics advancement could improve early cancer detection, nanoelectronics manufacturing and scientists' ability to observe single molecules May 23rd, 2015

Aspen Aerogels to Present at the Cowen and Company Technology, Media & Telecom Conference May 21st, 2015

Samtec, Global Provider of Interconnect Systems, Joins IRT Nanoelec Silicon Photonics Program May 21st, 2015

Laboratories

Visualizing How Radiation Bombardment Boosts Superconductivity: Atomic-level flyovers show how impact sites of high-energy ions pin potentially disruptive vortices to keep high-current superconductivity flowing May 23rd, 2015

Sandia researchers first to measure thermoelectric behavior by 'Tinkertoy' materials May 20th, 2015

Govt.-Legislation/Regulation/Funding/Policy

This Slinky lookalike 'hyperlens' helps us see tiny objects: The photonics advancement could improve early cancer detection, nanoelectronics manufacturing and scientists' ability to observe single molecules May 23rd, 2015

Visualizing How Radiation Bombardment Boosts Superconductivity: Atomic-level flyovers show how impact sites of high-energy ions pin potentially disruptive vortices to keep high-current superconductivity flowing May 23rd, 2015

Nanotherapy effective in mice with multiple myeloma May 21st, 2015

Turn that defect upside down: Twin boundaries in lithium-ion batteries May 21st, 2015

Announcements

Nanostructures Increase Corrosion Resistance in Metallic Body Implants May 24th, 2015

Iranian Scientists Use Magnetic Field to Transfer Anticancer Drug to Tumor Tissue May 24th, 2015

Basel physicists develop efficient method of signal transmission from nanocomponents May 23rd, 2015

This Slinky lookalike 'hyperlens' helps us see tiny objects: The photonics advancement could improve early cancer detection, nanoelectronics manufacturing and scientists' ability to observe single molecules May 23rd, 2015

Tools

This Slinky lookalike 'hyperlens' helps us see tiny objects: The photonics advancement could improve early cancer detection, nanoelectronics manufacturing and scientists' ability to observe single molecules May 23rd, 2015

Nanometrics Announces Live Webcast of Upcoming Investor and Analyst Day May 20th, 2015

Taking control of light emission: Researchers find a way of tuning light waves by pairing 2 exotic 2-D materials May 20th, 2015

DELMIC announces a workshop hosted by Phenom World on Integrated CLEM to be held on Wednesday June 24th at the Francis Crick Institute (Lincoln Inn Fields Laboratory). May 19th, 2015

Patents/IP/Tech Transfer/Licensing

Researchers develop new way to manufacture nanofibers May 21st, 2015

Novel superconducting undulator provides first x-ray light at ANKA May 1st, 2015

Long Island Capital Alliance Announces Participants for Brookhaven National Laboratory Technology Transfer Capital Forum on May 8: Keynote Speaker Dr. Doon Gibbs, Director of Brookhaven National Laboratory April 16th, 2015

MIT sensor detects spoiled meat: Tiny device could be incorporated into 'smart packaging' to improve food safety April 15th, 2015

NanoNews-Digest
The latest news from around the world, FREE




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More










ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project