Nanotechnology Now

Our NanoNews Digest Sponsors





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

Iranian Scientists Use Artemisia Annua Plant to Produce Breast Cancer Drugs August 29th, 2015

Small but heading for the big time: Nanobiotix half year results for the six months ended 30 June 2015, in line with expectations: Major clinical achievements and corporate developments August 28th, 2015

A new technique to make drugs more soluble August 28th, 2015

Nanocatalysts improve processes for the petrochemical industry August 28th, 2015

National Space Society Welcomes Janet Ivey As New NSS Governor: Janet Ivey of Janet's Planet is NOW IN ORBIT as a member of the Board of Governors of the National Space Society August 27th, 2015

Imaging

Nanolab Technologies LEAPS Forward with High-Performance Analysis Services to the World: Nanolab Orders Advanced Local Electrode Atom Probe (LEAP®) Microscope from CAMECA Unit of AMETEK Materials Analysis Division August 27th, 2015

50 Years of Scanning Electron Microscopy from ZEISS: ZEISS celebrates the birth of the first commercial scanning electron microscope in 1965 August 26th, 2015

Announcing Oxford Instruments and School of Physics signing a Memorandum of Understanding August 26th, 2015

Laboratories

Major innovation in molecular imaging delivers spatial and spectral info simultaneously: Berkeley Lab scientist invents technique to combine spectroscopy with super-resolution microscopy, enabling new ways to examine cell structures and study diseases August 17th, 2015

Drexel engineers 'sandwich' atomic layers to make new materials for energy storage August 15th, 2015

Surprising discoveries about 2-D molybdenum disulfide: Berkeley Lab researchers use award-winning campanile probe on promising semiconductor August 15th, 2015

New ORNL hybrid microscope offers unparalleled capabilities August 10th, 2015

Govt.-Legislation/Regulation/Funding/Policy

These microscopic fish are 3-D-printed to do more than swim: Researchers demonstrate a novel method to build microscopic robots with complex shapes and functionalities August 26th, 2015

Glitter from silver lights up Alzheimer's dark secrets August 25th, 2015

Southampton scientists find new way to detect ortho-para conversion in water August 25th, 2015

Industrial Nanotech, Inc. Provides Update On Hospital Project, PCAOB Audit, and New Heat Shield™ Line August 24th, 2015

Announcements

Iranian Scientists Use Artemisia Annua Plant to Produce Breast Cancer Drugs August 29th, 2015

Small but heading for the big time: Nanobiotix half year results for the six months ended 30 June 2015, in line with expectations: Major clinical achievements and corporate developments August 28th, 2015

A new technique to make drugs more soluble August 28th, 2015

Nanocatalysts improve processes for the petrochemical industry August 28th, 2015

Tools

Nanolab Technologies LEAPS Forward with High-Performance Analysis Services to the World: Nanolab Orders Advanced Local Electrode Atom Probe (LEAP®) Microscope from CAMECA Unit of AMETEK Materials Analysis Division August 27th, 2015

Nanometrics to Participate in the Citi 2015 Global Technology Conference August 26th, 2015

50 Years of Scanning Electron Microscopy from ZEISS: ZEISS celebrates the birth of the first commercial scanning electron microscope in 1965 August 26th, 2015

Announcing Oxford Instruments and School of Physics signing a Memorandum of Understanding August 26th, 2015

Patents/IP/Tech Transfer/Licensing

Developing Component Scale Composites Using Nanocarbons August 26th, 2015

Industrial Nanotech, Inc. Provides Update On Hospital Project, PCAOB Audit, and New Heat Shield™ Line August 24th, 2015

Revolutionary MIT-Developed Nanotechnology Company Showcases at CAMX in Dallas August 20th, 2015

'Quantum dot' technology may help light the future August 19th, 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







Car Brands
Buy website traffic