Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > Discovery to aid study of biological structures, molecules

Researchers in the United States and Spain have discovered that an atomic force microscope - a tool widely used in nanoscale imaging - works differently in watery environments, a step toward better using the instrument to study biological molecules and structures. The researchers demonstrated their new understanding of how the instrument works in water to show details of the mechanical properties of a virus called Phi29. The images in "a" and "c" show the topography, and the image in "b" shows the different stiffness properties of the balloonlike head, stiff collar and hollow tail of the Phi29 virus, called a bacteriophage because it infects bacteria. (C. Carrasco-Pulido, P. J. de Pablo, J. Gomez-Herrero, Universidad Autonoma de Madrid, Spain)
Researchers in the United States and Spain have discovered that an atomic force microscope - a tool widely used in nanoscale imaging - works differently in watery environments, a step toward better using the instrument to study biological molecules and structures. The researchers demonstrated their new understanding of how the instrument works in water to show details of the mechanical properties of a virus called Phi29. The images in "a" and "c" show the topography, and the image in "b" shows the different stiffness properties of the balloonlike head, stiff collar and hollow tail of the Phi29 virus, called a bacteriophage because it infects bacteria. (C. Carrasco-Pulido, P. J. de Pablo, J. Gomez-Herrero, Universidad Autonoma de Madrid, Spain)

Abstract:
Origins of Phase Contrast in the Atomic Force Microscope in Liquids

John Melchera, Carolina Carrascob,c, Xin Xua, José L. Carrascosad, Julio Gómez-Herrerob,
Pedro José de Pablob, and Arvind Ramana

(a) School of Mechanical Engineering and Birck Nanotechnology Center, Purdue University, West Lafayette, IN 47907; (b) Departamento de Física de la Materia Condensada C-III, Universidad Autónoma de Madrid, 28049 Madrid, Spain; (c) Instituto de Ciencia de Materiales de Madrid, Centro National de Biotecnología, Consejo Superior de Investigaciones Científicas, 28049 Madrid, Spain; (d) Departmento de Estructura de Macomoléculas, Centro National de Biotecnología, Consejo Superior de Investigaciones Científicas, 28049 Madrid, Spain

We study the physical origins of phase contrast in dynamic atomic force microscopy (dAFM) in liquids where low-stiffness microcantilever probes are often used for nanoscale imaging of soft biological samples with gentle forces. Under these conditions, we show that the phase contrast derives primarily from a unique energy flow channel that opens up in liquids due to the momentary excitation of higher eigenmodes. Contrary to the common assumption, phase-contrast images in liquids using soft microcantilevers are often maps of short-range conservative interactions, such as local elastic response, rather than tip-sample dissipation. The theory is used to demonstrate variations in local elasticity of purple membrane and bacteriophage _29 virions in buffer solutions using the phase-contrast images.

Discovery to aid study of biological structures, molecules

WEST LAFAYETTE, IN | Posted on August 11th, 2009

Researchers in the United States and Spain have discovered that a tool widely used in nanoscale imaging works differently in watery environments, a step toward better using the instrument to study biological molecules and structures.

The researchers demonstrated their new understanding of how the instrument - the atomic force microscope - works in water to show detailed properties of a bacterial membrane and a virus called Phi29, said Arvind Raman, a Purdue professor of mechanical engineering.

"People using this kind of instrument to study biological structures need to know how it works in the natural watery environments of molecules and how to interpret images," he said.

An atomic force microscope uses a tiny vibrating probe to yield information about materials and surfaces on the scale of nanometers, or billionths of a meter. Because the instrument enables scientists to "see" objects far smaller than possible using light microscopes, it could be ideal for studying molecules, cell membranes and other biological structures.

The best way to study such structures is in their wet, natural environments. However, the researchers have now discovered that in some respects the vibrating probe's tip behaves the opposite in water as it does in air, said Purdue mechanical engineering doctoral student John Melcher.

Purdue researchers collaborated with scientists at three institutions in Madrid, Spain: Universidad Autónoma de Madrid, Instituto de Ciencia de Materiales de Madrid and the Centro Nacional de Biotecnología.

Findings, which were detailed in a paper appearing online last week in the U.S. publication Proceedings of the National Academy of Sciences, are related to the subtle differences in how the instrument's probe vibrates. The probe is caused to oscillate by a vibrating source at its base. However, the tip of the probe oscillates slightly out of synch with the oscillations at the base. This difference in oscillation is referred to as a "phase contrast," and the tip is said to be out of phase with the base.

Although these differences in phase contrast reveal information about the composition of the material being studied, data can't be properly interpreted unless researchers understand precisely how the phase changes in water as well as in air, Raman said.

If the instrument is operating in air, the tip's phase lags slightly when interacting with a viscous material and advances slightly when scanning over a hard surface. Now researchers have learned the tip operates in the opposite manner when used in water: it lags while passing over a hard object and advances when scanning the gelatinous surface of a biological membrane.

Researchers deposited the membrane and viruses on a sheet of mica. Tests showed the differing properties of the inner and outer sides of the membrane and details about the latticelike protein structure of the membrane. Findings also showed the different properties of the balloonlike head, stiff collar and hollow tail of the Phi29 virus, called a bacteriophage because it infects bacteria.

"The findings suggest that phase contrast in liquids can be used to reveal rapidly the intrinsic variations in local stiffness with molecular resolution, for example, by showing that the head and the collar of an individual virus particle have different stiffness," Raman said.

The research was funded by the National Science Foundation and was conducted at the Birck Nanotechnology Center in Purdue's Discovery Park. The biological membrane images were taken at Purdue, and the virus studies were performed at the Universidad Autónoma de Madrid.

The paper was authored by Melcher; Carolina Carrasco, a postdoctoral researcher at Universidad Autónoma de Madrid and the Instituto de Ciencia de Materiales de Madrid; Purdue postdoctoral researcher Xin Xu; José L. Carrasco, a researcher at Departmento de Estructura de Macomoléculas, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas; Julio Gómez-Herrero and Pedro José de Pablo, both researchers from Universidad Autónoma de Madrid; and Raman.

####

For more information, please click here

Contacts:
Writer: Emil Venere
(765) 494-4709


Sources: Arvind Raman
(765) 494-5733


John Melcher


Purdue News Service
(765) 494-2096

Copyright © Purdue University

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

Researchers printed graphene-like materials with inkjet August 17th, 2017

Candy cane supercapacitor could enable fast charging of mobile phones August 17th, 2017

Freeze-dried foam soaks up carbon dioxide: Rice University scientists lead effort to make novel 3-D material August 16th, 2017

Gold shines through properties of nano biosensors: Researchers discover that fluorescence in ligand-protected gold nanoclusters is an intrinsic property of the gold particles themselves August 16th, 2017

Imaging

Industry’s First Dedicated Cryo-DualBeam System Automates Preparation of Frozen, Biological Samples: New Thermo Scientific Aquilos FIB/SEM protects sample integrity and enhances productivity for cryo-electron tomography workflow August 8th, 2017

Thermo Fisher Scientific Advances Cryo-EM Leadership to Drive Structural Biology Discoveries: New Thermo Scientific Krios G3i raises bar for performance, automation and time-to-results Breakthrough Thermo Scientific Glacios provides a cryo-EM entry path for a broader range of res August 8th, 2017

New Quattro Field Emission ESEM Emphasizes Versatility and Ease of Use: Thermo Scientific Quattro ESEM allows materials science researchers to study nanoscale structure in almost any material under a range of environmental conditions August 8th, 2017

Thermo Fisher Scientific’s New Talos F200i S/TEM Delivers Flexible, High-Performance Imaging: New compact S/TEM can be configured to meet specific imaging and analytical requirements for materials characterization in research laboratories August 8th, 2017

Nanomedicine

Freeze-dried foam soaks up carbon dioxide: Rice University scientists lead effort to make novel 3-D material August 16th, 2017

Gold shines through properties of nano biosensors: Researchers discover that fluorescence in ligand-protected gold nanoclusters is an intrinsic property of the gold particles themselves August 16th, 2017

Two Scientists Receive Grants to Develop New Materials: Chad Mirkin and Monica Olvera de la Cruz recognized by Sherman Fairchild Foundation August 16th, 2017

JPK reports on how the University of Glasgow is using their NanoWizard® AFM and CellHesion module to study how cells interact with their surroundings August 2nd, 2017

Discoveries

Researchers printed graphene-like materials with inkjet August 17th, 2017

Candy cane supercapacitor could enable fast charging of mobile phones August 17th, 2017

Freeze-dried foam soaks up carbon dioxide: Rice University scientists lead effort to make novel 3-D material August 16th, 2017

Gold shines through properties of nano biosensors: Researchers discover that fluorescence in ligand-protected gold nanoclusters is an intrinsic property of the gold particles themselves August 16th, 2017

Announcements

Researchers printed graphene-like materials with inkjet August 17th, 2017

Candy cane supercapacitor could enable fast charging of mobile phones August 17th, 2017

Freeze-dried foam soaks up carbon dioxide: Rice University scientists lead effort to make novel 3-D material August 16th, 2017

Gold shines through properties of nano biosensors: Researchers discover that fluorescence in ligand-protected gold nanoclusters is an intrinsic property of the gold particles themselves August 16th, 2017

Tools

Scientists from the University of Manchester and Diamond Light Source work with Deben to develop and test a new compression stage to study irradiated graphite at elevated temperatures August 15th, 2017

FRITSCH • Milling and Sizing! Innovations at POWTECH 2017 - Hall 2 • Stand 227 August 9th, 2017

New Quattro Field Emission ESEM Emphasizes Versatility and Ease of Use: Thermo Scientific Quattro ESEM allows materials science researchers to study nanoscale structure in almost any material under a range of environmental conditions August 8th, 2017

Thermo Fisher Scientific’s New Talos F200i S/TEM Delivers Flexible, High-Performance Imaging: New compact S/TEM can be configured to meet specific imaging and analytical requirements for materials characterization in research laboratories August 8th, 2017

Research partnerships

Researchers printed graphene-like materials with inkjet August 17th, 2017

Freeze-dried foam soaks up carbon dioxide: Rice University scientists lead effort to make novel 3-D material August 16th, 2017

2-faced 2-D material is a first at Rice: Rice University materials scientists create flat sandwich of sulfur, molybdenum and selenium August 14th, 2017

Moving at the Speed of Light: University of Arizona selected for high-impact, industrial demonstration of new integrated photonic cryogenic datalink for focal plane arrays: Program is major milestone for AIM Photonics August 10th, 2017

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