Intermolecular Forces between Extracellular Polysaccharides Measured Using the Atomic Force Microscope

Langmuir ◽  
1997 ◽  
Vol 13 (23) ◽  
pp. 6234-6240 ◽  
Author(s):  
Brian P. Frank ◽  
Georges Belfort
Keyword(s):  
Atomic Force Microscope ◽  
Intermolecular Forces ◽  
Extracellular Polysaccharides ◽  
Atomic Force

Measuring intermolecular binding forces with the Atomic-Force Microscope: The magnetic jump method

1994 ◽  
Vol 52 ◽  
pp. 1054-1055
Author(s):  
J. H. Hoh ◽  
P. E. Hillner ◽  
P. K. Hansma
Keyword(s):  
Bond Strength ◽  
Atomic Force Microscope ◽  
Interaction Force ◽  
Intermolecular Forces ◽  
Atomic Force ◽  
Novel Approach ◽  
Binding Forces ◽  
Afm Cantilever ◽  
Paramagnetic Beads ◽  
Direct Readout

The atomic-force microscope (AFM) can measure forces between atoms and molecules with a sensitivity of <10−12 N. By coating the AFM tip with specific molecules the types of interactions that can be examined will be greatly extended. Recently tips with biotin attached have been used to probe surfaces coated with avidin or streptavidin, to measure the respective bond strength.We have developed a novel approach to measuring intermolecular forces with the AFM that employs paramagnetic beads coated with one of the molecules to be studied. Beads are incubated with a surface coated with the second molecule, and allowed to form a specific bond. A small magnet glued to an AFM cantilever is then advanced toward the bead until the bond with between the two molecules breaks and the bead “jumps” to the magnet. The deflection of the cantilever provides a direct readout of the interaction force at the “jump,” and thereby a measure of the bond strength.

Exploring local properties of biological surfaces with the Atomic Force Microscope

1995 ◽  
Vol 53 ◽  
pp. 664-665
Author(s):  
Jan H. Hoh
Keyword(s):  
Atomic Force Microscope ◽  
Feedback Loop ◽  
Intermolecular Forces ◽  
Atomic Force ◽  
Biological Surfaces ◽  
Afm Imaging ◽  
Local Measurements ◽  
Local Properties ◽  
Rms Amplitude ◽  
General Tool

The atomic force microscope (AFM) is developing into a very general tool for exploring biological surfaces. At present there are four broad areas of applications for the AFM: imaging surfaces, manipulating surfaces, measuring intermolecular forces and determining micromechanical properties. Because the dimensions of the apex of the tip used are typically on the order of 10's of nanometers, local measurements of properties are possible on a much smaller length scale than previously. Several reviews that provide further details on AFM instrumentation and biological applications have been published. These reviews also provide specific references for the range of applications that will be reviewed in this tutorial.AFM imaging modes can be divided into two groups based on the detection method, the DC method detects the absolute deflections of a cantilever while the AC method detects the RMS amplitude of an oscillating cantilever. Conventional contact AFM, sometimes called repulsive mode, is based on DC detection of the cantilever movement as the tip moves across a surface, usually in direct contact with the surface. The deflection of the cantilever is used to control the height of the sample, and the force applied to the sample, through a feedback loop.

Characterization of photosystem II with the atomic-force microscope

1992 ◽  
Vol 50 (2) ◽  
pp. 1146-1147
Author(s):  
Kathleen M. Marr ◽  
Mary K. Lyon
Keyword(s):  
Photosystem Ii ◽  
Atomic Force Microscope ◽  
Three Dimensional ◽  
Biologically Active ◽  
Atomic Force ◽  
Freeze Etching ◽  
Image Averaging ◽  
Oxygen Evolving ◽  
Averaging Techniques

Photosystem II (PSII) is different from all other reaction centers in that it splits water to evolve oxygen and hydrogen ions. This unique ability to evolve oxygen is partly due to three oxygen evolving polypeptides (OEPs) associated with the PSII complex. Freeze etching on grana derived insideout membranes revealed that the OEPs contribute to the observed tetrameric nature of the PSIl particle; when the OEPs are removed, a distinct dimer emerges. Thus, the surface of the PSII complex changes dramatically upon removal of these polypeptides. The atomic force microscope (AFM) is ideal for examining surface topography. The instrument provides a topographical view of individual PSII complexes, giving relatively high resolution three-dimensional information without image averaging techniques. In addition, the use of a fluid cell allows a biologically active sample to be maintained under fully hydrated and physiologically buffered conditions. The OEPs associated with PSII may be sequentially removed, thereby changing the surface of the complex by one polypeptide at a time.

Imaging polymers, proteins and dna in aqueous solutions with the atomic force microscope

1989 ◽  
Vol 47 ◽  
pp. 32-33
Author(s):  
S.A.C. Gould ◽  
B. Drake ◽  
C.B. Prater ◽  
A.L. Weisenhorn ◽  
S.M. Lindsay ◽  
...  
Keyword(s):  
Amino Acids ◽  
Dna Sequencing ◽  
Aqueous Solutions ◽  
Atomic Force Microscope ◽  
Piezoelectric Crystal ◽  
Atomic Force ◽  
Structure Of Molecules ◽  
Optical Lever

The atomic force microscope (AFM) is an instrument that can be used to image many samples of interest in biology and medicine. Images of polymerized amino acids, polyalanine and polyphenylalanine demonstrate the potential of the AFM for revealing the structure of molecules. Images of the protein fibrinogen which agree with TEM images demonstrate that the AFM can provide topographical data on larger molecules. Finally, images of DNA suggest the AFM may soon provide an easier and faster technique for DNA sequencing.The AFM consists of a microfabricated SiO2 triangular shaped cantilever with a diamond tip affixed at the elbow to act as a probe. The sample is mounted on a electronically driven piezoelectric crystal. It is then placed in contact with the tip and scanned. The topography of the surface causes minute deflections in the 100 μm long cantilever which are detected using an optical lever.

The atomic-force microscope and its future in biology

1993 ◽  
Vol 51 ◽  
pp. 704-705
Author(s):  
Jean-Paul Revel
Keyword(s):  
Silicon Nitride ◽  
Laser Beam ◽  
Atomic Force Microscope ◽  
Scanning Tunneling Microscope ◽  
Point Of View ◽  
Scanning Tunneling ◽  
Close Relative ◽  
Tunneling Microscope ◽  
Atomic Force ◽  
Sharp Point

The last few years have been marked by a series of remarkable developments in microscopy. Perhaps the most amazing of these is the growth of microscopies which use devices where the place of the lens has been taken by probes, which record information about the sample and display it in a spatial from the point of view of the context. From the point of view of the biologist one of the most promising of these microscopies without lenses is the scanned force microscope, aka atomic force microscope.This instrument was invented by Binnig, Quate and Gerber and is a close relative of the scanning tunneling microscope. Today's AFMs consist of a cantilever which bears a sharp point at its end. Often this is a silicon nitride pyramid, but there are many variations, the object of which is to make the tip sharper. A laser beam is directed at the back of the cantilever and is reflected into a split, or quadrant photodiode.

The application of atomic force microscope in microbiological research

2014 ◽  
Vol 5 (1) ◽  
pp. 27-30
Author(s):  
Małgorzata Tokarska-Rodak ◽  
Maria Kozioł-Montewka ◽  
Jolanta Paluch-Oleś ◽  
Dorota Plewik ◽  
Grażyna Olchowik ◽  
...  
Keyword(s):  
Atomic Force Microscope ◽  
Atomic Force ◽  
Microbiological Research

Failure Analysis of Laser Blown Metal Fuse Failures in Submicron Technology by C-AFM

2006 ◽  
Author(s):  
Liang-Feng Wen ◽  
Chien-Hui Chen ◽  
Allen Timothy Chang
Keyword(s):  
Failure Analysis ◽  
Atomic Force Microscope ◽  
Laser Cutting ◽  
Spot Size ◽  
Repair Rate ◽  
Atomic Force ◽  
Measurement Laser

Abstract This paper presents a method of using a conductive atomic force microscope (C-AFM) to characterize a submicron metal fuse that has been blown open inadequately by laser. In order to obtain a proper I-V curve measured using the C-AFM without affecting the incompletely opened fuse, the paper proposes a method of preserving the fuse by coating its surface with spin-on glass. The paper explains how differences in laser cutting machines resulted in the high failure repair rate of customer product despite equivalent energy and spot size settings. Analysis of the fuse bank circuitry on wafers helped to find the critical physical differences between a fully blown and a poorly blown fuse. By overcoming difficulties in preserving the blown fuse failure sites for C-AFM measurement, laser settings could be easily optimized to ensure proper fuse opening.

A Study of the Photoelectric Effect Caused by a Laser Beam Used in a Beam Bounce Technique in a C-AFM System

2008 ◽  
Author(s):  
Hung-Sung Lin ◽  
Mong-Sheng Wu
Keyword(s):  
Laser Beam ◽  
Failure Analysis ◽  
Atomic Force Microscope ◽  
Photoelectric Effect ◽  
Scanning Probe ◽  
Nanometer Scale ◽  
Electrical Characteristics ◽  
Atomic Force ◽  
Probe Microscope ◽  
Probe Head

Abstract The use of a scanning probe microscope (SPM), such as a conductive atomic force microscope (C-AFM) has been widely reported as a method of failure analysis in nanometer scale science and technology [1-6]. A beam bounce technique is usually used to enable the probe head to measure extremely small movements of the cantilever as it is moved across the surface of the sample. However, the laser beam used for a beam bounce also gives rise to the photoelectric effect while we are measuring the electrical characteristics of a device, such as a pn junction. In this paper, the photocurrent for a device caused by photon illumination was quantitatively evaluated. In addition, this paper also presents an example of an application of the C-AFM as a tool for the failure analysis of trap defects by taking advantage of the photoelectric effect.

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