scholarly journals Exocytosis at the Atomic Level

1997 ◽  
Vol 5 (4) ◽  
pp. 3-4
Author(s):  
Stephen W. Carmichael
Keyword(s):  
Atomic Force Microscope ◽  
Atomic Level ◽  
Cellular Structures ◽  
Aqueous Environment ◽  
Yale University ◽  
Atomic Force ◽  
The University

As reviewed in this column on previous occasions, the atomic force microscope (AFM) is steadily making headway as an instrument that can make important contributions to biologic observations. Although the AFM is capable of operating in an aqueous environment, relatively little use has been made of this property to examine cellular structures under conditions that resemble those in vivo. A breakthrough in this regard was recently made by Stefan Schneider, Kumudesh Sritharan, John Geibel, Hans Oberleithner, and Bhanu Jena. of Yale University and the University of Würzburg.

scholarly journals A Tiny Toolbox

1997 ◽  
Vol 5 (7) ◽  
pp. 3-7
Author(s):  
Stephen W. Carmichael
Keyword(s):  
Atomic Force Microscope ◽  
Single Molecule ◽  
Recent Article ◽  
Single Molecules ◽  
Force Spectroscopy ◽  
Atomic Level ◽  
Single Molecule Force Spectroscopy ◽  
Binding Force ◽  
Atomic Force

A recent article by Matthias Rief, Filipp Oesterhelt. Berthold Heymann, and Hermann Gaub concluded with this sentence: "Single molecule force spectroscopy by AFM has proven to be a powerful addition to the nanoscopic piconewton toolbox," Everything about that conclusion is tiny. Clearly, the atomic force microscope (AFM) has given us a tool to examine structure at or near the atomic level. Earlier work from Gaub's laboratory, reviewed in this column, demonstrated that the AFM could directly measure the binding force between single molecules of biotin and avidin. This established that the AFM could be used as a tool to measure forces, not just observe structure. Their most recent experiments has added to this tiny toolbox.

scholarly journals More Than a Feeling

2006 ◽  
Vol 128 (04) ◽  
pp. 31-33 ◽  
Author(s):  
F. Michael Serry
Keyword(s):  
Atomic Force Microscope ◽  
Long Range ◽  
Mechanical Systems ◽  
Water Layer ◽  
Atomic Level ◽  
Nanometer Scale ◽  
Force Sensitivity ◽  
Atomic Force ◽  
Highly Sensitive ◽  
Basic Level

The atomic force microscope (AFM) is enabling engineers to understand mechanical systems at the most basic level. The heart of the AFM is a probe comprising a microfabricated cantilever with an extraordinarily sharp tip. The AFM tip can be thought of as a nanometer-scale finger that we have at our disposal to interface with matter on the scale of individual molecules, and even atoms. The paper highlights that it is the only instrument that allows us to ‘touch’ the surface of a sample with nanometer-scale resolution and atomic-level force sensitivity. Researchers using AFM have now established that after relatively weak bonds break, untying segments of a relatively large structural molecule, the energy needed to stretch the untied segment can be orders of magnitude larger than the broken bond's energy. The AFM has evolved into a highly modular instrument. Advanced AFMs such as the BioScope II from Veeco Instruments operate in liquid to image and probe biologically important matter, both organic and synthetic. Also, there are AFMs for operating in vacuum, useful in investigating properties of matter without a water layer adsorbed on it, or for probing tip-sample interactions with highly sensitive probes in long range or in contact.

Advanced Vibration Control of Atomic Force Microscope Scanner

2015 ◽  
pp. 84-106
Author(s):  
Sajal K. Das ◽  
Hemanshu R. Pota ◽  
Ian R. Petersen
Keyword(s):  
Vibration Control ◽  
Atomic Force Microscope ◽  
Atomic Level ◽  
Degree Of Freedom ◽  
Experimental Results ◽  
Surface Imaging ◽  
Atomic Force Microscopes ◽  
Atomic Force ◽  
Three Degree Of Freedom ◽  
Damping Controller

Atomic Force Microscopes (AFMs) are used in many nanopositioning applications in order to measure the topography of various specimens at an atomic level through surface imaging. The imaging of the samples in AFMs is carried out by using a three degree-of-freedom positioning unit called Piezoelectric Tube Scanner (PTS). The performance of the AFM mostly depends on the performance of the PTS. However, the PTS of the AFM suffers from the problem of vibration. This chapter presents a design of a damping controller to compensate the induced vibration of the scanner. Experimental results are presented to show the effectiveness of the proposed controller. The experimental results show that the proposed controller is able to compensate 90% of the vibration of the PTS.

Probing the mechanical stability of proteins using the atomic force microscope

2007 ◽  
Vol 35 (6) ◽  
pp. 1564-1568 ◽  
Author(s):  
D.J. Brockwell
Keyword(s):  
Mechanical Strength ◽  
Atomic Force Microscope ◽  
Mechanical Stability ◽  
Mechanical Deformation ◽  
Mechanical Resistance ◽  
Atomic Force ◽  
Wide Range ◽  
Protein Molecules ◽  
Single Protein

The mechanical strength of single protein molecules can be investigated by using the atomic force microscope. By applying this technique to a wide range of proteins, it appears that the type of secondary structure and its orientation relative to the extension points are important determinants of mechanical strength. Unlike chemical denaturants, force acts locally and the mechanical strength of a protein may thus appear to be mechanically weak or strong by simply varying the region of the landscape through which the protein is unfolded. Similarly, the effect of ligand binding on the mechanical resistance of a protein may also depend on the relative locations of the binding site and force application. Mechanical deformation may thus facilitate the degradation or remodelling of thermodynamically stable proteins and their complexes in vivo.

scholarly journals Microscopy Reveals Molecular Motion

1994 ◽  
Vol 2 (8) ◽  
pp. 6-7
Author(s):  
Stephen W. Carmichael
Keyword(s):  
Atomic Force Microscope ◽  
Conformational Change ◽  
Molecular Motion ◽  
Single Molecules ◽  
University Of California ◽  
Santa Barbara ◽  
Atomic Force ◽  
Suitable Substrate ◽  
The University ◽  
Biologic Function

Microscopes are known for demonstrating structure, but there have been many examples of how this is changing. A novel use of the atomic force microscope (AFM) by Manfred Radmacher, Monika Fritz, Helen Hansma, and Paul Hansma at the University of California, Santa Barbara, has extended the versatility of this instrument even further. They demonstrated a conformational change in a molecule that happened in a fraction of a second.Radmacher et al. pointed out that enzymes perform their biologic function by undergoing a conformational change and that this change is within the spatial and temporal resolving capabilities of the AFM. They set out to prove this by lowering the tip of the AFM onto lysozyme, a molecule that is roughly egg-shaped, measuring about 4.5 nm by 3 nm by 3 nm. Using the tapping mode in liquid, they found that single molecules exhibited a spike-like height fluctation when in the presence of a suitable substrate.

scholarly journals Photothermal excitation efficiency enhancement of cantilevers by electron beam deposition of amorphous carbon thin films

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Marcos Penedo ◽  
Ayhan Yurtsever ◽  
Keisuke Miyazawa ◽  
Hirotoshi Furusho ◽  
Kiyo-Aki Ishii ◽  
...  
Keyword(s):  
Atomic Force Microscope ◽  
Amorphous Carbon ◽  
Biological Samples ◽  
Oscillation Amplitude ◽  
Carbon Layer ◽  
Stable Operation ◽  
Excitation Efficiency ◽  
Atomic Force ◽  
Excitation Laser

Abstract In recent years, the atomic force microscope has proven to be a powerful tool for studying biological systems, mainly for its capability to measure in liquids with nanoscale resolution. Measuring tissues, cells or proteins in their physiological conditions gives us access to valuable information about their real ‘in vivo’ structure, dynamics and functionality which could then fuel disruptive medical and biological applications. The main problem faced by the atomic force microscope when working in liquid environments is the difficulty to generate clear cantilever resonance spectra, essential for stable operation and for high resolution imaging. Photothermal actuation overcomes this problem, as it generates clear resonance spectra free from spurious peaks. However, relatively high laser powers are required to achieve the desired cantilever oscillation amplitude, which could potentially damage biological samples. In this study, we demonstrate that the photothermal excitation efficiency can be enhanced by coating the cantilever with a thin amorphous carbon layer to increase the heat absorption from the laser, reducing the required excitation laser power and minimizing the damage to biological samples.

Taking atomic force microscope advances to the university classroom

2002 ◽  
Author(s):  
J.D. Adams ◽  
G. Priyadarshan ◽  
A. Mabogunje ◽  
L.J. Leifer ◽  
C.F. Quate ◽  
...  
Keyword(s):  
Atomic Force Microscope ◽  
Atomic Force ◽  
The University

Using AFM Phase Lag Data to Indentefy Microconstituents With Varying Values of Elastic Modulus

1998 ◽  
Vol 4 (S2) ◽  
pp. 334-335
Author(s):  
D.N. Leonard ◽  
A.D. Batchelor ◽  
P.E. Russell
Keyword(s):  
Elastic Modulus ◽  
Atomic Force Microscope ◽  
Material Properties ◽  
Atomic Level ◽  
Phase Image ◽  
Nanometer Scale ◽  
Phase Lag ◽  
Atomic Force ◽  
Quantitative Understanding ◽  
Imaging Mode

The atomic force microscope (AFM) has allowed microscopists to observe surface topography of non-conductive samples on the atomic level. One AFM mode that scanned probe microscopists have recently shown an interest in is the phase lag imaging mode. It has already been demonstrated that the resulting phase lag data can be used to identify different densities of microlayered polyethylene. However a quantitative understanding of phase lag imaging has yet to be fully developed. With a better understanding of the phase lag data it may be possible to estimate the modulus or other material properties of a sample from an AFM phase image alone.The need for better understanding phase lag data is essential to increasing the knowledge of a how a material's microstructure behaves on the nanometer scale. This investigation focused on AFM phase lag data produced while scanning microstructures with large differences in modulus values between the compositional phases.

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