Scanned probe microscopy in biology

1993 ◽  
Vol 51 ◽  
pp. 508-509
Author(s):  
Knute A. Fisher
Keyword(s):  
Pyrolytic Graphite ◽  
Piezoelectric Transducers ◽  
Atomic Resolution ◽  
Scanning Tunneling ◽  
Whole Cells ◽  
Flat Surfaces ◽  
The Past ◽  
Atomic Force ◽  
Scanned Probe Microscopy ◽  
And Control

Numerous scanned probe microscopes (SPM) have been developed over the past decade. Most are based on the precise positioning of sample and probe using piezoelectric transducers, and some have the capability of imaging flat surfaces with atomic resolution. The first atomic resolution SPM applied to biological samples was the scanning tunneling microscope (STM). The atomic force microscope (AFM) was subsequently developed and over the past few years has become the instrument of choice for biological applications.Early investigators applied the STM to examinations of organic and biological systems ranging from small molecules to nucleic acids, globular and fibrillar proteins, and larger structures such as viruses, membranes, and even whole cells. Much of this work was done during the mid-80s using electricallyconductive highly-oriented pyrolytic graphite (HOPG) as a substrate. Images were often difficult to obtain and control experiments were lacking. Unfortunately, when careful experiments were undertaken, they revealed that HOPG itself was capable of generating images previously thought to be biological.

scholarly journals Scanned Probe Microscopy in Biology

1995 ◽  
Vol 3 (8) ◽  
pp. 16-17 ◽  
Author(s):  
Knute A. Fisher
Keyword(s):  
Scanning Tunneling Microscope ◽  
Piezoelectric Transducers ◽  
Atomic Resolution ◽  
Scanning Tunneling ◽  
Biological Applications ◽  
Precise Positioning ◽  
Flat Surfaces ◽  
The Past ◽  
Atomic Force ◽  
Scanned Probe Microscopy

Numerous scanned probe microscopes (SPM) have been developed over the past decade. Most are based on the precise positioning of sample and probe using piezoelectric transducers, and some have the capability of imaging flat surfaces with atomic resolution. The first atomic resolution SPM applied to biological samples was the scanning tunneling microscope (STM). The atomic force microscope (AFM) was subsequently developed and over the past few years has become the instrument of choice for biological applications.

Resolution Issues in Scanned Probe Microscopy

1997 ◽  
Vol 3 (S2) ◽  
pp. 1187-1188
Author(s):  
P. E. Russell
Keyword(s):  
Scanning Force Microscopy ◽  
Atomic Resolution ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Probe Microscopy ◽  
Force Microscopy ◽  
Atomic Force ◽  
Sample Height ◽  
Scanned Probe Microscopy ◽  
Scanning Force

Scanned Probe Microscopy first received widespread recognition in the form of scanning tunneling microscopy (STM) images clearly showing atomic resolution of the Si 111 surface in the characteristic 7×7 surface reconstruction. For this sample, STM imaging under carefully controlled ultrahigh vacuum conditions reveals the clear image of each atom position within the surface unit cell with excellent contrast and clearly atomic resolution. Over the past few years, versions of scanning force microscopy (commonly referred to as atomic force microscopy or AFM) have become much more widespread than STM. A very common, and very difficult question, is: What is the resolution of AFM? The simple answer is that SPM in general, and STM and AFM in particular, routinely obtain sub-angstrom resolution—in the z axis, or the sample height direction. This high resolution capability is easily demonstrated by scanning a cleaved crystal of known lattice spacing and observing single and multiple atomic steps.

Prospects for scanned-probe microscopy

1994 ◽  
Vol 52 ◽  
pp. 6-7
Author(s):  
Jean-Paul Revel
Keyword(s):  
High Vacuum ◽  
Physiological Saline ◽  
Scanning Probe ◽  
Aqueous Environment ◽  
Whole Cells ◽  
Material Scientist ◽  
Biological Objects ◽  
Spatially Resolved ◽  
Atomic Force ◽  
Scanned Probe Microscopy

In the last 50+ years the electron microscope and allied instruments have led the way as means to acquire spatially resolved information about very small objects. For the material scientist and the biologist both, imaging using the information derived from the interaction of electrons with the objects of their concern, has had limitations. Material scientists have been handicapped by the fact that their samples are often too thick for penetration without using million volt instruments. Biologists have been handicapped both by the problem of contrast since most biological objects are composed of elements of low Z, and also by the requirement that sample be placed in high vacuum. Cells consist of 90% water, so elaborate precautions have to be taken to remove the water without losing the structure altogether. We are now poised to make another leap forwards because of the development of scanned probe microscopies, particularly the Atomic Force Microscope (AFM). The scanning probe instruments permit resolutions that electron microscopists still work very hard to achieve, if they have reached it yet. Probably the most interesting feature of the AFM technology, for the biologist in any case, is that it has opened the dream of high resolution in an aqueous environment. There are few restrictions on where the instrument can be used. AFMs can be made to work in high vacuum, allowing the material scientist to avoid contamination. The biologist can be made happy as well. The tips used for detection are made of silicon nitride,(Si3N4), and are essentially unaffected by exposure to physiological saline (about which more below). So here is an instrument which can look at living whole cells and at atoms as well.

Scanning Tunneling Microscopy and Atomic Force Microscopy Investigation of Organic Tetracyanoquinodimethane Thin Films

1997 ◽  
Vol 12 (8) ◽  
pp. 1942-1945 ◽  
Author(s):  
H. J. Gao ◽  
H. X. Zhang ◽  
Z. Q. Xue ◽  
S. J. Pang
Keyword(s):  
Thin Films ◽  
Atomic Force Microscopy ◽  
Scanning Tunneling Microscopy ◽  
Pyrolytic Graphite ◽  
Film Surface ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Force Microscopy ◽  
Atomic Force ◽  
Microscopy Investigation

Scanning tunneling microscopy (STM) and atomic force microscopy (AFM) investigation of tetracyanoquinodimethane (TCNQ) and the related C60-TCNQ thin films is presented. Periodic molecular chains of the TCNQ on highly oriented pyrolytic graphite (HOPG) substrates were imaged, which demonstrated that the crystalline (001) plane was parallel to the substrate. For the C60-TCNQ thin films, we found that there were grains on the film surface. STM images within the grain revealed that the well-ordered rows and terraces, and the parallel rows in different grains were generally not in the same orientation. Moreover, the grain boundary was also observed. In addition, AFM was employed to modify the organic TCNQ film surface for the application of this type of materials to information recording and storage at the nanometer scale. The nanometer holes were successfully created on the TCNQ thin film by the AFM.

Comparative Surface Studies at Atomic Resolution with Ultrahigh Vacuum Variable-Temperature Atomic Force and Scanning Tunneling Microscopes

1999 ◽  
Vol 5 (3) ◽  
pp. 208-215 ◽  
Author(s):  
Masashi Iwatsuki ◽  
Kazuyuki Suzuki ◽  
Shin-ich Kitamura ◽  
Mike Kersker
Keyword(s):  
Detection Method ◽  
Variable Temperature ◽  
Contact Potential Difference ◽  
Oscillation Amplitude ◽  
Ultrahigh Vacuum ◽  
Atomic Resolution ◽  
Scanning Tunneling ◽  
Contact Potential ◽  
Atomic Force ◽  
Temperature Scanning

With the ultrahigh vacuum variable-temperature scanning tunneling microscope (UHV-VT-STM), atomic-level observation has been achieved. An ultrahigh vacuum atomic force microscope (UHV-AFM) has also been developed, with success in obtaining atom images where observation in noncontact (NC) mode with a frequency modulation (FM) detection method was attempted. Using the FM detection method in the constant oscillation amplitude of the cantilever excitation mode, we have obtained atomic-resolution images of Si(111) 7 × 7 structures and Si(100) 2 × 1 structures and other structures together with STM images in an ultrahigh vacuum environment. Also shown here are contact potential difference (CPD) images using the NC-AFM method.

scholarly journals Atomic Resolution with the Atomic Force Microscope

1995 ◽  
Vol 3 (4) ◽  
pp. 6-7
Author(s):  
Stephen W. Carmichael
Keyword(s):  
Atomic Force Microscopy ◽  
Scanning Tunneling Microscopy ◽  
Atomic Force Microscope ◽  
Recent Article ◽  
Atomic Scale ◽  
Atomic Resolution ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Force Microscopy ◽  
Atomic Force

For biologic studies, atomic force microscopy (AFM) has been prevailing over scanning tunneling microscopy (STM) because it has the capability of imaging non-conducting biologic specimens. However, STM generally gives better resolution than AFM, and we're talking about resolution on the atomic scale. In a recent article, Franz Giessibl (Atomic resolution of the silicon (111)- (7X7) surface by atomic force microscopy, Science 267:68-71, 1995) has demonstrated that atoms can be imaged by AFM.

Scanned Probe Microscopy: Past, present, and future

1992 ◽  
Vol 50 (1) ◽  
pp. 18-19
Author(s):  
Knute A. Fisher
Keyword(s):  
Ambient Pressure ◽  
Electrical Potential ◽  
Scanning Tunneling ◽  
Vertical Position ◽  
Tunneling Microscope ◽  
Probe Microscopy ◽  
The Past ◽  
Atomic Force ◽  
Wide Range ◽  
Significant Difference

In the past decade a new family of image-forming devices has been developed, machines that do not use lenses and are collectively called scanned probe microscopes (SPM). The SPM family evolved from the scanning tunneling microscope (STM) developed by Binnig and Rohrer in the early 1980s. The tunneling microscope and subsequent probe microscopes, such as the atomic force microscope (AFM), are based on the precise positioning and scanning of a probe within nanometer distances of a surface. Sub-nanometer precision is accomplished using piezoelectric ceramics that change shape with applied electrical potential allowing probes to be moved laterally with less than 0.1-nm resolution and vertically with less than 0.01-nm resolution. This method of positioning has been routinely used with SPM over the past 10 years, during which time many different probes have been developed. These probes measure signals from a variety of physical phenomena such as electron tunneling, atomic force, electrical conductivity, temperature gradients, light absorption, ion currents, and magnetic properties. A significant difference between SPM and conventional light and electron microscopes is that the probes can operate in a wide range of environments including pressures that range from ultrahigh vacuum to ambient pressure, temperatures that range from liquid helium to hundreds of degrees Kelvin, and physical states that include immersion in hydrophobic liquids such as oil and hydrophilic liquids such biological buffers. The probes are usually scanned in either a constant signal mode or in a constant height mode. Signals are amplified and can be used to control the probe's vertical position. The signal is recorded digitally and displayed on a computer screen and thus can be manipulated by image-processing tools to generate topographic maps of the surface. The references at the end of this article cite several of the major reviews of probe microscopy.

COMPARATIVE STUDY OF THIOL FILMS ON C(0001) AND Au(111) SURFACES BY SCANNING PROBE MICROSCOPY

1997 ◽  
Vol 04 (04) ◽  
pp. 637-649 ◽  
Author(s):  
F. TERÁN ARCE ◽  
M. E. VELA ◽  
R. C. SALVAREZZA ◽  
A. J. ARVIA
Keyword(s):  
Pyrolytic Graphite ◽  
Scanning Probe ◽  
Scanning Tunneling ◽  
Electrochemical Characteristics ◽  
Tunneling Microscopy ◽  
Test Reaction ◽  
Force Microscopy ◽  
Atomic Force ◽  
Electron Transfer Processes ◽  
Substrate Nature

The structures resulting from 1-dodecanethiol, 1-butanethiol and 1,9-nonanedithiol films produced on highly oriented pyrolytic graphite (HOPG) and gold(111) have been comparatively studied by scanning probe microscopies. Molecular resolution images resulting from atomic force microscopy (AFM) and scanning tunneling microscopy (STM) of different thiol films show the formation of arrays of molecules parallel to the HOPG surface. The electrochemical response of the ferro-ferricyanide reaction was used to test the characteristics of electron transfer processes in thiol-covered HOPG as compared to the bare substrate. The decrease in the heterogeneous rate constant for the test reaction appears to be directly related to the degree of film thickness uniformity. For comparison, films with the same kind of thiols were produced on Au(111). Although the electrochemical characteristics of these films appear to be the same irrespective of the substrate nature, the structure of the films on Au(111) is different from that produced on HOPG.

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