A scanning tunneling microscope (STM) for biological applications: design and performance

Guckenberger, R.; Kößlinger, Conrad; Gatz, R.; Breu, H.; Levai, N.; Baumeister, Wolfgang

doi:10.1016/0304-3991(88)90218-5

Cited by 66 publications

(25 citation statements)

References 19 publications

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“…Commonly used bio-STM tips include tungsten wire shaped by grinding or etching (Guckenberger et al, 1988b), gold tips chemically etched in concentrated HC1 (Amrein et al, 1988a1, and platinum/iridium or platinumlrhodium tips formed by cutting or grinding (Amrein et al, 1988a;Dahn et al, 1988;Sleator and Tycko, 1988) or etching in 20% KCN (Sleator and Tycko, 1988). Similar to the findings of others we have observed that mechanically cut tips are sharper than chemically etched tips.…”

Section: Hydrated Samplessupporting

confidence: 87%

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Monolayer freeze‐fracture and scanning tunneling microscopy

Fisher

1989

J. Elec. Microsc. Tech.

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This article reviews research on planar monolayer methods, application of the methods to analyses of transmembrane signaling, and the combination of these methods with scanning tunneling microscopy (STM). Past research has involved the development of monolayer freeze-fracture methods. These include monolayer freeze-fracture autoradiography (MONOFARG), an electron microscopic cytochemical method to analyze in-plane distributions of radioisotopes, and double-labeled membrane splitting (DBLAMS) and single-membrane monolayer splitting (SMMS), methods to analyze transmembrane distributions of native and radiolabeled proteins and lipids. Present research has focussed on using these methods to investigate mechanisms of transmembrane signaling mediated by protein kinase C (PKC), including the transbilayer distribution of the tumor promoter TPA, a lipophilic activator of PKC, and the transbilayer distribution of peripheral membrane proteins phosphorylated by PKC. Future work will involve the combination of planar sample preparation with STM. The principles and applications of biological STM are briefly reviewed and a low-resolution STM image of a planar purple-membrane monolayer is included. The combination of planar methods and STM can provide the chemical information lacking in STM images enabling microscopists to investigate biochemical phenomena at nanometer resolution.

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Section: Hydrated Samplessupporting

confidence: 87%

“…A strikingly convincing, albeit low-resolution, STM image of a bacterial surface protein, HPI, was also recently published (Guckenberger et al, 1988b). The HPI layer of Deinococcus radiodurans naturally forms two-dimensional periodic arrays that were clearly imaged by STM.…”

Section: Hydrated Samplesmentioning

confidence: 93%

Monolayer freeze‐fracture and scanning tunneling microscopy

Fisher

1989

J. Elec. Microsc. Tech.

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“…The size of the grains ranges from -2 to 4 nm in width and the measured rms corrugation is -0.3 nm (see also ref. 13). To remove the influence of the granularity of the coating film, one must take averages over selected areas of the purple membrane as well as of the adjacent substrate devoid of purple membrane.…”

Section: Resultsmentioning

confidence: 99%

“…Most of the experiments described in this communication were performed with an STM ofthe Besocketype (12) described in detail elsewhere (13). This STM uses a tube scanner and operates at ambient pressure.…”

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confidence: 99%

Thickness determination of biological samples with a zeta-calibrated scanning tunneling microscope.

Wang

Hartmann

Baumeister

et al. 1990

Proc. Natl. Acad. Sci. U.S.A.

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A single-tube scanning tunneling microscope has been z-calibrated by using atomic steps of crystalline gold and was used for measuring the thickness of two biological samples, metal-coated as well as uncoated. The hexagonal surface layer of the bacterium Deinococcus radiodurans with an open network-type structure shows thickness values that are strongly influenced by the substrate and the preparation method. In contrast, the thickness of the purple membrane of Halobacterium halobium with its densely packed lesscorrugated structure exhibits very little variation in thickness in coated preparations and the values obtained are in good agreement with x-ray data.Transmission electron microscopy is a very powerful technique for determining the size and shape of biological macromolecules. Technical advances have made it possible to attain subnanometer resolution with various two-dimensional periodic arrays (e.g., refs. 1-5). Any transmission electron micrograph, however, is basically a two-dimensional projection of a three-dimensional object. z-axis information about the specimen, in particular its thickness, is only obtained by indirect means [e.g., shadow-length measurements of samples coated with metal films at an oblique angle (6) or thin sectioning of positively or negatively stained material (7)]. The accuracy of these measurements is not better than 2-4 nm. Tomographic techniques (i.e., combining the information from tilt series) retrieve the three-dimensional structure and, therefore, the thickness of the specimen with higher accuracy but at the expense of considerable experimental effort. Due to the incompleteness of data caused by the restricted range of tilt angles, resolution is usually anisotropic; the z resolution may be considerably lower than the lateral resolution.In contrast, the scanning tunneling microscope (STM) provides direct thickness information: the STM monitors the z position of the tunneling tip, which follows the surface profile of the sample when scanning in the constant current mode. At the same time the STM allows the experimenter to apply a wide range of experimental conditions, including ambient pressure and aqueous environments. Therefore, in spite of the limited lateral resolution so far achieved with biological samples, high-precision thickness measurements by STM represent valuable complementary information to transmission electron microscope (TEM) data. Such data may also be used to constrain the three-dimensional reconstructions from TEM data, thus improving their z resolution.In this communication we describe methods for z calibration of STMs, which is a prerequisite for accurate thickness measurements, and we apply the technique to two types of biological specimens. The first is the purple membrane from Halobacterium halobium, a membrane crystal containing one protein species, bacteriorhodopsin (8,9). The highly ordered hexagonal lattice (plane group p3) has a lattice constant of 6.3 nm. The purple membrane is a very compact structure; the membrane thickness is -4.7 nm,...

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“…SPM has many advantages for the study of mechanical, structural and functional properties of biological samples as well as for obtaining high-resolution topographic images. Various types of SPM techniques have been used for biological samples such as atomic force microscopy (AFM) [1][2][3][4][5][6][7][8][9], scanning tunneling microscopy (STM) [10][11][12][13], near-field scanning optical microscopy (NSOM) [14], and scanning ion conductance microscopy (SICM) [15,16]. However, to the best of our knowledge, an SPM technique for investigating local electrical properties of biological samples at high frequency has not been developed.…”

mentioning

confidence: 99%