Scanning Probe Microscopy

Bottomley, Lawrence A.

doi:10.1021/a1980011o

Cited by 104 publications

(72 citation statements)

References 601 publications

(19 reference statements)

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“…During recent years, atomic force microscopy (AFM) has been increasingly used in the biosciences (5,16). Theoretically, it combines the two most important aspects of studying structure-function relationships of biological specimens: it performs high-resolution imaging with a high signal-to-noise ratio on a molecular or submolecular scale and has the ability to operate in aqueous environments, allowing the observation of dynamic molecular events in real time and under physiological conditions.…”

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confidence: 99%

Comparison of Atomic Force Microscopy Interaction Forces between Bacteria and Silicon Nitride Substrata for Three Commonly Used Immobilization Methods

Vadillo-Rodrı́guez¹,

Busscher²,

Norde

et al. 2004

Appl Environ Microbiol

114

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Atomic force microscopy (AFM) has emerged as a powerful technique for mapping the surface morphology of biological specimens, including bacterial cells. Besides creating topographic images, AFM enables us to probe both physicochemical and mechanical properties of bacterial cell surfaces on a nanometer scale. For AFM, bacterial cells need to be firmly anchored to a substratum surface in order to withstand the friction forces from the silicon nitride tip. Different strategies for the immobilization of bacteria have been described in the literature. This paper compares AFM interaction forces obtained between Klebsiella terrigena and silicon nitride for three commonly used immobilization methods, i.e., mechanical trapping of bacteria in membrane filters, physical adsorption of negatively charged bacteria to a positively charged surface, and glutaraldehyde fixation of bacteria to the tip of the microscope. We have shown that different sample preparation techniques give rise to dissimilar interaction forces. Indeed, the physical adsorption of bacterial cells on modified substrata may promote structural rearrangements in bacterial cell surface structures, while glutaraldehyde treatment was shown to induce physicochemical and mechanical changes on bacterial cell surface properties. In general, mechanical trapping of single bacterial cells in filters appears to be the most reliable method for immobilization.During recent years, atomic force microscopy (AFM) has been increasingly used in the biosciences (5, 16). Theoretically, it combines the two most important aspects of studying structure-function relationships of biological specimens: it performs high-resolution imaging with a high signal-to-noise ratio on a molecular or submolecular scale and has the ability to operate in aqueous environments, allowing the observation of dynamic molecular events in real time and under physiological conditions. The AFM is surprisingly simple in its concept. A sharp tip located at the free end of a flexible cantilever scans over a surface. Interaction forces between the tip and the sample surface subsequently cause the cantilever to deflect. The deflection signal is acquired and digitized to provide a threedimensional image of the surface.Several biological specimens have been imaged, with lateral and vertical resolution on a nanometer and a subnanometer scale, respectively (9, 14, 23). However, when living microbial cell surfaces are imaged, the softness of the cell surface together with the high pressure over the contact area between the tip and the cell can prevent high-resolution imaging. Image contrast is indeed influenced by the probe's geometry, the imaging parameters, the surface topography, and the viscoelastic and physicochemical properties of the cell surface. Additional problems arise from friction and from lateral displacement of the organism under study, which makes immobilization strategies critical.Beyond being an imaging device, the AFM has evolved as an instrument for measuring molecular interaction forces (21,22). Bio...

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confidence: 99%

Comparison of Atomic Force Microscopy Interaction Forces between Bacteria and Silicon Nitride Substrata for Three Commonly Used Immobilization Methods

Vadillo-Rodrı́guez¹,

Busscher²,

Norde

et al. 2004

Appl Environ Microbiol

114

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“…10 The technique is, from an instrumental point of view, very closely related to AFM except for the use of a magnetized probe. The microscope's cantilever equipped with the ferromagnetic probe achieves a local magnetostatic interaction between the probe and a magnetic sample on the substrate or the sample surface.…”

Section: Chartmentioning

confidence: 99%

Magnetic Force Microscopic Images of Nanometer-Sized Polyradical Particles

Michinobu

Inui

Nishide

2003

Polym J

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ABSTRACT:Nanometer-sized polymer particles bearing 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) radicals were prepared. The emulsifier-free emulsion polymerization of methacrylic acid, methyl methacrylate, and methylenebisacrylamide and the following introduction of the TEMPO moiety produced polyradical particles with different spin concentrations. The TEMPO-combined particle was also prepared in one step by the anionic dispersion polymerization of 4-methacryloyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl. The position and horizontal shape in the atomic and magnetic force microscopic images of the polyradical particle coincided with each other. The vertical scale of the magnetic image responded to the spin concentration of the particle. The particle bearing the radicals on its surface gave a hollow dot image.KEY WORDS Polyradical / Microparticle / Magnetic Force Microscopy (MFM) / Emulsifier-Free Emulsion Polymerization / Anionic Dispersion Polymerization / In recent years, magnetic dots consisting of metals or metal oxides of 10-100 nm sizes have been significantly investigated because of their potential use as future high-density magnetic recording media. 1 However, there has been no report, to our knowledge, on a magnetically responsible "dot" composed of purelyorganic derived materials. Among the nm-sized materials, organic polymers that possess a single molecularbased size in the nanometer range have received considerable attention, because they are prepared by conventional polymer chemistry and their molecular structure is designable. 2 In particular, the preparation of organic polymer-based particles with a size from 10 nm to µm has been established and their applications have been widely investigated. 3 The emulsion and dispersion polymerizations are useful for preparing polymer particles in that size range.One of the ways to make non-diamagnetic and paramagnetic organic macromolecules is the accumulation of stable open shell molecules by preparing the polymer bearing stable radicals pendantly or integrating them into the main chain. 4 They are often called polyradicals and have been studied as a redox polymer and an antioxidant. Nevertheless, no attempt has been made using a nm-sized polyradical particle composed of persistent organic radical species up to now (We have already reported π-conjugated but non-Kekulé-type and highspin polyradicals with a nm-size, but they were not persistent under air at room temperature 5 ). We selected, in this study, the 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) radical as a persistent radical, and describe the preparation of nm-sized and single molecular-based † To whom correspondence should be addressed.particles bearing TEMPO radicals and the detection of a very weak magnetic signal of the polyradical particles by magnetic force microscopy (MFM) as a dot image.

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“…Scanning probe microscopy (SPM) is widely used to analyze the surface structures and properties of semiconductor and bio-molecular films [1][2][3][4][5][6][7][8][9][10]. The merits of the SPM method are that it does not require any process for sample preparation, and minimizes damages of the probing sample [11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Creation of Optimal Frequency for Electrostatic Force Microscopy Using Direct Digital Synthesizer

et al. 2017

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Electrostatic force microscopy (EFM) is a useful technique when measuring the surface electric potential of a substrate regardless of its topography. Here, we have developed a frequency detection method for alternating current (AC) bias in EFM. Instead of an internal lock-in amplifier (LIA) for EFM that only detects ω e and 2ω e , we have used other LIAs that can amplify the amplitude of specific frequency by direct digital synthesizer (DDS), that finds the optimal frequency of surface charge images. In order to confirm the performance of the proposed methods, the electrical properties of lead zirconate titanate (PZT) and triglycine sulfate (TGS) samples were measured. In addition, we compared the performances of the frequency-detection method and the conventional EFM method. Ultimately, enhanced images could be achieved using the frequency-detection method. The optimal modulated frequency-shift for force-gradient measurements was found to be 2 kHz. Additionally, we have shown that it is possible to use a hard cantilever (K = 42 N/m, 330 kHz). Therefore, we expect that this technique can be applied to measure the electrical properties of bio-molecular films.

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Scanning Probe Microscopy

Cited by 104 publications

References 601 publications

Comparison of Atomic Force Microscopy Interaction Forces between Bacteria and Silicon Nitride Substrata for Three Commonly Used Immobilization Methods

Comparison of Atomic Force Microscopy Interaction Forces between Bacteria and Silicon Nitride Substrata for Three Commonly Used Immobilization Methods

Magnetic Force Microscopic Images of Nanometer-Sized Polyradical Particles

Creation of Optimal Frequency for Electrostatic Force Microscopy Using Direct Digital Synthesizer

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