qPlus magnetic force microscopy in frequency-modulation mode with millihertz resolution

Schneiderbauer, Maximilian; Wastl, Daniel S.; Giessibl, Franz J.

doi:10.3762/bjnano.3.18

Cited by 20 publications

(18 citation statements)

References 23 publications

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“…21,22 The sensors had a characteristic resonance frequency of f 0 = 32768 Hz and a stiffness 8 measuring more than one sample per preparation condition. However, to be sure that we would not measure any outlier, the layer built-up of the AFM samples was performed in the SPR measuring cell.…”

Section: Quartz Cantilever Atomic Force Microscopy (Afm)mentioning

confidence: 99%

Oligolayer-Coated Nanoparticles: Impact of Surface Topography at the Nanobio Interface

Wurster

Liebl

Michaelis

et al. 2015

ACS Appl. Mater. Interfaces

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Layer-by-layer coating of nanoparticles with a layer number in the single-digit range has gained increasing attention in the field of nanomedicinal research. However, the impact of using various polyelectrolytes on oligolayer formation and, more importantly, their influence on the interaction with the biological system has not often been considered in the past. Hence, we investigated the polyelectrolyte deposition profiles and resulting surface topographies of up to three polyelectrolyte layers on a flat gold sensor surface using three different polycations, namely, poly(ethylene imine) (PEI), poly(allylamine hydrochloride) (PAH), and poly(diallylammonium chloride) (PD), each in combination with poly(styrenesulfonate) (PSS). Surface plasmon resonance spectroscopy and atomic force microscopy revealed that the PEI/PSS pair in particular showed a so-called overshoot phenomenon, which is associated with partial polyelectrolyte desorption from the surface. This is also reflected by a significant increase in the surface roughness. Then, after having transferred the oligolayer assembly onto nanoparticles of ∼32 nm, we realized that quite similar surface topographies must have emerged on a curved gold surface. A major finding was that the extent of surface roughness contributes significantly to the fashion by which the oligolayer-coated nanoparticles interact with serum proteins and associate with cells. For example, for the PEI/PSS system, both the surface roughness and protein adsorption increased by a factor of ∼12 from the second to third coating layer and, at the same time, the cell association massively decreased to only one-third. Our study shows that surface roughness, along with other particle properties such as size, shape, zeta potential, and hydrophobicity, is another decisive factor for nanoparticles in a biological context, which has indeed been discussed previously but has not to date been investigated for oligolayers.

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Section: Quartz Cantilever Atomic Force Microscopy (Afm)mentioning

confidence: 99%

Oligolayer-Coated Nanoparticles: Impact of Surface Topography at the Nanobio Interface

Wurster

Liebl

Michaelis

et al. 2015

ACS Appl. Mater. Interfaces

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“…One prong of the QTF (type E158 from Nanosurf AG, Liestal, Switzerland) was glued with Torr Seal on an L-shaped sapphire piece, which was in turn mounted by the same glue on a dither piezo plate. This type of QTF with one prong being fixed is often called qPlus QTF [ 31 – 33 ]. Another sapphire piece was sandwiched between the dither piezo and the base of the apparatus for good isolation.…”

Section: Methodsmentioning

confidence: 99%

“…Recently, quartz tuning forks (QTF) have been widely used as force sensors in scanning probe microscopes such as the atomic force microscope (AFM) and magnetic force microscope [ 29 – 31 ], in which the frequency shift of the QTFs is detected to measure the interaction between tip and sample.…”

Section: Introductionmentioning

confidence: 99%

The Coefficient of the Voltage Induced Frequency Shift Measurement on a Quartz Tuning Fork

Hou

2014

Sensors

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We have measured the coefficient of the voltage induced frequency shift (VIFS) of a 32.768 KHz quartz tuning fork. Three vibration modes were studied: one prong oscillating, two prongs oscillating in the same direction, and two prongs oscillating in opposite directions. They all showed a parabolic dependence of the eigen-frequency shift on the bias voltage applied across the fork, due to the voltage-induced internal stress, which varies as the fork oscillates. The average coefficient of the VIFS effect is as low as several hundred nano-Hz per millivolt, implying that fast-response voltage-controlled oscillators and phase-locked loops with nano-Hz resolution can be built.

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“…For a qPlus sensor there is no restriction of the tip. In general every tip material and tip geometry is possible (Giessibl, 2003;Pielmeier & Giessibl, 2013;Schneiderbauer et al, 2012;Wastl et al, 2013bWastl et al, , 2014Wastl et al, , 2015Wastl, Speck, Wutscher, & Ostler, 2013c). This opens the way for a huge variety of different experiments and allows a much more precise adaption of the measurements to different problems (Pielmeier & Giessibl, 2013;Wastl et al, 2013aWastl et al, , 2013bWastl et al, , 2014.…”

Section: Ambient Conditions: Definition Challenges and Sensorsmentioning

confidence: 99%

Ambient atomic resolution atomic force microscopy with qPlus sensors: Part 1

Wastl

2016

Microscopy Res & Technique

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Atomic force microscopy (AFM) is an enormous tool to observe nature in highest resolution and understand fundamental processes like friction and tribology on the nanoscale. Atomic resolution in highest quality was possible only in well-controlled environments like ultrahigh vacuum (UHV) or controlled buffer environments (liquid conditions) and more specified for long-term high-resolution analysis at low temperatures (∼4 K) in UHV where drift is nearly completely absent. Atomic resolution in these environments is possible and is widely used. However, in uncontrolled environments like air, with all its pollutants and aerosols, unspecified thin liquid films as thin as a single molecular water-layer of 200 pm or thicker condensation films with thicknesses up to hundred nanometer, have been a problem for highest resolution since the invention of the AFM. The goal of true atomic resolution on hydrophilic as well as hydrophobic samples was reached recently. In this manuscript we want to review the concept of ambient AFM with atomic resolution. The reader will be introduced to the phenomenology in ambient conditions and the problems will be explained and analyzed while a method for scan parameter optimization will be explained. Recently developed concepts and techniques how to reach atomic resolution in air and ultra-thin liquid films will be shown and explained in detail, using several examples. Microsc. Res. Tech. 80:50-65, 2017. © 2016 Wiley Periodicals, Inc.

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qPlus magnetic force microscopy in frequency-modulation mode with millihertz resolution

Cited by 20 publications

References 23 publications

Oligolayer-Coated Nanoparticles: Impact of Surface Topography at the Nanobio Interface

Oligolayer-Coated Nanoparticles: Impact of Surface Topography at the Nanobio Interface

The Coefficient of the Voltage Induced Frequency Shift Measurement on a Quartz Tuning Fork

Ambient atomic resolution atomic force microscopy with qPlus sensors: Part 1

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