Calibration of atomic-force microscope tips

Hutter, Jeffrey L.; Bechhoefer, John

doi:10.1063/1.1143970

Cited by 3,866 publications

(2,387 citation statements)

References 23 publications

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“…A silicon nitride V-shaped probe comprising a cantilever (Veeco DNP-20, 0.06 N/m nominal spring constant) with nominal dimensions of 196 µm length, 15 µm width and 0.6 µm thickness, and a 3 µm height silicon nitride pyramidal tip were employed for the tests. The determination of the spring constant of the probe was undertaken in fluid using the in-built Thermal Tune Method in air [24] prior to commencement of the experiments. Prior to using the Thermal Tune Method, the deflection sensitivity of the cantilever was obtained in liquid fluid by using the value of the inverse of the slope of the force curve while the cantilever was in contact with a hard glass surface.…”

Section: Methodsmentioning

confidence: 99%

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Numerical study of the hydrodynamic drag force in atomic force microscopy measurements undertaken in fluids

Méndez-Méndez

Alonso-Rasgado

Faria

et al. 2014

Micron

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When atomic force microscopy (AFM) is employed for in vivo study of immersed biological samples, the fluid medium presents additional complexities, not least of which is the hydrodynamic drag force due to viscous friction of the cantilever with the liquid. This force should be considered when interpreting experimental results and any calculated material properties. In this paper, a numerical model is presented to study the influence of the drag force on experimental data obtained from AFM measurements using computational fluid dynamics (CFD) simulation. The model provides quantification of the drag force in AFM measurements of soft specimens in fluids.The numerical predictions were compared with experimental data obtained using AFM with a V-shaped cantilever fitted with a pyramidal tip. Tip velocities ranging from 1.05 to 105 µm/s were employed in water, polyethylene glycol and glycerol with the platform approaching from a distance of 6000 nm. The model was also compared with an existing analytical model. Good agreement was observed between numerical results, experiments and analytical predictions. Accurate predictions were obtained without the need for extrapolation of experimental data. In addition, the model can be employed over the range of tip geometries and velocities typically utilized in AFM measurements.

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Section: Methodsmentioning

confidence: 99%

“…The spring constant k of the cantilever was 0.03544 N/m, which was determined using the Thermal Tune Method [24].…”

Section: Numerical Simulations 31 Numerical Modelmentioning

confidence: 99%

Numerical study of the hydrodynamic drag force in atomic force microscopy measurements undertaken in fluids

Méndez-Méndez

Alonso-Rasgado

Faria

et al. 2014

Micron

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“…111,112 The radius of curvature can be measured indirectly by using latex spheres or gold nanoparticles as a calibration standard. 113,114 After the geometric description of the probe is complete, a mathematical treatment of the data, typically using Legendre transforms, is performed to reconstruct the sample geometry.…”

Section: Measuring Dissolution By Atomic Force Microscopymentioning

confidence: 99%

Controlled Evaluation of Silver Nanoparticle Dissolution Using Atomic Force Microscopy

Kent

Vikesland

2012

Environ. Sci. Technol.

127

129

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Incorporation of silver nanoparticles (AgNPs) into an increasing number of consumer products has led to concern over the potential ecological impacts of their unintended release to the environment. Dissolution is an important environmental transformation that affects the form and concentration of AgNPs in natural waters; however, studies on AgNP dissolution kinetics are complicated by nanoparticle aggregation. Herein, nanosphere lithography (NSL) was used to fabricate uniform arrays of AgNPs immobilized on glass substrates. Nanoparticle immobilization enabled controlled evaluation of AgNP dissolution in an air-saturated phosphate buffer (pH 7, 25 °C) under variable NaCl concentrations in the absence of aggregation. Atomic force microscopy (AFM) was used to monitor changes in particle morphology and dissolution. Over the first day of exposure to ≥10 mM NaCl, the in-plane AgNP shape changed from triangular to circular, the sidewalls steepened, and the height increased by 6-12 nm. Subsequently, particle height and inplane radius decreased at a constant rate over a 2-week period. Dissolution rates varied linearly from 0.4 to 2.2 nm/d over the 10-550 mM NaCl concentration range tested. NaCl-catalyzed dissolution of AgNPs may play an important role in AgNP fate in saline waters and biological media. This study demonstrates the utility of NSL and AFM for the direct investigation of unaggregated AgNP dissolution.iii Acknowledgements I thank my advisor, Dr. Peter Vikesland, for his insight, guidance, and innovative ideas throughout my time at Virginia Tech, and for giving me the opportunity to work on this research project. He was ready and available to help whenever I needed his input. I also thank the other members of my committee,

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“…The force measurements and AFM imaging were performed with a Topometrix Explorer Tm AFM fitted with a specially constructed holder on a Nikon inverted microscope, using a 10 mm liquid scanner and silicon nitride cantilevers, as previously described. 34 AFM cantilevers were calibrated as described, 35 with the spring constant determined in air (nominal 0.03 N/m, measured values from 0.03 to 0.045 N/m). Fluorescein biotin (Molecular Probes) was used as AFM probe, and was fixed noncovalently with polyethylene glycol (PEG) (molecular range up to 8000, Sigma Chemicals, UK) 36 into the cantilever tip.…”

Section: Atomic Force Microscopymentioning

confidence: 99%

Targeting of biotinylated compounds to its target tissue using a low-density lipoprotein receptor–avidin fusion protein

et al. 2003

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The very high binding affinity of avidin to biotin is one of the highest to occur in nature. We constructed a fusion protein composed of avidin and the endocytotic LDL receptor in order to target biotinylated molecules to cells of the desired tissues. In addition to the native avidin, charge-mutated and nonglycosylated avidins were utilized as part of the fusion proteins, in order to modify its properties. All of the fusion protein versions retained the biotin-binding capacity. Although the specificity was not increased, however, fusion proteins composed of natural avidin and nonglycosylated avidin bound most efficiently to the biotinylated ligands. Fluorescence microscopy and atomic force microscopy studies revealed the expression of the fusion protein on cell membranes, and demonstrated specific and high-affinity binding of biotin to the low-density lipoprotein receptor (LDLR)-avidin fusion protein in vitro. Additionally, systemically administered biotinylated ligand targeted with high specificity the intracerebral tumors of rats that were expressing fusion protein after the virus-mediated gene transfer. These results suggest that local gene transfer of the fusion protein to target tissues may offer a novel tool for the delivery of biotinylated molecules in vitro and in vivo for therapeutic and imaging purposes.

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Calibration of atomic-force microscope tips

Cited by 3,866 publications

References 23 publications

Numerical study of the hydrodynamic drag force in atomic force microscopy measurements undertaken in fluids

Numerical study of the hydrodynamic drag force in atomic force microscopy measurements undertaken in fluids

Controlled Evaluation of Silver Nanoparticle Dissolution Using Atomic Force Microscopy

Targeting of biotinylated compounds to its target tissue using a low-density lipoprotein receptor–avidin fusion protein

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