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Atomic Force Microscopy

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Nick Allen

on 24 September 2014

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Transcript of Atomic Force Microscopy

Thank You!
Nick Allen
Phil Choiniere
Ming Hsieh
Xuan Yao Zhang

Atomic Force Microscopy
What is Atomic Force Microscopy?
How Exactly Does AFM Work?
Practical Applications of AFM
Limitations of AFM Use
Mapping the surface of a cell

Measuring the mechanical properties of a microscopic material

Imaging of small, individual molecules

Testing the mechanical function and response of cellular components
1. only for SMALL sample size
It is not particle to measure a sample larger than 100 um
To get an idea, evenly divide 1 mm into 10 parts, and you will get 100 um

2. It take times to measure, why?
The measurement scale is too small.
3. It does not truly show the surface;
it shows the representation instead.
AFM can't show the step change of the depth.

4. Sample preparation
1. Samples need to be solid or semisolid: such as gels.
2. Sample need to attach to a supported plate.
Living cells are not good samples. Their contact surface is too small, so it is very easy to get swept away by the AFM probe.
Atomic Force Microscopy is a type of microscopy used for measuring forces and displacements on both molecular and cellular scales [5].
A tapered probe is attached to a cantilever arm.
When the probe interacts with the sample, the arm is deflected
This displacement is measured
by a laser, and converted into a readable signal [6]

Why Atomic Force Microscopy?

Atomic Force Microscopy allows us to
measure the properties of cells, which is really important for biomedical research!
The force required to change the shape of the cell can be calculated by looking at how far the AFM cantilever moves from its resting position [2].
The surface of a cell can be mapped by running the cantilever over the entire surface of the cell. The change in cantilever position can be used to generate a surface image [1].
The charges generated by individual atoms in a molecule can be enough to deform the cantilever tip of an AFM machine. These displacements can be used to map the structure of a single molecule, such as the pentacene above [3].
A well known cellular interaction is the biotin-avidin interaction. When applying the force of an AFM machine to individual biotin molecules, the small force needed to initiate a biotin-avidin reaction can be measured [4].
[1] Hogan, Hank. "Three Techniques Used to Study the Cell Surface of a Human Pathogen." Photonics.com: Optics, Lasers, Imaging & Fiber Information Resource. Biophotonics, n.d.
[2] Jun Xi, Lynn S. Penn, Ning Xi, Jennifer Y. Chen and Ruiguo Yang (2012). Dynamic Mechanical Response of Epithelial Cells to Epidermal Growth Factor, Viscoelasticity - From Theory to Biological Applications, Dr. Juan De Vicente (Ed.), ISBN: 978-953-51-0841-2, InTech, DOI: 10.5772/49977.
[3] "Molecules Revealed in All Their Glory by Microscope." Physicsworld.com Homepage. Institute of Physics, n.d. Web.
[4] Atomic Force Microscopy - Basics and Applications (n.d.): n. pag. Astrid Kronenberger School of Engineering and Science, June 2006. Web.
[5] Ethier, C. R., & Simmons, C. A. (2007). Introductory biomechanics: From cells to organisms. Cambridge: Cambridge University Press.
[6] "Atomic Force Microscopy - Google Search." Atomic Force Microscopy - Google Search. N.p., n.d. Web. 22 Sept. 2014.
[7] Atomic Force Microscopy, Psylla Christina, http://www.e21.ph.tum.de/uploads/media/Atomic_Force_Psylla.pdf
[8]Advantages and disadvantages of atomic force microscopy, The Manufacturer, 2011/05/10. http://machinemakers.typepad.com/machine-makers/2011/05/advantages-and-disadvantages-of-atomic-force-microscopy.html
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