Atomic Force Microscopy

48 %
52 %
Information about Atomic Force Microscopy
Science-Technology

Published on February 27, 2014

Author: amitkumarbiotech

Source: authorstream.com

Sequential adaptation in latent tuberculosis bacilli: observation by atomic force microscopy (AFM): Sequential adaptation in latent tuberculosis bacilli: observation by atomic force microscopy (AFM) Ali Akbar Velayati , Parissa Farnia , Mohammad Reza Masjedi , Gennady Konstantinovich Zhavnerko,Muayad,Aghali Merza , Jalladein Ghanavi , Payam Tabarsi , Poopak Farnia , Nikolai Nikolaevich Poleschuyk , George Ignatyev Amit Kumar M.Sc Computational Biology Objectives: Objectives General Applications Background and History How Does AFM Work? 3 Modes: Contact mode Non-contact mode Tapping Mode Figures of Merit Advantages of AFM Biological Applications Future Work General Applications: General Applications Materials Investigated: Thin and thick film coatings, ceramics, composites, glasses, synthetic and biological membranes, metals, polymers, and semiconductors. Used to study phenomena of: Abrasion, adhesion, cleaning, corrosion, etching, friction, lubricating, plating, and polishing. AFM can image surface of material in atomic resolution and also measure force at the nano-Newton scale. Background and History: Background and History 1 st AFM made by Gerd Binnig and Cristoph Gerber in 1985 Constructed by gluing tiny shard of diamond onto one end of tiny strip of gold foil Small hook at end of the tip pressed against sample surface Sample scanned by tracking deflection of cantilever by monitoring tunneling current to 2 nd tip position above cantilever Developed in order to examine insulating surfaces Parts of AFM: Parts of AFM 1. Laser – deflected off cantilever 2. Mirror –reflects laser beam to photodetector 3. Photodetector –dual element photodiode that measures differences in light intensity and converts to voltage 4. Amplifier 5. Register 6. Sample 7. Probe –tip that scans sample made of Si 8. Cantilever –moves as scanned over sample and deflects laser beam How Does AFM Work?: How Does AFM Work? 3 Modes of AFM: 3 Modes of AFM Contact Mode Non-Contact Mode Tapping (Intermittent contact) Mode Contact Mode: Contact Mode Measures repulsion between tip and sample Force of tip against sample remains constant Feedback regulation keeps cantilever deflection constant Voltage required indicates height of sample Problems: excessive tracking forces applied by probe to sample Non-Contact Mode: Non-Contact Mode Measures attractive forces between tip and sample Tip doesn ’ t touch sample Van der Waals forces between tip and sample detected Problems: Can ’ t use with samples in fluid Used to analyze semiconductors Doesn ’ t degrade or interfere with sample- better for soft samples Tapping (Intermittent-Contact) Mode: Tapping (Intermittent-Contact) Mode Tip vertically oscillates between contacting sample surface and lifting of at frequency of 50,000 to 500,000 cycles/sec. Oscillation amplitude reduced as probe contacts surface due to loss of energy caused by tip contacting surface Advantages: overcomes problems associated with friction, adhesion, electrostatic forces More effective for larger scan sizes Figures of Merit: Figures of Merit Can measure surface features with dimensions ranging from inter-atomic spacing to 0.1mm Resolution limited by size of tip (2-3nm) Resolution of imaging 5nm lateral and .01nm vertical PowerPoint Presentation: Advantages of AFM AFM versus STM (scanning tunneling microscope): both conductors and i nsulators AFM versus SEM (scanning electron microscope): greater topographic contrast AFM versus TEM (transmission electron microscope): no expensive sample prep Biological Applications: Biological Applications Used to analyze DNA, RNA, protein-nucleic acid complexes, chromosomes, cell membranes, proteins and peptides, molecular crystals, polymers, biomaterials, ligand-receptor binding Little sample prep required Nanometer resolved images of nucleic acids Imaging of cells Quantification of molecular interactions in biological systems Quantification of electrical surface charge The case study: The case study Mycobacterium tuberculosis (MTB) (H37RV) Latent tuberculosis Sequential adaptation PowerPoint Presentation: M. tuberculosis at exponential phase . PowerPoint Presentation: M. tuberculosis under anaerobic cultures developed a dense and homogenous layer that covers the bacilli. The thickness of cell wall reaches to 20.5±1.8 nm. PowerPoint Presentation:  Shows budding type of cell division in M. tuberculosis. This type of division was present till 3 months post latency. Thereafter, no divisions were observed. From 4 to 10 months of dormancy” Folding phenomena” observed in latent TB bacilli.: From 4 to 10 months of dormancy” Folding phenomena” observed in latent TB bacilli. Spore- like cells at 18 months of dormancy. These cells could not withstand the temp at 65 ºC, therefore, they are not real spore.: Spore- like cells at 18 months of dormancy. These cells could not withstand the temp at 65 ºC, therefore, they are not real spore. Spore –like cells at 24 months of dormancy: Spore –like cells at 24 months of dormancy Spore-like cells ruptured and produced a smaller progeny.: Spore-like cells ruptured and produced a smaller progeny. Non acid fast cell wall defective forms of TB bacilli; at 36 months of dormancy.: Non acid fast cell wall defective forms of TB bacilli; at 36 months of dormancy. These Nonacid-fast cells induced active tuberculosis in mice model.: These Nonacid-fast cells induced active tuberculosis in mice model. Nonacid fast cells increased their number by symmetrical type of cell –division.: Nonacid fast cells increased their number by symmetrical type of cell –division. Conclusion: Conclusion Temporary changes in which cell remain acid fast, but developed differences in shape, size and thickness of cell. A second alteration includes development of specialized cells with conspicuous loss of cell wall. The sequential adaptation that is demonstrated here may help to improve our understanding on life cycle of latent bacilli and may help scientists to identify targets for novel therapies. Future Work and Improvements: Future Work and Improvements Sharper tips by improved microfabrication processes: tip – sample interaction tends to distort or destroy soft biological molecules Atomic or angstrom resolution images of live cell surfaces: development of more flexible cantilever springs and less damaging and non-sticky probes needed References: References Bhanu, Jena P. and Heinrich J. K. Horber, eds. Methods in Cell Biology Vol 68. Academic Press. New York, 2002. Serry, Michael F., John T. Thornton, Kevin Kjoller. R and D. August 2002, v42 p53. “What is an Atomic Force Microscope?” University of Toledo Engineering. http://www.che.utoledo.edu/nadarajah/ webpages/whatsafm.html Li, Hong-Qiang. “Atomic Force Microscopy”. http://www.chembio.uoguelph.ca/educmat/chm729.afm.htm Baselt, David. “Atomic force microscopy”. http://stm2.nrl.navy.mil/how-afm/how-afm.html “Atomic Force Microscopy”. http://www.topometrix.com/spmguide/1-2-0.htm PowerPoint Presentation: Thank you

Add a comment

Related presentations

Related pages

Rasterkraftmikroskop – Wikipedia

Das Rasterkraftmikroskop, auch atomares Kraftmikroskop oder Atomkraftmikroskop (engl. atomic/scanning force microscope; Abkürzungen AFM bzw. SFM, seltener ...
Read more

Fundamental Theory of Atomic Force Microscopy

Fundamental Theory of Atomic Force Microscopy. by Wenjie Mai. What is AFM? The atomic force microscope (AFM) is one kind of scanning probe microscopes (SPM).
Read more

Bruker: Atomic Force Microscopy | AFM Microscope

Bruker’s industry-best AFM microscopes & atomic force microscopy technology incorporate the very latest advances in AFM techniques. Learn more today.
Read more

Atomic Force Microscopy - AFM Overview: nanoScience ...

Atomic Force Microscopes. Nanoscience Instruments has provided innovative Atomic Force Microscopy solutions for over 13 years. Our history and knowledge of ...
Read more

Atomic Force Microscopy Basics (Flash Animation)

Produced by: Imaging Technology Group Beckman Institute for Advanced Science and Technology University of Illinois at Urbana-Champaign
Read more

Atomic Force Microscopy – Asylum Research

Asylum Research manufactures advanced scanning probe and atomic force microscopes (SPM/AFMs) and accessories for nanoscience and nanotechnology. Our atomic ...
Read more

Atomic Force Microscopy - Home - Nanosurf

Nanosurf is a Swiss-based high-tech company providing scanning probe microscopes to customers around the globe. Our product range starts with very compact ...
Read more

Atomic Force Microscopy - Product Overview - Nanosurf

Atomic force microscopy products Flex-ANA — AFM for force mapping. The perfect tool for fully automated nanomechanical data acquisition and analysis.
Read more

Atomic Force Microscopy - asdlib.org

Atomic Force Microscopy HOW DOES THE AFM WORK? AFM provides a 3D profile of the surface on a nanoscale, by measuring forces between a sharp probe (<10 nm ...
Read more

Atomic Force Microscopy: Biomedical Methods and ...

Pier Carlo - Atomic Force Microscopy: Biomedical Methods and Applications (Methods in Molecular jetzt kaufen. ISBN: 9781588290946, Fremdsprachige Bücher ...
Read more