Quantitative manipulation of DNA and viruses with the nanomanipulator scanning force microscope
✍ Scribed by Guthold, M.; Matthews, G.; Negishi, A.; Taylor, R. M.; Erie, D.; Brooks, F. P.; Superfine, R.
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 522 KB
- Volume
- 27
- Category
- Article
- ISSN
- 0142-2421
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✦ Synopsis
The nanoManipulator, a modiÐed scanning force microscope with a direct manipulation interface that allows natural and controlled manipulation of nanometer-sized samples, was used to investigate DNA and adenoviruses. During a manipulation, the scanning tip is coupled to a hand-held stylus via a force-feedback loop. Accordingly, the tip follows the movement of the userÏs hand ; moreover, the user is able to feel the topography of the sample. For imaging fragile biological samples, a magnetically driven intermittent contact (MDIC) mode in Ñuid was implemented and added to the microscope. In this mode, a cantilever with a magnetic particle glued onto its back is driven by an external, oscillating magnetic Ðeld. In contrast to regular intermittent contact (tapping) mode imaging in liquids, where the whole liquid cell is excited (resulting in many resonance peaks in the spectrum), in this mode the cantilever is driven directly and the spectrum usually displays a single, easily identiÐable resonance peak. Using this set-up, adenoviruses were manipulated in liquids and 1100 bp DNA molecules were manipulated in ambient conditions while recording lateral force data. In these experiments, the rupture force of DNA was measured directly for the Ðrst time. In an e †ort to measure the interaction force between a virus and a substrate, adenoviruses were pushed over a silicon substrate. A force of ¿25 nN was measured to move the virus on this surface.