[Spm] baseline slope in force curves

[Igor Sokolov]

Hi there,
It seems I missed the original question. However, the question was clear,
and important. 
I would not recommend just subtract the base line blindly. We saw a similar
phenomenon on epithelial cells, and initially thought that it was artifact.
But when we got a scanner with larger Z-range, we found that was a real
signal from cell microvilli etc. (cell brush). As a result we developed a
bit more complicated model. This is described in a paper: 
Igor Sokolov, Swaminathan Iyer, Venkatesh Subba-Rao, Ravi M. Gaikwad, and
Craig D. Woodworth, "Atomic Force Microscopy Detects Surface Brush on Cells
In-Vitro", Applied Physics Letters, 91, 023902 _2007.
Best regards,
Igor
 
_____________________________________
Igor Sokolov, Ph.D.
Director of Nano-Bio Laboratory (NABLAB), Clarkson University,
Professor,
Department of Physics, 
Department of Chemical and Biomolecular Science,
Clarkson University,
NY Center for Advanced Materials Processing,
Potsdam, NY 13699-5820, USA

office:        315-268-2375
fax:            315-268-6610
E-mail:       isokolov at clarkson.edu <blocked::mailto:isokolov at clarkson.edu> 
Web:          <blocked::http://www.clarkson.edu/~isokolov/>
http://www.clarkson.edu/~isokolov/
______________________________________
 

  _____  

From: Olivier Arnould [mailto:arnould at lmgc.univ-montp2.fr] 
Sent: Thursday, September 18, 2008 8:16 AM
To: spm at spmlist.di.com
Cc: schille at uni-muenster.de
Subject: [Spm] baseline slope in force curves


Hi,
 
If I have well understood, I think that this baseline slope is due to the
cantilever deflection that must be substract to the z-displacement to obtain
the indentation depth. This is usually done by doing a force-distance curve
on a stiff material that will give you the baseline slope due to the
cantilever deflection only, i.e., only a negligible indentation occurs so
z-displacement ~ cantilever deflection. You have then to substract this
displacement to the one you obtain on your cell.
 
Best regards,
 
Olivier Arnould
 
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