---
_id: '3727'
abstract:
- lang: eng
  text: Since its invention in the 1990s single-molecule force spectroscopy has been
    increasingly applied to study protein (un-)folding, cell adhesion, and ligand–receptor
    interactions. In most force spectroscopy studies, the cantilever of an atomic
    force microscope (AFM) is separated from a surface at a constant velocity, thus
    applying an increasing force to folded bio-molecules or bio-molecular bonds. Recently,
    Fernandez and co-workers introduced the so-called force-clamp technique. Single
    proteins were subjected to a defined constant force allowing their life times
    and life time distributions to be directly measured. Up to now, the force-clamping
    was performed by analogue PID controllers, which require complex additional hardware
    and might make it difficult to combine the force-feedback with other modes such
    as constant velocity. These points may be limiting the applicability and versatility
    of this technique. Here we present a simple, fast, and all-digital (software-based)
    PID controller that yields response times of a few milliseconds in combination
    with a commercial AFM. We demonstrate the performance of our feedback loop by
    force-clamp unfolding of single Ig27 domains of titin and the membrane proteins
    bacteriorhodopsin (BR) and the sodium/proton antiporter NhaA.
author:
- first_name: Christian
  full_name: Bippes, Christian A
  last_name: Bippes
- first_name: Harald L
  full_name: Harald Janovjak
  id: 33BA6C30-F248-11E8-B48F-1D18A9856A87
  last_name: Janovjak
  orcid: 0000-0002-8023-9315
- first_name: Alexej
  full_name: Kedrov, Alexej
  last_name: Kedrov
- first_name: Daniel
  full_name: Mueller, Daniel J
  last_name: Mueller
citation:
  ama: Bippes C, Janovjak HL, Kedrov A, Mueller D. Digital force-feedback for protein
    unfolding experiments using atomic force microscopy. <i>Nanotechnology</i>. 2007;18(4).
    doi:<a href="https://doi.org/10.1088/0957-4484/18/4/044022">10.1088/0957-4484/18/4/044022</a>
  apa: Bippes, C., Janovjak, H. L., Kedrov, A., &#38; Mueller, D. (2007). Digital
    force-feedback for protein unfolding experiments using atomic force microscopy.
    <i>Nanotechnology</i>. IOP Publishing Ltd. <a href="https://doi.org/10.1088/0957-4484/18/4/044022">https://doi.org/10.1088/0957-4484/18/4/044022</a>
  chicago: Bippes, Christian, Harald L Janovjak, Alexej Kedrov, and Daniel Mueller.
    “Digital Force-Feedback for Protein Unfolding Experiments Using Atomic Force Microscopy.”
    <i>Nanotechnology</i>. IOP Publishing Ltd., 2007. <a href="https://doi.org/10.1088/0957-4484/18/4/044022">https://doi.org/10.1088/0957-4484/18/4/044022</a>.
  ieee: C. Bippes, H. L. Janovjak, A. Kedrov, and D. Mueller, “Digital force-feedback
    for protein unfolding experiments using atomic force microscopy,” <i>Nanotechnology</i>,
    vol. 18, no. 4. IOP Publishing Ltd., 2007.
  ista: Bippes C, Janovjak HL, Kedrov A, Mueller D. 2007. Digital force-feedback for
    protein unfolding experiments using atomic force microscopy. Nanotechnology. 18(4).
  mla: Bippes, Christian, et al. “Digital Force-Feedback for Protein Unfolding Experiments
    Using Atomic Force Microscopy.” <i>Nanotechnology</i>, vol. 18, no. 4, IOP Publishing
    Ltd., 2007, doi:<a href="https://doi.org/10.1088/0957-4484/18/4/044022">10.1088/0957-4484/18/4/044022</a>.
  short: C. Bippes, H.L. Janovjak, A. Kedrov, D. Mueller, Nanotechnology 18 (2007).
date_created: 2018-12-11T12:04:50Z
date_published: 2007-01-31T00:00:00Z
date_updated: 2021-01-12T07:51:46Z
day: '31'
doi: 10.1088/0957-4484/18/4/044022
extern: 1
intvolume: '        18'
issue: '4'
month: '01'
publication: Nanotechnology
publication_status: published
publisher: IOP Publishing Ltd.
publist_id: '2501'
quality_controlled: 0
status: public
title: Digital force-feedback for protein unfolding experiments using atomic force
  microscopy
type: journal_article
volume: 18
year: '2007'
...