title: Mechanical properties of MDCK II cells exposed to gold nanorods.
abstract: BACKGROUND
  The impact of gold nanoparticles on cell viability has been extensively studied in the past. Size, shape and surface functionalization including opsonization of gold particles ranging from a few nanometers to hundreds of nanometers are among the most crucial parameters that have been focussed on. Cytoxicity of nanomaterial has been assessed by common cytotoxicity assays targeting enzymatic activity such as LDH, MTT and ECIS. So far, however, less attention has been paid to the mechanical parameters of cells exposed to gold particles, which is an important reporter on the cellular response to external stimuli.
  
  
  RESULTS
  Mechanical properties of confluent MDCK II cells exposed to gold nanorods as a function of surface functionalization and concentration have been explored by atomic force microscopy and quartz crystal microbalance measurements in combination with fluorescence and dark-field microscopy.
  
  
  CONCLUSIONS
  We found that cells exposed to CTAB coated gold nanorods display a concentration-dependent stiffening that cannot be explained by the presence of CTAB alone. The stiffening results presumably from endocytosis of particles removing excess membrane area from the cell's surface. Another aspect could be the collapse of the plasma membrane on the actin cortex. Particles coated with PEG do not show a significant change in elastic properties. This observation is consistent with QCM measurements that show a considerable drop in frequency upon administration of CTAB coated rods suggesting an increase in acoustic load corresponding to a larger stiffness (storage modulus).
authors: Institute of Physical Chemistry, Tammannstr. 6, University of Goettingen, 37077 Goettingen, Germany.
authors: Anna
authors: A
authors: Pietuch
authors: Institute of Physical Chemistry, Tammannstr. 6, University of Goettingen, 37077 Goettingen, Germany.
authors: Bastian Rouven
authors: BR
authors: Brückner
authors: Max Planck Institute for Biology of Ageing, Joseph-Stelzmann-Strasse 9b, 50931 Cologne, Germany.
authors: David
authors: D
authors: Schneider
authors: Max-Planck-Institute for Dynamics and Self-Organization (MPIDS), Laboratory for Fluid Dynamics, Pattern Formation and Biocomplexity, Am Fassberg 17, 37077 Goettingen, Germany.
authors: Marco
authors: M
authors: Tarantola
authors: Institute of Physical Chemistry, Duesbergweg 10-14, University of Mainz, 55128 Mainz, Germany.
authors: Christina
authors: C
authors: Rosman
authors: Institute of Physical Chemistry, Duesbergweg 10-14, University of Mainz, 55128 Mainz, Germany.
authors: Carsten
authors: C
authors: Sönnichsen
authors: Institute of Physical Chemistry, Tammannstr. 6, University of Goettingen, 37077 Goettingen, Germany.
authors: Andreas
authors: A
authors: Janshoff
keywords: CTAB; MDCK II cells; QCM; atomic force microscopy; gold nanorods; membrane tension