Elastic response of cells to the photo-oxidative stress: AFM study

Scanning probe microscopy has been identified as a promising tool to characterize biological systems at scales of nanometers to microns. In particular, atomic force microscopy (AFM) and related techniques, such as force-mode AFM or molecular recognition AFM, are very well suited to the characterization of biological systems.  AFM probes the interaction of a tiny sharp tip in contact with the investigated specimen to provide information about its topography and elastic properties.  Thus, AFM, unlike other high-resolution microscopic techniques, provides not only the high resolution topographic images, but also enables one to investigate mechanical properties of living objects, for e.g., elasticity and adhesion of living cells under nearly physiological conditions.

Over the last couple of years, we have extensively used force-mode AFM, for studying the early oxidative damages to living cells at the single-cell-level [1-3]. In these experiments, by measuring the local cell elasticity, we could follow the cellular response to the deleterious action of the photo-generated ROS in the presence of water-soluble fullerol C60(OH)n [1-3] and nano-TiO2 [4]. From the AFM indentation measurements we could extract the variation of the cell´s Young´s modulus as the oxidative stress was progerssing with the time of the illumination (figure below).

AFM image a the metastatic Lu1205 cell. It was exposed to C60 derivate in the presence of UVA illumination.

The evolution of the Youmg´s modulus of the Lu1205 cell with progressive UVA illumination in the presence of C60 derivate measured  by AFM.

We have tested some anti-oxidants like curcumin, caroten, which scavange certain types of free radicals and prevent the oxidative stress and softening of cells.

[1] B. Vileno et al., CARBON 42, pp. 1195-1198 (2004).
[2] B. Vileno et al., J. Phys.: Cond. Mat. 17, pp. S1471-S1482 (2005).
[3] B. Vileno et al., Adv. Funct. Mat. 16, pp. 120-128 (2006).
[4] B. Vileno et al., Environ. Sci. Technol. 41, pp. 5149-5153 (2007).
[5] L. Chun, “Nanoparticles: Softer Skin”, Nature Nanotechnology 2, p. 459 (2007).
[6] Vileno B.; Jeney S.; Sienkiewicz A.; et al., Biophysical Chemistry, 152, 164-169 (2010).
[7] K. Pierzchała, M. Lekka, A. Magrez, A. J. Kulik, L. Forro, and A. Sienkiewicz, “Photocatalytic and phototoxic properties of TiO2–based nanofilaments: ESR and AFM assays”, Nanotoxicology doi:10.3109/17435390.2011.625129 (2012).