Emerging of fractal geometry on surface of human cervical epithelial cells during progression towards cancer.

Despite considerable advances in understanding the molecular nature of cancer, many biophysical aspects of malignant development are still unclear. Here we study physical alterations of the surface of human cervical epithelial cells during stepwise in vitro development of cancer (from normal to immortal (premalignant), to malignant). We use atomic force microscopy to demonstrate that development of cancer is associated with emergence of simple fractal geometry on the cell surface. Contrary to the previously expected correlation between cancer and fractals, we find that fractal geometry occurs only at a limited period of development when immortal cells become cancerous; further cancer progression demonstrates deviation from fractal. Because of the connection between fractal behaviour and chaos (or far from equilibrium behaviour), these results suggest that chaotic behaviour coincides with the cancer transformation of the immortalization stage of cancer development, whereas further cancer progression recovers determinism of processes responsible for cell surface formation.

Cell surface as a fractal: normal and cancerous cervical cells demonstrate different fractal behavior of surface adhesion maps at the nanoscale.

Here we show that the surface of human cervical epithelial cells demonstrates substantially different fractal behavior when the cell becomes cancerous. Analyzing the adhesion maps of individual cervical cells, which were obtained using the atomic force microscopy operating in the HarmoniX mode, we found that cancerous cells demonstrate simple fractal behavior, whereas normal cells can only be approximated at best as multifractal. Tested on ~300 cells collected from 12 humans, the fractal dimensionality of cancerous cells is found to be unambiguously higher than that for normal cells.

Towards nano-physiology of insects with atomic force microscopy.

Little study of insects with modern nanotechnology tools has been done so far. Here we use one of such tool, atomic force microscopy (AFM) to study surface oscillations of the ladybird beetles (Hippodamia convergens) measured in different parts of the insect at picometer level. This allows us to record a much broader spectral range of possible surface vibrations (up to several kHz) than the previously studied oscillations due to breathing, heartbeat cycles, coelopulses, etc. (up to 5-10Hz). Here we demonstrate three different ways with which one can identify the origins of the observed peaks - by physical positioning the probe near a specific organ, and by using biological or chemical stimuli. We report on identification of high frequency peaks associated with H. convergens heart, spiracular closer muscles, and oscillations associated with muscles activated while drinking. The method, being a relatively non-invasive technique providing a new type of information, may be useful in developing "nanophysiology" of insects.

A novel in vitro stripping method to study geometry of corneocytes with fluorescent microscopy: example of aging skin.

BACKGROUND/PURPOSE: To develop modification of stripping method allowing high-resolution fluorescent visualization of corneocytes of human skin in vitro. To validate the method, the measured corneocyte areas on skin flakes are collected from individuals of different ages. MATERIALS AND METHODS: Two complimentary fluorescent dyes were used sequentially. First the adhesive layer of the stripping tape was stained with a cationic dye (rhodamine 640). This tape was used to collect skin flakes. Then both the tape and collected flakes were stained with anionic dye (fluorescein). The fluorescence of the adhesive tape exposed to the second staining is substantially decreased due to the mutual quenching of the dyes. Thirteen healthy, 6-86-year-old males participated to validate the method. The measurements were done on backhand and forearm. RESULTS: The method allows high-resolution imaging of corneocytes by means of fluorescent microscopy. Both absolute areas and the dependence of corneocyte areas on the individual age are in good agreement with the data reported previously. CONCLUSION: The developed method is fast and easy. It requires minimum interaction with the individual and allows using a broad variety of fluorescent dyes that may be potentially unsafe but beneficial for imaging. It can be used on any part of human or animal body.