Biophysically oriented studies

The leitmotif of our biophysically oriented studies is oxidative stress caused by reactive oxygen species (ROS). We are interested in mechanisms of ROS formation in the presence of various kinds and forms of nano-engineered materials. We focus on nano-ZnO, nano-TiO2, fullerenes and carbon nanotubes (CNTs), which are now becoming the most popularized man-made nanoparticulate systems. In particular, nano-ZnO and nano-TiO2 have found numerous applications in food and construction industries as well as in drugs and cosmetic products. Fullerenes are used as ingredients of certain polymers and as anti-oxidants.

We study the efficacy of these materials to generate ROS in aqueous media as a function of their characteristic features, such as type, primary grain size, crystalline phase, aspect ratio and agglomeration state. In particular, to tackle the mechanisms of ROS generation, as well as to evaluate the toxic potential of nano-engineered materials, we use such techniques as Electron Spin Resonance (ESR), Atomic Force Microscopy (AFM), optical fluorescence microscopy and spectro-photometry.

Photonic Force Microscope (PFM) is an excellent tool for biophysical studies since it operates in aqueous environment. We have developed the best of its kind, which is suitable to address basic physical questions such as Brownian motion at short time-scales, next to surfaces, constrictions, viscosity inside cells and to perform biomechanical measurements.

The spectrum of our biophysical related activity is listed below:

1. Cell elasticity measured by AFM.

We use extensively force-mode AFM, for studying the early oxidative damages to living cells at single-cell-level. 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 nanoparticles.

2. Scanning infrared spectro-microscopy study of biomatter.

Based on synchrotron radiation, the scanning infrared spectro-microscopy (SIRMS) enables the creation of a vibrational map of tissues, cells with a spatial resolution of few microns. This allows the localization of regions where structural/biochemical changes have happened. These maps carry quantitative information of the sample in contrast to simple fluorescence imaging.

3. Detection of Reactive Oxygen Species

To detect and distinguish various Reactive Oxygen Species, we use Electron Spin Resonance (ESR), a very sensitive and most definitive method to detect short-lived reactive oxygen intermediates applying a spin-trapping technique to stabilize highly reactive free radicals.

4. Biophysical application of up-converting nanoparticles.

We are interested in physical and photo-physical aspects of inorganic up-converting materials. Our goal is to develop efficient up-converting systems for very improved biological imaging and deep-tissue photo-oxidations (such as in PDT).

5. Photonic Force Microscopy in soft condensed matter.

In high performence optical tweezers, called a Photonic Force Microscope we use a Brownian particle which explores the surrounding, the interactions, viscosity etc. The deviations from the free Brownian motion carries the information.

6. Malaria inspired research.

The parasite of malaria detoxifies the liberated Fe species from the red blod cells by forming a hemozoin single crystal. Its magnetic structure is one of the goals of our research.