Fluoresence Based Molecular Methods and Technologies
Professor Pekka Hänninen, Ph.D.
The main goal of the Laboratory of Biophysics is to produce new tools to monitor biomolecular interactions. The application fields lie in in-vitro diagnostics, drug discovery studies and research.
Optical methods have become the method of choice in studies of living (aqueous) samples. The use of visible light and fluorescence detection combines the fields of optical physics, chemistry, biochemistry and biology in a joint effort to solve questions related to the function of organelles at the cellular level and beyond. Among the most known paradigms in physical sciences is the limit of spatial resolution imposed by the use of light. One of the aims of the photonics research at the laboratory of biophysics is to go beyond this limit using different technologies: optical nanoscopy, non-linear excitation of fluorescence and the use of nanometer scale rulers.
The optical nanoscopy aims at fluorescence optical imaging with an enhanced imaging resolution compared to the normal confocal microscopy. Achieving a resolution down to tens of nanometers is possible using saturable switchable states of molecular fluorophores. The classical limits of optical resolution can be circumvented by exploiting the switchable dark (or light) states of molecules, thus generating for the sample frequencies far beyond the classical limits. This approach is studied in collaboration with the Max-Planck Institute for Biophysical Chemistry.
Another approach to optical nanoscopy is the scanning near field microscopy. Although the techniques (SNOM, AFM tip enhanced fluorescence) are limited to surface phenomena, the technique provides complementary information since the movement of the tip can be controlled very precisely making it almost an ideal nano-manipulator withe the capability of measuring infinitecimal forces.
Non-linear excitation of fluorescence confines the volume of excitation to a fraction of a femtoliter yielding an excellent signal-to-background ratio and enabling detection limits down to single molecule level even in samples where conventional confocal systems fail. The best known technology belonging to this area is the two-photon excitation of fluorescence.
In the approach of nanometer scale rulers, near field effects of small metallic nanoparticles, labels or dyed nanoparticles are used in quenching or enhancing the luminescence of molecular labels. The effects are non-linear and can change orders of magnitude with just nanometer changes in distances between the two "partners" of this interaction.
The Laboratory of Biophysics has also directed studies on fundamental properties of biomolecular interactions and modeling of these interaction are being exploited by the academic community and industrial partners.
| Senior Scientists | Docent Juhani Soini, Ph.D. Dr. Juha Toivonen, Ph.D. Dr. Harri Härmä, Ph.D. |
| Graduate students | Pilvi Ylander, M.Sc. Rina Wahlroos, M.Sc. Marko Tirri, M.Sc. Teppo Stenholm, M.Sc. Janne Koskinen, M.Sc. |
| Secretary | Soili Huhta |