Analytical tools for surface characterization at the nano scale

Dr. Wesner will discuss analytical techniques to study different interactions at interfaces ranging from biomolecules to organic thin film.

ABSTRACT:  Surfaces and interfaces play a central role in the interactions between materials and due to their accessibility they offer an important means to control them. Apart from the chemical composition itself, essential aspects are material characteristics like the topography and mechanical properties, as well as characteristics in the interrelation with the surrounding medium like hydrophilicity and zeta potential. The relevant distances in the nm range require suitable techniques to study the effects that are crucial for biological as well as materials science. In this talk I will discuss analytical techniques to study different interactions at interfaces ranging from biomolecules to organic thin films:

•Nanoparticles, proteins and cells
•Polymer vesicles, surface nanobubbles
•Thermoresponsive polymer brushes
•Organic thin films (OFET)

Due to its versatility atomic force microscopy (AFM) is used in all studies and complemented by other microscopic or spectroscopic techniques like electron microscopy, fluorescence microscopy, confocal fluorescence lifetime imaging (FLIM), and surface plasmon resonance (SPR). The combination of multiple techniques and especially simultaneous measurements at the same location add significant information that would otherwise be unattainable.

Daniel Wesner is a postdoctoral researcher in Biological and Environmental Engineering in the lab of Prof. Tammo Steenhuis at Cornell University. There he works on the adhesion of colloidal particles on surfaces and the impact of meniscus forces during drying of particle suspensions. Daniel studied biochemistry and biophysics at University of Bielefeld in Germany and obtained his Ph.D. under the supervision of Prof. Dario Anselmetti studying the binding and uptake of nanoparticles by lung cells. He worked for JPK Instruments, a Berlin based manufacturer of AFMs, before joining the group of Prof. Holger Schoenherr at the University of Siegen as postdoctoral researcher. There he set up a combined system of AFM and confocal fluorescence lifetime imaging microscopy to study surface nanobubbles and polymer vesicles, which are developed as diagnostic tool for bacterial infections. He was responsible for the new established cell culture lab to analyze the effect of the microenvironment on cell adhesion and growth. During a research stay in Adelaide, Daniel worked with Prof. Nico Voelcker on an AFM based study of nanoparticles in cancer therapy.