Open positions

Formulations for transdermal vaccination
 
Peter Langguth (FB09, Pharmacy), Hansjörg Schild (Medicine), Markus Radsak (Medicine) 

[new May 2011]

In this project formulations for dermal administration of antigens and immuno potentiators are developed with the aim of crating transdermal vaccination protocols. Various formulation principles are being evaluated based on conventional ointments, nanosuspensions and nanoemulsions. In vitro and in vivo models are being used to predict the performance of the formulated compounds.
 

Activation of type 3 copper proteins with artificial and natural lipid vesicles

Heinz Decker (FB10, Biology, E-mail), Dirk Schneider (FB9, Biochemistry)

[new April 2011]

Type 3 copper proteins occur in almost all organisms and comprises the enzymes tyrosinase and catecholoxidase as well as the oxygen carriers hemocyanin which can also be converted to enzymes. The enzymes start the synthesis of the complex polymer melanin which is responsible for the browning of fruit, skin and hair as well as immunological responses and for protection against UV sun light. The proteins are therefore important for the food and cosmetic industry as well as for immunology and in arthropods for wound healing to build up the new cuticula after injury and molting. Activation of these proteins to active enzymes is induced by artificial micelles and lipid vesicles. In order to mimic the natural activation process of these proteins as tyrosinases/catecholoxidases synthetic vesicles with various lipid compositions are prepared and tested. Thus, we hope to understand the activation and catalytic process and will be able to control and optimize the function of these proteins by mutagenesis and the design of inhibitors.
 

Hemocyanin as oxygen carrier

Heinz Decker (FB10, Biology, E-mail), Jürgen Markl (FB10, Biology)

[new in April 2011]

Atmospheric dioxygen is essential for complex life on Earth. To avoid problems with its radical forms, the reactive oxygen species (ROS), oxygen carriers such as hemocyanins are needed to transport dioxygen from the lungs or gills to the muscles. Hemocyanins are the largest protein complexes (Mr up to 8 MDa) found in nature with up to 160 interacting oxygen binding centers arranged in various cooperative aggregates. The extreme cooperativity in oxygen binding is based on the hierarchy in allosteric interactions being assigned to obvious hierarchies in the structure. Thus, hemocyanins may also serve as natural objects for synthetic devices for nanomachines.

In addition these complex hemocyanins serve as oxygen carriers since hundreds of millions of years during which the atmosphere did undergo big changes. We want to learn more about the adaptation of hemocyanins with respect to respiration and binding of other gases.

To understand the mechanisms, crystal structure determination and cryo-electron microscopy will resolve the 3D structure while x-ray and light scattering and analytical ultracentrifugation provide the information about the behavior in physiological like solutions.
 

Optical Probes of Charge Generation and Recombination in Dye-sensitized Solar Cells

Frédéric Laquai (MPRG Organic Optoelectronics – MPIP) and Rudolf Zentel (Chemistry, Uni Mainz)

[new March 2011]

Dye-sensitized solar cells (DSSCs) are a potentially low-cost and efficient technology to generate electrical power from the most abundant energy source, the sun. However, the interfacial processes leading to charge generation and the efficiency-limiting charge recombination pathways are still not entirely understood.

The main focus of the project is thus the investigation of charge injection and charge recombination in dye-sensitized solar cells by using optical probes, for instance femtosecond to millisecond time-resolved absorption (pump-probe) spectroscopy as well as steady-state photoinduced absorption experiments among other techniques that are all available within the group. Preparation, characterisation and optimization of functional devices are secondary topics.

The Max Planck Research Group for Organic Optoelectronics has a great expertise in time-resolved optical spectroscopy as well as charge transport experiments on organic semiconductors and works closely together with internal and external academic and industrial material developers. Apart from state-of-the-art laboratories, we also offer a stimulating and pleasant work environment.
 
 

Charge Generation and Recombination in Bulk Heterojunction Organic Solar Cells

Frédéric Laquai (MPRG Organic Optoelectronics – MPIP) and Thomas Basché (Physical Chemistry, Uni Mainz)

[new in March 2011]

Bulk heterojunction photovoltaic devices that use a blend of an organic electron donor and acceptor material for photon to charge conversion have many interesting advantages compared to traditional silicon-based solar cells, such as low weight and mechanical flexibility, which will be of importance for future mobile applications.

Although recently power conversion efficiencies exceeding 8 % have been demonstrated, the loss processes limiting the device efficiency as well as the degradation pathways of the organic material that impede commercialization are still poorly understood. In this project novel combinations of donor polymers and acceptor materials will be investigated by means of time-resolved optical spectroscopy to elucidate the charge generation and recombination processes. In combination with charge transport and device measurements as well as morphology investigations a precise picture of the photophysics of different material systems will be developed.

The Max Planck Research Group for Organic Optoelectronics has a great expertise in time-resolved optical spectroscopy as well as charge transport experiments on organic semiconductors and works closely together with internal and external academic and industrial material developers. Apart from state-of-the-art laboratories, we also offer a stimulating and pleasant work environment.
 

Trace metals in the atmosphere: sources, transport and impact on atmospheric chemistry

Holger Tost(Uni Mainz (FB08)), Jos Lelieveld (MPI for Chemistry)

[new in March 2011]

Metal ions are found in aerosol particles all trough the atmosphere originating from both natural (mineral dust, volcanoes) and anthropogenic (industry) sources. They occur in all size ranges from the fine mode particles which cannot easily removed by filters in industrial facilities to the largest particles (crustal material). Once in the atmosphere these ions can be transported by the wind and undergo chemical reactions influencing the composition of the atmosphere and altering reaction pathways as catalysts. Furthermore, some metals, e.g. iron, are important fertilisers for the oceans, but the fertilising efficiency depends on the oxidation state of the metals of the atmospheric input.

This project will link the expertise in atmospheric multiphase chemistry from the MPI-C and Earth System Modelling at the Institute for Physics of the Atmosphere at the University.

The project involves the creation of suitable emission maps for trace metals (based on the categories of emission sources for other atmospheric relevant species), and the development and application of a suitable chemical reaction mechanism for trace metals for the aqueous phase chemistry to be applied in the global chemistry climate model EMAC, which is used at both institutes. Numerical simulations should shed light onto the importance of the global impact of trace metals, the transport and dispersion from the source regions, as well as the anthropogenic versus natural contributions.
 

Multiscale processes responsible for the tracer transport from the atmospheric boundary layer into the free troposphere

Volkmar Wirth (Uni Mainz), Mark Lawrence (MPI-C)

[updated April 2011]

Atmospheric moist convection is a key process which determines the distribution of trace gases on the local, regional and global scale. Current regional-scale models allow the simulation of the evolution of individual clouds. However, the details of the evolution and, especially, the coupling to the turbulent boundary layer are either underrepresented or parameterized. This can influence the triggering of moist convection and the ensuing cumulus dynamics, as well as the
concentration of gases and aerosols in the cloud inflow regions. 
This project shall connect the experience in Large-Eddy-Simulation (LES) at the University of Mainz with the expertise in cloud resolving modeling at the MPI-C. It aims to enhance our understanding on how turbulent processes in the boundary layer influence the effective tracer transport into the free troposphere.

Flow Properties of Ordered Colloidal Suspensions in Restricted Geometry

Thomas Palberg (FB08, Physics) and Hans-Jürgen Butt (MPI Polymer Research)   

updated March 2011

Colloidal suspensions form fluid or crystalline ordered states once the range and strength of interaction between the colloidal particles becomes sufficiently large and long-ranged. Due to the excellent accessibility by optical methods most of their corresponding bulk properties are already well understood. We here aim at a deeper understanding of ordering and dis-ordering processes in such soft matter model systems under extreme mechanical load and conditions far off equilibrium. We therefore plan a comprehensive study of their behaviour under flow through narrow slits and pores. Using microscopy and light scattering the response to different driving fields, the mechanisms of shear induced melting and crystallization and the location of non equilibrium phase boundaries will be addressed. Data interpretation will proceed in close collaboration with theoretical groups at Düsseldorf and Utrecht. For a successful approach the involved PhD-Student should have experience in at least two of the following areas: condensed matter physics, light scattering, optical microscopy, image analysis, physics and chemistry of colloids.