Alexander Eychmüller

Nanomaterials for biology and medicine

Previous and current research

We have long lasting expertise in colloidal synthesis, characterisation, surface functionalisation and various types of assemblies of semiconductor and metal nanoobjects. Semiconductor nanocrystals are synthesised in water or organic solvents and possess narrow and strong emissions covering, depending on particle composition and size almost the whole UV-Vis-NIR spectral region, namely 350-2000 nm. Metal and metal oxide nanocrystals possess attractive size-dependent optical or magnetic properties. We apply these nanoparticles as thin films, in polymer or silica nano- and microparticles, as colloidal photonic crystals, as thin-film polymer-nanocrystal composites, in LEDs, solar cells, and as bio-labels. Biolabelling is the addition of a marking substance, a label, which can subsequently be detected, to a biological sample in order to learn something about the local biological and/or biochemical environment. One example is immunofluorescence which is the labeling of antibodies or antigens with fluorescent dyes. This technique is sometimes used to make viral plaques more readily visible to the human eye. Immunofluorescently labeled tissue sections may then be studied using a fluorescence microscope. The role of the dye is to emit (fluoresce) when the sample is illuminated and the emission can then be detected using a fluorescence detector. These dyes may be substituted by nanoparticles with the following advantages:

• Nanoparticles can be made exceptionally chemically and photo-chemically stable. They can deliver the same intensely bright signals in diverse harsh environments and following prolonged periods of irradiation that would completely bleach the signal from conventional dyes.
  
• Nanoparticles can achieve quantum yields comparable to the brightest traditional dyes available and can absorb 10 - 1000 times more light than competitive dyes. These two properties combined can result in the single brightest class of fluorescence materials available anywhere. This unsurpassed stability and brightness may allow access to observe rare molecules that by using conventional sources would be unobservable.
  
• The emission from nanoparticles is narrow and symmetric which means spectral overlap with other colors is minimized. That translates into minimal bleed through into adjacent detection channels and attenuated crosstalk, in spite of the fact that many more colors can be used simultaneously.
  
• Since each emitted color is based upon the same underlying material the chemistry and methods used for one color are easily extrapolated to all of the colors.
  
• All the nanoparticles can be excited using a single light source and so both narrow laser and broad lamp excitation may be used. Hence three or four-color detection may be achieved without the need for two or more lasers and laborious alignments and compensations.

Future prospects and goals

• Investigations on new synthetic approaches leading to NIR-emitting materials with potential bio-medical applications.
• Participation in the DFG Priority Program “Biological Responses to Nanoscale Particles” with the project  “Interactions of hydrophobic and hydrophilic semiconductor quantum dots with cell model systems for liver and adipose tissue”.
• Coupling of semiconductor and metal nanoparticles aimed to the fabrication of “artificial molecules” from “artificial atoms”.
• Development of new approaches to the synthesis, assembly and characterization of these structures.
• Fabrication and optimization a nanocrystals-based injection solar cells.
  

About

1987: PhD in Physics, Max-Planck-Institut for Biophysical Chemistry , Göttingen, Germany 1987-1988: Research fellowship of the German Science Foundation (DFG) with Prof. M. A. El-Sayed at the University of California Los Angeles on "Catalytic Processes on the Molecular Level" 1988-1994: Researcher at the Hahn-Meitner-Institute in Berlin in the Dept. of Photochemistry with Prof. A. Henglein working on Structure and Photophysics of Colloidal Semiconductor Nanocrystals 1994-2005: Senior Researcher at the Institute for Physical Chemistry, University of Hamburg in the group of Prof. H. Weller 1999: Habilitation for Physical Chemistry, "Structure and Photophysics of Nanocrystalline Semiconductor Particles" since 2005: Chair for Physical Chemistry/Electrochemistry, TU Dresden

Selected publications

N. C. Bigall, A. K. Herrmann, M. Vogel, M. Rose, P. Simon, W. Carrillo- Cabrera, D. Dorfs, S. Kaskel, N. Gaponik, A. Eychmüller: Hydrogels and Aerogels from Noble Metal Nanoparticles, Angew. Chem. Int. Ed. 48 (2009) 9731, Angew. Chem. 121 (2009) 9911

B. Nandan, E. B. Gowd, N. C. Bigall, A. Eychmüller, P. Formanek, P. Simon,  M. Stamm: Arrays of Inorganic Nanodots and Nanowires Using Nanotemplates Based on Switchable, Block Copolymer Supramolecular Assemblies Adv. Funct. Mat. 19 (2009) 2805

O. T. Bruns, H. Ittrich, K. Peldschus, M. G. Kaul, U. I. Tromsdorf, J.Lauterwasser, M. S., Nikolic, B. Mollwitz, M. Merkel, N. C. Bigall, S. Sapra, R. Reimer, H. Hohenberg, H., Weller, A. Eychmüller, G. Adam, U. Beisiegel, J. Heeren: Real time MR imaging of lipoprotein metabolism using lipophilic nanocrystals in vivo, Nature Nanotechnology 4 (2009) 193

S. G. Hickey, C. Waurisch, B. Rellinghaus, A. Eychmüller: Size and Shape Control of Colloidally Synthesized IV-VI Nanoparticulate Tin(II) Sulfide(SnS), J. Am. Chem. Soc. 130 (2008) 14978

N.C. Bigall, M. Reitzig, W. Naumann, P. Simon, K.-H. van Pée, A. Eychmüller: Fungal Templates for Noble Metal Nanoparticles and their Application in Catalysis, Angew. Chemie Int. Ed. 47 (2008) 7876, Angew. Chemie 120 (2008) 7994

Home page