Timm Heek

An Amphiphilic Perylene Imido Diester for Selective Cellular Imaging

A new amphiphilic membrane marker based on a water-soluble dendritic polyglycerol perylene imido dialkylester has been designed, synthesized, and its optical properties characterized. In water it forms fluorescently quenched micellar self-aggregates, but when incorporated into a lipophilic environment, it monomerizes, and the highly fluorescent properties of the perylene core are recovered. These properties make it an ideal candidate for the imaging of artificial and cellular membranes as demonstrated by biophysical studies.

Synthesis and Optical Properties of Water-Soluble Polyglycerol-Dendronized Rylene Bisimide Dyes

Four new water-soluble polyglycerol-dendronized perylene, terrylene, and quaterrylene bisimides have been synthesized and characterized with respect to their optical properties in polar organic solvents and water by using UV/Vis and fluorescence spectroscopy. All of these dyes were highly soluble in water, but the size of the chosen polyglycerol dendron was only sufficient to completely suppress dye aggregation for the core-unsubstituted perylene derivative. Their high solubility in water and their absorption and emission wavelengths up to the NIR region make the core-unsubstituted perylene and terrylene bisimides ideal candidates for applications in bioimaging, whilst the lack of fluorescence for quaterrylene bisimide in all polar solvents does not warrant further investigation of this chromophore in fluorescence and imaging applications. Likewise, tuning of the emission of rylene bisimides towards longer wavelengths by employing electron-donating bay substituents is not a promising strategy, owing to the lower fluorescence quantum yields in polar solvents and, in particular, in water.

Excitation characteristics of different energy transfer in nanotube-perylene complexes

We report the properties of perylene-nanotube complexes that form efficient energy transfer systems. Most perylene-derivatives yield similar ratios between transfer and direct luminescence (0.66 ± 0.04). The photoluminescence spectra of the free compounds and the transfer complex are similar indicating that perylene and nanotubes act as separate systems. A further increase in interaction yields 40% higher transfer rates and luminescence excitation spectra that indicate a change in stacking of the perylene on the nanotube wall. All measurements are consistent with a transfer mechanism based on a dipole-dipole interaction at a distance much smaller than the Forster radius.

Synthesis, Photophysical, and Biological Evaluation of Sulfated Polyglycerol Dendronized Perylenebisimides (PBIs)—A Promising Platform for Anti-Inflammatory Theranostic Agents?

A set of four water-soluble perylene bisimides (PBI) based on sulfated polyglycerol (PGS) dendrons were developed, their photophysical properties determined via UV/vis and fluorescence spectroscopy, and their performance as possible anti-inflammatory agents evaluated via biological in vitro studies. It could be shown that in contrast to charge neutral PG-PBIs the introduction of the additional electrostatic repulsion forces leads to a decrease in the dendron generation necessary for aggregation suppression, allowing the preparation of PBIs with fluorescence quantum yields of >95% with a considerable decreased synthetic effort. Furthermore, the values determined for L-selectin binding down to the nanomolar range, their limited impact on blood coagulation, and their minor activation of the complement system renders these systems ideal for anti-inflammatory purposes.