Microscopy and optical manipulation of dendrimer-built vesicles*
T. Gensch1,**, K. Tsuda1, G. C. Dol1, L. Latterini1, J. W. Weener2,
A. P. H. J. Schenning2, J. Hofkens1, E. W. Meijer2, and F. C. De Schryver1
1Department of Chemistry, Katholieke Universiteit Leuven,
Celestijnenlaan 200F, 3001 Heverlee, Belgium; 2Laboratory of Macromolecular
and Organic Chemistry, Eindhoven University of Technology, P.O. Box
513, 5600 MB Eindhoven, The Netherlands
Abstract: A fifth-generation poly(propylene imine) dendrimer
decorated with palmitoyl- and azobenzene-containing alkyl groups forms
giant vesicles in aqueous solutions with diameters from 50 nm up to
20 mm and a multilaminar onion-like structure. Dense and ordered arrangement
of the azobenzene chromophores in the bilayer structure leads to fluorescence
with lmax= 600 nm. The fluorescence intensity can be increased by irradiation
with blue light, and at low pH a distinctive blue shift of the spectrum
is observed. With the aid of a single-beam optical tweezers it is possible
to trap vesicles and direct them in a billiard-like fashion against
each other using forces in the range of several pN. In collision experiments,
the vesicles behave like hard spheres, and merging is not observed.
*Lecture presented at the XVIIIth IUPAC Symposium on
Photochemistry, Dresden, German , 22-27 July 2000.Other presentations
are published in this issue, pp.395-548.
** Corresponding author
