Dresden 2003 – wissenschaftliches Programm

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CPP: Chemische Physik und Polymerphysik

CPP 21: POSTER B

CPP 21.2: Poster

Dienstag, 25. März 2003, 19:00–21:00, ZEU/250

Direct Observation of DNA Complexation with Positively Charged Latex Particles — •Binyang Du, Jingjing Nie, Stephan Herminghaus, and Thomas Pfohl — Applied Physics Laboratory, University of Ulm, D-89069 Ulm

The complexation of charged particles with oppositely charged polyelectrolytes has attracted great interest due to its importance in many industrial and biological systems. Recent theoretical and simulation studies show that these complexes can form rich structures, depending on the conditions of the considered systems. Herein, we present the direct observation of the complexation of positively charged polystyrene latex beads with negatively charged DNA by using fluorescence microscopy. Fixing the concentration of positive latex beads, first single complexes are formed, then they condense into big aggregates, and reenter into single complexes when the charge ratio of DNA to latex beads (-/+) is increased from 1:8 up to 100:8. Huge complexes are found in the charge ratio regime close the isoelectric point. Typical complexes with special structures, named as beads-on-a-string complex and one-tail complex, which are expected by the theorectical and simulation studies, are experimentally observed at a charge ratio of 100:8. Our results also indicate that complexes of different structures can coexist in polydisperse polyelectrolyte systems.