Regensburg 2016 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

CPP: Fachverband Chemische Physik und Polymerphysik

CPP 8: Hydrogels and Microgels

CPP 8.4: Vortrag

Montag, 7. März 2016, 16:00–16:15, H40

Thermal traps trigger sol-gel phase transitions of DNA with single base sequence selectivity — •Christof B. Mast, Matthias Morasch, Emil Agerschou, Jonathan Liu, and Dieter Braun — Systems Biophysics, Physics Department, Center for Nanoscience, LMU Munich, Germany

Sol-gel phase transitions of DNA normally require long strands, high concentrations and multivalent ions for condensation. We demonstrate that a thermal gradient across a water-filled chamber creates DNA hydrogels from dilute, nanomolar concentrations of short, 36 nts DNA strands without condensation agents. The thermal gradient leads to fluid convection and thermophoresis, which in combination accumulate long biomolecules over short ones. The DNA is composed out of three self-complementary sequences which elongate by hybridization once millimolar concentrations are achieved. At nanomolar concentration, the DNA is an unbound single molecule. Inside the thermal gradient, the molecules accumulate and the self-complementary DNA connect cooperatively to longer and subsequently even better accumulating strands, ultimately leading to the formation of a DNA hydrogel. This localized phase transition is highly sequence selective: self-elongating DNA with a single base pair change per binding site separates from the unchanged DNA upon gelation which leads to the formation of two distinct, sequence pure gels. One single point-mutation at a single binding site can prevent the formation of the hydrogel. The mechanism implements a prebiotic machine that selects and stores oligonucleotides with very similar sequences starting from nanomolar concentration.