We actuate with light & magnets, we fold & unfold DNA, we cell-free express proteins, we play with drops, marbles & interfaces, we organize particles, we harness coffee rings.

Photosensitive polyamines make DNA photocontrollable and ACS Nano!

28 Feb2014. Our manuscript "Photosensitive Polyamines for High-Performance Photocontrol of DNA Higher-Order Structure" has just been accepted in ACS Nano.

Abstract: Polyamines are small, ubiquitous positively-charged molecules that play an essential role in numerous biological processes such as DNA packaging, gene regulation, neuron activity, and cell proliferation. Here, we synthesize the first series of photosensitive polyamines (PPAs) and demonstrate their ability to photoreversibly control nanoscale DNA higher-order structure with high efficiency. We show with fluorescence microscopy imaging that the efficiency of the PPAs as DNA compacting agents is directly correlated to their molecular charge. Micromolar concentrations of the most efficient molecule described here, a PPA containing three charges at neutral pH, compacts DNA molecules from a few kilobase pairs to a few hundred kilobase pairs, while subsequent 3 min UV illuminations at 365 nm triggers complete unfolding of DNA molecules. Additional application of blue light (440 nm for 3 min) induces the refolding of DNA into the compact state. Atomic force microscopy reveals that the compaction involves a global folding of the whole DNA molecules whereas UV-induced unfolding is a modification initiated from the periphery of the compacted DNA, resulting in the occurrence of intermediate flower-like structures prior to the fully unfolded state.


Photosensitive Polyamines for High-Performance Photocontrol of DNA Higher-Order Structure
A. Venancio-Marques, A. Bergen, C. Rossi-Gendron, S. Rudiuk, D. Baigl*
ACS Nano 2014, in press
 - doi : 10.1021/nn500266b