In this review we summarize and discuss the different methods we can use to achieve reversible DNA compaction
in vitro. Reversible DNA compaction is a natural process that occurs in living cells and viruses. As a result these
process long sequences of DNA can be concentrated in a small volume (compacted) to be decompacted only when the information
carried by the DNA is needed. In the current work we review the main artificial compacting agents looking at
their suitability for decompaction. The different approaches used for decompaction are strongly influenced by the nature
of the compacting agent that determines the mechanism of compaction. We focus our discussion on two main artificial
compacting agents: multivalent cations and cationic surfactants that are the best known compacting agents. The reversibility
of the process can be achieved by adding chemicals like divalent cations, alcohols, anionic surfactants, cyclodextrins
or by changing the chemical nature of the compacting agents via pH modifications, light induced conformation changes or
by redox-reactions. We stress the relevance of electrostatic interactions and self-assembly as a main approach in order to
tune up the DNA conformation in order to create an on-off switch allowing a transition between coil and compact states.
The recent advances to control DNA conformation in vitro, by means of molecular self-assembly, result in a better understanding
of the fundamental aspects involved in the DNA behavior in vivo and serve of invaluable inspiration for the development
of potential biomedical applications.
DNA, compaction, decompaction, reversibility, condensation, gene delivery.
Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, 2100 Copenhagen Ø / Denmark.