DNA condensation using cationic dendrimers-morphology and supramolecular structure of formed aggregates

The control of DNA condensation, i.e. packaging or compaction, is essential for the living cell, but also important in many applications. One example is gene therapy that often utilises vehicles with the ability to condense DNA and thereby protect DNA against degradation, transport DNA across membranes (which act as barriers towards gene delivery), and regulate gene expression. This review discusses the ability of poly(amido amine) dendrimers to condense DNA molecules via attractive electrostatic interactions, which in turn leads to self-assembled structures with a rich variety of morphologies. The process of condensation is cooperative and kinetically controlled, and the structure of the aggregates strongly depends on the size and charge of the dendrimer, and the salt concentration of the aqueous solution. While globular aggregates are formed by large dendrimers, rods and toroids are formed by smaller sized dendrimers with lower total charge per molecule. The globular aggregates appear to be disordered, but the smaller dendrimers give rise to high-ordered packing of the DNA in ordered arrays according to a square or hexagonal unit cell. The high-ordered packing also indicates that the dendrimers deform while inducing the DNA to condense.