Polymeric effects on DNA condensation by cationic polymers observed by atomic force microscopy

Compaction of DNA by condensing agents can provide insights into DNA assembly processes, which is keenly related to the essence of gene transfection and gene therapy in vivo. In this paper, the morphology of different cationic polymer/DNA complexes was studied by using atomic force microscopy (AFM), which is keen to the mechanism of DNA condensation induced by amine-based cationic block copolymers with poly(poly(ethylene glycol) methyl ether methacrylate). It is found that the structures and dimensions of condensing agent/DNA complexes are sensitively dependent on the condensing agents. The size of DNA aggregates can be affected appreciably by polymers rather than monomers. The amount of nitrogen elements per polymer unit, rather than the molecular weights of polymers, appears to be more effective on the dimension of the condensates. The impact of the copolymer chain structures on the DNA aggregates indicates an effective venue for regulating the dimensions and structures of the DNA condensates, which is beneficial for optimizing delivery systems for gene transfection.