Polymer-DNA complex

This type of DNA/polymer complex includes DNA alone, since both DNA strands are linked via hydrogen bonding. Also included are DNA assemblies containing sequence blocks that do not participate in double-helix formation. 

Fig. 1 Proposed mechanism of gene transfection [117]. (1) Formation of the DNA/polymer complex (polyplex), (2) endocytosis of the polyplex, (3) fusion of endosome and lysosome, (4) release of the polyplex into the cytosol, (5a) incorporation of the polyplex into the nucleus, (5b) release of the siRNA into the cytosol, (6) transcription of the DNA into mRNA followed by release of the polyamine back into the cytosol, (7a) translation of mRNA, and (7b) mRNA degradation. The metabolism of the polyamine is still unclear. Reproduced with permission from [117]. Copyright 2002 Elsevier...

Figure 3.7 A tapping mode AFM image of plasmid DNA-polymer complexes (obtained using tapping mode in aqueous buffer) showing double tipping. The repeating features allow this type of imaging artefact to be easily recognized (image provided courtesy of 3.E. Ellis, University of...

Figure 3.2 Schematic of cellular uptake ofnonviral vector DMA complexes and evasion from lysosomal degradation (a) shows the general proposed method and (b) Illustrates more detailed mechanism of endolysosomal escape. In (b), the top figure outlines normal lysosomal degradation through active hydrolytic enzymes due to the buffering capacity of many polycations, hydrolytic enzymes are not activated and the DNA-polymer complex is able to escape degradation (lower figure).

Finally, building on the previous success of both EUis et al. [89] and Bezanilla et al. [18], Abdelhady et aL [9] used AFM to depict a series of time-lapse images (Fig. 6) of the degradation of DNA-polymer complexes by DNasel. Here DNA was exposed to the enzyme either in its condensed state (condensed by poly(amidoamine) (PAMAM) dendrimers) or its naked state (in the absence of polymer). The protection conferred to DNA by the PAMAM... 

---