Transfection dendrimers

Genetic methods, in multiobjective optimization, 26 1033 Genetics, of yeast, 26 480 481 Genetic selection, 12 452 Genetic software techniques, 10 342 Gene transfection, dendrimers in, 26 791-792... 

Keywords. Polyamidoamine dendrimers. Activation of PAMAM dendrimers. Transfection, Gene transfer, DNA-dendrimer complex... 

Newly synthesized PAMAM dendrimers have a defined size and shape and can be used in gene transfer experiments, but the efficiency of transfection can be greatly increased by a process called activation of the dendrimer. In activation, some of the tertiary amines are removed, resulting in a molecule with a higher... 

PAMAM dendrimers have the following characteristics which are important for their use as transfection reagents. They bind and form complexes with nucleic acids, allow transfer of the DNA-dendrimer complex into the cytoplasm of the... 

Activated PAMAM dendrimers interact with DNA to form a DNA-dendrimer complex with a toroid-like structure (Fig. 2). Such DNA-dendrimer complexes have diameters of 50-100 nm [10],which means that the DNA molecules are highly condensed in these complexes. A 6-kb plasmid alone, for example, has an extended structure several hundred nanometers in diameter. In transfection experiments, typically an 8- to 12-fold excess of positive amino groups over negatively... 

Fig. 3. Comparison of transfection efficiencies obtained using PolyFect Reagent, a dendrimer-based transfection reagent, and a calcium phosphate-mediated procedure. COS-7 and HeLa cells were transfected in srx-weU plates with a /3-galactosidase expression plasmid using the appropriate protocol. For the calcium phosphate-mediated transfection, 6 pg of plasmid DNA was used and the medium was changed after 5 h incubation. Transfections were performed in triplicate, and transfection efficiency was measured by monitoring the /3-galactosidase activity of extracts obtained from the transfected cells. The amoimt of /3-galactosidase activity in the extracts correlates with the transfection efficiency. Cells were harvested 48 h post-trans-fection...

Dendrimers bearing certain fluorescent molecules attached on their periphery have been shown to be environmentally sensitive probes for the presence of certain metal ions or to changes in pH (Balzani et al., 2000 Paola et al., 2005). In addition, PAMAM dendrimers modified with the relatively hydrophobic dye Oregon Green 488 were shown to be a more effective transfection agent for anti-sense oligonucleotides than the dendrimer alone-plus the complex could be tracked within the cell due to the fluorescence of the dye (Yoo and Juliano, 2000). 

Dendrimer-based MRI agents, 26 795-796 Dendrimer-based transfection agent,... 

See also Luminescent dendrimers antibacterial, 26 799 biocompatibility studies of, 26 800-801 in catalysis, 26 805-806 in cell targeting, 26 797-798 as chelators, 26 806-807 core and interior shells of, 26 789 cytotoxicity of, 26 800-801 in drug delivery, 26 792-795 in gene transfection, 26 791-792 as imaging agents, 26 795-797 luminescent, 26 801-804 medical applications of, 26 791-801 micelle-mimetic behavior of, 26 789 multiphoton applications of, 26 803-804... 

They used different generations of intact dendrimers to transfect plasmid DNA in a variety of cells (Table 18.2) using luciferase, CAT (chloramphenicol acetyltransferase) and /i-galactosidasc reporter genes to quantify transfection efficiency. 

Table 18.2 Cell lines transfected with PAMAM dendrimers...

A number of experimental in vivo gene therapy trials on animals using PAMAM dendrimers are in their preliminary stages. Numerous in vivo experiments are currently being conducted in order to optimize the dendrimer generation, concentration, and complex charge ratio to obtain optimal transfection efficiency. 

---