Delivery Agents for Nucleic Acids and Drugs

The use of liposomes for transfection purposes was first described in 1987. Cationic lipids prepared for this purpose are commercially available i.e. Cytofectintrade or Lipofectintrade). However, failure of transfection in the presence of serum is possible, but much more important are side-effects such as lung inflammatory reactions.The main drawback of the use of conventional degradable polymers as delivery agents is their thermodynamic instability, which results in a short in vivo lifetime of the active species, besides their polydispersity.  

Applications of cationic dendrimers as transport vehicles have been described, with an emphasis on their use as transfection agents for nucleic acids. They can transfect them into a large number of cell lines and primary culture cells.Dendrimers with protonable amine groups can interact with all forms of nucleic acid by electrostatic interactions to form complexes that condense the nucleic acids. Whereas linear polymers often adopt random coil structures, the 3D structure of a dendrimer is characterized by radial symmetry. To solve many cellular obstacles of gene delivery, functionalization and variation of the dendrimer structure is an important tool that can be applied. These systems have shown stability and non-immunogenic properties for their potential use in a high variety of therapeutic applications and have been successfully used as carriers for nucleic acids and drug delivery.  

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