Chemically based transfection systems

Dendrimers have been investigated as a vector for nucleic acid-based therapies for nearly 20 years, and PAMAM and PPI dendrimers are the two most commonly used kinds that are commercially available.[113-115] Their unique chemical architecture with all primary, secondary, and tertiary amines enabling the proton-sponge effect described above make dendrimers one of the ideal platforms for gene delivery. Furthermore, the close-to-monodispersed chemical structure of dendrimers allows the precise control over their functionalities, which can minimize the unpredictable transfection efficiencies observed in the cases of heterogeneous liposomes and other polymer-based systems.[l 16]... 

Spectroscopy is the study of the interactions of electromagnetic radiation, or light, with matter in order to gain information about the atoms or bonds present within the system. There are many different types of spectroscopic techniques however, most of the techniques are based on the absorption or emission of photons from the material being studied. The applications of spectroscopy span a variety of disciplines and can allow scientists to, among countless other things, determine the elemental composition of a nearby dwarf star, the chemical identity of an unknown white powder sample, whether a transfected gene has been expressed, or the types of individual bonds within a molecule. 

Nonviral gene transfer systems are based on a variety of technologies that employ physical/chemical means to deliver genes [6], These technologies include direct plasmid injection, bombardment with DNA coated microprojectiles, and DNA complexed with liposomes or polymers. Some nonviral transfection techniques are too inefficient (e.g., coprecipitation of DNA with calcium phosphate [7], DNA complexed with diethylaminoethyl (DEAE)-dextran [8], electroporation [9]), or laborious (e.g., microinjection of DNA [ 10 ]) for clinical use. Only those gene delivery systems (viral and nonviral) with potential for clinical application are discussed in this chapter. The main features of these technologies (Table 18.3) are described and specific examples of their applications highlighted. 

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