Lipid-based transfection reagents
Lipid-based transfection (Lipofection) is one of a range of biochemical transfection methods which include polymers, DEAE, dextran and calcium phosphate. The main advantages of lipofection techniques are the low cost, ease of use and ability to transfect nucleic acids in a wide range of cell types, although efficiency and viability may be an issue with hard-to-transfect cells where magnet assisted transfection is particularly beneficial.
Lipid-based reagents are generally composed of cationic lipids that are often mixed with helper lipids such as DOPE (L-a-dioleoyl phosphatidyl-ethanolamine) or cholesterol. These mixtures assemble in liposomes or micelles with an overall positive charge at physiological pH and form complexes (lipoplexes) with negatively charged nucleic acids. This results in a tight compaction and protection of the nucleic acids with these cationic complexes mainly being internalized by endocytosis. Once inside cells the nucleic acids release into the cytoplasm by the endosomes buffering capacity of the polycationic residues (the “proton sponge effect”) and ability of cellular negatively charged lipids to neutralize cationic residues of the transfection reagent leading to destabilization of endosomal membranes.
Cationic lipids (lipoplexes) and polymers (polyplexes) are the most commonly used non-viral gene delivery systems. A new generation of lipopolyamines containing a lipophilic part, like lipids, and a charged polyamine moiety, like cationic polymers combines the properties of both entities to achieve efficient nucleic acid delivery into cells.
Levels of transfection efficiency, transgene expression, gene silencing and cytotoxicity depend on multiple factors including cell type, nucleic acid characteristics and purity, siRNA sequence and purity, cell culture conditions, cell number and amount of nucleic acid and reagents to name a few. As a result, transfection reagents need to be specifically designed according to the nucleic acids to be delivered and the cell types used in order to achieve optimal efficiency. To achieve this nanoTherics offers several lipid based transfection reagents which include: