First-generation transfection reagents
These reagents are generally based on monocationic lipids with a quaternary ammonium ion. They do not feature buffering properties and therefore do not offer the option of endosome buffering, which explains their lower efficiency compared to modern reagents (e.g. METAFECTENE®). In addition, serum inhibition is reported for many of these transfection reagents with the exception of DOTAP.
A further feature of these reagents is a generally conventional transfection sequence providing for cell seeding and growth prior to the actual transfection and for change of medium after transfection. As a rule the proportion of DNA to lipids must be optimized carefully to ensure satisfactory results.