The proven first-generation transfection reagent DOTAP (1,2-Di-(9Z-octadecenoyl)-3-trimethylammonium propane methylsulfate) in sterile water (concentration 1 mg/ml) is supplied by Biontex (AFSBio's supplier) as a ready-to-use liposome formulation. Many experiments with DOTAP, as one of the longest-standing known "first-generation" reagents, are described in the scientific literature available, both in vitro & in vivo. Although DOTAP does not offer all the features of modern transfection reagents, in many cases it delivers reliable results.

First-generation transfection reagents

The unsatisfactory and unreliable results of the calcium phosphate transfection method led to the development of transfection reagents of the First Generation based on cationic lipids or liposomes.

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.

DOTAP was Biontex's starting point for the development of new transfection reagents. The temporal development series includes, in particular: METAFECTENE® < METAFECTENE® PRO < K2® Transfection System < K4® Transfection System. With the development degree the probability of a successful transfection increases (see also General Selection Aid).