Nitrogen-containing lipids prepared from the conjugate addition of amines to acrylates, acrylamides, or other carbon-carbon double bonds conjugated to electron-withdrawing groups are described. Methods of preparing these lipids from commercially available starting materials are also provided. These amine-containing lipids or salts forms of these lipids are preferably biodegradable and biocompatible and may be used in a variety of drug delivery systems. Given the amino moiety of these lipids, they are particularly suited for the delivery of polynucleotides. Complexes or nanoparticles containing the inventive lipid and polynucleotide have been prepared. The inventive lipids may also be used to in preparing microparticle for drug delivery. They are particularly useful in delivering labile agents given their ability to buffer the pH of their surroundings.