There were two objectives for this study. First, it focused on eight lipids having cholesterol as hydrophobic tails,
carbamate linkers, and different polar headgroups. Second, it aimed to study the physicochemical properties of those eight lipids,
including DNA binding, size, zeta potential, and the transfection efficiency. Cholesterol-1,2-diaminoethane and
tetramethylguanidinium conjugated lipid showed the highest transfection efficacy into human embryonic kidney cells cells. The
optimal formulation of this lipid was found to be 1:1 (weight/weight) for cationic lipid/DOPE, and 1:20 for DNA/liposome. GFP
expression experiments further revealed that the liposome exhibited higher transfection efficiency under a 10−40% serum
condition than LipofectamineTM 2000.