Preparation and Physical Characterization of DNA-Binding Cationic Liposomes

DNA-binding cationic liposomes are routinely employed as one of the major non-viral transfecting agents delivering DNA and other genes inside the cells. Cationic liposomes when complexed with DNA form a strong positively charged liposome-DNA complex or lipoplex. The chapter discusses primarily the major preparation technique for cationic liposomes and its physical characterization, with a focus on SYBR Green-I dye exclusion assay and DNA encapsulation enhancement by freeze-thaw technique. SYBR Green-I dye exclusion assay is a technique to determine the total amount of liposomal lipids required to bind a unit weight of DNA, which is critical for transfection experiments. Freeze-thaw technique on the other hand is one of the major techniques to improve DNA encapsulation in cationic liposomes.