Lyophilized liposomes product series are freeze-dried liposomes with various types of lipids and wide range of zeta potentials and different properties. These products should be used by scientists who understand liposome formulation and have the proper equipment to check the size, separate non-encapsulated drugs and do the proper assays.
Liposomes are extensively used to study the interaction of proteins, peptides and other molecules with the surface of a lipid membrane. One of the parameters that affects this interaction is the charge of the liposomal membrane. Liposomes are always made in aqueous environment and they are sized to the desired size in liquid state using various methods such as high-pressure extrusion through nano sized pore track etch membranes. Liposome without water is meaningless. In rare occasions, liposomes are freeze dried and proliposomes are formed in the presence of a lyoprotectant such as trehalose. Using a lyoprotectant is necessary in order to maintain the size of the liposomes after rehydration.
DOTAP is a cationic lipid and the liposomes made from DOTAP are positively charged. The amount of the positive charge depends on the percentage of the DOTAP in the formulation. For many different types of experiments and especially the studies that involve the interaction of a protein or peptide with the surface of liposomes, charged liposomes (cationic or anionic) are used. Charged liposomes are also used for many different types of blood complement studies. Cationic liposomes are mainly used for delivery of genetic material.