For most surface reactive liposome formulations, the reactive lipid is incorporated into the liposomes and the ligand, protein or peptide is conjugated directly to the liposomes that contain reactive lipids. However, this strategy might not work if the reactive lipid is prone to hydrolysis such as maleimide or NHS lipid. In order to get around this issue, the liposomes are made without the PEGylated (reactive and non-reactive) lipids. The scientist who is planning to use the kit will conjugate the ligand, protein or peptide to the reactive lipid. Next, the buffer is added to the lipid-conjugated ligand and micelle solution is formed. Another micelle solution is formed after the PEGylated non-reactive lipid is hydrated with the buffer. The two micelle solutions are mixed and incubated together at a temperature above the liquid-to-gel phase transition temperature of the HSPC (saturated matrix lipid). The PEGylated lipids in the micelles insert themselves with a high efficiency (above 80%) to the liposomes and form the immunoliposomes. Surface reactive doxorubicin liposomes (using various types of chemistries) suitable for conjugation of various antibodies, proteins, peptides and ligands are also available. For more information about surface reactive doxorubicin liposomes (Immundox) see here.