During the past five decades, various types of chemistries have been used for conjugation of molecules such as antibodies, peptides, proteins or other reactive ligands to the surface of liposomes. In general, the conjugation can be achieved through the N-terminus, the C-terminus or the available sulfur (e.g. Fab’ fraction or thiolated antibodies). Not all chemistries have the same yield and efficiency of conjugation and often reproducing biocompatible batches can be a challenge. Folate binding protein (FBP) is an endogenous protein, which shows a very high affinity for folate. An antibody can be tagged by FBP and an immunoliposome can be formed by non-covalent and high affinity interaction between FBP and folate lipid on the surface of the liposomes. In this method, the antibody, which has been already covalently linked to FBP through a thioether linkage, is conjugated with folate-derivative liposomes. Having a relatively low molecular weight (MW ～40 kDa) and a single binding site prevents liposomes from crosslinking. For other reactive Immunodox products suitable for other types of conjugation method see here.