Conjugation to liposomes

Addition of Protein-Palmitate Conjugate to Liposomal Membranes... 

Figure 22.21 Antibodies may be conjugated to liposomes using an indirect approach incorporating a (strept)avidin-biotin system. Biotinylated liposomes may be complexed with biotinylated antibodies using (strept)avidin as a bridging molecule or may be complexed with an antibody-(strept)avidin conjugate.

Finally, besides conventional liposomes that are made from natural (e.g., egg yolk and soybean) or synthetic phospholipids, novel liposomes called archaeosomes that are prepared from the polar ether lipids extracted from various archaeobacteria proved also interesting for the design of vaccines as peptide antigen carriers (71) and as powerful self-adjuvanting vaccine delivery vesicles that promote both humoral and cell-mediated immunity (72). Related to this, one can mention that pseudopeptides, which are less prone to proteolysis when conjugated to liposomes, were also competent in triggering a humoral immune response (73). 

For antibody conjugation, the liposomal phospholipid concentration needs to be determined using Bartlett assays (94) (see Subheading 3.3). Both antibodies of the matched set should be conjugated to liposomes to determine which serves as the better detection antibody. Liposomes should be mixed with antibodies with the latter at 0.05 mol% of the total lipid input. Then, just before use, dilute EDC to a concentration of lOOmg/mL with 0.1 M MES buffer, pH 4.65 then add five molar equivalents (based on total W-glutaryl DPPE lipid input) to the liposome/ antibody mixture. Note that EDC is very hydroscopic - use care... 

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