Functional Group | Azide |
Storage | Should always be stored at in the dark at 4 °C, except when brought to room temperature for brief periods prior to animal dosing. DO NOT FREEZE. If the suspension is frozen, the encapsulated drug can be released from the liposomes thus limiting its effectiveness. In addition, the size of the liposomes will also change upon freezing and thawing. |
Appearance | White translucent liquid made of nano size unilamellar liposomes. Usually due to the small size of liposomes no settling will occur in the bottom of the vial. The liposomes are packaged in an amber vial. |
Description | Copper-free click chemistry is a fairly new chemistry that has been commercialized during the past few years. More and more click chemistry based reagents are becoming available commercially which makes the formulation development much easier for scientists. The great advantage of this chemistry is biocompatibility since no cytotoxic copper catalyst is required. By far, click chemistry is the most efficient and easiest conjugation chemistry available for coupling of antibodies and other reactive ligands to the surface of the liposomes. The conjugation chemistry is based on the reaction of the dibenzocyclooctyne (DBCO) reagent with an azide linker to form a stable triazole. DBCO moiety can be on the antibody and azide moiety can be on liposomes and vice versa. This conjugation protocol is based on the reaction of the dibenzocyclooctyne (DBCO) group of the liposomes with an azide linker on the antibody, peptide or proteins. There are many commercialized reagent that can be used for azide modification of proteins, peptides and antibodies. |
Lipid composition | HSPC/Cholesterol/DSPE-PEG(2000)/DSPE-PEG(2000)-Azide (57/38/4/1 molar ratio) |
Liposome Size | 100 nm |
Lipid Molar Concentration | 21.58 mM |
Buffer | Phosphate Buffered Saline, pH 7.4 |
Shelf-life | 4 months. |
Technical Notes | Before starting the conjugation process please make sure to avoid buffers that contain azides, which can react with DBCO. DBCO group is known to be hydrophobic and it buries itself in the lipid bilayer of the liposomes. Direct conjugation of a ligand to the liposomes containing DBCO has produced immunoliposomes with yield of above 60% which is quite acceptable and much higher than many other conjugation chemistries. Post-insertion of DBCO lipid conjugated ligands into the liposomes increases the yield to above 80%. For more information see reference 11. Reactions of DBCO and azides are more efficient at high concentrations and temperatures (i.e., up to 37 °C). In order to avoid denaturation of proteins, peptides and antibodies it is recommended to incubate molecules with liposomes at room temperature followed by refrigeration (see step 1). Typical reaction times are less than 12 h, however, incubating for longer can improve efficiency. Spin columns can be used for the immunoliposome separation, and they are very fast method for purification. However, a large quantity of the samples are lost on the column. Dialysis is a slower process with minimal sample loss and therefore, we recommend dialysis over spin columns. If you are using a ligand or peptide that is hydrophobic then it is recommended to solubilize it in DMSO or DMF and then add the buffer to it. It is recommended not to use more than 5% volume of DMSO or DMF in the solution. DMF and DMSO are both compatible with liposomes and they are also miscible in water. Other organic solvent such as ethanol and chloroform are not compatible with liposomes and will cause the liposomes to lyse. If you end up using DMSO or DMF then after the conjugation reaction is done, you need to remove DMSO and DMF from the liposomes. In order to do that you need to use a dialysis cassette that is made from REGENERATED CELLULOSE MEMBRANE. NOTE: Not all membranes are compatible with DMF and DMSO. We recommend using a Slide-A-Lyzer? MINI Dialysis Device with MWCO of 2K made from regenerated cellulose membrane manufactured by ThermoFisher. After DMSO or DMF is removed, you can use Float-A-Lyzer? dialysis device for the final step of cleaning up the prep. |
Lipid Mass Concentration | 15.90 mg/mL |
Product Name | Catalog | Lipid composition | Liposome Size | Price |
---|---|---|---|---|
Clipos™ Azide Liposomes, PEGylated | CDEIMS-1518 | L-a-PC/Cholesterol/1,2-Dipalmitoyl-sn-glycero-3-phosphoethanolamine-N-(6-azidohexanoyl) (69/30/1 molar ratio) | 100 nm | $1480 |
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