Lyophosome™ made from Diether Lipids
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.
The fundamental structure of cell membranes is bilayers composed of phospholipids, and the vital function of the phospholipids in the membrane is to help keep it fluid and semi-permeable. Conventional glycerophospholipids have acyl chains attached to the sn-1 and sn-2 positions of the glycerol backbone via an ester bond. Ether lipids are a unique class of glycerophospholipids that have an alkyl chain attached to the sn-1 position by an ether bond (glycerol-ether lipids). In ether lipids, the alcohol group attached to the phosphate is generally choline or ethanolamine. Ether-linked phospholipids such as 1-alkyl-2-acyl-phosphatidylcholine and dialkylphosphatidylcholine are also found in the plasma and organelle membranes of mammalian species. Ether lipids form approximately 20% of the total phospholipid in mammals with different tissue distribution; brain, heart, spleen and white blood cells have the highest levels, while liver have a very little amount of ether lipids.
Studies on the formation and thermodynamic properties of ether-linked phospholipid bilayer membranes have indicated that in contrast to ester-linked phospholipid, the formation of the non-bilayer structure takes place spontaneously. This is attributed to the weaker interaction between polar headgroups in the ether-linked than that in the ester-linked phospholipids. It has also shown that the phase behavior of the ether-linked phospholipid bilayer membranes in ambient pressure is almost equivalent to that of the ester-linked phospholipid bilayer membranes under high temperatures and pressures, and the difference in the phase behavior decrease as the alkyl-chain length increases.
Due to distinctive properties of ether lipids, liposomes made from ether lipids exhibit very unique characteristics and performance: a) the ether bonds are more stable than ester linkages over a wide range of acidic or alkaline pH; b) stability properties of the liposomes is enhanced by bipolar lipids, and the saturated alkyl chains gives stability towards degradation in oxidative conditions; c) the unusual stereochemistry of the glycerol backbone enhance the resistance against the attacks by other organism phospholipases.
Lyophosome™ product catalog is composed of a large selection of freeze-dried liposomes with various types of lipids and wide range of zeta potentials and different properties. Lyophosome™ 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. Freeze-dried liposomes cannot be used blindly.
Phospholipase A2 (PLA2) cannot hydrolyze the ether lipid liposomes. Diether lipids do not go through hydrolysis due to having an ether bond instead of an acyl bond and therefore to do that, they are a suitable candidate for experiments that needs to be performed at a higher temperature for an extended period of time. For more information about hydrolysis and oxidation of phospholipids see here.
Saturated diether lipids can neither be hydrolyzed nor oxidized.
Lyophosome™ made from Diether Lipids
For more information on the lipid composition of the liposomes mentioned above click here.
|Buffer, Lyoprotectant and Liposome Size|
|Liposome size||100 nm (after hydration)|
|*If you prefer a different buffer please specify in your order.|
- Liposomes are formed upon hydration of the lyophilized formulation. If the lyophilized liposomes are hydrated with solution containing a water-soluble drug, then a large percentage of the drug will stay outside of the liposomes and in non-encapsulated form. It is advised to use a micro dialysis cassette or a spin column using the right-side beads (depending on the size of your drug) and separate the drug encapsulated liposomes from free drug and perform the drug assay in order to calculate the encapsulation efficiency.
- Lyophilized liposomes are mainly recommended to be used with drugs that have a short life in aqueous solution mainly due to hydrolysis. After adding the solution of the drug to lyophilized liposomes, the liposomes should be used immediately.
- Lyophosome™ products should be used by scientists who understand liposome formulation and have the proper equipment in order to check the size, separate the non-encapsulated drug and do the proper assays.
- Trehalose is used as a lyoprotectant in all freeze-dried liposome formulation. The size distribution after hydration of the freeze-dried formulation will be around 100 nm.
Lyophosome™ is a white lyophilized powder. Liposomes are formed upon adding water to the freeze-dried proliposomes and the appearance of the formulation will be white translucent liquid.
- All proliposome lyophilized formulations are shipped on dry ice at -78.5°C in insulated packages using overnight shipping or international express shipping.
- Lyophilized proliposomes should be frozen at -20°C. Upon adding water to proliposomes, liposomes are formed.
- Clients who order from outside of the United States of America are responsible for their government import taxes and customs paperwork. Encapsula NanoSciences is NOT responsible for importation fees to countries outside of the United States of America.
- We strongly encourage the clients in Japan, Korea, Taiwan and China to order via a distributor. Tough customs clearance regulations in these countries will cause delay in custom clearance of these perishable formulations if ordered directly through us. Distributors can easily clear the packages from customs. To see the list of the distributors click here.
- Clients ordering from universities and research institutes in Australia should keep in mind that the liposome formulations are made from synthetic material and the formulations do not require a “permit to import quarantine material”. Liposomes are NOT biological products.
- If you would like your institute’s FedEx or DHL account to be charged for shipping, then please provide the account number at the time of ordering.
- Encapsula NanoSciences has no control over delays due to inclement weather or customs clearance delays. You will receive a FedEx or DHL tracking number once your order is confirmed. Contact FedEx or DHL in advance and make sure that the paperwork for customs is done on time. All subsequent shipping inquiries should be directed to Federal Express or DHL.
Storage and Shelf Life
Lyophosome™ products should always be stored in a freezer at -20°C. Upon adding water to proliposomes, liposomes are formed.
Lyophosome™ is made on order. The batch that is shipped is manufactured on the same day. It is advised to use the products within 12 months of the manufacturing date.
References and background reading
4. Matsuki H, Miyazaki E, Sakano F, Tamai N, Kaneshina S. Thermotropic and barotropic phase transitions in bilayer membranes of ether-linked phospholipids with varying alkyl chain lengths. Biochimica et Biophysica Acta (BBA)-Biomembranes. 2007 Mar 31;1768(3):479-89.