Neutral Liposomes (Lyophosome™-PEGylated)
Liposome formulations can be broadly divided into cationic, anionic and neutral subtypes. Cellsome® liposomes made from anionic PEGylated lipids provide certain benefits. One of the most well-known Neutral PEGylated Lipids used if for the drug Doxil®. Liposomal doxorubicin (Doxil®) is a liposome formulation encapsulating the chemotherapeutic drug, doxorubicin, thereby decreasing its toxicity.
To improve liposome stability and enhance their circulation times in the blood, a sterically stabilized, hydrophilic polymer, polyethylene glycol (PEG), has been shown to be the optimal choice for obtaining sterically stabilized liposomes. Using a Neutral Liposome with PEG will protect the liposomes from circulating proteins, improving their plasma clearance and enhancing their therapeutic effects. Doxil® also contains polyethylene glycol (PEG)-lipid resulting in pegylation of the liposome surface, which enables it to have a prolonged circulation and a reduced volume of distribution, thereby improving tumor uptake through the enhanced permeability and retention effect (EPR) and extending effective tumor therapy.
The four products provided that are made from Neutral PEGylated Lipids provided here consist of either HSPC:Chol:PEG2000-DSPE (65:30:5 molar ratio), DSPC:Chol:PEG2000-DSPE (65:30:5 molar ratio), PC:Chol:PEG2000-DOPE (65:30:5 molar ratio), or DOPC:Chol:PEG2000-DOPE (65:30:5 molar ratio).
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.
Neutral Liposomes (Lyophosome™-PEGylated)
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.
- Freeze-dried liposomes should be kept at -20°C.
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
1. Crowe LM, Crowe JH, Rudolph A, Womersley C, Appel L. Preservation of freeze-dried liposomes by trehalose. Archives of biochemistry and biophysics. 1985 Oct 1;242(1):240-7.
2. Crommelin DJ, Van Bommel EM. Stability of liposomes on storage: freeze dried, frozen or as an aqueous dispersion. Pharmaceutical research. 1984 Jul 1;1(4):159-63.
3. van Winden EC, Crommelin DJ. Short term stability of freeze-dried, lyoprotected liposomes. Journal of controlled release. 1999 Mar 8;58(1):69-86.