Long-Circulating, pH-Sensitive Liposomes

Momekova D, Rangelov S, Yanev S, Nikolova E, Konstantinov S, Romberg B, Storm G, Lambov N (2007) Long-circulating, pH-sensitive liposomes sterically stabilized by copolymers bearing short blocks of lipid-mimetic units. Eur J Pharm Sci 32 308-317... 

Momekova D, Rangelov S, Lambov N. Long-circulating, pH-sensitive liposomes. Methods Mol Biol 2010 605 527 4. 

Serum-Stable, Long-Circulating, pH-Sensitive PEGylated Liposomes... 

Chemical composition Conventional liposomes (CL), pH sensitive liposomes, cationic liposomes, immunoliposomes and long circulating liposomes. The chemical composition of each liposome type gives particular characteristics to the final liposomal formulation that tnay be ideal for its systematic administration. 

Simoes S et al (2004) On the formulation of pH-sensitive liposomes with long circulation times. Adv Drug Deliv Rev 56 947-965... 

Roux E, Passirani C, Scheffold S, Benoit J-P, Leroux J-C (2004) Serum stable and long-circulating, PEGylated, pH-sensitive liposomes. J Control Release 94 447-451... 

Theoretically, to achieve long-circulating properties and avoid extensive uptake by the liver and spleen, injected colloids should have a size between 70 nm and 200 nm (16). Atypical diameter of 100-200 nm is obtained for the pH-sensitive PEGylated liposomes presented here. The number of times the formulation is extruded through the membrane regulates size distribution, the latter becoming more uniform as the number increases. In DLS, the polydispersity index (Pdl) is calculated from the square of the normalized standard deviation (Pdl = (o/Z ) ). Acceptable Pdl values will depend on the desired properties of the vesicles, but values under 0.1 can be usually attained. 

---