Liposomes functionalized polymeric

Fig. 23. Release of entrapped 6-carboxyfluorescein from liposomes of monomeric ( ) and polymeric ( ) (19) as a function of added sodium dodecyl sulfate (SDS). For comparison dipalmitoylphos-phatidylcholine vesicles (A)25 ...

Whether polymerized model membrane systems are too rigid for showing a phase transition strongly depends on the type of polymerizable lipid used for the preparation of the membrane. Especially in the case of diacetylenic lipids a loss of phase transi tion can be expected due to the formation of the rigid fully conjugated polymer backbone 20) (Scheme 1). This assumption is confirmed by DSC measurements with the diacetylenic sulfolipid (22). Figure 25 illustrates the phase transition behavior of (22) as a function of the polymerization time. The pure monomeric liposomes show a transition temperature of 53 °C, where they turn from the gel state into the liquid-crystalline state 24). During polymerization a decrease in phase transition enthalpy indicates a restricted mobility of the polymerized hydrocarbon core. Moreover, the phase transition eventually disappears after complete polymerization of the monomer 24). 

Reppy and co-workers reported the detection of microorganisms based on antibody functionalized poly diacetylene vesicles prepared from 10,12-pen tacosa-diynoic acid. The polymerized liposomes were deposited on polylysine treated membranes. Out of PDVF, MCE, CN, Nylon, and PC, only MCE and PC membranes were found suitable for storing the Uposome-eoated membranes for extended periods of time (up to 13 months). The coated membranes act as sieves and were used to detect the presence of E. coli. Filtration of the solution increases E. coli concentration at the membrane and enhanced the color changes. 

By living cationic polymerization, our group has investigated the synthesis of polymers of various shapes including gradient copolymers,PVA graft copolymers,and end-functional polymers for the modification of liposomes to provide controlled release of drugs. 

Clickable , polymerized liposomes as a general liposomal platform for rapid attachment of functional moieties to their peripheries via click chemistry. The platform was based on polydiacetylene lipids terminated with alkynyl groups... 

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