Polypeptides vesicles

Keywords Drug delivery Encapsulation Polymer Polypeptide Vesicle... 

Many polypeptide-based materials are able to self-assemble into vesicles when directly dissolved into the appropriate solvent. In fact, this method was used to form some of the earliest polypeptide vesicles in the literature. Lecommandoux and... 

Fig. 3 Polypeptide vesicle with endocytosis capability, (a) Vesicles formed from poly(L-arginme)6o-h-poly(L-leucme)2o- The poly(L-arginme) block provides an added cell-penetrating feature to the vesicles, (b, c) LCSM images of internalized vesicles (green) containing Texas-Red-labeled dextran (red) in (b) epithelial and (c) endothelial cells. Colocalization of the vesicles and Texas-Red-labeled dextran appears as a yellow fluorescent signal. Adapted from [44] with permission.Copyright 2007 Macmillan Publishers...

Fig. 5 Polypeptide vesicles demonstrate the ability to utilize the EPR effect, (a) Chemical structure of the amphiphilic block polypeptide PSar-b-PMLG. (b) Fluorescence image using fluorescently labeled PEG. Fluorescence is not observed in the cancer site although accumulation is observed in the bladder, (c) Fluorescence image using ICG-labeled vesicles, showing evidence of vesicle accumulation due to the EPR effect. Adapted from [41] with permission. Copyright 2008 American Chemical Society...

Holowka EP, Pochan DJ, Deming TJ (2005) Charged polypeptide vesicles with controllable diameter. J Am Chem Soc 127 12423-12428... 

The long-chain a-amino acid esters (40), (41), and (42) form bilayers on sonication in water under acidic conditions. Liposomes prepared from (40) and (42) precipitate if the aqueous medium is neutralized by titration with NaOH. Only liposomes made from (41) are stable even in basic solutions, as shown by electron microscopy52). Polypeptide formation in oriented spherical vesicles was confirmed by FT-IR spectroscopy. The liposomal solution of (41) was freeze-dried and the spectrum obtained from the residue was comparable with one of the polycondensed monolayers. The formation of polypeptide vesicles is illustrated in Scheme 4. 

Polycondensation reactions in oriented monolayers and bilayers proceed without catalysis, and simply occur due to the high packing density of the reactive groups and their orientation in these layers. Bulk condensation of the a-amino acid esters at higher temperatures does not lead to polypeptides but to 2,5-diketopiperazines. No diketopiperazines are found in polycondensed monolayers or liposomes. Polycondensation in monolayers and liposomes leading to oriented polyamides represents a new route for stabilizing model membranes under mild conditions. In addition, polypeptide vesicles may be cleavable by enzymes in the blood vessels. In this case, they would represent the first example of stable but biodegradable polymeric liposomes. 

Bellomo EG, Wyrsta MD, Pakstis L, Pochan DJ, Deming TJ. 2004. Stimuli responsive polypeptide vesicles by conformation specific assembly. Nat Mater 3 244 248. 

The literature on controlled release from amphiphilic polymer aggregates is reviewed. Two terms, biodegradation and organisation of polymers, are discussed as characteristic points for the authors approach to polymer aggregates. Microcapsules are considered, with particular reference to sustained release from polypeptide microcapsules, pH-responsive release from polypeptide microcapsules, thermoresponsive microcapsules, and degradation. Microspheres are then discussed and polypeptide vesicles are examined. 81 refs. JAPAN... 

In analogy to the polycondensation of long chain a -amino acid esters in monolayers the formation of polypeptide vesicles from these compounds is also possible (6). 

In addition it can be expected that the polypeptide vesicles are enz3miatically cleavable, thus providing stable, but biodegradable vesicles. 

Bellomo, E. G., Wyrsta, M. D., Pakstis, L., Pochan, D. J., Deming, T. J. (2004). Stimuli-iesponsive polypeptide vesicles by conformation-specific assembly. Nature Materials, 3, 244—248. 

Fig. 3 Non-ionic polypeptide vesicles (a) LSCM image (50 pm wide) of a K iooL20 vesicle suspension visualized with fluorescent probes and a Z-direction slice thickness of 490 nm. (b) Proposed packing of chains in vesicle walls, (c) Structure and cartoon of chains. Adapted from [88]...

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