Chemistry

Tougher Liposomes

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Science  30 Nov 2007:
Vol. 318, Issue 5855, pp. 1353
DOI: 10.1126/science.318.5855.1353a

Although liposomes can be used for drug delivery, efforts continue toward improving both the stability of these spherical bilayer structures and the control over how they release their aqueous contents. Lee et al. describe a method to generate caged liposomes surrounded by a cholesterol-anchored polymer coating whose stability is pH dependent. Cholesterol-terminated poly(acrylic acid) was mixed with dipalmitoyl-phosphatidylcholine liposomes. After an overnight incubation period, these coated liposomes, which had a mean diameter of 90 nm, were cross-linked with 2,2′-(ethylenedioxy)-bis(ethylamine). The coated vesicles retained their spherical shape after freeze-drying and were resistant to leakage after 500 hours in bovine calf serum. However, the carboxylic acid cross-links helped facilitate release of the vesicles' content through compressive rupture after introduction into modestly acidic solutions (pH range of 4.0 to 5.5) over periods of 150 hours. This type of modified liposome has the potential to provide a stable, controllable drug-delivery vehicle. — PDS

J. Am. Chem. Soc. 129, 10.1021/ja070748i (2007).

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