Thermal-Sensitive Liposomes

Duke University Eye Center, Durham, North Carolina, U.S.A. 

Wilmer Ophthalmological Institute, Johns Hopkins University, Baltimore, Maryland, U.S.A. 

The current methods of drug administration to the retina and choroid are based on topical, periorbital, intravitreal, and systemic administrations. The first 

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A commonly used strategy to prepare a liposome-based NIR-responsive vehicle, while optimizing liposome composition and structure to enhance circulation time and drug retention, is to incorporate Au nanostructures into the thermally sensitized liposome membranes. On NIR irradiation, Au nanostructures, such as nanoshells, nanorods or NPs, convert NIR light into heat, increasing the permeability of the liposome membrane via a photothermal conversion process. Finally, the anticancer drugs or genes are released from the liposomes. 

The specific applications require different bulk and surface properties of liposomes. Among others, for example, the unique properties of stealth, targeted, and cationic liposomes could be achieved by surface modification. Figure 1 illustrates examples of liposomal surface modifications for such specific applications. The goals of these surface modifications are (1) to increase liposome longevity and stability in the circulation, (2) to change liposome biodistribution, (3) to achieve targeting effect, and (4) to impart to liposomes some unusual properties such as pH or thermal sensitivity. 

The design of light sensitive polymeric amphiphiles is discussed and their aggregation behaviour and the properties of LB—multilayers made from them are investigated. Enhanced thermal stability and annealing effects were found. In addition the photoreaction of amphiphilic Benzylammoniumsalts in Liposomes and LB—multilayers and its influence on the structure of these supramolecular systems was investigated. 

Bowen ME, Weninger K, Brunger AT, Chu S. Single molecule observation of liposome-bilayer fusion thermally induced by soluble N-ethyl maleimide sensitive-factor attachment protein receptors (SNAREs). Biophys. J. 2004 87 3569-3584. 

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