Synthesis and surface engineering of iron oxide nanoparticles for biomedical applications

Liposomes — microscopic phospholipid bubbles with a bilayered membrane structure — have received a lot of attention during the past 30 years as pharmaceutical carriers of great potential. More recently, many new developments have been seen in the area of liposomal drugs — from clinically approved products to new experimental applications, with gene delivery and cancer therapy still being the principal areas of interest. For further successful development of this field, promising trends must be identified and exploited, albeit with a clear understanding of the limitations of these approaches.

Recent advances with liposomes as pharmaceutical carriers.

Drug delivery systems (DDS) such as lipid- or polymer-based nanoparticles can be designed to improve the pharmacological and therapeutic properties of drugs administered parenterally. Many of the early problems that hindered the clinical applications of particulate DDS have been overcome, with several DDS formulations of anticancer and antifungal drugs now approved for clinical use. Furthermore, there is considerable interest in exploiting the advantages of DDS for in vivo delivery of new drugs derived from proteomics or genomics research and for their use in ligand-targeted therapeutics.

http://science.sciencemag.org/content/sci/303/5665/1818.full.pdf

Drug Delivery Systems: Entering the Mainstream

Liposomal drug delivery systems: from concept to clinical applications.

The rapid recognition of intravenously injected colloidal carriers, such as liposomes and polymeric nanospheres from the blood by Kupffer cells, has initiated a surge of development for "Kupffer cell-evading" or long-circulating particles. Such carriers have applications in vascular drug delivery and release, site-specific targeting (passive as well as active targeting), as well as transfusion medicine. In this article we have critically reviewed and assessed the rational approaches in the design as well as the biological performance of such constructs. For engineering and design of long-circulating carriers, we have taken a lead from nature. Here, we have explored the surface mechanisms, which affords red blood cells long-circulatory lives and the ability of specific microorganisms to evade macrophage recognition. Our analysis is then centered where such strategies have been translated and fabricated to design a wide range of particulate carriers (e.g., nanospheres, liposomes, micelles, oil-in-water emulsions) with prolonged circulation and/or target specificity. With regard to the targeting issues, attention is particularly focused on the importance of physiological barriers and disease states.

Long-Circulating and Target-Specific Nanoparticles: Theory to Practice

Part 1 General Introduction to Liposomes: 1. Chemistry of lipids and liposomes. 2. Structure of amphiphilic aagregates. 3. Preparation of liposomes. 4. Mechanism of liposome formation. 5. Liposome characterization methods. Part 2 Applications of Liposomes in Basic Sciences: 6. Applications of liposomes in theoretical sciences. 7. Applications in biophysics. 8. Liposomes in the studies of the evolution of life. 9. Applications in chemistry. 10. Reconstitution of proteins. Part 3 Applications of Liposomes in Pharmacology and Medicine: 11. Liposomes as a drug delivery system. 12. Liposomes in the treatment of infectious diseases. 13. Liposomes as immunoadjuvants. 14. Liposomes in anticancer therapy. 15. Liposomes and inflammations. 16. Other medical applications of liposomes. 17. Other administration routes of liposomes. 18. Site specific drug delivery. Part 4 Other Applications of Liposomes: 19. Cosmetic applications of liposomes. 20. Liposomes as a carrier system in genetic engineering. 21. Liposomes in diagnostics. 22. Liposomes in food industry. 23. Liposomes in ecology and other applications. 24. Industrial manufacturing of liposomes.

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Liposomes: From Physics to Applications

Sterically stabilized liposomes

Surface modification of nanoparticles to oppose uptake by the mononuclear phagocyte system

To increase cationic liposome-mediated intravenous DNA delivery extruded DOTAP:cholesterol liposomes were used to form complexes with DNA, resulting in enhanced expression of the chloramphenicol acetyltransferase gene in most tissues examined. The DNA:liposome ratio, and mild sonication, heating, and extrusion steps used for liposome preparation were crucial for improved systemic delivery. Size fractionation studies showed that maximal gene expression was produced by a homogeneous population of DNA:liposome complexes between 200 to 450 nm in size. Cryo-electron microscopy examination demonstrates that the DNA:liposome complexes have a novel morphology, and that the DNA is condensed on the interior of invaginated liposomes between two lipid bilayers. This structure could account for the high efficiency of gene delivery in vivo and for the broad tissue distribution of the DNA:liposome complexes. Ligands can be placed on the outside of this structure to provide for targeted gene delivery.

Danilo D. Lasic

Papers

Liposomes: From Physics to Applications

Sterically stabilized liposomes

Surface modification of nanoparticles to oppose uptake by the mononuclear phagocyte system

Improved DNA: liposome complexes for increased systemic delivery and gene expression.

Sterically stabilized liposomes: a hypothesis on the molecular origin of the extended circulation times