Freeze-fracture Electron Microscopy Characterization of Nano-&Microparticles Suitable for Drug&Gene Delivery

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Title: Freeze-fracture Electron Microscopy Characterization of Nano-&Microparticles Suitable for Drug&Gene Delivery
Author: Papahadjopoulos-Sternberg B.
Abstract: Freeze-fracture electron microscopy, Nanoparticles, Drug &Gene DeliveryThe potency of drug/gene-loaded nanoparticles is frequently depending upon their morphology adopted in a biological relevant environment. Freeze-fracture electron microscopy (ff-em) is a powerful techniques to monitor the self-assembling of lipid-, polymer-, as well as protein/peptide-based drug and gene carries on a nano-size resolution scale (resolution limit in our hands is 2 nm for periodical structures). Ff-em allows not only the characterization of nano- and micoparticles suitable for drug/gene delivery but also is the method of choice to study their fate related to drug/gene load, application milieu, and during interaction with cells [1-3]. Furthermore it allows distinguishing between bilayer and non-bilayer structures [4-7]. Using ff-em we studied the morphology of a wide variety of nano- and microparticles suitable for drug and gene delivery such as quantum dots, micelles, including spherical-, disc-, and worm-type micelles, small unilamellar liposomes, multilamellar liposomes, niosomes, lipid-stabilized gas bubbles, cochleate cylinder, depofoam particles, and drug crystals[1-3, 8-13]. Because of their small size, nanoparticles such as spherical micelles (<50nm) and small liposomes (<100nm) accumulate in pathological areas and are excellent carriers for poorly water-soluble drugs [10, 11]. Depending upon helper lipid, ionic strength, and gene component CLDC adopt polymorph structures such as spaghetti/ meatballs, map-pins, as well as honeycomb structures [12, 13]. Parallel studies of transfection activity and morphology of CLDC showed that lipid precipitates displaying honeycomb structure are associated with high transfection rates under in vitro conditions. In vivo transfection activity seems to be associated with small complexes such as map-pin structure [13]. Furthermore the fracture behavior of lipid-based macromolecular assemblies indicates their adoption of bilayer or non-bilayer structures. While bilayer vesicles such as liposomes display convex and concave fracture faces, monolayer-coated gas bubbles show concave, and nanoparticles such as micelles convex fracture faces respectively. References [1] B. Sternberg, Liposome Technology, CRC Press I (1992) 363. [2] B. Sternberg, Handbook Nonmedical Applications of Liposomes CRC Press (1996) 271. [3] B. Sternberg, Medical Applications of Liposomes, Elsevier (1998) 395. [4] A. Angelova et al. J. Drug Del. Sci. Tech. (2005) 15 (1) 108. [5] A. Angelova, et al. J. Phys. Chem. B (2005), 109 (8), 3089. [6] A. Angelova, et al. Langmuir (2005), 21, 4138. [7] B. Angelova, et al. Accepted by J. Am. Chem. Soc. 01-05, (2006) [8] P. L. Kan et al. J. Phys. Chem. B (2004) 108, 8129. [9] B. Sternberg et al., Nature 378 (1995) 21. [10] V. P. Torchilin et al. PNAS (2003) 100 (4) 1972. [11] V. P. Torchilin et al. PNAS (2003) 100 (10) 603. [12] B. Sternberg et al., FEBS-Letters 356 (1994) 361. [13] B. Sternberg et al., BBA 1375 (1998) 1375.
Subject: Freeze-fracture electron microscopy, Nanoparticles, Drug & Gene Delivery
Publisher: TIMA Editions , Grenoble, France
Date: 2006

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