@article {23, title = {PEG-PE/phosphatidylcholine mixed immunomicelles specifically deliver encapsulated taxol to tumor cells of different origin and promote their efficient killing.}, journal = {J Drug Target}, volume = {11}, year = {2003}, month = {2003 Feb}, pages = {87-92}, abstract = {

Mixed micelles were prepared from poly(ethyleneglycol)-distearyl phosphoethanolamine (PEG2000-PE) and egg phosphatidylcholine. The micelles were covalently modified with the nucleosome-specific monoclonal antibody 2C5 known to recognize and bind a variety of tumor cells via their surface-bound nucleosomes. Covalent attachment of 2C5 antibody was performed via a micelle-incorporated PEG-PE with the distal terminus of the PEG block activated with p-nitrophenylcarbonyl group (pNP-PEG-PE). Micelle surface-attached 2C5 antibody maintained its specific activity. 2C5-targeted immunomicelles were able to carry more than 3 wt\% of taxol. Taxol-loaded immunomicelles specifically recognized tumor cell lines of several types. The cytotoxicity of 2C5-targeted taxol-loaded immunomicelles in a cell culture model was much higher when compared with free taxol or taxol in non-targeted micelles.

}, keywords = {Animals, Antibodies, Monoclonal, Antineoplastic Agents, Cell Survival, Chromatography, High Pressure Liquid, Drug Carriers, Electrophoresis, Polyacrylamide Gel, Mice, Micelles, Nucleosomes, Paclitaxel, Particle Size, Phosphatidylcholines, Phosphatidylethanolamines, Polyethylene Glycols, Tumor Cells, Cultured}, issn = {1061-186X}, doi = {10.1080/1061186031000138623}, author = {Gao, Z and Lukyanov, A N and Chakilam, A R and Torchilin, V P} } @article {30, title = {p-Nitrophenylcarbonyl-PEG-PE-liposomes: fast and simple attachment of specific ligands, including monoclonal antibodies, to distal ends of PEG chains via p-nitrophenylcarbonyl groups.}, journal = {Biochim Biophys Acta}, volume = {1511}, year = {2001}, month = {2001 Apr 2}, pages = {397-411}, abstract = {

We have attempted to simplify the procedure for coupling various ligands to distal ends of liposome-grafted polyethylene glycol (PEG) chains and to make it applicable for single-step binding of a large variety of a primary amino group-containing substances, including proteins and small molecules. With this in mind, we have introduced a new amphiphilic PEG derivative, p-nitrophenylcarbonyl-PEG-1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (pNP-PEG-DOPE), synthesized by reaction of DOPE with excess of bis(p-nitrophenylcarbonyl)-PEG in a chloroform/triethylamine mixture. pNP-PEG-DOPE readily incorporates into liposomes via its PE residue, and easily binds primary amino group-containing ligands via its water-exposed pNP groups, forming stable and non-toxic urethane (carbamate) bonds. The reaction between the pNP group and the ligand amino group proceeds easily and quantitatively at pH around 8.0, and remaining free pNP groups are promptly eliminated by spontaneous hydrolysis. Therefore, pNP-PEG-DOPE could serve as a very convenient tool for protein attachment to the distal ends of liposome-grafted PEG chains. To investigate the applicability of the suggested protocol for the preparation of long-circulating targeted liposomes, we have coupled several proteins, such as concanavalin A (ConA), wheat germ agglutinin (WGA), avidin, monoclonal antimyosin antibody 2G4 (mon2G4), and monoclonal antinucleosome antibody 2C5 (mon2C5) to PEG-liposomes via terminal pNP groups and studied whether the specific activity of these immobilized proteins is preserved. The method permits the binding of several dozens protein molecules per single 200 nm liposome. All bound proteins completely preserve their specific activity. Lectin-liposomes are agglutinated by the appropriate polyvalent substrates (mannan for ConA-liposomes and glycophorin for WGA-liposomes); avidin-liposomes specifically bind with biotin-agarose; antibody-liposomes demonstrate high specific binding to the substrate monolayer both in the direct binding assay and in ELISA. A comparison of the suggested method with the method of direct membrane incorporation was made. The effect of the concentration of liposome-grafted PEG on the preservation of specific protein activity in different coupling protocols was also investigated. It was also shown that pNP-PEG-DOPE-liposomes with and without attached ligands demonstrate increased stability in mouse serum.

}, keywords = {Animals, Antibodies, Monoclonal, Avidin, Drug Stability, Hydrogen-Ion Concentration, Lectins, Ligands, Liposomes, Mice, Models, Chemical, Nitro Compounds, Phosphatidylethanolamines, Polyethylene Glycols, Protein Binding, Proteins, Surface-Active Agents}, issn = {0006-3002}, author = {Torchilin, V P and Levchenko, T S and Lukyanov, A N and Khaw, B A and Klibanov, A L and Rammohan, R and Samokhin, G P and Whiteman, K R} } @article {31, title = {Formation of high axial ratio microstructures from peptides modified with glutamic acid dialkyl amides.}, journal = {Biochim Biophys Acta}, volume = {1371}, year = {1998}, month = {1998 May 28}, pages = {168-84}, abstract = {

A growing number of amphiphiles are known to form high axial ratio microstructures (HARMs) such as the hollow cylindrical microstructures called lipid tubules. As a prelude to exploring the potential of HARMs formed from lipopeptides in controlled release drug delivery, several microstructure formation conditions were investigated. We report the preparation of several glutamic acid dialkyl amides with varying alkyl chain lengths bearing a verity of peptides (1-4 amino acids) [peptide-Glu-(NHCnH2n+1)2, n=12, 14, 16]. These surfactants have been rapidly and efficiently converted into HARMs in aqueous buffer at physiological pH and ionic strength, or in buffer containing MeOH or EtOH. Helical ribbons and tubular HARMs were produced that were stable for as long as 6 months below the phase transition temperatures of the compounds. To estimate the stability of HARMs in vivo, HARMs formed from (Pro)3-Glu(NHC16H33)2 were incubated with DOPC liposomes or fetal calf serum at 40 degreesC. HARM size and shape did not change significantly, suggesting that such lipopeptide particles can retain their morphology long enough in vivo to be useful as drug delivery vehicles.

}, keywords = {Amides, Calorimetry, Differential Scanning, Drug Carriers, Drug Stability, Glutamic Acid, Light, Lipoproteins, Liposomes, Peptides, Cyclic, Phosphatidylcholines, Scattering, Radiation}, issn = {0006-3002}, author = {Lee, K C and Lukyanov, A N and Gelb, M H and Yager, P} } @article {32, title = {Formation of high-axial-ratio-microstructures from natural and synthetic sphingolipids.}, journal = {Chem Phys Lipids}, volume = {88}, year = {1997}, month = {1997 Aug 8}, pages = {21-36}, abstract = {

Amphiphiles that form high-axial-ratio-microstructures (HARMs) are being considered as novel materials for controlled release of drugs and other biologically functional molecules. HARMs consisting of tubules, ribbons, solid rods and helices are formed from sphingolipids by addition of water to a solution of amphiphile in DMF. Single molecular species of galactocerebroside (GalCer) containing long unsaturated fatty acid chains or natural GalCer containing mixed-length, non-hydroxy fatty acids (NFA-GalCer) or alpha-hydroxy fatty acids (HFA-GalCer) form cylindrical structures. In contrast, single molecular species of GalCer containing long saturated fatty acids form ribbons and helices. GalCer HARMs are typically under 100 nm in diameter and have lengths of several microns. The importance of the amide of GalCer for HARM formation was evaluated using psychosine, which forms solid fibers, whereas sphingosine and an analog of GalCer in which the amide is reduced to a secondary amine form amorphous aggregates. Single molecular species of ceramide containing long unsaturated fatty acid chains form cylindrical structures, whereas those with long saturated fatty acids form ribbons and helices. Short chain saturated ceramide also forms cylindrical structures. GalCer analogs with N-acetyl-glycine in place of the galactose form fibers whereas those with N-acetyl-proline yield amorphous material. The N-acetyl-proline-containing amphiphile can de doped into pure GalCer or NFA-GalCer without perturbing tubule formation.

}, keywords = {Amides, Amino Acids, Calorimetry, Differential Scanning, Ceramides, Delayed-Action Preparations, Fatty Acids, Galactosylceramides, Sphingolipids}, issn = {0009-3084}, author = {Goldstein, A S and Lukyanov, A N and Carlson, P A and Yager, P and Gelb, M H} }