Phosphatidylcholine polymerization

Table 1. Effect of short chain phosphatidylcholine (spacer) on the diacetylenic phosphatidylcholine polymerization. Samples were polymerized at -5 C for 120 seconds. Monomer polymer ratio remain unchanged after 5 minute of UV irradiation.

Hentze H-P, Co CC, McKelvey CA, Kaler EW (2003) Templating Vesicles, Microemulsions and Lyotropic Mesophases by Organic Polymerization Processes. 226 197-223 Hergenrother PJ, Martin SF (2000) Phosphatidylcholine-Preferring Phospholipase C from B. 

The neutral fats used in the preparation of the hydrophobic core of the several liposphere-vaccine formulations described here included tricaprin and tristearin, stearic acid, and ethyl stearate. The phospholipids used to form the surrounding layer of lipospheres were egg phosphatidylcholine and dimyristoyl phosphatidylg-lycerol. Polymeric biodegradable lipospheres were prepared from low molecular weight polylactide (PLA) and polycaprolactone-diol (PCL). 

Fig. It. Structures of crosslinkable phosphatidylcholines which have been usefully employed for polymerization-induced domain formation left to right the compounds are bis-DenPCig,ig bis-SorbPC1717 and bis-AcrylPC1616, where the subscripts indicate the number of atoms in the fatty acid chain.

The realization that tubules may be formed on temperature reduction of polymerized SUVs, prepared from polymerizable diacetylenic phosphatidylcholines (21 where n = 7-16 and m = 5-11), represented a major breakthrough in obtaining the desired supramolecular structure [355-360]. In the initial experiments, 0.4- to 1.0-pm-diameter and 10- to 1000-pm-long tubules were prepared by the gradual lowering of the temperature (to about 38 °Q of 21 (m = 8, n = 9) SUVs [358]. The walk of the tubules had thickness of 10-40 nm and were coated by spiral ripples and helical bilayer strips. Many tubules contained trapped SUVs. Polymerization of the acetylenic moieties greatly enhanced the mechanical and thermal stabilities of the tubules [355-360]. 

Several investigations dealing with the characterization of polymeric membrane systems have been reported lately. A. Kusumi 99> studied phase transitions, fluidity and polarity properties of polymerized and nonpolymerized methacryloyl-derivatized phosphatidylcholine (57) vesicles by DSC and electron spin resonance (ESR). 

A multistep reaction pathway leads to polymers 43 and 44 with phosphatidylcholine moieties in the main chain and long alkyl groups in the side chain [122]. These polymers exhibit thermotropic liquid-crystalline behavior. Polyamides 45 were obtained by interfacial polycondensation they are insoluble in any normal solvent [123]. Poly-MPC capped with cholesteryl moieties at one or both polymer ends was prepared by the radical polymerization of MFC initiated with 4,4 -azobis[(3-cholesteryl)-4-cyanopentanoate] in the presence of a chain transfer agent [124]. The self-organization of these polymers was analyzed with fluorescence and NMR measurements. 

The storage and reactivity of electroactive molecules in polymerized diacetylene vesicles was the subject of studies reported by Stanish, Singh, and coworkers [109, 110], They entrapped ferricyanide in large unilamellar vesicles of photopolymerized PCg PC (1 - palmitoyl - 2 - (tricosa - 10,12-diynoyl)-OT-glycero-3-phosphocholine). Cyclic voltammetry was used to demonstrate that the ferricyanide was electrochem-ically isolated by the poly(lipid) bilayer [110]. At pH7 and 25°C, an anomalously long half-life of 2.4 weeks was calculated for Fe (CN)g- retention in polymerized vesicles. In a subsequent study [109], vesicles with entrapped ferricyanide were prepared from 2-bis(10,12-tricosadiynoyl)-OT-glycero-3-phosphatidylcholine (DCs.gPC) doped with a disulfide-capped lipid (Af-3-(pyridyl-2-dithio)propionyl-2-... 

The early acute pulmonary response of Mstar rats exposed nose-only to respirable polymeric diphenyl-methane 4,4 -diisocyanate aerosol for 6 h were bronchoalveolar lavage cells markedly loaded with phosphatidylcholine (Pauluhn 2000). Bronchoalveolar lavage cells from rats repeatedly exposed to 12.9 mg polymeric diphenyl-methane 4,4 -diisocyanate m" air (6 h/day, 5 days/week for 14 days exposure was from days 0-17 followed by a post-exposure period to day 35) increased in number and phospholipid content significantly in a time-dependent marmer and returned to almost... 

A cross-linked structure has been obtained by in situ polymerization, producing a stable substrate to surfactant solutions, organic solvents, and to transfer across the air/water interface, yet retaining the resistance to the nonspecific protein adsorption characteristic of a fluid phosphatidylcholine bilayer. 

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