title: Fluorogenic pH-sensitive polydiacetylene (PDA) liposomes as a drug carrier.
abstract: A crucial issue for current liposomal carriers in clinical applications is the sustained-release property of the encapsulated drugs. We have developed novel fluorogenic pH-sensitive polymerized liposomes composed of polydiacetylene (PDA) lipids and other types of lipids. Unilamellar liposomes containing 10,12-pentacosadiynoic acid (PCDA), 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE), and N-palmitoyl homocysteine (PHC) were loaded with ampicillin. These liposomes fused to each other rapidly when the medium pH was lowered from 7 to 4. The polymerized liposomes were characterized in terms of particle size distribution. The liposome size increased approximately 20-fold from 110.0 +/- 19.3 nm to 2046.7 +/- 487.4 nm as the pH was lowered. Cross-linking of the diacetylene lipids prevents drug leakage and the encapsulated drug can be instantaneously released at acidic pH condition. The ampicillin was nearly completely released (74.4 +/- 3.9%) from liposomes within 4 h under acidic pH conditions and the released amounts of ampicillin were analyzed by HPLC. Finally, the therapeutic effect was observed by the appearance of plaques on a lawn of E. coli, and fluorescent images of the PDA liposomes were taken from the plaques for drug release monitoring. As a result, this research demonstrates that such novel pH-sensitive polymerized liposomes have great prospects as a drug carrier.
authors.affiliation: School of Chemical Engineering, Sungkyunkwan University, Suwon 440-746, Korea.
authors.forename: Sang Ho
authors.initials: SH
authors.lastname: Won
authors.forename: Jong Uk
authors.initials: JU
authors.lastname: Lee
authors.forename: Sang Jun
authors.initials: SJ
authors.lastname: Sim
mesh_terms: D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid; D004337:Drug Carriers; D004926:Escherichia coli / Q000187:drug effects / Q000254:growth & development; D005453:Fluorescence; D006863:Hydrogen-Ion Concentration; D008081:Liposomes; D046529:Microscopy, Electron, Transmission; D000078789:Polyacetylene Polymer; D011108:Polymers / Q000737:chemistry*; D053279:Polyynes / Q000737:chemistry*
chemical_list: D000900:Anti-Bacterial Agents; D004337:Drug Carriers; D008081:Liposomes; D000078789:Polyacetylene Polymer; D011108:Polymers; D053279:Polyynes; C082361:polydiacetylene