Confocal Raman microscopy for monitoring the membrane polymerization and thermochromism of individual, optically trapped diacetylenic phospholipid vesicles

摘要: Optical-trapping confocal Raman microscopy allows the 1, 4-addition reaction of diacetylenic functional groups in 1,2-bis(10,12-tricosadiynoyl)-sn-glycero-3-phosphocholine lipids to be monitored individual phospholipid vesicles. Optical trapping a single vesicle observed over time, allowing direct observation structural changes membrane during polymerization. Confocal excludes light collection outside optical-trap region avoiding interferences from surrounding solution, while chemical reactions occurring trapped can measured with high sensitivity. Individual, optically liposomes (0.6 µm diameter) were exposed photolysis radiation at 254 nm. Upon exposure UV light, cross-linking polymerization formed conjugated ene–yne backbone bilayer vesicle. Polymerization produces two different polymers, red and yellow color, which distinguished structurally by their spectra. Rates polymer formation scattering intensities both C = C stretching vibrations 1455 cm–1 1508 cm–1 C ≡ C 2080 2110 cm–1, respectively. Polymer rates depended linearly on 254-nm intensity, consistent one-photon excited reacting photostationary state. Relative populations polymerized depend sensitively sample temperature. From temperature-dependent spectra, enthalpy change red-to-yellow thermochromic response corresponding could determined. Copyright © 2011 John Wiley & Sons, Ltd.