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Lipidi u vodenom mediju tvore liposome, sferične strukture u kojima se slažu u dvosloje. Faza, odnosno način slaganja lipida u dvosloje, funkcija je temperature. Glavni fazni prijelaz je prijelaz lipida iz faze gela u fazu fluida i opaža se pri temperaturi mekšanja Tm. Uz razlikovnu pretražnu kalorimetriju kao rutinsku tehniku određivanja Tm odnedavno se ističe i UV/Vis spektroskopija. U sklopu ovog rada pripremljene su suspenzije 1,2-dipalmitoil-sn-glicero-3- fosfokolina (DPPC), 1,2-dipalmitoil-sn-glicero-3-fosfoetanolamina (DPPE), 2-oleil-1- palmitoil-glicero-3-fosfoetanolamina (POPE) i sfingomijelina (SM) u acetatnom, fosfatnom i karbonatnom puferu (pH = 4,09; 7,01; 9,19). Razlikovnom pretražnom kalorimetrijom i temperaturno-ovisnom UV/Vis spektroskopijom određene su vrijednosti Tm lipida te je ispitan utjecaj pH medija na Tm. Pokazano je da je temperaturno-ovisna UV/Vis spektroskopija prikladna za određivanje Tm te da promjena pH najviše utječe na DPPE i POPE liposome. Lipids form liposomes in which they arrange into bilayers. The transition of lipids from the gel to the fluid phase, namely the main phase transition, is observed at the melting temperature Tm. Alongside differential scanning calorimetry (DSC), a routine technique for Tm determination, UV/Vis spectroscopy recently stood out. As part of this thesis, suspensions of 1,2-dipalmitoylsn-glycero-3-phosphocholine (DPPC), 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE), 2-oleyl-1-palmitoyl-glycero-3-phosphoethanolamine (POPE) and sphingomyelin (SM) in three buffers (pH = 4.09; 7.01; 9.19) were prepared. Using DSC and temperaturedependent UV/Vis spectroscopy, Tm of lipids were determined and the influence of pH on Tm was examined. It was shown that temperature-dependent UV/Vis spectroscopy is suitable for determining Tm and that DPPE and POPE liposomes are affected by the change in the pH. |
