Vpliv surfaktantov, trehaloze in temperature na stabilnost veziklov iz jajčnega lecitina

Brezovar, Neža (author), Kogej, Ksenija (mentor)

Delci nanometrskih velikosti z lipidnim dvoslojem, katerim krajše pravimo kar vezikli, so zadnja leta predmet raziskovanj mnogih znanstvenikov, saj so potencialno uporabni za diagnosticiranje in zdravljenje različnih bolezni. Vezikli nastajajo v naravi, lahko pa jih ustvarimo tudi sami. V magistrskem delu smo se ukvarjali z vezikli, ki smo jih pripravili sami, iz koncentriranega jajčnega lecitina, s postopkom imenovan ekstrudiranje. Zanimalo nas je predvsem, kakšen vpliv ima dodajanje različnih surfaktantov na velikost in zeta potencial pripravljenih veziklov. Velikost smo ocenili z merjenjem hidrodinamskega radija. Spreminjanje velikosti hidrodinamskega radija smo spremljali preko dinamičnega sipanja svetlobe, velikosti zeta potenciala pa preko elektrokinetičnih meritev. V suspenzijo smo dodajali tri surfaktante: kationski - dodecil piridinijev klorid (DPC), anionski - natrijev dodecil sulfat (SDS) in neionski - Brij 30. Prav tako smo spremljali vpliv dodatka sladkorja (trehaloze) in temperature na stabilnost veziklov. Vse eksperimente in meritve smo opravljali pod enakimi pogoji, da bi zagotovili čim boljšo primerjavo med rezultati. Dodajanje kationskega surfaktanta DPC je povzročilo povečanje veziklov pri nižjih koncentracijah surfaktanta, ter razgradnjo pri višjih koncentracijah surfaktanta. Zeta potencial pa se je bolj približal pozitivnim vrednostim. Višanje temperature pa ni imelo opaznega vpliva niti na velikost radija niti na zeta potencial veziklov. Dodajanje anionskega surfaktanta SDS je pokazalo nenavadne rezultate, predvsem glede velikosti radija veziklov, saj je večinoma do sprememb prišlo pri vzorcih, ki so vsebovali trehalozo, torej le-ta ni poskrbela za zaščito veziklov. Zeta potencial pa je postal še bolj negativen, vendar pa se s temperaturo ni bistveno spreminjal. Dodajanje neionskega surfaktanta Brij 30 je prav tako povzročilo spreminjanje velikosti veziklov. Pri višjih koncentracijah surfaktanta in višji koncentraciji trehaloze je prišlo do razgradnje veziklov, pri nižjih dodatkih in manjši koncentraciji trehaloze pa do vgradnje surfaktanta v vezikle. Rezultati meritev zeta potenciala pa so pričakovano ostali podobni prvotnim vrednostim.

• Language: Slovenian
• Keywords: vezikli, dinamično sipanje svetlobe, surfaktant, trehaloza, zeta potencial
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: FKKT - Faculty of Chemistry and Chemical Technology
• Year: 2019
• PID: 20.500.12556/RUL-109923
• COBISS.SI-ID: 1538406083
• Publication date in RUL: 10.09.2019

Secondary language

• Language: English
• Title: Effect of surfactants, trehalose and temperature on the stability of vesicles made from egg's lecithin

Abstract

Nanometer-sized particles with lipid double layer, named vesicles, are lately being investigated by many scientists because of their potential in diagnostic and treatment of different diseases. Vesicles are made naturally, but they can be produced in a laboratory as well. In this master's thesis, we were researching vesicles which we made from egg's lecithin concentrate with a process called extrusion. We wanted to know the effect on the size and the zeta potential of vesicles after adding different surfactants. The size was evaluated by measuring the hydrodynamic radius. We were following the changes in the size of the hydrodynamic radius through dynamic light scattering and the changes in the size of zeta potential through electrophoretic measurements. In suspension, we added three surfactants: cationic - dodecyl pyridinium chloride (DPC), anionic - sodium dodecyl sulfate (SDS)) and non-ionic - Brij 30. We were also following the effect of added sugar (trehalose) and temperature on vesicle stability. All the experiments and measurements were made under the same conditions to ensure the optimal comparison between results. Adding cationic surfactant DPC caused bigger vesicles at lower concentrations of surfactants and degradation at higher concentrations of surfactants. Zeta potential came closer to positive values. Rising the temperature did not have any significant effect on the size of the radius and the zeta potencial of vesicles. Adding of the anionic surfactant SDS gave a little less expected results, mostly about the size of the vesicle's radius, because the most changes happened with samples which have had trehalose in it, so it did not protect the vesicles. Zeta potential became more negative, and it did not change a lot with temperature. Adding neutral surfactant Brij 30 also made changes in the size of vesicles. At higher concentration of surfactant and higher concentration of trehalose the vesicles degraded, at lower concentration and at lower concentration of trehalose the surfactant incorporated into vesicle's bilayer. Results of zeta potential stayed similar to original values, as expected.

• Keywords: vesicles, dynamic light scattering, surfactant, trehalose, zeta potential