Liposomes in polymer matrix. Stability of liposomes in PEG 400 and PEG 8000 solutions.

Integration of liposomes in polymer matrix is a new concept of controlled drug delivery system. Those kind of materials allow to control dosage of applied drug and time of its release. Certain types of liposomes are unstable, so they require structural support. The main aim of the paper is to investigate how polymers influence aggregation of liposomes. Two different polymers were used for this purpose: polyethylene glycol 400 (PEG 400) and polyethylene glycol 8000 (PEG 8000). Considered liposomes were formed from phospholipon 90G. Viscosity of each sample was measured using Ubbelohde viscometer. 100 nm liposomes were prepared using thin film hydratation method followed by extrusion and subsequently mixed with polymer solutions. Molar concentration of liposomes in each sample was equal to 1,3 mM. The polydispersities of samples were measured using DLS method (Malvern ZetaSizer Nano), at temperature 25. It has been shown that above certain polymers concentrations liposomes aggregate due the crowding effect. Those concentrations for PEG 600 and PEG 8000 are equal to 6 % and 1.1%, respectively.