Physical Stability of Liposomes
Author:
Matt Brennan ’24Co-Authors:
Faculty Mentor(s):
Kenny Mineart, Chemical EngineeringFunding Source:
Program for undergraduate researchAbstract
Liposomes have proven to be effective nanocarriers of various drugs and pharmaceutical compounds. Their spherical lipid bilayer composition enables the entrapment of such molecules in their internal aqueous environment. A concern with these nanocarriers is their stability over time. Specifically, I investigated how liposomes degrade in different pH buffer solutions over an 8-day period. Fabrication of liposomes was accomplished by extruding DOPC lipids in buffer solutions of varying pH’s through a 100 nm pore size polycarbonate membrane. The samples were stored in a 70 °C recirculatory bath throughout the experiment and were tested daily. To characterize degradation, I utilized Dynamic Light Scattering (DLS) and UV-Vis spectroscopy. The DLS was used to determine average liposome size and the UV-Vis was used to determine light transmittance. We found liposome diameter increased for all pH’s with a significant increase in polydispersity among all samples. While some pH’s did cause greater increases than others, we were unable to make a strong correlation between the rate of degradation and the pH. The UV-Vis was not useful as the initial solutions were too opaque. The overall increase in polydispersity is significant because it points towards a “soup” of particles that may form from the various degradation products. These products may include various sized liposomes, long cylindrical micelles, and surfactant particles. Further study of these particles may give insight into the degradation processes occurring.