Date of Thesis

Spring 2025

Description

Liposomes are lipid-based nanoparticles with significant applications in drug delivery and membrane research. One of the most common methods for fabricating liposomes of specific sizes is membrane extrusion, where liposomes are passed through porous membranes to reduce their size. The precise number of passes needed and the factors influencing this process remain unclear. This thesis investigates the relationship between the number of passes through a track-etched polycarbonate membrane and size and lamellarity of extruded liposomes with a focus on lipid type (DOPC, DMPC, Soy PC), membrane pore size (50, 100, 200, 400 nm), and the effect of freeze-thaw cycling. To explore this, liposome samples were extruded between 1 and 1001 passes. Dynamic and static light scattering (DLS/SLS) and light transmission techniques were used to quantify size, the latter of which also provided insights to lamellarity. Small-angle x-ray scattering (SAXS) was used to quantify lamellarity with cryo-transmission electron microscopy (CryoTEM) providing visual validation. These metrics were normalized with the convergence ratio (κ), defined as a given point divide by its two-point moving average. The optimal number of passes for each experimental case was determined at the first point where κ = 1.00 ± 0.05, indicating that further passes do not significantly alter liposome properties. It was determined that the optimal number of passes range from 11-51 passes with no clear trend across pore size or lipid type.

Keywords

Liposomes, Drug Delivery, Optimization

Access Type

Honors Thesis

Degree Type

Bachelor of Science in Chemical Engineering

Major

Chemical Engineering

Minor, Emphasis, or Concentration

Mathematics

First Advisor

Kenneth Mineart

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