At a 1:1 ratio, the interaction between CDs and POPC vesicles leads to a heterogeneous population of vesicle sizes, as indicated by the presence of three distinct peaks at 17 nm, 53 nm, and 110 nm. This suggests that the CDs induce partial vesicle disruption, fragmentation, or fusion, resulting in an equilibrium where some vesicles remain largely intact while others break apart or reorganize into smaller structures. The 17 nm and 53 nm peaks likely correspond to vesicle fragments or restructured vesicles, while the 110 nm peak may represent partially intact or reassembled vesicles.
As the CD concentration increases (1:5, 1:10, 1:100), the interaction becomes more extensive, leading to a single, stable vesicle population at 110 nm. The uniform size distribution at these higher ratios suggests that CDs more effectively integrate into the vesicle bilayer, promoting complete restructuring and eliminating intermediate-sized vesicles. Additionally, the increasing intensity of the 110 nm peak indicates that CDs facilitate vesicle reorganization into a thermodynamically stable form.
The original POPC vesicles (360 nm) undergo significant size reduction upon interacting with CDs, which implies that the CDs alter membrane curvature and packing. At a 1:1 ratio, the interaction is incomplete or uneven, leading to vesicle heterogeneity. However, at higher ratios, CDs drive a more uniform structural transformation, resulting in a single vesicle population. This behavior supports the conclusion that CDs interact with and penetrate the vesicles, ultimately leading to a stabilized and homogeneous vesicle system at higher CD concentrations.
These findings provide further insight into how CDs interact with lipid bilayers and influence vesicle morphology. The observed size reduction and restructuring suggest that CDs could play a role in modulating membrane properties, which has implications for their potential use in drug delivery systems. Future studies utilizing techniques such as transmission electron microscopy (TEM) and electron paramagnetic resonance (EPR) could provide further confirmation of CD-induced membrane restructuring at the molecular level.