Multiscale characterization of lipid bilayer disruption induced by Methyl-β-cyclodextrin (MβCD)

This study investigated the biophysical impacts of methyl-β-cyclodextrin (MβCD) on supported lipid bilayers composed of DPPC/POPE (1:1) and DPPC/POPE/Chol (1:1:2). Using Quartz Crystal Microbalance with Dissipation (QCM-D), Atomic Force Microscopy (AFM) imaging and force–distance (F–D) curve analysis, we monitored vesicle fusion, assessed bilayer symmetry, and evaluated mechanical stability before and after MβCD treatment. The DPPC/POPE bilayer initially showed a distinct “kink” in its F–D curve and a single breakthrough force, indicating a relatively asymmetric and heterogenous structure. Upon MβCD treatment, the bilayer exhibited symmetry, as evidenced by breakthrough force profiles. Similarly, the cholesterol-containing DPPC/POPE/Chol bilayers displayed two breakthrough points, signifying distinct lipid domains, higher rigidity, and heterogeneity. After one hour of MβCD treatment, these bilayers became more homogeneous and showed a single breakthrough peak—evidence of successful cholesterol or phospholipid extraction. Breakthrough force histograms reinforced these findings by revealing substantial shifts in force distributions. Complementary dynamic light scattering (DLS) and zeta potential measurements confirmed vesicle size and surface charge, while QCM detected notable mass loss in cholesterol-rich bilayers at elevated temperatures. Collectively, these findings underscore the role of cholesterol in bilayer architecture and validate MβCD as an effective modulator of bilayer composition and symmetry.