High resolution membrane structures within hybrid lipid-polymer vesicles revealed by combining x-ray scattering and electron microscopy

29 September 2022, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


Hybrid vesicles consisting of phospholipids and block-copolymers are increasingly finding applications in science and technology. Herein, small angle X-ray scattering (SAXS) and cryo-electron tomography (cryo-ET) were used to obtain detailed structural information about hybrid vesicles with different ratios of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and poly(1,2-butadiene-block-ethylene oxide) (PBd22-PEO14, Ms = 1800 gmol-1) . Using single particle analysis (SPA) we were able to further interpret the information gained from SAXS and cryo-ET experiments, showing that increasing PBd22-PEO14 mole fraction increases the membrane thickness from 52 Å for a pure lipid system to 97 Å for pure PBd22-PEO14 vesicles. We find two vesicle populations with different membrane thicknesses in hybrid vesicle samples. As these lipids and polymers are known to homogeneously mix, bistability is inferred between weak and strong interdigitation regimes of PBd22-PEO14 within the hybrid membranes. It is hypothesized that membranes of intermediate structure are not energetically favourable. Therefore, upon formation, each vesicle selects one of these two membrane structures, which are assumed to have comparable free energies. We conclude that, by combining biophysical methods, an accurate determination of the influence of composition on the structural properties of hybrid membranes is achieved, revealing that two distinct membranes structures can coexist in homogeneously mixed lipid-polymer hybrid vesicles.


Hybrid vesicles
Block copolymers
Membrane structure
Small angle x-ray scattering
Cryo-electron tomography
Single particle analysis

Supplementary materials

Supplementary Information
Further supporting data and analysis


Comments are not moderated before they are posted, but they can be removed by the site moderators if they are found to be in contravention of our Commenting Policy [opens in a new tab] - please read this policy before you post. Comments should be used for scholarly discussion of the content in question. You can find more information about how to use the commenting feature here [opens in a new tab] .
This site is protected by reCAPTCHA and the Google Privacy Policy [opens in a new tab] and Terms of Service [opens in a new tab] apply.