Mechanical Properties of Poly(dimethylsiloxane)-block-poly(2-methyloxazoline) Polymersomes Probed by Atomic Force Microscopy

Abstract

Poly(dimethylsiloxane)-block-poly(2-methyloxazoline) (PDMS-b-PMOXA) vesicles were characterized by a combination of dynamic light scattering (DLS), cryogenic transmission electron microscopy (cryo-TEM), and atomic force microscopy imaging and force spectroscopy (AFM). From DLS data, a hydrodynamic radius of ~150 nm was determined, and cryo-TEM micrographs revealed a bilayer thickness of ~16 nm. In AFM experiments on a silicon wafer substrate, adsorption led to a stable spherical caplike conformation of the polymersomes, whereas on mica, adsorption resulted also in vesicle fusion and formation of bilayer patches or multilayer stacks. This indicates a delicate balance between the mechanical stability of PDMS-b-PMOXA polymersomes on one hand and the driving forces for spreading on the other. A Young's modulus of 17 ± 11 MPa and a bending modulus of 7 ± 5 × 10(-18) J were derived from AFM force spectroscopy measurements. Therefore, the elastic response of the PDMS-b-PMOXA polymersomes to external stimuli is much closer to that of lipid vesicles compared to other types of polymersomes, such as polystyrene-block-poly(acrylic acid) (PS-b-PAA).

Immobilized Multifunctional Polymersomes on Solid Surfaces: Infrared Light-Induced Selective Photochemical Reactions, pH Responsive Behavior, and Probing Mechanical Properties under Liquid Phase

“…This is in agreement with a previous report where the flattening effect of surface activeness on (PDMS-b-PMOXA) vesicles adsorbed on oxidized Si wafers and mica substrates was explored. 21 This behavior was also supported by another study which showed that the increasing molecular recognition between streptavidin layers and biotinylated liposomes induced a height decrease in the vesicle structures. 49 Furthermore, particle size distributions of the surfaceimmobilized polymersomes were compared with the data obtained from cryo-TEM analysis ( Figure 5, Figure S1).…”

“…Similar approaches have been applied previously for liposomes, 33 polyelectrolyte multilayer capsules, 34 natural membrane nanovesicles, 35 and different polymersome structures. 21,22 Hence, as illustrated in Scheme 1, we first performed the surface immobilization of multifunctional and photo-crosslinked polymersomes by strong adamantane−β-cyclodextrin host−guest interactions. Before proceeding to responsive behavior analysis, the level of binding forces between β-cyclodextrin coated substrates and adamantane decorated polymersomes was studied to gain information about the shape deformation of the vesicles when adhering to the surfaces.…”

Hierarchical Self‐Assembly of PDMA‐b‐PS Chains into Granular Nanoparticles: Genesis and Fate

“…This finding indicates that our nanoparticles are mechanically stable enough to be shape‐persistent during adsorption and also drying, where strong capillary forces will occur. In comparison, for poly(dimethylsiloxane)‐ b ‐poly(2‐methyloxazoline), which is known to form spherical vesicles in solutions, a height‐to‐width ratio of 1:6.25 has been reported upon adsorption to a solid substrate …”

Polimerossomos versus lipossomos: a evolução da "Bala Mágica"

“…69,70 A microscopia de fluorescência também necessita de marcador fluorescente nas vesículas e permite estudar processos dinâmicos como difusão. 66 A microscopia de força atômica (MFA) pode ser usada para avaliar características mecânicas da bicamada dos PL 71 como fizeram Chen e coloaboradores que, por meio de MFA, avaliaram a rigidez de membranas de poliestireno-b-poli(ácido)acrílico. 72 Assim como para outros NC, a taxa de encapsulação pode ser calculada diretamente nos sistemas após tratamentos que desagregam os PL ou indiretamente no sobrenadante após centrifugação dessas nanoestruturas.…”