Electric Field Controlled Self-Assembly of Hierarchically Ordered Membranes.

Abstract

Self-assembly in the presence of external forces is an adaptive, directed organization of molecular components under nonequilibrium conditions. While forces may be generated as a result of spontaneous interactions among components of a system, intervention with external forces can significantly alter the final outcome of self-assembly. Superimposing these intrinsic and extrinsic forces provides greater degrees of freedom to control the structure and function of self-assembling materials. In this work we investigate the role of electric fields during the dynamic self-assembly of a negatively charged polyelectrolyte and a positively charged peptide amphiphile in water leading to the formation of an ordered membrane. In the absence of electric fields, contact between the two solutions of oppositely charged molecules triggers the growth of closed membranes with vertically oriented fibrils that encapsulate the polyelectrolyte solution. This process of self-assembly is intrinsically driven by excess osmotic pressure of counterions, and the electric field is found to modify the kinetics of membrane formation, and also its morphology and properties. Depending on the strength and orientation of the field we observe a significant increase or decrease of up to nearly 100% in membrane thickness, as well as the controlled rotation of nanofiber growth direction by 90 degrees, resulting in a significant increase in mechanical stiffness. These results suggest the possibility of using electric fields to control structure in self-assembly processes involving diffusion of oppositely charged molecules.

AI evidence extraction

Main findings

In an aqueous in vitro self-assembly system (negatively charged polyelectrolyte with positively charged peptide amphiphile), an applied electric field modified the kinetics of membrane formation and altered membrane morphology and properties. Field strength and orientation were associated with increases or decreases in membrane thickness (reported up to nearly 100%), a 90° rotation of nanofiber growth direction, and increased mechanical stiffness.

Outcomes measured

• membrane formation kinetics
• membrane thickness
• nanofiber growth direction/orientation
• membrane morphology
• mechanical stiffness

Limitations

• No electric field parameters (e.g., field strength values, waveform/frequency, exposure duration) are provided in the abstract.
• No sample size or replication details are provided in the abstract.
• In vitro materials self-assembly study; not a health or epidemiology outcome.

Suggested hubs

• engineering (0.9)
  Study investigates how applied electric fields control material self-assembly and membrane properties.

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    "outcomes": [
        "membrane formation kinetics",
        "membrane thickness",
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    "main_findings": "In an aqueous in vitro self-assembly system (negatively charged polyelectrolyte with positively charged peptide amphiphile), an applied electric field modified the kinetics of membrane formation and altered membrane morphology and properties. Field strength and orientation were associated with increases or decreases in membrane thickness (reported up to nearly 100%), a 90° rotation of nanofiber growth direction, and increased mechanical stiffness.",
    "effect_direction": "mixed",
    "limitations": [
        "No electric field parameters (e.g., field strength values, waveform/frequency, exposure duration) are provided in the abstract.",
        "No sample size or replication details are provided in the abstract.",
        "In vitro materials self-assembly study; not a health or epidemiology outcome."
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    "peer_reviewed_likely": "yes",
    "keywords": [
        "electric field",
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        "kinetics"
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