Stimuli-Responsive Directional Vesicular Assembly with Tunable Surface Functionality and Impact on Enzyme Inhibition

Area of Science:

• Supramolecular Chemistry
• Materials Science
• Nanotechnology

Background:

• Bola-amphiphiles are molecules with two hydrophilic groups and one or two hydrophobic groups.
• Self-assembly of amphiphiles is crucial for creating nanostructures with tunable properties.
• Naphthalene-diimide (NDI) based molecules offer unique photophysical and self-assembly characteristics.

Purpose of the Study:

• To synthesize and characterize unsymmetrical bola-shaped π-amphiphiles with a naphthalene-diimide (NDI) core.
• To investigate the self-assembly behavior of these amphiphiles in aqueous solutions.
• To explore the influence of headgroup location and type on vesicle formation and biomolecular recognition.

Main Methods:

• Synthesis of NDI-based bola-amphiphiles (NDI-1, NDI-1a, NDI-2, NDI-3, NDI-4).
• Characterization of self-assembled structures using electron microscopy, small-angle neutron scattering, and dynamic light scattering.
• Spectroscopic studies to analyze molecular interactions and assembly.
• Enzyme inhibition assays to evaluate biomolecular recognition capabilities.

Main Results:

• Most NDI derivatives spontaneously formed vesicle structures in water (pH 9.0).
• Self-assembly led to non-symmetric membranes with functional groups directed by hydrazide group placement.
• Vesicle properties, including surface charge density and size, were tunable by modifying headgroups.
• Lower critical solution temperature (LCST) behavior was observed, leading to nanoparticle formation above ~40 °C.
• Vesicle performance in biomolecular recognition and enzyme inhibition varied based on surface charge and functionalization.

Conclusions:

• Unsymmetrical NDI bola-amphiphiles can self-assemble into functional vesicles with controllable surface properties.
• The location of the hydrazide group dictates the orientation of functional groups within the vesicle membrane.
• These self-assembled vesicles demonstrate tunable capabilities for electrostatic-driven biomolecular recognition.
• The study highlights the potential of NDI-based amphiphiles for applications in sensing and drug delivery.