Measuring ligand-receptor binding events on polymeric surfaces with periodic wave patterns using liquid crystals

Area of Science:

• Materials Science
• Nanotechnology
• Biophysics

Background:

• Developing sensitive biosensors for detecting ligand-receptor interactions is crucial in various scientific fields.
• Utilizing nanostructured surfaces can enhance sensor performance by increasing surface area and controlling molecular orientation.
• Liquid crystals (LCs) offer unique optical properties that can be modulated by surface interactions.

Purpose of the Study:

• To develop and characterize a novel sensor for detecting ligand-receptor binding events.
• To investigate the use of liquid crystals (LCs) on nanostructured polymeric substrates for sensing applications.
• To demonstrate the capability of this system to provide optical readouts of molecular interactions.

Main Methods:

• Fabrication of periodic nanostructured polymeric surfaces (poly-(urethane acrylate)) using a poly-(dimethylsiloxane) template.
• Immobilization of avidin onto a gold-coated surface via self-assembled monolayers (NHS/EDC chemistry).
• Measurement of liquid crystal (LC) orientation (nematic 4-cyano-4'-pentylbiphenyl) and optical response upon avidin-biotin complex formation.
• Confirmation of interactions using ellipsometry and atomic force microscopy (AFM).

Main Results:

• The orientation of nematic 4-cyano-4'-pentylbiphenyl (5CB) was initially parallel to the avidin-functionalized surface.
• Avidin-biotin complex formation disrupted the surface nanostructures, inducing a random LC orientation.
• This disruption resulted in a distinct and measurable change in the optical response of the device.
• Ellipsometry and AFM confirmed specific ligand-receptor interactions and surface topography changes.

Conclusions:

• Polymeric surfaces with continuous wavy nanostructures can be effectively used for biosensing.
• Liquid crystal (LC) orientation is sensitive to surface topography changes induced by ligand-receptor binding.
• This approach offers a promising platform for developing novel LC-based sensors for molecular detection.