Integrating Cu₂O Colloidal Mie Resonators in Structurally Colored Butterfly Wings for Bio-Nanohybrid Photonic...

Area of Science:

• Materials Science
• Nanotechnology
• Biophotonics

Background:

• Colloidal copper(I) oxide (Cu₂O) nanoparticles possess photocatalytic and Mie scattering properties.
• Immobilizing nanoparticles on substrates is crucial for practical applications.
• Butterfly wings offer complex hierarchical photonic nanoarchitectures suitable for nanoparticle integration and optical property tuning.

Purpose of the Study:

• To develop a bio-nanohybrid photonic nanoarchitecture by immobilizing Cu₂O nanoparticles on butterfly wings.
• To investigate the integration of Cu₂O nanoparticles within the natural photonic structures of *Polyommatus icarus* butterfly wings.
• To tune the optical properties of butterfly wing scales using Cu₂O nanoparticles.

Main Methods:

• Preparation of *P. icarus* butterfly wings by removing the native wax layer with ethanol.
• Deposition of Cu₂O nanoparticles onto the prepared wing scales using drop casting.
• Characterization using optical and electron microscopy, FTIR, UV-Vis spectrophotometry, microspectrophotometry, and hyperspectral spectrophotometry.

Main Results:

• Reproducible deposition of Cu₂O nanoparticles on the dorsal blue wing scales of *P. icarus* was achieved.
• Cu₂O nanoparticles integrated effectively into the wing's photonic nanoarchitecture.
• Mie resonance of Cu₂O nanoparticles was observed on glass slides but absent on Si(100).
• The spectral properties of the butterfly wings were modified by the integrated Cu₂O nanoparticles.

Conclusions:

• A novel bio-nanohybrid photonic nanoarchitecture was successfully fabricated.
• The Cu₂O nanoparticles tuned the spectral properties of the butterfly wing scales.
• Backscattering due to Mie resonance was suppressed in the bio-nanohybrid structure, despite the low refractive index of chitin.