Fluorescence Switchable Block Copolymer Particles with Doubly Alternate-Layered Nanoparticle Arrays

Area of Science:

• Materials Science
• Nanotechnology
• Chemistry

Background:

• Block copolymers (BCPs) and inorganic nanoparticles (NPs) self-assemble into functional microparticles under 3D confinement.
• Precise control over nanostructure and functionality is achievable through this self-assembly process.

Purpose of the Study:

• To develop fluorescence-switchable hybrid microspheres using block copolymers and nanoparticles.
• To investigate the modulation of nonradiative energy transfer (NRET) by controlling interparticle distance.

Main Methods:

• Fabrication of hybrid microspheres via self-assembly of polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) BCPs with gold nanoparticles (Au NPs) and CdSe/ZnS quantum dots (QDs).
• Formation of doubly alternating arrays of Au NPs and QDs within BCP domains.
• Solvent-selective swelling to tune the distance between NP and QD layers.

Main Results:

• Achieved controlled NRET between QDs and Au NPs, dependent on layer-to-layer distance.
• Demonstrated switchable fluorescence: 'OFF' in water (strong NRET) and 'ON' in alcohols (reduced NRET).
• Observed enhanced NRET quenching efficiencies in 3D confinement compared to theoretical predictions.

Conclusions:

• The developed hybrid microspheres exhibit robust and reversible fluorescence switching based on solvent environment.
• These particles show significant potential for applications in bioimaging, sensing, and diagnostics.