Cucurbit[8]uril Confinement-Based Secondary Coassembly for High-Efficiency Phosphorescence Energy Transfer Behavior

Area of Science:

• Supramolecular Chemistry
• Materials Science
• Biomedical Imaging

Background:

• Developing aqueous supramolecular materials with long-lived near-infrared (NIR) emission is challenging.
• Existing materials often lack stability or efficient energy transfer in aqueous environments.

Purpose of the Study:

• To create a stable, water-compatible supramolecular system exhibiting long-lived NIR phosphorescence.
• To achieve efficient phosphorescence energy transfer within the supramolecular assembly.
• To demonstrate the utility of the developed material as an imaging agent in biological systems.

Main Methods:

• Hierarchical confinement strategy involving cucurbit[8]uril (CB[8]) and poly(4-styrene-sulfonic sodium) (PSS).
• Fabrication of linear polypseudorotaxane (G⊂CB[8]) nanofibers and subsequent assembly with PSS into spherical nanoparticles.
• Doping with Rhodamine 800 as an energy acceptor to facilitate phosphorescence energy transfer.

Main Results:

• Formation of linear polypseudorotaxane G⊂CB[8] nanofibers with phosphorescent emission at 510 nm.
• Secondary assembly with PSS yielded nanoparticles with significantly enhanced phosphorescence lifetime (2.39 ms).
• Efficient phosphorescence energy transfer (up to 80.1%) achieved, resulting in red-shifted NIR emission at 710 nm.

Conclusions:

• The hierarchical confinement strategy effectively creates stable aqueous supramolecular materials with enhanced phosphorescence.
• The developed system demonstrates efficient energy transfer and long-lived NIR emission.
• The material serves as a promising and versatile imaging agent for NIR window labeling and detection in living cells.