A Deep-Red Emissive Cage-in-Rings Complex for Lysosome Imaging

Area of Science:

• Supramolecular Chemistry
• Bioimaging Probes
• Chemical Biology

Background:

• Developing biocompatible, long-wavelength emissive, and selective bioprobes is crucial for bioimaging and clinical applications.
• Existing bioimaging probes often face challenges with water solubility, non-specific interactions, and limited emission wavelengths.

Purpose of the Study:

• To construct a novel cage-in-rings bioimaging probe with enhanced properties for subcellular imaging.
• To investigate the supramolecular assembly of a hexacationic cage (TPBCage⁶⁺) with cucurbit[8]uril (CB[8]) and its impact on optical and biological characteristics.

Main Methods:

• Stepwise assembly protocol utilizing noncovalent association between TPBCage⁶⁺ and CB[8].
• Characterization of the resulting complex's conformation, cellular uptake, and photophysical properties (emission wavelength, quantum yield).
• Evaluation of biocompatibility and lysosome-selective imaging capabilities in vitro.

Main Results:

• Successfully synthesized the TPBCage⁶⁺⊂3CB[8] complex with a C₂-symmetrical conformation.
• The complex demonstrated improved aqueous solubility, suppressed π-π stacking, and efficient cellular uptake.
• Encapsulation by CB[8] induced a significant red shift in emission (552 nm to 652 nm) and enhanced fluorescence quantum yield.

Conclusions:

• The developed cage-in-rings supramolecular strategy enables precise control over bioimaging probe properties.
• The TPBCage⁶⁺⊂3CB[8] probe facilitates effective lysosome-selective imaging in the deep-red region due to its enhanced characteristics.
• This approach offers a new avenue for designing intrinsically selective and advanced bioimaging agents.