Cucurbiturils: molecular nanocapsules for time-resolved fluorescence-based assays

Area of Science:

• Supramolecular Chemistry
• Fluorescence Spectroscopy
• Biochemical Assays

Background:

• Development of novel fluorescent probes is crucial for sensitive detection methods.
• Host-guest chemistry offers unique platforms for modulating fluorophore properties.
• Cucurbiturils (CBs) are macrocyclic hosts with tunable cavities.

Purpose of the Study:

• To design and characterize a new fluorescent host-guest system using 2,3-diazabicyclo[2.2.2]oct-2-ene (DBO) and cucurbit[7]uril (CB7).
• To evaluate the potential of this system as an enhancer in time-resolved fluorescence-based assays.

Main Methods:

• Synthesis and characterization of the CB7.DBO complex.
• Measurement of fluorescence emission lifetime and binding constants.
• Assessment of the complex's stability against fluorescence quenchers.
• Demonstration of utility in enzyme activity and inhibition screening assays.

Main Results:

• The CB7.DBO system exhibits an exceptionally long emission lifetime (690 ns in aerated water).
• A high binding constant ((4 +/- 1) x 10(5) M(-1)) was determined for the CB7.DBO complex.
• The complex demonstrated resistance to common external fluorescence quenchers.
• The system proved effective in time-resolved fluorescence assays using DBO-labeled peptides.

Conclusions:

• The designed CB7.DBO host-guest system offers a robust platform for enhanced fluorescence detection.
• Its long-lived emission and quencher resistance make it suitable for sensitive time-resolved fluorescence assays.
• This system has significant potential for applications in biochemical screening, including enzyme activity and inhibition studies.