Biomarker-Triggered Fluorogenic Label in Live Systems via Switchable Iminosydnone-Alkyne Cycloaddition

Area of Science:

• Chemical Biology
• Molecular Imaging
• Bioconjugation Chemistry

Background:

• Precise spatiotemporal control is essential for studying biological processes in living systems.
• Existing bioorthogonal labeling methods often lack responsiveness to intrinsic cellular stimuli.
• External triggers like light offer control but intrinsic cellular triggers are scarce.

Purpose of the Study:

• To develop a modular, stimulus-activated bioorthogonal platform for precise labeling in live cells.
• To create a 'turn-on' labeling system responsive to various cellular stimuli.
• To demonstrate selective labeling of target cells within complex environments.

Main Methods:

• Development of a modified iminosydnone-alkyne cycloaddition (ISAC) platform.
• Gating the ISAC reaction using a cleavable, electron-withdrawing carbamate protecting group at the 6-N position.
• Utilizing stimuli such as light, enzymes, or reactive oxygen species to remove the protecting group and restore reactivity.

Main Results:

• The modified iminosydnone exhibited suppressed cycloaddition reactivity until the protecting group was removed.
• Stimuli rapidly restored high ISAC reactivity, accompanied by a fluorogenic response.
• Achieved wash-free, stimulated-controlled fluorescent labeling of proteins and glycoproteins in live cells.
• Demonstrated selective protein labeling on target cells in cocultures by leveraging cell-specific enzymes, showcasing high spatial selectivity.

Conclusions:

• The developed platform offers a versatile strategy for precise biomolecular interrogation in complex biological systems.
• This stimulus-activated bioorthogonal approach enables highly specific labeling with potential applications in studying intercellular communication and targeted delivery.
• The modular design and fluorogenic response facilitate wash-free, stimulated-controlled imaging in live cells.