"Close-to-Release": Spontaneous Bioorthogonal Uncaging Resulting from Ring-Closing Metathesis

Area of Science:

• Chemical Biology
• Organic Chemistry
• Biotechnology

Background:

• Bioorthogonal uncaging reactions are crucial for manipulating molecules within biological systems.
• Existing methods often require specific conditions or lack efficiency under physiological settings.
• Developing novel uncaging strategies is essential for advancing chemical biology tools.

Purpose of the Study:

• To introduce a novel bioorthogonal uncaging strategy termed "close-to-release" based on ring-closing metathesis (RCM).
• To demonstrate the efficiency and applicability of this method for releasing various payloads, including drugs and fluorescent probes.
• To validate the method's performance in complex biological environments, such as within mammalian cells and bacterial periplasm.

Main Methods:

• Utilizing ring-closing metathesis (RCM) to trigger a subsequent spontaneous 1,4-elimination reaction.
• Covalently linking a caged molecule to a diolefinic substrate designed for RCM.
• Testing the uncaging efficiency and kinetics with different drug molecules and fluorescent probes.
• Evaluating the method's performance in vitro, in the presence of mammalian cells, and within the periplasm of *Escherichia coli*.

Main Results:

• The "close-to-release" strategy successfully uncaged various molecules, including drugs and fluorescent probes, with high efficiency.
• Fast uncaging rates were observed, demonstrating the method's responsiveness.
• The uncaging reaction proceeded effectively in the presence of mammalian cells and within the periplasm of *E. coli*, indicating good biocompatibility and applicability in vivo.
• The RCM-initiated 1,4-elimination mechanism proved robust for controlled molecular release.

Conclusions:

• The "close-to-release" strategy represents a novel and efficient bioorthogonal uncaging method.
• This RCM-based approach offers a versatile tool for controlled release of molecules in diverse biological contexts.
• The method holds significant potential for applications in chemical biology, bioengineering, and medicine, enabling precise spatiotemporal control over molecular function.