Release and report: a new photolabile caging system with a two-photon fluorescence reporting function

Area of Science:

• Organic Chemistry
• Photochemistry
• Molecular Biology

Background:

• Photolabile protecting groups are crucial for controlled release of bioactive molecules.
• Existing photocaging systems often lack integrated reporting or efficient uncaging mechanisms.

Purpose of the Study:

• To develop an efficient photocaging system with a fluorescence reporting capability.
• To enable quantification and spatial monitoring of released biological effectors using microscopy.

Main Methods:

• Design and synthesis of photolabile latches based on C-nucleophile adducts of aromatic ketones (thioxanthones, xanthones).
• Utilizing single- and two-photon fluorescence microscopy for monitoring.
• Investigating the photoinduced uncaging mechanism involving radical disproportionation.

Main Results:

• Demonstrated a photocaging system where nucleophilic addition disrupts conjugation, causing a blue shift and fluorescence quenching.
• Showcased photoinduced uncaging via one- or two-photon excitation, restoring fluorescence.
• Successfully synthesized and uncaged dendrimer- and polymeric bead-based model systems.

Conclusions:

• The developed photocaging system offers efficient uncaging and fluorescence reporting.
• This system provides a powerful new tool for spatiotemporal control and monitoring in molecular life sciences.
• The mechanism involves reversible disruption and restoration of ketone conjugation and fluorescence.