Surface functionalization of exosomes using click chemistry.

Area of Science:

• Bioconjugation Chemistry
• Nanomedicine
• Cell Biology

Background:

• Exosomes are nanoscale vesicles with therapeutic potential.
• Modifying exosome surfaces is crucial for targeted delivery and diagnostics.
• Existing conjugation methods can be harsh, affecting exosome integrity.

Purpose of the Study:

• To develop a mild and efficient method for conjugating ligands to exosome surfaces.
• To utilize click chemistry for robust exosome modification.
• To assess the impact of the conjugation method on exosome structure and function.

Main Methods:

• Developed a method using copper-catalyzed azide alkyne cycloaddition (click chemistry) for exosome surface conjugation.
• Cross-linked exosomes with alkyne groups via carbodiimide chemistry.
• Conjugated a model azide-fluor 545 to the alkyne-modified exosomes.
• Assessed exosome size, adherence, and internalization by recipient cells post-conjugation.
• Quantified the extent of exosomal protein modification with alkyne groups using liposome standards.

Main Results:

• Successfully conjugated azide-functionalized molecules to alkyne-modified exosome surfaces using click chemistry.
• The conjugation process did not alter exosome size or their adherence/internalization by recipient cells.
• Mild reaction conditions preserved exosome structure and function.
• Estimated approximately 1.5 alkyne groups per 150 kDa of exosomal protein.

Conclusions:

• Click chemistry provides a versatile and efficient platform for exosome surface functionalization.
• The developed method is mild, preserving exosome integrity and biological activity.
• This approach holds promise for advancing exosome-based therapeutics and diagnostics.