Copper-free Click Chemistry: Applications in Drug Delivery, Cell Tracking and Tissue Engineering.

Traditionally, organic chemical reactions require organic solvents, toxic catalysts, heat, or high pressure. However, copper-free click chemistry has been shown to have favorable reaction rates and orthogonality in water, buffer solutions, and physiological conditions without toxic catalysts. Strain-promoted azide-alkyne cycloaddition and inverse electron-demand Diels-Alder reactions are representative of copper-free click chemistry. Artificial chemical reactions via click chemistry can also be used outside of the laboratory in a controllable manner on live cell surfaces, in the cytosol, and in living bodies. Consequently, copper-free click chemistry has many features that are of interest in biomedical research, and various new materials and strategies for its use have been proposed. Herein, we describe recent remarkable trials that have used copper-free click chemistry, focusing on their applications in molecular imaging and therapy. We have categorized the research as nanoparticles for drug delivery, imaging agents for cell tracking, and hydrogels for tissue engineering, which are rapidly advancing fields based on click chemistry. The content is based primarily on our experience with click chemistry-based biomaterials over the last ten years. This article is protected by copyright. All rights reserved.