Click-and-Release: Dissociative Bioorthogonal Chemical Reactions for Drug Delivery and Diagnostics

Bioorthogonal chemical reactions have been utilised in bioconjugation and imaging strategies. While these reactions could be considered as “click-and-stick” type reactions, our group is interested in taking advantage of a “click-and-release” type strategy for controlled drug delivery and diagnostic applications. To achieve sufficient activation in vivo, the initial reaction must be fast and the drug must dissociate from the linker to exert its biological response. We have identified a new and general bioorthogonal activation strategy based on the 1,3-dipolar cycloaddition of an azide-substituted self-immolative linker (SIL) and trans-cyclooctene (TCO). Substituents on the SIL can influence the rate of the bioorthogonal reaction, the subsequent hydrolysis of intermediates, and elimination of the linker. Our in vitro and in vivo proof-of-concept studies demonstrating how we have applied our approach to both raid and slow release drug delivery (prodrugs and nanoparticles) will be discussed.