A Triazolium‐Anchored Self‐Immolative Linker Enables Self‐Assembly‐Driven siRNA Binding and Esterase‐Induced Release

Abstract

The increased importance of RNA-based therapeutics comes with a need to develop next-generation stimuliresponsive systems capable of binding, transporting and releasing RNA oligomers. In this work, we describe triazoliumbased amphiphiles capable of siRNA binding and enzymeresponsive release of the nucleic acid payload. In aqueous medium, the amphiphile self-assembles into nanocarriers that can disintegrate upon the addition of esterase. Key to the molecular design is a self-immolative linker that is anchored to the triazolium moiety and acts as a positively-charged polar head group. We demonstrate that addition of esterase leads to a degradation cascade of the linker, leaving the neutral triazole compound unable to form complexes and therefore releasing the negatively-charged siRNA. The reported molecular design and overall approach may have broad utility beyond this proof-of-principle study, because the underlying CuAAC "click" chemistry allows bringing together three groups very efficiently as well as cleaving off one of the three groups under the mild action of an esterase enzyme.

The Dynamic Chemistry of Orthoesters and Trialkoxysilanes: Making Supramolecular Hosts Adaptive, Fluxional, and Degradable

“… 38 Installation of a stimuli-responsive trigger, that can be cleaved e.g. by esterase, 41 would allow application of such compounds for the targeted delivery of ions in tissue where esterases are overexpressed and pH is low (e.g., cancer cells).…”

A Comprehensive Review of Small Interfering RNAs (siRNAs): Mechanism, Therapeutic Targets, and Delivery Strategies for Cancer Therapy

“…2023;29(8):e202203311. 238 Creative Commons CC BY license. Copyright 2022, The Authors, published by Wiley-VCH GmbH.…”

“…Hollstein et al performed a study on triazolium-based amphiphiles that demonstrated their ability to bind to siRNA and facilitate enzyme-responsive release of the nucleic acid payload. Upon the addition of esterases, the linker undergoes cascade degradation, preventing the formation of complexes with neutral triazole compounds and resulting in the release of negatively charged siRNA 238 ( Figure 6C ). Additionally, Shi et al designed a novel siRNA carrier called polyfluorinated polyarginine (PFC-PR), which is responsive to both oxidoreductases and enzymes.…”

Trans‐N‐alkylation Covalent Exchanges on 1,3,4‐Trisubstituted 1,2,3‐Triazolium Iodides

“…[13][14][15] TILs have been valuably applied as ligands of metal complexes, [16] chemosensors for anion recognition, [17,18] organocatalysts, [19,20] electrolytes for dye sensitized solar cells, [21] or therapeutics. [22,23] The combination of CuAAC and quantitative N-alkylation of 1,2,3-triazole groups with diverse polymerization or postpolymerization chemical modification approaches has paved the way for the development of 1,2,3-triazolium-based poly(ionic liquid)s, as a recent class of polymer electrolytes with enhanced ion conducting properties. [24][25][26][27] Moreover, polymer networks including 1,2,3-triazolium cross-links featuring all attributes of covalent adaptable networks (CANs) were reported.…”

“…Meanwhile, the synthesis of 1,3,4‐trisubstituted 1,2,3‐triazolium salts by N‐ alkylation of the N‐ 3 position of 1,4‐disubstituted 1,2,3‐triazoles has provided a broad library of task‐specific 1,2,3‐triazolium ionic liquids (TILs) with highly tunable chemical and physical properties [13–15] . TILs have been valuably applied as ligands of metal complexes, [16] chemosensors for anion recognition, [17,18] organocatalysts, [19,20] electrolytes for dye sensitized solar cells, [21] or therapeutics [22,23] …”