Programmed Synthesis by Stimuli-Responsive DNAzyme-Modified Mesoporous SiO₂ Nanoparticles

DNAzyme-capped mesoporous SiO₂ nanoparticles (MP SiO₂ NPs) are applied as stimuli-responsive containers for programmed synthesis. Three types of MP SiO₂ NPs are prepared by loading the NPs with Cy3-DBCO (DBCO=dibenzocyclooctyl), Cy5-N₃, and Cy7-N₃, and capping the NP containers with the Mg²⁺, Zn²⁺, and histidine-dependent DNAzyme sequences, respectively. In the presence of Mg²⁺ and Zn²⁺ ions as triggers, the respective DNAzyme-capped NPs are unlocked, leading to the "click" reaction product Cy3-Cy5. In turn, in the presence of Mg²⁺ ions and histidine as triggers the second set of DNAzyme-capped NPs is unlocked leading to the Cy3-Cy7 conjugated product. The unloading of the respective NPs and the time-dependent formation of the products are followed by fluorescence spectroscopy (FRET). A detailed kinetic model for the formation of the different products is formulated and it correlates nicely with the experimental results. Cofactor-dependent DNAzymes trigger the selective unlocking of a mixture of loaded mesoporous SiO₂ nanoparticles. This results in the programmed synthesis of click-chemistry products.