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-N-3, and Cy7-N-3, 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.