Figure 5.

Schematic illustration of mercuric-ion-triggered drug release from mesoporous silica nanoparticles (MSNs) that were capped by dsDNA. The hydroxy functional groups on the surfaces of the MSNs were first conjugated to the isocyanate groups (-NCO) of 3(triethoxysilyl)propyl isocyanate (MSN-NCO). After model drug rhodamine 6G dye was loaded into the MSNs (MSN-R6G), the -NCO groups were conjugated with aminomodified two-arm-DNA strands [MSN (uncapped)]. The arm-DNA strands were further hybridized by a linker DNA to cap the dye-loaded MSNs [MSN (capped)]. Upon exposure to Hg²⁺ ions, the DNA strands underwent dehybridization and released the loaded dye [MSN (after cleavage of linker DNA)]. Adapted, with permission, from [58].