Stimuliresponsive DNA‐funktionalisierte Nano‐ und Mikrocontainer zur schaltbaren und kontrollierten Freisetzung

Abstract

Nanotechnology enables the design of materials with outstanding performance. A key element of nanotechnology is the ability to manipulate and control matter on the nanoscale to achieve a certain desired set of specific properties. Here, we discuss recent insight into the formation mechanisms of inorganic nanoparticles during precipitation reactions. We focus on calcium carbonate, and describe the various transient stages potentially occurring on the way from the dissolved constituent ions to finally stable macrocrystals—including solute ion clusters, dense liquid phases, amorphous intermediates, and nanoparticles. The role of polymers in nucleating, templating, stabilizing, and/or preventing these structures is outlined. As a specific example for applied nanotechnology, the properties of cement are shown to be determined by the formation and interlocking of calcium‐silicate‐hydrate nanoplatelets. The aggregation of these platelets into mesoscale architectures can be controlled with polymers.

Dynamic Nanostructures from DNA‐Coupled Molecules, Polymers, and Nanoparticles

“…Smart DNA‐based diagnostic and therapeutic systems have been developed based on nanoparticle assemblies responding to the slightly acidic environment inside cancer cells . Ling and co‐workers have constructed pH‐responsive iron oxide nanoparticle assemblies (termed RIAs) that can act as an inverse magnetic resonance imaging (MRI) contrast agent for cancer cells ( Figure a) .…”

Topologically switchable and gated transcription machinery

“…For example, ion-induced formation of G-quadruplexes and their separation in the presence of crown ethers, 7,8 the stabilization of T-T and C-C mismatched duplexes by metal ions, such as Hg 2+ or Ag + , and their separation by metal-ion binding ligands, [9][10][11] the reversible pH-stimulated formation of i-motif structures, 12 the formation of T-A$T triplex structures and their disassembly by fuel strand-driven displacement processes, 13 and the photochemical stabilization/ destabilization of DNA duplexes by photoisomerizable intercalators, such as azobenzene units, 14,15 provide a rich "tool-box" of recongurable DNA topologies. Indeed, these switchable DNA structures were applied to assemble DNA switches 16 and DNA machines, [17][18][19] such as tweezers, 20,21 walkers [22][23][24][25] or nanocarriers, [26][27][28] to design "smart" materials acting as gated drug carriers for controlled drug release, such as SiO 2 nanoparticles, [29][30][31] metal-organic framework nanoparticles [32][33][34] or microcapsules, 35,36 and to prepare stimuli-responsive hydrogels exhibiting switchable stiffness properties for shape-memory, 37,38 self-healing, 39,40 controlled drug-release 41 and mechanical actuating applications. 42 The recongurable DNA structures allow, in principle, the engineering of DNA templates that include topological barriers for operating reversible and cyclic transcription machineries.…”