Ladungstransfer durch die DNA: Vom Mechanismus zur Anwendung

DNA charge transfer chemistry has been subject of considerable interest with consequences in the formation of oxidative damage to the DNA which can result in mutagenesis or carcinogenesis. In this article, important examples of spectroscopical and biochemical assays are compared and discussed in terms of the effiencies, rates, and mechanisms. Coupled with the demonstration that such charge transfer can be modulated both negatively and positively by DNA‐binding proteins, these observations therefore suggest the intriguing possibility that DNA‐mediated charge transfer chemistry is biological relevant and may play a role in cellular processes. Additionally, charge transfer chemistry plays a growing role in the recent development of DNA chips detecting mutations or lesions of nucleic acids.     

Crystallization of DNA‐Capped Gold Nanoparticles in High‐Concentration,Divalent Salt Environments

The multiparametric nature of nanoparticle self‐assembly makes it challenging to circumvent the instabilities that lead to aggregation and achieve crystallization under extreme conditions. By using non‐base‐pairing DNA as a model ligand instead of the typical base‐pairing design for programmability, long‐range 2D DNA–gold nanoparticle crystals can be obtained at extremely high salt concentrations and in a divalent salt environment. The interparticle spacings in these 2D nanoparticle crystals can be engineered and further tuned based on an empirical model incorporating the parameters of ligand length and ionic strength.     

Binding‐Induced DNA Nanomachines Triggered by Proteins and Nucleic Acids

We introduce the concept and operation of a binding‐induced DNA nanomachine that can be activated by proteins and nucleic acids. This new type of nanomachine harnesses specific target binding to trigger assembly of separate DNA components that are otherwise unable to spontaneously assemble. Three‐dimensional DNA tracks of high density are constructed on gold nanoparticles functionalized with hundreds of single‐stranded oligonucleotides and tens of an affinity ligand. A DNA swing arm, free in solution, is linked to a second affinity ligand. Binding of a target molecule to the two ligands brings the swing arm to AuNP and initiates autonomous, stepwise movement of the swing arm around the AuNP surface. The movement of the swing arm, powered by enzymatic cleavage of conjugated oligonucleotides, cleaves hundreds of oligonucleotides in response to a single binding event. We demonstrate three nanomachines that are specifically activated by streptavidin, platelet‐derived growth factor, and the Smallpox gene. Substituting the ligands enables the nanomachine to respond to other molecules. The new nanomachines have several unique and advantageous features over DNA nanomachines that rely on DNA self‐assembly.