DNA origami technology allows for the precise nanoscale assembly of chemical entities that give rise to sophisticated functional materials. We have created a versatile DNA origami nanofork antenna (DONA) by assembling Au or Ag nanoparticle dimers with different gap sizes down to 1.17 nm, enabling signal enhancements in surface-enhanced Raman scattering (SERS) of up to 1011. This allows for single-molecule SERS measurements, which can even be performed with larger gap sizes to accommodate differently sized molecules, at various excitation wavelengths. A general scheme is presented to place single analyte molecules into the SERS hot spots using the DNA origami structure exploiting covalent and noncovalent coupling schemes. By using Au and Ag dimers, single-molecule SERS measurements of three dyes and cytochrome c and horseradish peroxidase proteins are demonstrated even under nonresonant excitation conditions, thus providing long photostability during time-series measurement and enabling optical monitoring of single molecules.

The article describes a systematic investigation of the effects of an aqueous NaOH treatment of 3D printed poly(lactic acid) (PLA) scaffolds for surface activation. The PLA surface undergoes several morphology changes and after an initial surface roughening, the surface becomes smoother again before the material dissolves. Erosion rates and surface morphologies can be controlled by the treatment. At the same time, the bulk mechanical properties of the treated materials remain unaltered. This indicates that NaOH treatment of 3D printed PLA scaffolds is a simple, yet viable strategy for surface activation without compromising the mechanical stability of PLA scaffolds.

molecules simultaneously, which facilitates coupling reactions of two or more molecules. [7][8][9] On the other hand, nanoscale heating can increase the speed of molecular reorganization and surface diffusion, thereby increasing the rate of favorable reactive encounters. Several important examples of plasmon-driven bond formation were demonstrated in recent years, [10,11] including CC bond formation in hydrocarbons, [7,12] Suzuki-Miyaura type reactions, [13] and molecular dimerization reactions by NN bond formation. [7,14,15] Until recently, the question if the dominating effect of plasmonic nanoparticles is to act as charge donors [16,17] or heat sources [14,18] has been heavily debated. Nowadays, most authors agree that depending on the reaction, one or the other effect can dominate. [19] For example, the dissociation of diatomic compounds on gold-particles, in particular of H 2 [1,20] and O 2 , [21,22] is likely determined by the transfer of energetic electrons, while the fragmentation of organic molecules, such as the decomposition of dicumyl-peroxide, [18] is rather dominated by the plasmon-mediated photo-heating. Although much progress has been made in understanding such dissociation reactions, our understanding of plasmon-driven multistep bond-formation processes is still in its infancy. In these reactions, different reaction steps might profit from the presence of plasmonic excitations. As a prominent example, the dimerization reaction of 4-nitrothiophenol (4NTP) to 4-4′-dimercaptoazobenzene (DMAB) was confirmed by many

Light induced electron transfer reactions of molecules on the surface of noble metal nanoparticles (NPs) depend significantly on the electronic properties of the metal–organic interface. Hybridized metal–molecule states and dipoles...

The study of biologically relevant molecules and their interaction with external stimuli on a single molecular scale is of high importance due to the availability of distributed rather than averaged information.