Hybrid Nanostructures

Ein mögliches Startbild

Welcome to the pages of the Hybrid Nanostructures group. In our research we combine different methods from DNA nanotechnology, optical spectroscopy and scanning probe microscopy in order to study physico-chemical processes in nanoscale materials and at the single-molecule level. Apart from methods development we investigate specific questions such as the mechanisms of plasmon-induced chemical reactions, the nucleotide sequence dependence of DNA radiation damage and the mode of action of radiosensitizers that are applied in tumor radiation therapy.

We are members of the innovation center innoFSPEC and the research initiative "Elementary Processes of Light-Driven Reactions at Nanoscale Metals*.

Our recent work:

Schematic representation of the DNA origami nanofork having a DNA 90 nt long bridge. Two differently coated nanoparticles can be attached selectively via DNA hybridization to the two different sequences of DNA capture strands on the arms and the bridge of the DNA origami to form DONA structures.
Photo: https://pubs.acs.org/doi/full/10.1021/acscatal.1c01851

Plasmon-driven photocatalysis is an emerging and promising application of noble metal nanoparticles (NPs). An understanding of the fundamental aspects of plasmon interaction with molecules and factors controlling their reaction rate in a heterogeneous system is of high importance. Therefore, the dehalogenation kinetics of 8-bromoguanine (BrGua) and 8- bromoadenine (BrAde) on aggregated surfaces of silver (Ag) and gold (Au) NPs have been studied to understand the reaction kinetics and the underlying reaction mechanism prevalent in heterogeneous reaction systems induced by plasmons monitored by surface enhanced Raman scattering (SERS). We conclude that the time-average constant concentration of hot electrons and the time scale of dissociation of transient negative ions (TNI) are crucial in defining the reaction rate law based on a proposed kinetic model. An overall higher reaction rate of dehalogenation is observed on Ag compared with Au, which is explained by the favorable hot-hole scavenging by the reaction product and the byproduct. We therefore arrive at the conclusion that insufficient hole deactivation could retard the reaction rate significantly, marking itself as rate-determining step for the overall reaction. The wavelength dependency of the reaction rate normalized to absorbed optical power indicates the nonthermal nature of the plasmon-driven reaction. The study therefore lays a general approach toward understanding the kinetics and reaction mechanism of a plasmon-driven reaction in a heterogeneous system, and furthermore, it leads to a better understanding of the reactivity of brominated purine derivatives on Ag and Au, which could in the future be exploited, for example, in plasmon-assisted cancer therapy.

Schematic representation of the DNA origami nanofork having a DNA 90 nt long bridge. Two differently coated nanoparticles can be attached selectively via DNA hybridization to the two different sequences of DNA capture strands on the arms and the bridge of the DNA origami to form DONA structures.
Photo: https://pubs.acs.org/doi/full/10.1021/acscatal.1c01851

Kinetics and Mechanism of Plasmon-Driven Dehalogenation Reaction of Brominated Purine Nucleobases on Ag and Au; A. Dutta, R. Schürmann, S. Kogikoski Jr., N. S. Mueller, S. Reich and I. Bald ACS Catal. 2021, 11, XXX, 8370-8381