Articles
O. Verbitsky, S. Hinojosa, A. Mostafa, D. Ojha, I. Bald, and N. Kulak
Amphiphilic Cu(II) Oxacyclen Complexes: From Oxidative Cleavage to Condensation of DNA
ChemBioChem 2026, 27, e202500477
Cu(II) complexes with monoalkylated oxacyclen ligands (C12, C16, and C18) have been investigated regarding their interaction with DNA by different methods: circular dichroism, UV/VIS (ultraviolet-visible) and fluorescence spectroscopy as well as by gel electrophoresis. The results demonstrate that the complexes can cleave DNA through both hydrolytic and oxidative mechanisms, with hydroxyl radicals and hydrogen peroxide identified as the reactive oxygen species involved. The targeted incorporation of alkyl chains significantly enhances the DNA-binding affinity of the Cu(II) complexes, and the length of the alkyl substituents plays an important role, as they can interact with the major groove of the DNA. Alkylation is the determining structural factor responsible for the enhanced DNA interaction, since such an interaction is not observed with unsubstituted complexes. Moreover, the length of the alkyl chains significantly influences this behavior, as longer substituents induce a concentration-dependent DNA aggregation, a phenomenon absent in the nonalkylated analog. This aggregation and condensation behavior is examined using atomic force microscopy and dynamic light scattering. Moreover, DNA/small molecule interactions are also investigated using molecular dynamics simulations.
F. Stete, M. Bargheer, and W. Koopman
Capacitive photocharging of gold nanorods
Nature Communincations 17, 139 (2026)
Light can charge plasmonic nanoparticles by photoredox reactions, significantly modifying their optical and chemical properties. However, the charging process has been challenging to track experimentally, severely hindering its thorough evaluation. In this study, we investigate the charging of gold nanorods during a light-induced reaction in situ, utilizing the sensitivity of the rods’ longitudinal localized surface plasmon resonance to charge accumulation. Describing the particles as nanocapacitors, we present a model to quantify the number of charges on the particles and their connection to the illumination intensity. We find that the Fermi level, together with all other energy bands, is raised because of the repulsive potential of the additional charges. Experimental observations of the dependence on the solvent, the particle size, and ligand type further corroborate the proposed capacitor model. The results presented in this study lay the groundwork for the rational engineering of dynamic charge accumulation during plasmon-driven photoreactions.
