Potential biomedicinal applications of graphene oxide (GO), for example, as a carrier of biomolecules or a reagent for photothermal therapy and biosensing, are limited by its cytotoxicity and mutagenicity. It is believed that these properties are at least partially caused by GO-induced oxidative stress in cells. However, it is not known which chemical fragments of GO are responsible for this unfavorable effect. We generated four GOs containing variable redox-active groups on the surface, including Mn(2+), C-centered radicals, and endoperoxides (EPs). A comparison of the abilities of these materials to generate reactive oxygen species in human cervical cancer cells revealed that EPs play a crucial role in GO-induced oxidative stress. These data could be applied to the rational design of biocompatible nontoxic GOs for biomedical applications.

The variability of hydrogeochemical conditions can affect groundwater microbial communities and the natural attenuation of organic chemicals in contaminated aquifers. It is suspected that in situ biodegradation in anoxic plumes of chloroethenes depends on the spatial location of the contaminants and the electron donors and acceptors, as well as the patchiness of bacterial populations capable of reductive dechlorination. However, knowledge about the spatial variability of bacterial communities and in situ biodegradation of chloroethenes in aquifers is limited. Here, we show that changes of the bacterial communities, the distribution of putative dechlorinating bacteria and in situ biodegradation at the border of a chloroethenes plume (Bitterfeld, Germany) are related to local hydrogeochemical conditions. Biotic reductive dechlorination occurred along a 50 m vertical gradient, although significant changes of the hydrogeochemistry and contaminant concentrations, bacterial communities and distribution of putative dechlorinating bacteria (Dehalobacter spp., Desulfitobacterium spp., Dehalococcoides spp., and Geobacter spp.) were observed. The occurrence and variability of in situ biodegradation of chloroethenes were revealed by shifts in the isotope compositions of the chloroethenes along the vertical gradient (δ 13 C ranging from −14.4‰ to −4.4‰). Our results indicate that habitat characteristics were compartmentalized along the vertical gradient and in situ biodegradation occurred with specific reaction conditions at discrete depth. The polyphasic approach that combined geochemical and biomolecular methods with compound-specific analysis enabled to characterize the spatial variability of hydrochemistry, bacterial communities and in situ biodegradation of chloroethenes in a heterogeneous aquifer.

Potentielle biomedizinische Anwendungen von Graphenoxid (GO), z. B. als Träger von Biomolekülen, Reagentien für die photothermische Therapie oder Biosensoren, werden durch die Zytotoxizität und Mutagenität dieses Materials eingeschränkt. Es wird davon ausgegangen, dass diese Eigenschaften zumindest zum Teil auf eine von GO verursachte Erhöhung des oxidativen Stresses in Zellen zurückzuführen ist. Es ist jedoch nicht bekannt, auf welchen chemischen Fragmenten dieser ungünstige Effekt beruht. In dieser Arbeit wurden vier GOs entwickelt, welche verschiedene redoxaktive Gruppen wie Mn2+, C‐zentrierte Radikale sowie Endoperoxide (EPs) auf der Oberfläche besitzen. Der Vergleich der Fähigkeit der Materialien, reaktive Sauerstoffspezies in humanen Gebärmutterhalskrebszellen zu generieren, zeigt, dass EPs eine entscheidende Rolle im GO‐induzierten oxidativen Stress spielen. Diese Ergebnisse können für die gezielte Entwicklung von biokompatiblem und nicht‐toxischem GO für biomedizinische Anwendungen verwendet werden.

The inhibition of dihydropteroate synthase extracts by sulfones and sulfonamides has been determined. Structural dependency of the observed I50‐values has been quantitatively explained by multiple regression and principal component analysis. New highly active sulfones have been synthesized guided by the derived QSAR. The analysis leads to the conclusion that electronic and steric substituent effects are decisive and that sulfones and sulfonamides are binding to the same receptor site. The LFE‐descriptors used are correlated with the minimal conformational entropy. The results are also compared with the results obtained in cell‐free and whole cell systems of bacteria. The additional influence of cell‐wall permeability on inhibitory efficacy is demonstrated.

Ausgehend von den p‐Aminoacetophenonen (I) werden die Aminophenylalkylaminoethanole (II) nach bekannten Methoden synthetisiert.