2 research outputs found
Nanoparticles Inhibit DNA Replication by Binding to DNA: Modeling and Experimental Validation
Predictive models are beneficial tools for researchers to use in prioritizing nanoparticles (NPs) for toxicological tests, but experimental evaluation can be time-consuming and expensive, and thus, priority should be given to tests that identify the NPs most likely to be harmful. For characterization of NPs, the physical binding of NPs to DNA molecules is important to measure, as interference with DNA function may be one cause of toxicity. Here, we determined the interaction energy between 12 types of NPs and DNA based on the Derjaguin–Landau–Verwey–Overbeek (DLVO) model and then predicted the affinity of the NPs for DNA. Using the single-molecule imaging technique known as atomic force microscopy (AFM), we experimentally determined the binding affinity of those NPs for DNA. Theoretical predictions and experimental observations of the binding affinity agreed well. Furthermore, the effect of NPs on DNA replication <i>in vitro</i> was investigated with the polymerase chain reaction (PCR) technique. The results showed that NPs with a high affinity for DNA strongly inhibited DNA replication, whereas NPs with low affinity had no or minimal effects on DNA replication. The methodology here is expected to benefit the genotoxicological testing of NPs as well as the design of safe NPs
Evidence for Dechlorination of Polychlorinated Biphenyls and Polychlorinated Dibenzo-<i>p</i>-Dioxins and -Furans in Wastewater Collection Systems in the New York Metropolitan Area
Polychlorinated biphenyls (PCBs) and polychlorinated
dibenzo-<i>p</i>-dioxins and dibenzofurans (PCDD/Fs) are
persistent organic
pollutants targeted by the Stockholm Convention. Both contain aromatic
chlorines and are subject to microbial dechlorination. Dechlorination
of PCBs in sewers in the Delaware River basin was recently reported.
In this work, two data sets on concentrations of PCBs and PCBs+PCDD/Fs
in wastewater treatment plant influents and effluents were analyzed
to look for evidence that these compounds undergo dechlorination in
the sewers of the New York/New Jersey Harbor area. The two data sets
come from the Contamination Assessment and Reduction Project (CARP)
and were analyzed via Positive Matrix Factorization (PMF). Analysis
of the data set containing only PCB concentrations suggests that PCBs
are dechlorinated in the sewers of the NY/NJ Harbor via the same pathways
observed in the sewers of the Delaware River basin and that advanced
dechlorination of PCB mixtures is more likely to occur in combined
sewers vs separate sanitary sewers. When the combined data set of
PCBs+PCDD/Fs was analyzed, the factor containing PCB dechlorination
products also contained high proportions of 1,2,3,4,6,7,8-heptachlorodibenzo-<i>p</i>-dioxin (HpCDD), a known product of the dechlorination
of octachlorodibenzo-<i>p</i>-dioxin (OCDD), and other known
dechlorination products of PCDD/Fs. Despite being the most abundant
PCDD/F congener in all of the samples in the database, OCDD was a
minor component in the dechlorination factor. This provides the first
evidence that PCDD/Fs may be dechlorinated in sewers