Sustainably sourced components to generate high-strength adhesives.

Nearly all adhesives1,2 are derived from petroleum, create permanent bonds3, frustrate materials separation for recycling4,5 and prevent degradation in landfills. When trying to shift from petroleum feedstocks to a sustainable materials ecosystem, available options suffer from low performance, high cost or lack of availability at the required scales. Here we present a sustainably sourced adhesive system, made from epoxidized soy oil, malic acid and tannic acid, with performance comparable to that of current industrial products. Joints can be cured under conditions ranging from use of a hair dryer for 5 min to an oven at 180 °C for 24 h. Adhesion between metal substrates up to around 18 MPa is achieved, and, in the best cases, performance exceeds that of a classic epoxy, the strongest modern adhesive. All components are biomass derived, low cost and already available in large quantities. Manufacturing at scale can be a simple matter of mixing and heating, suggesting that this new adhesive may contribute towards the sustainable bonding of materials.

Examination of the Impact of Copper(II) α-(N)-Heterocyclic Thiosemicarbazone Complexes on DNA Topoisomerase IIα.

Type II DNA topoisomerases resolve topological knots and tangles in DNA that result from routine cellular processes and are effective targets for anticancer therapeutics. To this end, thiosemicarbazones have been identified as having the ability to kill cancer cells from several cell lines. Literature evidence suggests that at least some thiosemicarbazones have an impact on topoisomerase II activity. However, the mechanism is not as clearly defined. Therefore, we set out to analyze the activity of four α-(N)-heterocyclic thiosemicarbazone compounds against topoisomerase IIα. The ligands, acetylpyridine-ethylthiosemicarbazone (APY-ETSC) and acetylpyrazine-methylthiosemicarbazone (APZ-MTSC), and their copper(II) [Cu(II)] complexes [Cu(APY-ETSC)Cl] and [Cu(APZ-MTSC)Cl] were examined for the ability to impact the catalytic cycle of human topoisomerase IIα. Both [Cu(APY-ETSC)Cl] and [Cu(APZ-MTSC)Cl] were more effective at inhibiting DNA relaxation compared with the ligands alone. Further, both [Cu(APY-ETSC)Cl] and [Cu(APZ-MTSC)Cl] increased double-stranded DNA cleavage levels without inhibiting topoisomerase IIα-mediated DNA ligation. The Cu(II) complexes inactivate enzyme activity over time suggesting a critical interaction with the enzyme. Additionally, we found that the Cu(II)-thiosemicarbazone complexes do not significantly impact DNA cleavage by the catalytic core of the enzyme. This evidence is supported by the fact that both [Cu(APY-ETSC)Cl] and [Cu(APZ-MTSC)Cl], and to a lesser extent the ligands, inhibit topoisomerase IIα-mediated ATP hydrolysis. Based upon kinetic analysis, the Cu(II) complexes appear to be noncompetitive inhibitors of the ATPase domain of topoisomerase IIα. Taken together, our results provide evidence that Cu(II) complexes of α-(N)-heterocyclic thiosemicarbazones catalytically inhibit the enzyme through the ATPase domain but also promote double-stranded DNA cleavage by the enzyme.