H2ampa─Versatile Chelator for [203Pb]Pb2+, [213Bi]Bi3+, and [225Ac]Ac3.

A new decadentate chelator, H2ampa, was designed to be a potential radiopharmaceutical chelator component. The chelator involves both amide and picolinate functional groups on a large non-macrocyclic, ether-bridged backbone. With its large scaffold, H2ampa was paired with [nat/203Pb]Pb2+, [nat/213Bi]Bi3+, and natLa3+/[225Ac]Ac3+ ions. Nuclear magnetic resonance spectroscopy and high-resolution mass spectrometry were used to study the non-radioactive metal complexes. A single crystal of [Bi(ampa)](NO3) was obtained; its asymmetric, 10-coordinate complex structure was revealed by X-ray diffraction. Optimal conformations of the metal complexes were assessed by density functional theory studies to provide further structural information. Solution studies providing thermodynamic insights into metal complex formation revealed H2ampa coordinated Bi3+, Pb2+, and La3+ ions to obtain pM values of 26, 14.8, and 15.1, respectively. Preliminary concentration-dependent radiolabeling experiments were carried out between H2ampa and three different radiometals to evaluate their compatibility for radiopharmaceutical applications. The chelator radiolabeled [203Pb]Pb2+, [213Bi]Bi3+, and [225Ac]Ac3+ in short reaction times (7-30 min), at dilute concentrations, and under mild conditions. Thus, H2ampa was proven to be a versatile chelator able to well coordinate a small range of radiometals frequently considered to be alpha therapeutic candidates.

Silver nanoparticles as a viricidal agent to inhibit plant-infecting viruses and disrupt their acquisition and transmission by their aphid vector.

Silver nanoparticles (AgNPs) are a potentially effective tool for preventing viral plant diseases. This study was carried out to evaluate the effectiveness of AgNPs for managing bean yellow mosaic virus (BYMV) disease in faba bean plants from the plant-virus-vector interaction side. AgNPs were evaluated as foliar protective and curative agents. In addition, the effect of AgNPs on virus acquisition and transmission by its vector aphid was investigated. The results indicated that AgNPs exhibited curative viricidal activity and were able to inactivate BYMV when applied 48 hours after virus inoculation. The occurrence of disease was prevented using an AgNP concentration as low as 100 mg L-1, whereas virus infection was completely inhibited when plants were preventatively treated with AgNPs at a concentration of to 200 mg L-1 24 h before virus inoculation. AgNPs proved to be highly bio-reactive, binding to viral particles and suppressing their replication and accumulation within plant tissues. Moreover, AgNPs, at all concentrations tested, were found to upregulate the pathogenesis-related gene PR-1 and induce the production of defense-related oxidizing enzymes in treated plants. Exposure of aphids to AgNPs-treated plants before virus acquisition reduced BYMV acquisition and transmission efficiency by 40.65 to 100% at 24 h post-application, depending on the AgNP dosage. At 10 days after treatment, virus acquisition was reduced by 36.82% and 79.64% upon exposure to AgNPs at a concentration of 250 and 300 mg L-1, respectively. These results suggest that AgNPs have curative viricidal activity due to targeting the virus coat protein and affecting virus-vector interactions. Accordingly, AgNPs may contribute to alleviating the natural disease and virus transmission under field conditions. This is the first report on the activity of nanomaterials against plant virus acquisition and transmission by insects.