Synthesis and characterization of an insoluble polymer based on polyamidoamine: applications for the decontamination of metals in aqueous systems

Enhanced thermal activation of persulfate by coupling hydrogen peroxide for efficient degradation of pyrene

In this study, H₂O₂ was introduced into thermally activated persulfate oxidation system (T-HPS), and the oxidation of pyrene (PYR) was investigated by the combined T-HPS technology. The results showed that H₂O₂ could significantly improve the reactivity of the thermally activated persulfate system (T-PS), with 240-min PYR degradation ratio increasing from 79.3% to 97.2% at 70 °C. In the T-HPS system, as persulfate initial concentration increased from 5 to 100 μM, the kinetic rate constant (k_obs) of PYR degradation increased from 4.70 × 10^-3 to 3.01 × 10^-2 min^-1, but the k_obs did not show a positive association with H₂O₂ concentration with the same range, and the highest k_obs was obtained at the H₂O₂ initial concentration of 20 μM. The optimal ratio of PS and H₂O₂ was set at 1:1 with the initial concentrations of the two oxidants both being 20 μM. Furthermore, PYR could be removed efficiently in a wide range of pH, and the best PYR degradation performance was obtained under neutral pH. Scavenging experiments demonstrated that OH played a more important role in PYR degradation in the T-HPS system than in the T-PS system. As suggested by the Arrhenius equation, the activation energy decreased from 124.5 to 107.4 kJ mol^-1 after adding H₂O₂ to the T-PS system. This study provides a new oxidation approach that could prompt the T-PS activity by adding a suitable dosage of H₂O₂.

Enhancing PET Signal at Target Tissue in Vivo: Dendritic and Multimeric Tris(hydroxypyridinone) Conjugates for Molecular Imaging of αvβ3 Integrin Expression with Gallium-68

Tris(hydroxypyridinone) chelators conjugated to peptides can rapidly complex the positron-emitting isotope gallium-68 (68Ga) under mild conditions, and the resulting radiotracers can delineate peptide receptor expression at sites of diseased tissue in vivo. We have synthesized a dendritic bifunctional chelator containing nine 1,6-dimethyl-3-hydroxypyridin-4-one groups (SCN-HP9) that can coordinate up to three Ga3+ ions. This derivative has been conjugated to a trimeric peptide (RGD3) containing three peptide groups that target the αvβ3 integrin receptor. The resulting dendritic compound, HP9-RGD3, can be radiolabeled in 97% radiochemical yield at a 3-fold higher specific activity than its homologues HP3-RGD and HP3-RGD3 that contain only a single metal binding site. PET scanning and biodistribution studies show that [68Ga(HP9-RGD3)] demonstrates higher receptor-mediated tumor uptake in animals bearing U87MG tumors that overexpress αvβ3 integrin than [68Ga(HP3-RGD)] and [68Ga(HP3-RGD3)]. However, concomitant nontarget organ retention of [68Ga(HP9-RGD3)] results in low tumor to nontarget organ contrast in PET images. On the other hand, the trimeric peptide homologue containing a single tris(hydroxypyridinone) chelator, [68Ga(HP3-RGD3)], clears nontarget organs and exhibits receptor-mediated uptake in mice bearing tumors and in mice with induced rheumatoid arthritis. PET imaging with [68Ga(HP3-RGD3)] enables clear delineation of αvβ3 integrin receptor expression in vivo.

Design of PAMAM-COO dendron-grafted surfaces to promote Pb(ii) ion adsorption

A coarse-grained molecular dynamics study of carboxylate functionalized polyamidoamine (PAMAM-COO) dendrons grafted onto a surface for the adsorption of Pb ions.