[en] The development of high efficient electrocatalysts in water electrolysis is of great importance for sustainable hydrogen production. Herein, monodispersed bimetallic Pd_xCu_100-x nanoparticles with average size about 4.7 nm are prepared by a one-pot method in oleylamine medium. Electrochemical measurements toward hydrogen evolution reaction (HER) indicate that both the activity and stability of carbon black loaded Pd_xCu_100-x nanoparticles (Pd_xCu_100-x/C) are highly dependent on the Pd/Cu atomic ratios. Among these electrocatalysts, Pd₇₁Cu₂₉/C exhibits the best electrocatalytic activity in terms of onset potential (75 mV vs. RHE), exchange current density (0.38 mA cm⁻²) and Tafel slope (48 mV dec⁻¹) in 0.1 M H₂SO₄ among these nanoparticles. It is found that the activity toward HER of Pd₇₁Cu₂₉/C is better than that of commercial Pd/C and most of Pd-based electrocatalysts ever reported before. Moreover, Pd₇₁Cu₂₉/C shows superior catalytic stability to the commercial Pt/C. The superior HER activities and high durability (after 1000 CV cycles) of Pd₇₁Cu₂₉/C should be attributed to small size, the synergy effect between Cu and Pd. This work provides a facile strategy to develop the effective and stable Pt-free electrocatalyst for hydrogen generation.

[en] ¹⁸F-labeled amino acid O-(2-[¹⁸F]fluoroethyl)-L-tyrosine ([¹⁸F]FET) has been used as an in vivo positron emission tomography (PET) tracer for tumor metabolitic imaging. Here, the synthesis of [¹⁸F]FET using two different methods is reported. The first Method (I) for the [¹⁸F]FET synthesis was an indirect labeling route, which was a two-step reaction consisting of fluorination of 1,2-bis(tosyloxy)ethane and fluoroalkylation of unprotected L-tyrosine. The second Method (II) was a direct labeling route which was the direct nucleophilic radiofluorination of the protected precursor N-BOC-(O-(2-tosyloxyethyl))-L-tyrosine methyl ester, followed by a rapid removal of the protecting group. For the first method, the radiochemical yield was about 45% at the end of synthesis (EOS), and the radiochemical purity was over 97%. The radiochemical yield in the second method was 40% (EOS) on an average, and the radiochemical purity was over 96%. Microwave heating was also introduced into the synthesis of [¹⁸F]FET. For Method I, each of two steps could be completed within 2-3 minutes under microwave conditions and the radiochemical yields were 85% and 95%, respectively, which was reasonably high and reproducible. For Method II, the highest labeling efficiency in the radiofluorinated step was 37% in the synthesis time of 3 minutes under microwave conditions. (author)

[en] Herein, we introduce a facile strategy for the structure-controlled synthesis of one-dimensional PdCu nanocrystals via a seed-mediated approach. This developed strategy involves the synthesis of Cu nanowires with penta-twinned structure, and subsequent growth of Pd metal on Cu nanowires. The obtained one-dimensional PdCu nanocrystals are of rough surfaces and core-shell like architecture. Upon the tuning reactivity of (111) and (100) crystal faces on Cu nanowires in absence or presence of capping agent, one-dimensional PdCu nanocrystals with solid or hollow interiors (nanowires or nanotubes) can be controllably synthesized through galvanic displacement reaction, respectively. It is found that both PdCu nanowires and PdCu nanotubes exhibit better performance for oxygen reduction reaction compared with self-synthesized PdCu nanoparticles and commercial Pd/C in 0.1 M KOH electrolyte. Particularly, PdCu nanotubes show Pt-like performance, and achieve an onset potential of 0.941 V (vs. RHE) and a half potential of 0.825 V. The electron transfer number during oxygen reduction is close to 4 on PdCu nanotubes. Moreover, the catalytic stability of the obtained one-dimensional PdCu nanocrystals is much superior to that of commercial Pd/C and Pt/C catalysts.

[en] Hepatocellular carcinoma (HCC) has a very high incidence and mortality. Early diagnosis and timely treatments are therefore required to improve the quality of life and survival rate of HCC patients. Here, we developed a vascular endothelial growth factor (VEGF)-based multimodality imaging agent for single photon emission computed tomography (SPECT), computed tomography (CT) and magnetic resonance imaging (MRI) and used it to assess HCC mice and explore the combinative value of CT/MRI-based morphological imaging and SPECT functional imaging. HCC targeting with ¹²⁵I-labeled bevacizumab monoclonal antibody (mAb) was examined using SPECT/CT in HepG2 tumor-bearing mice after intravenous mAb injection. Based on this, an integrated, bimodal, VEGF-targeted, ultrasmall superparamagnetic iron oxide (USPIO)-conjugated ^99mTc-labeled bevacizumab mAb was synthesized to increase tumor penetration and accumulations. The in vivo pharmacokinetics and HepG2 tumor targeting were explored through in vivo planar imaging and SPECT/CT using a mouse model of HepG2 liver cancer. The specificity of the radiolabeled nanoparticles for HepG2 HCC was verified using in vitro immunohistochemistry and Prussian blue staining. With diethylenetriamine pentaacetic acid as a bifunctional chelating agent, USPIO-bevacizumab achieved a ^99mTc labeling efficiency of >90 %. The in vivo imaging results also exhibited the targeting of USPIO on HepG2 HCC. The specificity of these results was confirmed using in vitro immunohistochemistry and Prussian blue staining. Our preliminary findings showed the potential of USPIO as an imaging agent for the SPECT/MRI of HepG2 HCC. (author)

[en] Radiolabeling of biologically active molecules with fac-[¹⁸⁸Re(CO)₃(H₂O)₃]⁺ unit has been of primary interest in recent years. Therefore, we herein report ligands L¹-L⁴ (L¹=histidine, L²=nitrilotriacetic acid, L³=2-picolylamine-N,N-diacetic acid, L⁴=bis(2-pyridymethy)amine) that have been evaluated by radiochemical reactions with fac-[¹⁸⁸Re(CO)₃(H₂O)₃]⁺. These reactions yielded the radioactive complexes of fac-[¹⁸⁸Re(CO)₃L] (L = L¹-L⁴, ¹⁸⁸Re tricarbonyl complexes 1-4), which were identified by HPLC. Complexes 1-4, with log P_o/w values ranging from -2.23 to 2.18, were obtained with yields of ≥95% using ligand concentrations within 10^-6-10^-4M range. Thus, specific activities of 220 GBq/μmol could be achieved. Challenge studies with cysteine and histidine revealed high stability for all of these radioactive complexes, and biodistribution studies in mice indicated a fast rate of blood clearance and high rate of total radioactivity excretion occurring primarily through the renal-urinary pathway. In summary, the ligands L¹-L⁴ are potent chelators for the future functionalization of biomolecules labeling with fac-[¹⁸⁸Re(CO)₃(H₂O)₃]⁺. (author)