The preparation of well-dispersed nanoparticles (NPs) has been one of the challenges in the development of nanoscale processing. Here, we firstly prepared well-dispersed Pt-Pd NPs (average particle diameter 6.5 nm) by using octa-maleamic acid silsesquioxanes as the stabilizing agent with hydrothermal method and determined the best OM-POSS/metal precursors molar ratio (1:2). These well-dispersed Pt-Pd NPs exhibited enhanced electrocatalytic performance, stability and tolerance to CO poisoning in formic acid oxidation. Their current density of the first oxidation peak in the CV curve recorded in 0.5 M H2SO4 + 0.5 M HCOOH is 4.3 and 8.6 times higher than those of Pt NPs (0.24 A mg−1) and commercial Pt/C (0.08 A mg−1) catalysts, as well as the ratio of the two oxidation peaks 4.8 and 10 times higher, respectively.

Quaternized chitosan is a cationic biopolymer with good antibacterial activity, biocompatibility, and biodegradability, and it has been widely applied in many fields. We have developed a convenient method to evaluate the antibacterial activity of hydroxypropyltrimethylammonium chloride chitosan (HACC) with a nonionic surfactant poloxamer in aqueous solution by monitoring the change of the oxidation peak current in cyclic voltammetry. Increasing values of the oxidation peak current were positively correlated with the antibacterial activity of HACC–poloxamer solutions. Optical microscope images, the zeta potential, and fluorescence spectroscopy showed that the aggregation state of HACC–poloxamer was related to the ratio of the two polymers and also to the antibacterial activity and oxidation peak current. At an HACC-to-poloxamer ratio of 1:0.75, the maximum surface charge density and the smooth edge of HACC–poloxamer aggregates can accelerate diffusion in aqueous solution. It is expected that this convenient method can be applied for a quick evaluation of the antibacterial activity of cationic biopolymers in aqueous solution.

•Ga(III) complexes showed about 3–10 folds more anticancer activity than their ligands alone.•Ga(III) complexes have a high therapeutic index for tumor cells.•The Ga(III) complex (C4) caused topoisomerase-I inhibition and distinct DNA cleavage.•Ga(III) complex affects the expression of cell cycle related proteins.Thiosemicarbazone Ga(III) complexes (C3–C5) were synthesized and characterized by X-ray single crystal diffraction, and they were all 1:1 ligand/Ga(III) complexes. The antiproliferative activity of these Ga(III) complexes was tested against three cancer cell lines, demonstrating that Ga(III) complexes showed about 3–10 folds more anticancer activity than their ligands alone. Importantly, thiosemicarbazones and Ga(III) complexes have a low toxicity to human fetal lung fibroblast cells (MRC-5) and exhibit a high therapeutic index for tumor cells. The results of UV–visible spectroscopy showed that the binding constant of C4 with Topo-I-DNA was significantly higher than that of L4. The Ga(III) complex (C4) caused Topo-I inhibition and distinct DNA cleavage. Moreover, Ga(III) complex and thiosemicarbazone ligand prolonged the G1 phase in NCI-H460 cell cycle, which might be depended on the ability of these compounds to affect the expression of cell cycle related proteins.The Ga(III) complex (C4) caused topoisomerase-I inhibition and distinct DNA cleavage. Moreover, Ga(III) complex and thiosemicarbazone ligand prolonged the G1 phase in NCI-H460 cell cycle, which might be depended on the ability of these compounds to affect the expression of cell cycle related proteins.Download high-res image (288KB)Download full-size image

•We have design and synthesis of the 2:1 and 1:1 ligand/Ga (III) complexes.•Ga(III) complexes where the metal/ligand ratio was 1:1 (C4) had observably higher antiproliferative activity than 1:2 (C3).•Ga(III) complexes had more activity of promoting NCI-H460 cell apoptosis than the metal free ligand.•Both types of Ga(III) complexes showed more effective in inhibition of the G1/S transition than the ligand alone.Two types of 2-pyridinecarboxaldehyde thiosemicarbazones Ga(III) complexes, which are 2:1 and 1:1 ligand/Ga(III) complexes, were synthesized and determined by X-ray single crystal diffraction. The antiproliferative activity of these Ga(III) complexes have been examined to illuminate the structure-activity relationships essential to form Ga(III) complexes with remarkable anticancer activity. In addition, Ga(III) complexes where the metal/ligand ratio was 1:1 (C4) had observably higher antiproliferative activity than 1:2 (C3). Ga(III) complexes caused a marked increase of caspase-3 and 9 activity in NCI-H460 cells compared to the metal free ligand. Caspase activation was somewhat mediated by the release of Cyt C from mitochondria after incubation with selected agents. Both types of Ga(III) complexes showed more effective in inhibition of the G1/S transition than the ligand alone.Download high-res image (235KB)Download full-size image

•Octa Pt-Pd nanoparticles were synthesized with silsesquioxane as capping agent.•Octa Pt-Pd nanoparticles display uniform morphology and favorable dispersibility.•Octa Pt-Pd nanoparticles have high catalytic activity for formic acid by direct process.The octahedral Pt-Pd alloy nanoparticles (octahedral Pt-Pd NPs) with dominant {111} facets were successfully synthesized through a facile route in the presence of octa(3-aminopropyl) silsesquioxane as the capping agent and complexing agent, methanol as the reductant and solvent. Their morphology, composition and structure were charactered by transmission electron microscopy (TEM), energy dispersive spectrum (EDS) and X-ray diffraction (XRD). The electrocatalytic activity, CO tolerance and stability of the octahedral Pt-Pd NPs for the electrooxidation of formic acid were investigated by cyclic voltammetry, CO stripping voltammetry and chronoamperometry, respectively. Compared with the Pt nanoparticles and commercial Pt black, the octahedral Pt-Pd NPs display a significantly enhanced electrocatalytic activity, increased CO tolerance and favourable stability for the electrooxidation of formic acid. Therefore, the octahedral Pt-Pd NPs might be an alternative candidate for the anode catalyst for the electrooxidation of formic acid in future.The octahedral Pt-Pd alloy nanoparticles (octahedral Pt-Pd NPs) with dominant {111} facets were successfully synthesized through a facile route in the presence of octa(3-aminopropyl) silsesquioxane as the capping agent and complexing agent, methanol as the reductant and solvent. The octahedral Pt-Pd NPs display the significantly enhanced electrocatalytic activity, increased CO tolerance and favourable stability for the electrooxidation of formic acid.

Single-walled bismuth nanotubes (sw-BiNTs) were self-assembled with octa(3-aminopropyl) silsesquioxane as a framework and to govern morphology. Deposited on a glassy carbon electrode (GCE), the sw-BiNTs were used for the simultaneous analysis of Pb(II) and Cd(II) by square wave stripping voltammetry. The sw-BiNTs were prepared by (a) coordination interaction between the amino groups of the silsesquioxane and the Bi(III) ions, and by (b) reduction with sodium borohydride. Transmission electron microscopy images revealed single-walled tubular structures with diameters of ~4–6 nm, and with lengths of several hundreds nanometers. GCEs modified with such sw-BiNTs perform much better than bare GCEs in stripping analysis of Pb(II) and Cd(II). The effects of adsorption quantity of sw-BiNTs, solution pH, pulse amplitude, and pulse width were optimized. The modified electrode was then used for the analysis of Pb(II) and Cd(II) in a linear response range from 0.4 to 6 μM with a sensitivity of 4.692 μA μM−1 and 3.835 μA μM−1, and detection limits of 1 nM and 5 nM, respectively. The method was successfully applied to the analysis of Pb(II) and Cd(II) in toy leachates, and the results were in good agreement with those obtained with atomic absorption spectrometry. Sensitivity and detection limits were compared with other voltammetric methods, and the sw-BiNTs are deemed to be an attractive alternative for practical applications. Other features of the electrode include low costs, a well reproducible nanostructure, and ease of scale-up of the fabrication process.