[en] Cisplatin (CDDP) is the most frequently used chemotherapeutic agent for various types of advanced cancer, including gastric cancer. However, almost all cancer cells acquire resistance against CDDP, and this phenomenon adversely affects prognosis. Thus, new chemotherapeutic agents that can overcome the CDDP-resistant cancer cells will improve the survival of advanced cancer patients. We synthesized new glycoconjugated platinum (II) and palladium (II) complexes, [PtCl₂ (L)] and [PdCl₂ (L)]. CDDP-resistant gastric cancer cell lines were established by continuous exposure to CDDP, and gene expression in the CDDP-resistant gastric cancer cells was analyzed. The cytotoxicity and apoptosis induced by [PtCl₂ (L)] and [PdCl₂ (L)] in CDDP-sensitive and CDDP-resistant gastric cancer cells were evaluated. DNA double-strand breaks by drugs were assessed by evaluating phosphorylated histone H2AX. Xenograft tumor mouse models were established and antitumor effects were also examined in vivo. CDDP-resistant gastric cancer cells exhibit ABCB1 and CDKN2A gene up-regulation, as compared with CDDP-sensitive gastric cancer cells. In the analyses of CDDP-resistant gastric cancer cells, [PdCl₂ (L)] overcame cross-resistance to CDDP in vitro and in vivo. [PdCl₂ (L)] induced DNA double-strand breaks. These results indicate that [PdCl₂ (L)] is a potent chemotherapeutic agent for CDDP-resistant gastric cancer and may have clinical applications

[en] Monodispersive CoPt nanoparticles in sizes of about 2.2 nm are synthesized by superhydride reduction of CoCl₂ and PtCl₂ in diphenyl ether. The as-prepared nanoparticles show a chemically disordered A₁ structure and are superparamagnetic. Thermal annealing transforms the A₁ structure into chemically ordered L1₀ structure and the particles are ferromagnetic at room temperature

No abstract available

[en] Nanostructured Pt-based alloys show great promise, not only for catalysis but also in medical and magnetic applications. To extend the properties of this class of materials, we have developed a means of synthesizing Pt and Pt-based alloy nanoclusters in the capsid of a virus. Pure Pt and Pt-alloy nanoclusters are formed through the chemical reduction of [PtCl_4]"− by NaBH_4 with/without additional metal ions (Co or Fe). The opening and closing of the ion channels in the virus capsid were controlled by changing the pH and ionic strength of the solution. The size of the nanoclusters is limited to 18 nm by the internal diameter of the capsid. Their magnetic properties suggest potential applications in hyperthermia for the Co–Pt and Fe–Pt magnetic alloy nanoclusters. This study introduces a new way to fabricate size-restricted nanoclusters using virus capsid. (paper)

[en] We present a joint experimental and theoretical study of the electronic spectrum of hexachloroplatinate dianion. We have measured electronic photodissociation and photodetachment spectra of mass-selected PtCl₆²⁻ ions in vacuo and compare these with calculated band positions from time-dependent density functional theory and from relativistic calculations. Excitation of an electronic transition of the dianion leads to resonant enhancement of the photodetachment cross section superimposed on direct detachment. Photoexcitation results in loss of Cl⁻ and Cl⁰, depending on photon energy. The photofragmentation spectrum for formation of the PtCl₄⁻ fragment ion mirrors the UV/vis absorption spectrum of PtCl₆²⁻ in solution with a small solvatochromic shift

[en] Highlights: • Si–H groups present in cross-linked regular poly(vinylsiloxanes) reduce Pt⁴⁺ ions to Pt⁰. • Sizes of Pt crystallites formed are controlled by polymers' cross-link densities. • Pyrolysis of the systems leads to SiCO ceramics with dispersed Pt. • Unpyrolyzed and pyrolyzed systems can be applied as heterogeneous catalysts. In the work, the new approach to the preparation of metallic Pt dispersed in polysiloxane networks for catalytic applications is presented. Metal particles have been introduced into the preformed poly(vinylsiloxane) networks obtained by cross-linking of linear vinylsiloxane (D₂V and V₃) polymers with hydrosiloxanes of various contents of Si–H groups in the molecules and differing in molecular structures. The studies demonstrate unambiguously that Si–H groups remaining in the systems after cross-linking are capable of reducing Pt⁴⁺ ions from PtCl₄ solution to Pt⁰. Sizes of metal crystallites formed are controlled by cross-link densities in the systems. Pyrolysis of poly(vinylsiloxane) networks with incorporated Pt, performed at 1000 °C in Ar atmosphere leads, in turn, to metallic Pt particles dispersed in SiCO ceramics. All the prepared Pt-containing systems show activity in catalytic isopropyl alcohol conversion. Acetone is the major product of this process conducted in the presence of the unpyrolyzed materials. D₂V polymer-based systems are more active than the V₃-derived ones due to their lower cross-link densities which cause better accessibility of the catalytic sites for the reacting alcohol molecules. In the presence of the pyrolyzed systems, isopropyl alcohol transforms mainly to propene; these materials exhibit stable catalytic performance up to high temperatures.

[en] We demonstrate highly efficient organic-based Schottky junction solar cells (OSJSCs) obtained by poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) modification with solution-processed platinum chloride (PtCl₄) treatment. The effect of PtCl₄ on PEDOT:PSS properties and device performances of solar cells was investigated. Kelvin probe and 4-point probe studies demonstrated that PtCl₄ decreased the PEDOT:PSS sheet-resistance and increased the PEDOT:PSS work-function, thereby inducing an improved built-in potential and interface resistance. As a result, with the aid of the PtCl₄ treatment, the Schottky junction device had a high power conversion efficiency of 3%, which was more than 20% higher than the reference OSJSCs with no PtCl₄, indicating that PtCl₄ can be a promising PEDOT:PSS modifier for raising the cell-performances of Schottky-junction based organic solar cells. (paper)

[en] Highlights: • Ultra-sensitive detection of Pt ions was achieved by a novel UV-assisted strategy. • Stable Pt complexes were obtained selectively via charge-separated states. • A detection limit of 9.8 nM for Pt ions was revealed with a fluorometer. Increased utilization of platinum ions in chemicals and drugs escalates environmental pollution and toxicity associated with Pt ions. However, current analysis and detection strategies of Pt ions display limited sensitivity due to the similar inert metal nature of platinum to gold. Herein, a photoinduced charge-separated molecule (MTPA)₂Ab was synthesized as a probe for enhanced sensitive selection of Pt ions. Long-lived charge-separated states generated upon exposure to 365 nm light lead to a stable complex between (MTPA)₂Ab and PtCl₂/PtCl₄ with highly-selectivity via sequential photoinduced electron transfers. Owing to the linear relationship of complex characteristic absorption and fluorescence emission intensities to Pt²⁺/Pt⁴⁺ concentrations, ultrasensitive spectrum analysis of Pt ions is achieved with a detection limit of 14.2 nM (2.8 ppb) for Pt²⁺ and 12.6 nM (2.5 ppb) for Pt⁴⁺ by an absorption spectrometer and 9.8 nM (1.9 ppb) for Pt ions (Pt²⁺/Pt⁴⁺) by a fluorescence spectrometer, far less than the reported values. Furthermore, a portable test box is developed based on (MTPA)₂Ab test strips due to distinguishable color change with Pt²⁺/Pt⁴⁺ concentrations for rapid colorimetric detection of Pt ions. The results highlight the promise of photoinduced charge-separated molecular probe in ultrasensitive and rapid detection of Pt ions to overcome current limitations of detection strategies.

[en] Highlights: • Pt⁰ coatings are deposited on pc Au by galvanic displacement of xMLCu_ad (x = 0.25÷1.0) in PtCl₄²⁻ solution. • Pt_x⁰Au electrodes are characterized by CVA, SEM, XPS and Auger spectroscopy. • For Pt_x⁰Au electrodes, the inhibition of MOR and strong acceleration of FAOR (calculated per cm² of Pt) as compared with pc Pt are observed. • An explanation of these peculiarities of the electrocatalytic behavior of Pt_x⁰Au is put forward. - Abstract: Submonolayer Pt⁰ coatings are synthesized by the displacement of copper adatoms (Cu_ad) on polycrystalline (pc) Au in PtCl₄²⁻ solutions (supporting electrolyte 0.5 M H₂SO₄). Cyclic voltammograms (CVA) measured on Pt⁰Au demonstrate that for initial surface coverages θ_Cu < 0.5, the Pt⁰ adatoms that have displaced Cu_ad are mainly deposited in the first layer. At large surface coverages, the agglomeration of Pt⁰ and its partial deposition into the second layer take place; ∼30% of Au surface remains free. SEM, XPS and Auger-spectroscopic data confirm the absence of multilayer Pt⁰ agglomerates. The specific rates of SH₃OH electrooxidation (per cm² of Pt) on Pt⁰Au turn out to be much lower than on pc Pt⁰. This is explained by the fact that dehydrogenation of SH₃OH requires the presence of «areas» formed by a large number of platinum atoms (> 3). For HSOOH, the strong increase (more than by one order of magnitude) in both non-steady-state and steady-state specific electrooxidation currents is observed. It is assumed that new active sites are formed for the current-determining reaction that proceeds through the one-site adsorption of HSOOH molecules

[en] We detect the change in vibrational frequency associated with the transition from a delocalized to a localized electronic state using femtosecond vibrational wavepacket techniques. The experiments are carried out in the mixed-valence linear chain material [Pt(en)₂][Pt(en)₂Cl₂]⋅(ClO₄)₄ (en = ethylenediamine, C₂H₈N₂), a quasi-one-dimensional system with strong electron-phonon coupling. Vibrational spectroscopy of the equilibrated self-trapped exciton is carried out using a multiple pulse excitation technique: an initial pump pulse creates a population of delocalized excitons that self-trap and equilibrate, and a time-delayed second pump pulse tuned to the red-shifted absorption band of the self-trapped exciton impulsively excites vibrational wavepacket oscillations at the characteristic vibrational frequencies of the equilibrated self-trapped exciton state by the resonant impulsive stimulated Raman mechanism, acting on the excited state. The measurements yield oscillations at a frequency of 160 cm⁻¹ corresponding to a Raman-active mode of the equilibrated self-trapped exciton with Pt-Cl stretching character. The 160 cm⁻¹ frequency is shifted from the previously observed wavepacket frequency of 185 cm⁻¹ associated with the initially generated exciton and from the 312 cm⁻¹ Raman-active symmetric stretching mode of the ground electronic state. We relate the frequency shifts to the changes in charge distribution and local structure that create the potential that stabilizes the self-trapped state