Deposition of platinum nanoparticles on carbon nanotubes by supercritical fluid method.

PubMed

Yen, Clive H; Cui, Xiaoli; Pan, Horng-Bin; Wang, Shaofen; Lin, Yuehe; Wai, Chien M

2005-11-01

Carbon nanotube-supported platinum nanoparticles with a 5-15 nm diameter size range can be synthesized by hydrogen reduction of platinum(ll) acetylacetonate in methanol modified supercritical carbon dioxide. X-ray photoelectron spectroscopy and X-ray diffraction spectra indicate that the carbon nanotubes contain zero-valent platinum metal and high-resolution transmission electron microscopy images show that the visible lattice fringes of platinum nanoparticles are crystallites. Carbon nanotubes synthesized with 25% by weight of platinum nanoparticles exhibit a higher activity for hydrogenation of benzene compared with a commercial carbon black platinum catalyst. The carbon nanotube-supported platinum nanocatalyst can be reused at least six times for the hydrogenation reaction without losing activity. The carbon nanotube-supported platinum nanoparticles are also highly active for electrochemical oxidation of methanol and for reduction of oxygen suggesting their potential use as a new electrocatalyst for proton exchange membrane fuel cell applications.

Rapid biological synthesis of platinum nanoparticles using Ocimum sanctum for water electrolysis applications.

PubMed

Soundarrajan, C; Sankari, A; Dhandapani, P; Maruthamuthu, S; Ravichandran, S; Sozhan, G; Palaniswamy, N

2012-06-01

The leaf extract of Ocimum sanctum was used as a reducing agent for the synthesis of platinum nanoparticles from an aqueous chloroplatinic acid (H(2)PtCl(6)·6H(2)O). A greater conversion of platinum ions to nanoparticles was achieved by employing a tulsi leaf broth with a reaction temperature of 100 °C. Energy-dispersive absorption X-ray spectroscopy confirmed the platinum particles as major constituent in the reduction process. It is evident from scanning electron microscopy that the reduced platinum particles were found as aggregates with irregular shape. Fourier-transform infrared spectroscopy revealed that the compounds such as ascorbic acid, gallic acid, terpenoids, certain proteins and amino acids act as reducing agents for platinum ions reduction. X-ray diffraction spectroscopy suggested the associated forms of platinum with other molecules and the average particle size of platinum nanoparticle was 23 nm, calculated using Scherer equation. The reduced platinum showed similar hydrogen evolution potential and catalytic activity like pure platinum using linear scan voltammetry. This environmentally friendly method of biological platinum nanoparticles production increases the rates of synthesis faster which can potentially be used in water electrolysis applications.

The Next Generation of Platinum Drugs: Targeted Pt(II) Agents, Nanoparticle Delivery, and Pt(IV) Prodrugs

PubMed Central

Johnstone, Timothy C.; Suntharalingam, Kogularamanan; Lippard, Stephen J.

2016-01-01

The platinum drugs, cisplatin, carboplatin, and oxaliplatin, prevail in the treatment of cancer,, but new platinum agents have been very slow to enter the clinic. Recently, however, there has been a surge of activity, based on a great deal of mechanistic information, aimed at developing non-classical platinum complexes that operate via mechanisms of action distinct from those of the approved drugs. The use of nanodelivery devices has also grown and many different strategies have been explored to incorporate platinum warheads into nanomedicine constructs. In this review, we discuss these efforts to create the next generation of platinum anticancer drugs. The introduction provides the reader with a brief overview of the use, development, and mechanism of action of the approved platinum drugs to provide the context in which more recent research has flourished. We then describe approaches that explore non-classical platinum(II) complexes with trans geometry and with a monofunctional coordination mode, polynuclear platinum(II) compounds, platinum(IV) prodrugs, dual-treat agents, and photoactivatable platinum(IV) complexes. Nanodelivery particles designed to deliver platinum(IV) complexes will also be discussed, including carbon nanotubes, carbon nanoparticles, gold nanoparticles, quantum dots, upconversion nanoparticles, and polymeric micelles. Additional nanoformulations including supramolecular self-assembled structures, proteins, peptides, metal-organic frameworks, and coordination polymers will then be described. Finally, the significant clinical progress made by nanoparticle formulations of platinum(II) agents will be reviewed. We anticipate that such a synthesis of disparate research efforts will not only help to generate new drug development ideas and strategies, but also reflect our optimism that the next generation of platinum cancer drugs is about to arrive. PMID:26865551

Platinum stable isotopes in ferromanganese crust and nodules

NASA Astrophysics Data System (ADS)

Corcoran, Loretta; Seward, Terry; Handler, Monica R.

2015-04-01

Hydrogenetic ferromanganese (Fe-Mn) crust and nodules are slow-growing chemical sediments that form by direct precipitation from seawater, resulting in a record of changing seawater chemistry. These sediments are the primary sink for platinum in the modern oxic marine environment, hosting well-documented enrichments over other platinum-group elements (PGEs): the Pt anomaly [1]. Platinum is a non-bio-essential, highly siderophile, transition metal with six stable isotopes (190Pt, 192Pt, 194Pt, 195Pt, 196Pt, and 198Pt) with several oxidation states (Pt0, Pt2+ and Pt4+). Platinum is generally considered to exist in the hydrosphere as Pt2+ although its behaviour in the marine environment is poorly constrained, and Pt4+may also be present. Variations in ocean redox state, together with changes in source fluxes to the oceans, may therefore lead to small variations (< ±1) in the stable isotopic composition of marine platinum, raising the potential of adding platinum to the growing arsenal of paleoceanographic tracers. A method has been developed to measure the platinum isotopic composition using double spike MC-ICPMS analysis [2]and applied to a global suite of modern Fe-Mn crust and nodules. Combining synchrotron XAFS analyses of platinum adsorbed onto Fe-Mn oxide and oxyhydroxide surfaces to determine oxidation state and bonding environment, with platinum stable isotopic measurements allowing us to evaluate both platinum incorporation onto these sediments and the associated degree of platinum isotopic fractionation. Leaching experiments conducted on platinum rich terrestrial materials underwent platinum stable isotopic measurement as an analogue for the Pt isotopic fractionation associated with continental weathering. [1] Hodge, V.F. et al. (1985) Earth and Planetary Science Letters, 72, 158-162. [2] Creech, J. et al. (2013) Journal of Analytical Atomic Spectrometry, 28. 853-865.

Investigations of the Binding of [Pt2(DTBPA)Cl2](II) and [Pt2(TPXA)Cl2](II) to DNA via Various Cross-Linking Modes

PubMed Central

Yue, Hongwei; Yang, Bo; Wang, Yan; Chen, Guangju

2013-01-01

We have constructed models for a series of platinum-DNA adducts that represent the binding of two agents, [Pt2(DTBPA)Cl2](II) and [Pt2(TPXA)Cl2](II), to DNA via inter- and intra-strand cross-linking, and carried out molecular dynamics simulations and DNA conformational dynamics calculations. The effects of trans- and cis-configurations of the centers of these di-nuclear platinum agents, and of different bridging linkers, have been investigated on the conformational distortions of platinum-DNA adducts formed via inter- and intra-strand cross-links. The results demonstrate that the DNA conformational distortions for the various platinum-DNA adducts with differing cross-linking modes are greatly influenced by the difference between the platinum-platinum distance for the platinum agent and the platinum-bound N7–N7 distance for the DNA molecule, and by the flexibility of the bridging linkers in the platinum agent. However, the effects of trans/cis-configurations of the platinum-centers on the DNA conformational distortions in the platinum-DNA adducts depend on the inter- and intra-strand cross-linking modes. In addition, we discuss the relevance of DNA base motions, including opening, shift and roll, to the changes in the parameters of the DNA major and minor grooves caused by binding of the platinum agent. PMID:24077126

Impact of Prior Platinum-Based Therapy on Patients Receiving Salvage Systemic Treatment for Advanced Urothelial Carcinoma.

PubMed

Sonpavde, G; Pond, G R; Di Lorenzo, G; Buonerba, C; Rozzi, A; Lanzetta, G; Necchi, A; Giannatempo, P; Raggi, D; Matsumoto, K; Choueiri, T K; Mullane, S; Niegisch, G; Albers, P; Lee, J L; Kitamura, H; Kume, H; Bellmunt, J

2016-12-01

Trials of salvage therapy for advanced urothelial carcinoma have required prior platinum-based therapy. This practice requires scrutiny because non-platinum-based first-line therapy may be offered to cisplatin-ineligible patients. Data of patients receiving salvage systemic chemotherapy were collected. Data on prior first-line platinum exposure were required in addition to treatment-free interval, hemoglobin, Eastern Cooperative Oncology Group performance status, albumin, and liver metastasis status. Cox proportional hazard regression was used to evaluate their association with overall survival (OS) after accounting for salvage single-agent or combination chemotherapy. Data were obtained from 455 patients previously exposed to platinum-based therapy and 37 not exposed to platinum. In the group exposed to prior platinum therapy, salvage therapy consisted of a single-agent taxane (n = 184) or a taxane-containing combination chemotherapy (n = 271). In the group not exposed to prior platinum therapy, salvage therapy consisted of taxane or vinflunine (n = 20), 5-fluorouracil (n = 1), taxane-containing combination chemotherapy (n = 12), carboplatin-based combinations (n = 2), and cisplatin-based combinations (n = 2). The median OS for the prior platinum therapy group was 7.8 months (95% confidence interval, 7.0, 8.1), and for the group that had not received prior platinum therapy was 9.0 months (95% confidence interval, 6.0, 11.0; P = .50). In the multivariable analysis, prior platinum therapy versus no prior platinum exposure did not confer an independent impact on OS (hazard ratio, 1.10; 95% confidence interval, 0.75, 1.64; P = .62). Prior platinum- versus non-platinum-based chemotherapy did not have a prognostic impact on OS after accounting for major prognostic factors in patients receiving salvage systemic chemotherapy for advanced urothelial carcinoma. Lack of prior platinum therapy should not disqualify patients from inclusion onto trials of salvage therapy. Copyright © 2016 Elsevier Inc. All rights reserved.

Epirubicin, Cisplatin, and Capecitabine for Primary Platinum-Resistant or Platinum-Refractory Epithelial Ovarian Cancer

PubMed Central

Sayal, Karen; Gounaris, Ioannis; Basu, Bristi; Freeman, Sue; Moyle, Penny; Hosking, Karen; Iddawela, Mahesh; Jimenez-Linan, Mercedes; Abraham, Jean; Brenton, James; Hatcher, Helen; Earl, Helena; Parkinson, Christine

2015-01-01

Objective Primary platinum-resistant epithelial ovarian cancer (EOC) is an area of unmet medical need. There is limited evidence from small studies that platinum-based combinations can overcome “resistance” in a proportion of patients. We investigated the efficacy and toxicity of platinum-based combination chemotherapy in the platinum-resistant and platinum-refractory setting. Methods Epirubicin, cisplatin, and capecitabine (ECX) combination chemotherapy was used at our institution for the treatment of relapsed EOC. From the institutional database, we identified all patients with primary platinum-refractory or platinum-resistant relapse treated with ECX as second-line therapy between 2001 and 2012. We extracted demographic, clinical, treatment, and toxicity data and outcomes. We used logistic and Cox regression models to identify predictors of response and survival respectively. Results Thirty-four 34 patients (8 refractory, 26 resistant) were treated with ECX. Response Evaluation Criteria In Solid Tumors (RECIST) response rate was 45%, median progression-free survival (PFS) was 6.4 months, and overall survival (OS) was 10.6 months. Platinum-resistant patients had better outcomes than did platinum-refractory patients (response rate, 54% vs 0%, P = 0.047; PFS 7.2 vs 1.8 months, P < 0.0001; OS 14.4 vs 3 months, P < 0.001). In regression models, time to progression after first-line treatment and platinum-refractory status were the strongest predictors of response and PFS or OS, respectively. Patients with time to progression after first-line treatment longer than 3 months showed PFS and OS of 7.9 and 14.7 months, respectively. Toxicity was manageable, with only 13% of cycles administered at reduced doses. Conclusions Epirubicin, cisplatin, and capecitabine seems to be active in platinum-resistant relapsed EOC with manageable toxicity. Further prospective investigation of platinum-anthracycline combinations is warranted in patients who relapse 3 to 6 months after first-line platinum-taxane treatment. PMID:25962114

Platinum coat color in red fox (Vulpes vulpes) is caused by a mutation in an autosomal copy of KIT.

PubMed

Johnson, J L; Kozysa, A; Kharlamova, A V; Gulevich, R G; Perelman, P L; Fong, H W F; Vladimirova, A V; Oskina, I N; Trut, L N; Kukekova, A V

2015-04-01

The red fox (Vulpes vulpes) demonstrates a variety of coat colors including platinum, a common phenotype maintained in farm-bred fox populations. Foxes heterozygous for the platinum allele have a light silver coat and extensive white spotting, whereas homozygosity is embryonic lethal. Two KIT transcripts were identified in skin cDNA from platinum foxes. The long transcript was identical to the KIT transcript of silver foxes, whereas the short transcript, which lacks exon 17, was specific to platinum. The KIT gene has several copies in the fox genome: an autosomal copy on chromosome 2 and additional copies on the B chromosomes. To identify the platinum-specific KIT sequence, the genomes of one platinum and one silver fox were sequenced. A single nucleotide polymorphism (SNP) was identified at the first nucleotide of KIT intron 17 in the platinum fox. In platinum foxes, the A allele of the SNP disrupts the donor splice site and causes exon 17, which is part of a segment that encodes a conserved tyrosine kinase domain, to be skipped. Complete cosegregation of the A allele with the platinum phenotype was confirmed by linkage mapping (LOD 25.59). All genotyped farm-bred platinum foxes from Russia and the US were heterozygous for the SNP (A/G), whereas foxes with different coat colors were homozygous for the G allele. Identification of the platinum mutation suggests that other fox white-spotting phenotypes, which are allelic to platinum, would also be caused by mutations in the KIT gene. © 2015 Stichting International Foundation for Animal Genetics.

Determination of platinum surface contamination in veterinary and human oncology centres using inductively coupled plasma mass spectrometry.

PubMed

Janssens, T; Brouwers, E E M; de Vos, J P; de Vries, N; Schellens, J H M; Beijnen, J H

2015-09-01

The objective of this study was to determine the surface contamination with platinum-containing antineoplastic drugs in veterinary and human oncology centres. Inductively coupled plasma mass spectrometry was used to measure platinum levels in surface samples. In veterinary and human oncology centres, 46.3 and 68.9% of the sampled surfaces demonstrated platinum contamination, respectively. Highest platinum levels were found in the preparation rooms (44.6 pg cm(-2)) in veterinary centres, while maximal levels in human centres were found in oncology patient-only toilets (725 pg cm(-2)). Transference of platinum by workers outside areas where antineoplastic drugs were handled was observed in veterinary and human oncology centres. In conclusion, only low levels of platinum contamination attributable to carboplatin were found in the sampled veterinary oncology centres. However, dispersion of platinum outside areas where antineoplastic drugs were handled was detected in veterinary and human oncology centres. Consequently, not only personnel, but also others may be exposed to platinum. © 2013 Blackwell Publishing Ltd.

Method for forming porous platinum films

DOEpatents

Maya, Leon

2000-01-01

A method for forming a platinum film includes providing a substrate, sputtering a crystalline platinum oxide layer over at least a portion of the substrate, and reducing the crystalline platinum oxide layer to form the platinum film. A device includes a non-conductive substrate and a platinum layer having a density of between about 2 and 5 g/cm.sup.3 formed over at least a portion of the non-conductive substrate. The platinum films produced in accordance with the present invention provide porous films suitable for use as electrodes, yet require few processing steps. Thus, such films are less costly. Such films may be formed on both conductive and non-conductive substrates. While the invention has been illustrated with platinum, other metals, such as noble metals, that form a low density oxide when reactively sputtered may also be used.

Electrochemical oxygen reduction behavior of selectively deposited platinum atoms on gold nanoparticles.

PubMed

Sarkar, A; Kerr, J B; Cairns, E J

2013-07-22

Carbon-supported Pt@Au "core-shell" nanoparticles with varying surface concentration of platinum atoms have been synthesized using a novel redox-mediated synthesis approach. The synthesis technique allows for a selective deposition of platinum atoms on the surface of prefabricated gold nanoparticles. Energy dispersive spectroscopic analyses in a scanning electron microscope reveal that the platinum to gold atomic ratios are close to the nominal values, validating the synthesis scheme. X-ray diffraction data indicate an un-alloyed structure. The platinum to gold surface atomic ratio determined from cyclic voltammetry and copper under-potential deposition experiments reveal good agreement with the calculated values at low platinum concentration. However, there is an increase in non-uniformity in the deposition process upon increasing the platinum concentration. Koutecky-Levich analysis of the samples indicates a transition of the total number of electrons transferred (n) in the electrochemical oxygen reduction reaction from two to four electrons upon increasing the surface concentration of platinum atoms. Furthermore, the data indicate that isolated platinum atoms can reduce molecular oxygen but via a two-electron route. Moreover, successful four-electron reduction of molecular oxygen requires clusters of platinum atoms. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Determination of human body burden baseline date of platinum through autopsy tissue analysis.

PubMed Central

Vandiver, F; Duffield, F V; Yoakum, A; Bumgarner, J; Moran, J

1976-01-01

Results of analysis for platinum in 97 autopsy sets are presented. Analysis was performed by a specially developed emission spectrochemical method. Almost half of the individuals studied were found to have detectable platinum in one or more tissue samples. Platinum was found to be deposited in 13 of 21 tissue types investigated. Surprisingly high values were observed in subcutaneous fat, previously not considered to be a target site for platinum deposition. These data will serve as a human tissue platinum burden baseline in EPA's Catalyst Research Program. PMID:1001291

Theoretical Study of the Structure, Stability and Oxygen Reduction Activity of Ultrathin Platinum Nanowires

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matanovic, Ivana; Kent, Paul; Garzon, Fernando

2012-10-10

We use density functional theory to study the difference in the structure, stability and catalytic reactivity between ultrathin, 0.5- 1.0 nm diameter, platinum nanotubes and nanowires. Model nanowires were formed by inserting an inner chain of platinum atoms in small diameter nanotubes. In this way more stable, nonhollow structures were formed. The difference in the electronic structure of platinum nanotubes and nanowires was examined by inspecting the density of surface states and band structure. Furthermore, reactivity towards the oxygen reduction reaction of platinum nanowires was addressed by studying the change in the chemisorption energies of oxygen and hydroxyl groups, inducedmore » by inserting the inner chain of platinum atoms into the hollow nanotubes. Both ultrathin platinum nanotubes and nanowires show distinct properties compared to bulk platinum. Nanotubes with diameters larger than 1 nm show promise for use as oxygen reduction catalysts.« less

Density Functional Study of the Structure, Stability and Oxygen Reduction Activity of Ultrathin Platinum Nanowires

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matanovic, Ivana; Kent, Paul; Garzon, Fernando

2013-03-14

We used density functional theory to study the difference in the structure, stability and catalytic reactivity between ultrathin, 0.5–1.0 nm diameter, platinum nanotubes and nanowires. Model nanowires were formed by inserting an inner chain of platinum atoms in small diameter nanotubes. In this way more stable, non-hollow structures were formed. The difference in the electronic structure of platinum nanotubes and nanowires was examined by inspecting the density of surface states and band structure. Furthermore, reactivity toward the oxygen reduction reaction of platinum nanowires was assessed by studying the change in the chemisorption energies of oxygen, hydroxyl, and hydroperoxyl groups, inducedmore » by converting the nanotube models to nanowires. Both ultrathin platinum nanotubes and nanowires show distinct properties compared to bulk platinum. Single-wall nanotubes and platinum nanowires with diameters larger than 1 nm show promise for use as oxygen reduction catalysts.« less

Single-Atom Catalyst of Platinum Supported on Titanium Nitride for Selective Electrochemical Reactions.

PubMed

Yang, Sungeun; Kim, Jiwhan; Tak, Young Joo; Soon, Aloysius; Lee, Hyunjoo

2016-02-05

As a catalyst, single-atom platinum may provide an ideal structure for platinum minimization. Herein, a single-atom catalyst of platinum supported on titanium nitride nanoparticles were successfully prepared with the aid of chlorine ligands. Unlike platinum nanoparticles, the single-atom active sites predominantly produced hydrogen peroxide in the electrochemical oxygen reduction with the highest mass activity reported so far. The electrocatalytic oxidation of small organic molecules, such as formic acid and methanol, also exhibited unique selectivity on the single-atom platinum catalyst. A lack of platinum ensemble sites changed the reaction pathway for the oxygen-reduction reaction toward a two-electron pathway and formic acid oxidation toward direct dehydrogenation, and also induced no activity for the methanol oxidation. This work demonstrates that single-atom platinum can be an efficient electrocatalyst with high mass activity and unique selectivity. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nanocarriers for delivery of platinum anticancer drugs☆

PubMed Central

Oberoi, Hardeep S.; Nukolova, Natalia V.; Kabanov, Alexander V.; Bronich, Tatiana K.

2014-01-01

Platinum based anticancer drugs have revolutionized cancer chemotherapy, and continue to be in widespread clinical use especially for management of tumors of the ovary, testes, and the head and neck. However, several dose limiting toxicities associated with platinum drug use, partial anti-tumor response in most patients, development of drug resistance, tumor relapse, and many other challenges have severely limited the patient quality of life. These limitations have motivated an extensive research effort towards development of new strategies for improving platinum therapy. Nanocarrier-based delivery of platinum compounds is one such area of intense research effort beginning to provide encouraging preclinical and clinical results and may allow the development of the next generation of platinum chemotherapy. This review highlights current understanding on the pharmacology and limitations of platinum compounds in clinical use, and provides a comprehensive analysis of various platinum–polymer complexes, micelles, dendrimers, liposomes and other nanoparticles currently under investigation for delivery of platinum drugs. PMID:24113520

PLATINUM AND FUEL CELLS

EPA Science Inventory

Platinum requirements for fuel cell vehicles (FCVS) have been identified as a concern and possible problem with FCV market penetration. Platinum is a necessary component of the electrodes of fuel cell engines that power the vehicles. The platinum is deposited on porous electrodes...

Platinum recycling in the United States in 1998

USGS Publications Warehouse

Hilliard, Henry E.

2001-01-01

In the United States, catalytic converters are the major source of secondary platinum for recycling. Other sources of platinum scrap include reforming and chemical process catalysts. The glass industry is a small but significant source of platinum scrap. In North America, it has been estimated that in 1998 more than 20,000 kilograms per year of platinum-group metals from automobile catalysts were available for recycling. In 1998, an estimated 7,690 kilograms of platinum were recycled in the United States. U.S. recycling efficiency was calculated to have been 76 percent in 1998; the recycling rate was estimated at 16 percent.

Fuel cell electrodes

DOEpatents

Strmcnik, Dusan; Cuesta, Angel; Stamenkovic, Vojislav; Markovic, Nenad

2015-06-23

A process includes patterning a surface of a platinum group metal-based electrode by contacting the electrode with an adsorbate to form a patterned platinum group metal-based electrode including platinum group metal sites blocked with adsorbate molecules and platinum group metal sites which are not blocked.

Sorption and recovery of platinum from simulated spent catalyst solution and refinery wastewater using chemically modified biomass as a novel sorbent.

PubMed

Garole, Dipak J; Choudhary, Bharat C; Paul, Debajyoti; Borse, Amulrao U

2018-04-01

In this study, Lagerstroemia speciosa biomass modified by polyethylenimine (PEI-LS) was developed as a potential biosorbent for sorption and recovery of platinum(II) from platinum bearing waste solutions. Batch experiments were conducted to study the effect of various parameters on the sorption and recovery of platinum(II) using PEI-LS. The equilibrium time for platinum(II) sorption process was found to be 6 h. Both the sorption kinetics and sorption isotherm data fits pseudo second-order kinetic model and Langmuir isotherm, respectively. The maximum sorption capacity of platinum(II) onto PEI-LS at pH 2 for the studied temperature range (25-45 °C) is in the range of 122-154 mg/g. Evaluation of thermodynamic parameters suggests that the platinum(II) sorption is spontaneous and endothermic in nature. The regeneration of PEI-LS can be achieved using acidic thiourea as an eluent for recovery of platinum from the biosorbent. Fourier transform infrared (FT-IR) analysis suggests many functional groups were involved in platinum(II) sorption onto PEI-LS. Both the scanning electron microscope/energy dispersive spectroscopy (SEM/EDS) and X-ray photoelectron spectroscopy (XPS) analysis suggest a successful modification of raw biomass with PEI. The XPS analysis further concludes that platinum(II) sorption is governed by ion-exchange and co-ordination reaction. Finally, the PEI-LS was shown to recover ≥ 90% of platinum from two simulated solutions: the acid-leached spent catalyst solution and refinery wastewater. The biosorbent developed in this study is a low-cost and eco-friendly media that can be effectively used for platinum recovery from industrial wastewater.

Elution of platinum from carboplatin-impregnated calcium sulfate hemihydrate beads in vitro.

PubMed

Tulipan, Rachel J; Phillips, Heidi; Garrett, Laura D; Dirikolu, Levent; Mitchell, Mark A

2016-11-01

OBJECTIVE To characterize the elution of platinum from carboplatin-impregnated calcium sulfate hemihydrate (CSH) beads in vitro. SAMPLE 60 carboplatin-impregnated CSH beads and 9 CSH beads without added carboplatin (controls). PROCEDURES Carboplatin-impregnated CSH beads (each containing 4.6 mg of carboplatin [2.4 mg of platinum]) were placed into separate 10-mL plastic tubes containing 5 mL of PBSS in groups of 1, 3, 6, or 10; 3 control beads were placed into a single tube of PBSS at the same volume. Experiments were conducted in triplicate at 37°C and a pH of 7.4 with constant agitation. Eluent samples were collected at 1, 2, 3, 6, 12, 24, and 72 hours. Samples were analyzed for platinum content by inductively coupled plasma-mass spectrometry. RESULTS The mean concentration of platinum released per carboplatin-impregnated bead over 72 hours was 445.3 mg/L. Cumulative concentrations of platinum eluted increased as the number of beads per tube increased. There was a significant difference in platinum concentrations over time, with values increasing over the first 12 hours and then declining for all tubes. There was also a significant difference in percentage of total incorporated platinum released into tubes with different numbers of beads: the percentage of eluted platinum was higher in tubes containing 1 or 3 beads than in those containing 6 or 10 beads. CONCLUSIONS AND CLINICAL RELEVANCE Carboplatin-impregnated CSH beads eluted platinum over 72 hours. Further studies are needed to determine whether implantation of carboplatin-impregnated CSH beads results in detectable levels of platinum systemically and whether the platinum concentrations eluted locally are toxic to tumor cells.

Mineral resource of the month: platinum-group metals

USGS Publications Warehouse

Hilliard, Henry

2003-01-01

The precious metals commonly referred to as platinum-group metals (PGM) include iridium, osmium, palladium, platinum, rhodium and ruthenium. PGM are among the rarest of elements, and their market values — particularly for palladium, platinum and rhodium — are the highest of all precious metals.

Platinum single-atom and cluster catalysis of the hydrogen evolution reaction

NASA Astrophysics Data System (ADS)

Cheng, Niancai; Stambula, Samantha; Wang, Da; Banis, Mohammad Norouzi; Liu, Jian; Riese, Adam; Xiao, Biwei; Li, Ruying; Sham, Tsun-Kong; Liu, Li-Min; Botton, Gianluigi A.; Sun, Xueliang

2016-11-01

Platinum-based catalysts have been considered the most effective electrocatalysts for the hydrogen evolution reaction in water splitting. However, platinum utilization in these electrocatalysts is extremely low, as the active sites are only located on the surface of the catalyst particles. Downsizing catalyst nanoparticles to single atoms is highly desirable to maximize their efficiency by utilizing nearly all platinum atoms. Here we report on a practical synthesis method to produce isolated single platinum atoms and clusters using the atomic layer deposition technique. The single platinum atom catalysts are investigated for the hydrogen evolution reaction, where they exhibit significantly enhanced catalytic activity (up to 37 times) and high stability in comparison with the state-of-the-art commercial platinum/carbon catalysts. The X-ray absorption fine structure and density functional theory analyses indicate that the partially unoccupied density of states of the platinum atoms' 5d orbitals on the nitrogen-doped graphene are responsible for the excellent performance.

Mono- and di-bromo platinum(IV) prodrugs via oxidative bromination: synthesis, characterization, and cytotoxicity.

PubMed

Xu, Zoufeng; Wang, Zhigang; Yiu, Shek-Man; Zhu, Guangyu

2015-12-14

Platinum(IV)-based anticancer prodrugs have attracted much attention due to their relative inertness under physiological conditions, being activated inside cells, and their capacity for functionalization with a variety of small-molecule or macromolecule moieties. Novel asymmetric platinum(IV) compounds synthesized through expedient and unique methods are desired. Here we utilize N-bromosuccinimide (NBS) and carry out oxidative bromination on platinum(II) drugs, namely cisplatin, carboplatin, and oxaliplatin, to obtain asymmetric and mono-bromo platinum(IV) prodrugs. Different solvents are used to obtain various compounds, and the compounds are further functionalized. Di-bromo compounds are also obtained through NBS-directed oxidative bromination in ethanol. The crystal structures of representative compounds are discussed, and the reduction potentials of some compounds are examined. A cytotoxicity test shows that the mono- and di-bromo platinum(IV) compounds are active against human ovarian cancer cells. Our study enriches the family of asymmetric platinum(IV) prodrugs and provides with a convenient strategy to obtain brominated platinum(IV) complexes.

Platinum single-atom and cluster catalysis of the hydrogen evolution reaction

PubMed Central

Cheng, Niancai; Stambula, Samantha; Wang, Da; Banis, Mohammad Norouzi; Liu, Jian; Riese, Adam; Xiao, Biwei; Li, Ruying; Sham, Tsun-Kong; Liu, Li-Min; Botton, Gianluigi A.; Sun, Xueliang

2016-01-01

Platinum-based catalysts have been considered the most effective electrocatalysts for the hydrogen evolution reaction in water splitting. However, platinum utilization in these electrocatalysts is extremely low, as the active sites are only located on the surface of the catalyst particles. Downsizing catalyst nanoparticles to single atoms is highly desirable to maximize their efficiency by utilizing nearly all platinum atoms. Here we report on a practical synthesis method to produce isolated single platinum atoms and clusters using the atomic layer deposition technique. The single platinum atom catalysts are investigated for the hydrogen evolution reaction, where they exhibit significantly enhanced catalytic activity (up to 37 times) and high stability in comparison with the state-of-the-art commercial platinum/carbon catalysts. The X-ray absorption fine structure and density functional theory analyses indicate that the partially unoccupied density of states of the platinum atoms' 5d orbitals on the nitrogen-doped graphene are responsible for the excellent performance. PMID:27901129

Metabolic studies of an orally active platinum anticancer drug by liquid chromatography-electrospray ionization mass spectrometry.

PubMed

Poon, G K; Raynaud, F I; Mistry, P; Odell, D E; Kelland, L R; Harrap, K R; Barnard, C F; Murrer, B A

1995-09-29

Bis(acetato)amminedichloro(cyclohexylamine) platinum(IV) (JM216) is a new orally administered platinum complex with antitumor properties, and is currently undergoing phase II clinical trials. When JM216 was incubated with human plasma ultrafiltrate, 93% of the platinum species were protein-bound and 7% were unbound. The unbound platinum complexes in the ultrafiltrates of human plasma were analysed using a liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) method. Apart from the parent drug, four metabolites were identified and characterised. These include JM118 [amminedichloro(cyclohexylamine) platinum(II)], JM383 [bis(acetato)ammine(cyclohexylamine)dihydroxo platinum(IV)] and the two isomers JM559 and JM518 [bis(acetato)amminechloro(cyclohexylamine) hydroxo platinum(IV)]. Their elemental compositions were determined by accurate mass measurement during the LC analysis, to confirm their identities. Quantitation of these metabolites by off-line LC atomic absorption spectroscopy demonstrated that JM118 is the major metabolite in plasma from patients receiving JM216 treatment.

Hierarchical Nanoporous Gold-Platinum with Heterogeneous Interfaces for Methanol Electrooxidation

PubMed Central

Xiao, Shuang; Xiao, Fei; Hu, Yuan; Yuan, Songliu; Wang, Shuai; Qian, Lihua; Liu, Yunqi

2014-01-01

The electrocatalysts utilized as the prospective electrodes in fuel cells and high efficient energy conversion devices require both the interconnected channels for efficient electrolyte transportation and the superior catalytic activity with long service life. In this work, nanoporous gold with the rigid skeletons in three dimensions is partially decorated by porous platinum shell containing nanoscale interstitials, aiming to create the heterogeneous gold-platinum interfaces and facilitate the electrolyte transportation as well. In comparison with no catalytic activity of bare nanoporous gold, the catalytic activity of hierarchical nanoporous gold-platinum towards electrochemical oxidation of methanol increases with the loading level of platinum shells, resulting in the highest electrochemical area of 70.4 m2·g−1 after the normalization by the mass of platinum. Heterogeneous gold-platinum interfaces affect the tolerance of the absorbed intermediate species because of the oxidization by the oxygenated species absorbed on the gold surface and the enhanced ion transportation within the porous platinum shell. PMID:24621809

Outpatient desensitization in selected patients with platinum hypersensitivity reactions.

PubMed

O'Malley, David M; Vetter, Monica Hagan; Cohn, David E; Khan, Ambar; Hays, John L

2017-06-01

Platinum-based chemotherapies are a standard treatment for both initial and recurrent gynecologic cancers. Given this widespread use, it is important to be aware of the features of platinum hypersensitivity reactions and the subsequent treatment of these reactions. There is also increasing interest in the development of desensitization protocols to allow patients with a history of platinum hypersensitivity to receive further platinum based therapy. In this review, we describe the management of platinum hypersensitivity reactions and the desensitization protocols utilized at our institution. We also describe the clinical categorizations utilized to triage patients to appropriate desensitization protocols. Copyright © 2017 Elsevier Inc. All rights reserved.

Interactions of platinum metals and their complexes in biological systems.

PubMed Central

LeRoy, A F

1975-01-01

Platinum-metal oxidation catalysts are to be introduced in exhaust systems of many 1975 model-year automobiles in the U.S. to meet Clean Air Act standards. Small quantities of finely divided catalyst have been found issuing from prototype systems; platinum and palladium compounds may be found also. Although platinum exhibits a remarkable resistance to oxidation and chemical attack, it reacts chemically under some conditions producing coordination complex compounds. Palladium reacts more readily than platinum. Some platinum-metal complexes interact with biological systems as bacteriostatic, bacteriocidal, viricidal, and immunosuppressive agents. Workers chronically exposed to platinum complexes often develop asthma-like respiratory distress and skin reactions called platinosis. Platinum complexes used alone and in combination therapy with other drugs have recently emerged as effective agents in cancer chemotherapy. Understanding toxic and favorable interactions of metal species with living organisms requires basic information on quantities and chemical characteristics of complexes at trace concentrations in biological materials. Some basic chemical kinetic and thermodynamic data are presented to characterize the chemical behavior of the complex cis-[Pt(NH3)2Cl2] used therapeutically. A brief discussion of platinum at manogram levels in biological tissue is discussed. PMID:50943

Fabrication of Carbon-Platinum Interdigitated Array Electrodes and Their Application for Investigating Homogeneous Hydrogen Evolution Catalysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, F.; Divan, R.; Parkinson, B. A.

2015-01-01

Interdigitated array electrodes (IDAEs) with one carbon electrode and the other platinum electrode were constructed by electrodepositing platinum on one set of the carbon electrodes. Platinum deposition was confirmed by scanning electron microscope (SEM) and cyclic voltammetry. The width of the carbon and platinum digits is less than 2 μm and the gap between two adjacent digits is around 3 μm. The carbon-platinum IDAEs benefit from the characteristics of both carbon and platinum in that carbon can provide a wide nonreactive potential window while platinum is a good catalyst for hydrogen reactions making it useful to characterize the catalytic hydrogenmore » production cycle of the molecular electrocatalyst [Ni(PPh2NPh2)2(CH3CN)](BF4)2 (where PPh2NPh2 is 1,3,5,7-tetraphenyl-1,5-diaza-3,7-diphosphacyclooctane). With properly set potentials, the molecular electrocatalyst was reduced at the carbon digits to initiate a homogeneous H2 production reaction while the platinum digits detect the H2 by oxidation, providing direct evidence of its production rate from the catalytic cycles.« less

[Expression of MiR-130a in Serum Samples of Patients with Epithelial Ovarian Cancer and Its Association with Platinum Resistance].

PubMed

Chen, Cen; Wang, Hong-jing; Yang, Ling-Yun; Jia, Xi-biao; Xu, Pan; Chen, Jing; Liu, Ya

2016-01-01

To determine the expression of miR-130a in patients with epithelial ovarian cancer and its association with platinum resistance. 32 patients with platinum resistance and 30 patients without platinum resistance were recruited in this study. Real-time PCR was performed to detect the expression of miR-130a in the serum samples of the patients. ELISA was used to measure the expression level of phosphatase and tensin homolog deleted on chromosome ten (PTEN) and B-cell lymphoma-2 (BCL-2). Platinum-resistant patients had significantly higher levels of expression of miR-130a and BCL-2, and lower level of PTEN than platinum-sensitive patients (P < 0.05). The expression level of miR-130a increased with increased severity in histological classification and appearance of lymph node metastasis in the platinum-resistant patients (P < 0.05). MiR-130a may mediate the generation of platinum resistance in epithelial ovarian cancer through inhibiting PTEN to activate PI3K/AKT signaling pathway and increasing BCL-2 to inhibit tumor cell apoptosis. MiR-130a may be a new potential target of gene therapy in platinum-resistant ovarian cancers.

Platinum(II)-Oligonucleotide Coordination Based Aptasensor for Simple and Selective Detection of Platinum Compounds.

PubMed

Cai, Sheng; Tian, Xueke; Sun, Lianli; Hu, Haihong; Zheng, Shirui; Jiang, Huidi; Yu, Lushan; Zeng, Su

2015-10-20

Wide use of platinum-based chemotherapeutic regimens for the treatment for carcinoma calls for a simple and selective detection of platinum compound in biological samples. On the basis of the platinum(II)-base pair coordination, a novel type of aptameric platform for platinum detection has been introduced. This chemiluminescence (CL) aptasensor consists of a designed streptavidin (SA) aptamer sequence in which several base pairs were replaced by G-G mismatches. Only in the presence of platinum, coordination occurs between the platinum and G-G base pairs as opposed to the hydrogen-bonded G-C base pairs, which leads to SA aptamer sequence activation, resulting in their binding to SA coated magnetic beads. These Pt-DNA coordination events were monitored by a simple and direct luminol-peroxide CL reaction through horseradish peroxidase (HRP) catalysis with a strong chemiluminescence emission. The validated ranges of quantification were 0.12-240 μM with a limit of detection of 60 nM and selectivity over other metal ions. This assay was also successfully used in urine sample determination. It will be a promising candidate for the detection of platinum in biomedical and environmental samples.

The role of interleukin-8 (IL-8) and IL-8 receptors in platinum response in high grade serous ovarian carcinoma

PubMed Central

Stronach, Euan A.; Cunnea, Paula; Turner, Christina; Guney, Tankut; Aiyappa, Radhika; Jeyapalan, Senthuran; de Sousa, Camila H.; Browne, Alacoque; Magdy, Nesreen; Studd, James B.; Sriraksa, Ruethairat; Gabra, Hani; El-Bahrawy, Mona

2015-01-01

Platinum based drugs are the cornerstone of chemotherapy for ovarian cancer, however the development of chemoresistance hinders its success. IL-8 is involved in regulating several pro-survival pathways in cancer. We studied the expression of IL-8 and IL-8 receptors in platinum sensitive and resistant cell lines. Using qRT-PCR and immunohistochemistry, both platinum sensitive (PEA1, PEO14) and resistant (PEA2, PEO23) show increased expression of IL-8 and IL-8 receptors. IL-8RA shows nuclear and cytoplasmic expression, whilst IL-8RB is present solely in the cytoplasm. Knockdown of IL-8 increased sensitivity to cisplatin in platinum sensitive and reversed platinum resistance in resistant cell lines, decreased the expression of anti-apoptotic Bcl-2 and decreased inhibitory phosphorylation of pro-apoptotic Bad. IL-8 receptor antagonist treatment also enhanced platinum sensitivity. Nuclear localisation of IL-8RA was only detected in platinum resistant tumours. Inhibition of IL-8 signalling can enhance response in platinum sensitive and resistant disease. Nuclear IL-8RA may have potential as a biomarker of resistant disease. PMID:26267317

The role of interleukin-8 (IL-8) and IL-8 receptors in platinum response in high grade serous ovarian carcinoma.

PubMed

Stronach, Euan A; Cunnea, Paula; Turner, Christina; Guney, Tankut; Aiyappa, Radhika; Jeyapalan, Senthuran; de Sousa, Camila H; Browne, Alacoque; Magdy, Nesreen; Studd, James B; Sriraksa, Ruethairat; Gabra, Hani; El-Bahrawy, Mona

2015-10-13

Platinum based drugs are the cornerstone of chemotherapy for ovarian cancer, however the development of chemoresistance hinders its success. IL-8 is involved in regulating several pro-survival pathways in cancer. We studied the expression of IL-8 and IL-8 receptors in platinum sensitive and resistant cell lines. Using qRT-PCR and immunohistochemistry, both platinum sensitive (PEA1, PEO14) and resistant (PEA2, PEO23) show increased expression of IL-8 and IL-8 receptors. IL-8RA shows nuclear and cytoplasmic expression, whilst IL-8RB is present solely in the cytoplasm. Knockdown of IL-8 increased sensitivity to cisplatin in platinum sensitive and reversed platinum resistance in resistant cell lines, decreased the expression of anti-apoptotic Bcl-2 and decreased inhibitory phosphorylation of pro-apoptotic Bad. IL-8 receptor antagonist treatment also enhanced platinum sensitivity. Nuclear localisation of IL-8RA was only detected in platinum resistant tumours. Inhibition of IL-8 signalling can enhance response in platinum sensitive and resistant disease. Nuclear IL-8RA may have potential as a biomarker of resistant disease.

40 CFR 440.110 - Applicability; description of the platinum ore subcategory.

Code of Federal Regulations, 2011 CFR

2011-07-01

... platinum ore subcategory. 440.110 Section 440.110 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS ORE MINING AND DRESSING POINT SOURCE CATEGORY Platinum Ores Subcategory § 440.110 Applicability; description of the platinum ore subcategory. The provisions of this...

40 CFR 440.110 - Applicability; description of the platinum ore subcategory.

Code of Federal Regulations, 2010 CFR

2010-07-01

... platinum ore subcategory. 440.110 Section 440.110 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS ORE MINING AND DRESSING POINT SOURCE CATEGORY Platinum Ores Subcategory § 440.110 Applicability; description of the platinum ore subcategory. The provisions of this...

Neurotoxicity Associated with Platinum-Based Anti-Cancer Agents: What are the Implications of Copper Transporters?

PubMed

Stojanovska, Vanesa; McQuade, Rachel; Rybalka, Emma; Nurgali, Kulmira

2017-01-01

Platinum-based anti-cancer agents, which include cisplatin, carboplatin and oxaliplatin, are an important class of drugs used in clinical setting to treat a variety of cancers. The cytotoxic efficacy of these drugs is mediated by the formation of inter-strand and intrastrand crosslinks, or platinum adducts on nuclear DNA. There is also evidence demonstrating that mitochondrial DNA is susceptible to platinum-adduct damage in dorsal root ganglia neurons. Although all platinum-based agents form similar DNA adducts, they are quite different in terms of activation, systemic toxicity and tolerance. Platinum-based agents are well known for their neurotoxicity and gastrointestinal side-effects which are major causes for dose limitation and treatment discontinuation compromising the efficacy of anti-cancer treatment. Accumulating evidence in non-neuronal cells shows that the copper transport system is associated with platinum drug sensitivity and resistance. There is minimal research concerning the role of copper transporters within the central and peripheral nervous systems. It is unclear whether neurons are more sensitive to platinum-based drugs, are insufficient in drug clearance, or whether platinum accumulation affects intracellular copper status and coppermediated functions. Understanding these mechanisms is important as neurotoxicity is the predominant side-effect of platinum-based chemotherapy. This review highlights the role of copper transpor ters in drug influx, differences in drug activation and side-effects caused by platinum-based agents, as well as their association with central and peripheral neuropathies and gastrointestinal toxicities. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Platinum Publications, June 30–July 26, 2017 | Poster

Cancer.gov

Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected from among the most recently published Platinum Publications.

Platinum Publications, April 28–May 31, 2017 | Poster

Cancer.gov

Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected from among the most recently published Platinum Publications.

Platinum Publications, June 1–June 29, 2017 | Poster

Cancer.gov

Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected from among the most recently published Platinum Publications.

Platinum Publications, July 26–August 30, 2017 | Poster

Cancer.gov

Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected from among the most recently published Platinum Publications.

Platinum Publications, March 31–April 27, 2017 | Poster

Cancer.gov

Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected from among the most recently published Platinum Publications.

Platinum Publications, March 1–March 30, 2017 | Poster

Cancer.gov

Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected from among the most recently published Platinum Publications.

Platinum Publications, December 1–December 29, 2016 | Poster

Cancer.gov

Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected from among the most recently published Platinum Publications.

Platinum Publications, January 26–February 28, 2017 | Poster

Cancer.gov

Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected from among the most recently published Platinum Publications.

Low platinum catalyst and method of preparation

DOEpatents

Liu, Di-Jia; Chong, Lina

2017-11-21

A low platinum catalyst and method for making same. The catalyst comprises platinum-transition metal bimetallic alloy microcrystallites over a transition metal-nitrogen-carbon composite. A method of making a catalyst comprises preparation of transition metal organic frameworks, infusion of platinum, thermal treatment, and reduction to form the microcrystallites and composite.

PLATINUM HEXAFLUORIDE AND METHOD OF FLUORINATING PLUTONIUM CONTAINING MIXTURES THERE-WITH

DOEpatents

Malm, J.G.; Weinstock, B.; Claassen, H.H.

1959-07-01

The preparation of platinum hexafluoride and its use as a fluorinating agent in a process for separating plutonium from fission products is presented. According to the invention, platinum is reacted with fluorine gas at from 900 to 1100 deg C to form platinum hexafluoride. The platinum hexafluoride is then contacted with the plutonium containing mixture at room temperature to form plutonium hexafluoride which is more volatile than the fission products fluorides and therefore can be isolated by distillation.

The nature of platinum in silicones for biomedical and healthcare use.

PubMed

Lambert, James M

2006-07-01

Silicone is an important biomaterial in many different biomedical and healthcare applications. Network formation in one type of silicone relies upon a chemical crosslinking reaction that typically employs a platinum catalyst. As a consequence, low concentrations of platinum may remain in certain medical devices designed for human use. The characteristics of platinum in silicone before, during, and after the crosslinking reaction have been well described in the literature. This review summarizes the relevant literature on the organometallic and analytical chemistry of platinum in silicone and thus provides a foundation for understanding the effects this platinum may have, if any, in the various biomedical and healthcare applications where it may be present.

Platinum recycling going green via induced surface potential alteration enabling fast and efficient dissolution

PubMed Central

Hodnik, Nejc; Baldizzone, Claudio; Polymeros, George; Geiger, Simon; Grote, Jan-Philipp; Cherevko, Serhiy; Mingers, Andrea; Zeradjanin, Aleksandar; Mayrhofer, Karl J. J.

2016-01-01

The recycling of precious metals, for example, platinum, is an essential aspect of sustainability for the modern industry and energy sectors. However, due to its resistance to corrosion, platinum-leaching techniques rely on high reagent consumption and hazardous processes, for example, boiling aqua regia; a mixture of concentrated nitric and hydrochloric acid. Here we demonstrate that complete dissolution of metallic platinum can be achieved by induced surface potential alteration, an ‘electrode-less' process utilizing alternatively oxidative and reductive gases. This concept for platinum recycling exploits the so-called transient dissolution mechanism, triggered by a repetitive change in platinum surface oxidation state, without using any external electric current or electrodes. The effective performance in non-toxic low-concentrated acid and at room temperature is a strong benefit of this approach, potentially rendering recycling of industrial catalysts, including but not limited to platinum-based systems, more sustainable. PMID:27767178

Restoring platinum sensitivity in recurrent ovarian cancer by extending the platinum-free interval: Myth or reality?

PubMed

Tomao, Federica; D'Incalci, Maurizio; Biagioli, Elena; Peccatori, Fedro A; Colombo, Nicoletta

2017-09-15

The platinum-free interval is the most important predictive factor of a response to subsequent lines of chemotherapy and the most important prognostic factor for progression-free and overall survival in patients with recurrent epithelial ovarian cancer. A nonplatinum regimen is generally considered the most appropriate approach when the disease recurs very early after the end of chemotherapy, whereas platinum-based chemotherapy is usually adopted when the platinum-free interval exceeds 12 months. However, the therapeutic management of patients with intermediate sensitivity (ie, when the relapse occurs between 6 and 12 months) remains debatable. Preclinical and clinical data suggest that the extension of platinum-free interval (using a nonplatinum-based regimen) might restore platinum sensitivity, thus allowing survival improvement. The objective of this review was to critically analyze preclinical and clinical evidences supporting this hypothesis. Cancer 2017;123:3450-9. © 2017 American Cancer Society. © 2017 American Cancer Society.

Remarkable NO oxidation on single supported platinum atoms

DOE PAGES

Narula, Chaitanya K.; Allard, Lawrence F.; Stocks, G. M.; ...

2014-11-28

Our first-principles density functional theoretical modeling suggests that NO oxidation is feasible on fully oxidized single θ-alumina-supported platinum atoms via a modified Langmuir-Hinshelwood pathway. This is in contrast to the known decrease in NO oxidation activity of supported platinum with decreasing Pt particle size believed to be due to increased platinum oxidation. In order to validate our theoretical study, we evaluated single θ-Al 2O 3-supported platinum atoms and found them to exhibit remarkable NO oxidation activity. A comparison of turnover frequencies (TOF) of single supported Pt atoms with those of platinum particles for NO oxidation shows that single supported Ptmore » atoms are as active as fully formed platinum particles. The overall picture of NO oxidation on supported Pt is that NO oxidation activity decreases with decreasing Pt particle size but accelerates when Pt is present only as single atoms.« less

Platinum Publications, December 30, 2016–January 25, 2017 | Poster

Cancer.gov

Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected from among the most recently published Platinum Publications.

Surface Analysis of 4-Aminothiophenol Adsorption at Polycrystalline Platinum Electrodes

NASA Technical Reports Server (NTRS)

Rosario-Castro, Belinda I.; Fachini, Estevao R.; Contes, Enid J.; Perez-Davis, Marla E.; Cabrera, Carlos R.

2008-01-01

Formation of self-assembled monolayer (SAM) of 4-aminothiophenol (4-ATP) on polycrystalline platinum electrodes has been studied by surface analysis and electrochemistry techniques. The 4-ATP monolayer was characterized by cyclic voltammetry (CV), Raman spectroscopy, reflection absorption infrared (RAIR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). Cyclic voltammetry (CV) experiments give an idea about the packing quality of the monolayer. RAIR and Raman spectra for 4-ATP modified platinum electrodes showed the characteristic adsorption bands for neat 4-ATP indicating the adsorption of 4-ATP molecules on platinum surface. The adsorption on platinum was also evidenced by the presence of sulfur and nitrogen peaks by XPS survey spectra of the modified platinum electrodes. High resolution XPS studies and RAIR spectrum for platinum electrodes modified with 4-ATP indicate that molecules are sulfur-bonded to the platinum surface. The formation of S-Pt bond suggests that ATP adsorption gives up an amino terminated SAM. Thickness of the monolayer was evaluated via angle-resolved XPS (AR-XPS) analyses. Derivatization of 4-ATP SAM was performed using 16-Br hexadecanoic acid.

Markers of Oxidative Stress and Inflammation in Ascites and Plasma in Patients with Platinum-Sensitive, Platinum-Resistant, and Platinum-Refractory Epithelial Ovarian Cancer.

PubMed

Cantón-Romero, Juan Carlos; Miranda-Díaz, Alejandra Guillermina; Bañuelos-Ramírez, Jose Luis; Carrillo-Ibarra, Sandra; Sifuentes-Franco, Sonia; Castellanos-González, José Alberto; Rodríguez-Carrizalez, Adolfo Daniel

2017-01-01

Diverse proinflammatory biomarkers and oxidative stress are strongly associated with advanced epithelial ovarian cancer (EOC). Objective . To determine the behavior of markers of oxidative stress and inflammation in plasma and ascites fluid in patients with platinum-sensitive, platinum-resistant, and platinum-refractory EOC. Methods . A prospective cohort study. The colorimetric method was used to determine levels of the markers 8-isoprostanes (8-IP), lipid peroxidation products (LPO), and total antioxidant capacity (TAC) in plasma and ascites fluid; and with ELISA, the levels of interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF- α ) were determined in patients with EOC. Results . In ascites fluid, a significant increase in 8-IP versus baseline plasma levels was found ( p = 0.002). There was an important leakage of the TAC levels in ascites fluid versus baseline plasma levels ( p < 0.001). The IL-6 was elevated in ascites fluid versus baseline plasma levels ( p = 0.003), and there were diminished levels of TNF- α in ascites fluid versus baseline plasma levels ( p = 0.001). Discussion . We hypothesize that the ascites fluid influences the behavior and dissemination of the tumor. Deregulation between oxidants, antioxidants, and the proinflammatory cytokines was found to vary among platinum-sensitive, platinum-resistant, and platinum-refractory patients.

Rapid and Efficient Collection of Platinum from Karstedt's Catalyst Solution via Ligands-Exchange-Induced Assembly.

PubMed

Yang, Gonghua; Wei, Yanlong; Huang, Zhenzhu; Hu, Jiwen; Liu, Guojun; Ou, Ming; Lin, Shudong; Tu, Yuanyuan

2018-02-21

Reported herein is a novel strategy for the rapid and efficient collection of platinum from Karstedt's catalyst solution. By taking advantage of a ligand-exchange reaction between alkynols and the 1,3-divinyltetramethyldisiloxane ligand (M Vi M Vi ) that coordinated with platinum (Pt(0)), the Karstedt's catalyst particles with a size of approximately 2.5 ± 0.7 nm could be reconstructed and assembled into larger particles with a size of 150 ± 35 nm due to the hydrogen bonding between the hydroxyl groups of the alkynol. In addition, because the silicone-soluble M Vi M Vi ligand of the Karstedt's catalyst was replaced by water-soluble alkynol ligands, the resultant large particles were readily dispersed in water, resulting in rapid, efficient, and complete collection of platinum from the Karstedt's catalyst solutions with platinum concentrations in the range from ∼20 000 to 0.05 ppm. Our current strategy not only was used for the rapid and efficient collection of platinum from the Karstedt's catalyst solutions, but it also enabled the precise evaluation of the platinum content in the Karstedt's catalysts, even if this platinum content was extremely low (i.e., 0.05 ppm). Moreover, these platinum specimens that were efficiently collected from the Karstedt's catalyst solutions could be directly used for the evaluation of platinum without the need for pretreatment processes, such as calcination and digestion with hydrofluoric acid, that were traditionally used prior to testing via inductively coupled plasma mass spectrometry in conventional methods.

Genetic heterogeneity after first-line chemotherapy in high-grade serous ovarian cancer.

PubMed

Lambrechts, Sandrina; Smeets, Dominiek; Moisse, Matthieu; Braicu, Elena Ioana; Vanderstichele, Adriaan; Zhao, Hui; Van Nieuwenhuysen, Els; Berns, Els; Sehouli, Jalid; Zeillinger, Robert; Darb-Esfahani, Silvia; Cacsire Castillo-Tong, Dan; Lambrechts, Diether; Vergote, Ignace

2016-01-01

Most high-grade serous ovarian carcinoma (HGSOC) patients benefit from first-line platinum-based chemotherapy, but progressively develop resistance during subsequent lines. Re-activating BRCA1 or MDR1 mutations can underlie platinum resistance in end-stage patients. However, little is known about resistance mechanisms occurring after a single line of platinum, when patients still qualify for other treatments. In 31 patients with primary platinum-sensitive HGSOC, we profiled tumours collected during debulking surgery before and after first-line chemotherapy using whole-exome sequencing and single nucleotide polymorphism profiling. Besides germline BRCA1/2 mutations, we observed frequent loss-of-heterozygosity in homologous recombination (HR) genes and mutation spectra characteristic of HR-deficiency in all tumours. At relapse, tumours differed considerably from their primary counterparts. There was, however, no evidence of events reactivating the HR pathway, also not in tumours resistant to second-line platinum. Instead, a platinum score of 13 copy number regions, among other genes including MECOM, CCNE1 and ERBB2, correlated with platinum-free interval (PFI) after first-line therapy, whereas an increase of this score in recurrent tumours predicted the change in PFI during subsequent therapy. Already after a single line of platinum, there is huge variability between primary and recurrent tumours, advocating that in HGSOC biopsies need to be collected at relapse to tailor treatment options to the underlying genetic profile. Nevertheless, all primary platinum-sensitive HGSOCs remained HR-deficient, irrespective of whether they became resistant to second-line platinum, further suggesting these tumours qualify for second-line Poly APD ribose polymerase (PARP) inhibitor treatment. Finally, chromosomal instability contributes to acquired resistance after a single line of platinum therapy. Copyright © 2015 Elsevier Ltd. All rights reserved.

Aurora Kinase A expression predicts platinum-resistance and adverse outcome in high-grade serous ovarian carcinoma patients.

PubMed

Mignogna, Chiara; Staropoli, Nicoletta; Botta, Cirino; De Marco, Carmela; Rizzuto, Antonia; Morelli, Michele; Di Cello, Annalisa; Franco, Renato; Camastra, Caterina; Presta, Ivan; Malara, Natalia; Salvino, Angela; Tassone, Pierfrancesco; Tagliaferri, Pierosandro; Barni, Tullio; Donato, Giuseppe; Di Vito, Anna

2016-05-21

High-Grade Serous Ovarian Carcinoma (HGSOC) is the predominant histotype of epithelial ovarian cancer (EOC), characterized by advanced stage at diagnosis, frequent TP53 mutation, rapid progression, and high responsiveness to platinum-based-chemotherapy. To date, standard first-line-chemotherapy in advanced EOC includes platinum salts and paclitaxel with or without bevacizumab. The major prognostic factor is the response duration from the end of the platinum-based treatment (platinum-free interval) and about 10-0 % of EOC patients bear a platinum-refractory disease or develop early resistance (platinum-free interval shorter than 6 months). On these bases, a careful selection of patients who could benefit from chemotherapy is recommended to avoid unnecessary side effects and for a better disease outcome. In this retrospective study, an immunohistochemical evaluation of Aurora Kinase A (AURKA) was performed on 41 cases of HGSOC according to platinum-status. Taking into account the number and intensity of AURKA positive cells we built a predictive score able to discriminate with high accuracy platinum-sensitive patients from platinum-resistant patients (p < 0.001). Furthermore, we observed that AURKA overexpression correlates to worse overall survival (p = 0.001; HR 0.14). We here suggest AURKA as new effective tool to predict the biological behavior of HGSOC. Particularly, our results indicate that AURKA has a role both as predictor of platinum-resistance and as prognostic factor, that deserves further investigation in prospective clinical trials. Indeed, in the era of personalized medicine, AURKA could assist the clinicians in selecting the best treatment and represent, at the same time, a promising new therapeutic target in EOC treatment.

Disturbance of DNA conformation by the binding of testosterone-based platinum drugs via groove-face and intercalative interactions: a molecular dynamics simulation study

PubMed Central

2013-01-01

Background To explore novel platinum-based anticancer agents that are distinct from the structure and interaction mode of the traditional cisplatin by forming the bifunctional intrastrand 1,2 GpG adduct, the monofunctional platinum + DNA adducts with extensive non-covalent interactions had been studied. It was reported that the monofunctional testosterone-based platinum(II) agents present the high anticancer activity. Moreover, it was also found that the testosterone-based platinum agents could cause the DNA helix to undergo significant unwinding and bending over the non-testosterone-based platinum agents. However, the interaction mechanisms of these platinum agents with DNA at the atomic level are not yet clear so far. Results In the present work, we used molecular dynamics (MD) simulations and DNA conformational dynamics calculations to study the DNA distortion properties of the testosterone-based platinum + DNA, the improved testosterone-based platinum + DNA and the non-testosterone-based platinum + DNA adducts. The results show that the intercalative interaction of the improved flexible testosterone-based platinum agent with DNA molecule could cause larger DNA conformational distortion than the groove-face interaction of the rigid testosterone-based platinum agent with DNA molecule. Further investigations for the non-testosterone-based platinum agent reveal the occurrence of insignificant change of DNA conformation due to the absence of testosterone ligand in such agent. Based on the DNA dynamics analysis, the DNA base motions relating to DNA groove parameter changes and hydrogen bond destruction of DNA base pairs were also discussed in this work. Conclusions The flexible linker in the improved testosterone-based platinum agent causes an intercalative interaction with DNA in the improved testosterone-based platinum + DNA adduct, which is different from the groove-face interaction caused by a rigid linker in the testosterone-based platinum agent. The present investigations provide useful information of DNA conformation affected by a testosterone-based platinum complex at the atomic level. PMID:23517640

Formation, Characteristics and Electrocatalytic Properties of Nanoporous Metals Formed by Dealloying of Ternary-Noble Alloys

NASA Astrophysics Data System (ADS)

Vega Zuniga, Adrian A.

Nanoporous metals formed by electrochemical dealloying of silver from Ag-Au-Pt alloys, with 77 at.% silver and platinum contents of 1, 2 and 3 at.%, have been studied. The presence of platinum, which is immobile relative to gold, refine the ligament size and stabilized the nanostructure against coarsening, even under experimental conditions that would be expected to promote coarsening (e.g., exposure to high temperature, longer dealloying times). By adding only 1 at.% Pt to the alloy precursor, the ligament/pore size was reduced by 50% with respect to that in nanoporous gold (NPG), which was formed on a Ag-Au alloy with the same silver content as ternary alloys. A further decrease in the ligament size was observed by increasing the platinum content of the precursor; however, most of the improvement occurred with 1 at.% Pt. The adsorbate-induced surface segregation of platinum was also investigated for these nanoporous metals. By exposing freshly-dealloyed nanostructures to moderate temperatures in the presence of air, platinum segregated to the ligament surface; in contrast, in an inert atmosphere (Ar-H 2), platinum mostly reverted to the bulk of the ligaments. This thermally activated process was thermodynamically driven by the interaction between platinum and oxygen; however, at the desorption temperature of oxygen, platinum de-segregated from the surface. Moreover, the co-segregation of platinum and oxygen hindered the thermal coarsening of the ligaments. Finally, the electrocatalytic abilities of these nanostructures were studied towards methanol and ethanol electro-oxidation, in alkaline and acidic media, showing significantly improved response in comparison to that observed in NPG. The synergistic effect between gold and platinum atoms and the smaller feature size of the nanostructures were directly associated with this behaviour. In alkaline electrolyte, the nanostructure formed on the alloy with 1 at.% Pt showed higher catalytic response than the other two ternary nanostructures, which could be associated with the platinum/gold ratio on the surface of the structure. In acidic electrolyte, the nanostructure with the highest platinum content displayed the highest electrocatalytic response. Furthermore, the presence of platinum changed the selectivity of both reactions: the concentrations of carbonate produced increased by increasing the platinum content in the alloy precursor.

The effects of platinum on nickel electrodes in the nickel hydrogen cell

NASA Technical Reports Server (NTRS)

Zimmerman, Albert H.

1991-01-01

Interactions of platinum and platinum compounds with the nickel electrode that are possible in the nickel hydrogen cell, where both the nickel electrode and a platinum catalyst hydrogen electrode are in intimate contact with the alkaline electrolyte, are examined. Additionally, a mechanism of nickel cobalt oxyhydroxide formation in NiH2 cells is presented.

Platinum Publications as of December 3, 2013 | Poster

Cancer.gov

Platinum Publications are selected from articles by NCI at Frederick scientists published in 21 prestigious science journals. This list represents new publications generated from PubMed as of the date shown above. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from among the most recently published Platinum Publications.

Platinum Publications as of March 6, 2014 | Poster

Cancer.gov

Platinum Publications are selected from articles by NCI at Frederick scientists published in 21 prestigious science journals. This list represents new publications generated from PubMed as of the date shown above. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from among the most recently published Platinum Publications.

Platinum Publications as of April 30, 2014 | Poster

Cancer.gov

Platinum Publications are selected from articles by NCI at Frederick scientists published in 21 prestigious science journals. This list represents new publications generated from PubMed as of the date shown above. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from among the most recently published Platinum Publications.

Platinum Publications, October 1–29, 2015 | Poster

Cancer.gov

Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from among the most recently published Platinum Publications.

Platinum Publications as of May 29, 2014 | Poster

Cancer.gov

Platinum Publications are selected from articles by NCI at Frederick scientists published in 21 prestigious science journals. This list represents new publications generated from PubMed as of the date shown above. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from among the most recently published Platinum Publications.

Fluorometric imaging methods for palladium and platinum and the use of palladium for imaging biomolecules.

PubMed

Tracey, Matthew P; Pham, Dianne; Koide, Kazunori

2015-07-21

Neither palladium nor platinum is an endogenous biological metal. Imaging palladium in biological samples, however, is becoming increasingly important because bioorthogonal organometallic chemistry involves palladium catalysis. In addition to being an imaging target, palladium has been used to fluorometrically image biomolecules. In these cases, palladium species are used as imaging-enabling reagents. This review article discusses these fluorometric methods. Platinum-based drugs are widely used as anticancer drugs, yet their mechanism of action remains largely unknown. We discuss fluorometric methods for imaging or quantifying platinum in cells or biofluids. These methods include the use of chemosensors to directly detect platinum, fluorescently tagging platinum-based drugs, and utilizing post-labeling to elucidate distribution and mode of action.

Topographic PIXE analysis of platinum levels in kidney slices from CIS-platin treated patients

NASA Astrophysics Data System (ADS)

Dikhoff, T. G. M. H.; Van Der Heide, J. A.; McVie, J. G.

1985-05-01

Concentrations of platinum and several other trace elements have been measured exploiting a 50 × 50 μ proton beam for PIXE analysis. The thickness of a selective germanium absorber for the spectral resolution of platinum L β and selenium K α peaks optimized, taking into account the fluorescent X-rays excited in the absorber material. The measurements have been performed in the framework of a project on the assessment of the toxicity of cytostatic platinum compounds. The lateral distributions of platinum in human kidneys and in dog tissues were measured. The highest concentrations of platinum were seen in arterial walls, followed by glomeruli and tubules. Chronic kidney damage may be correlated to this pattern of retention.

Novel platinum compounds and nanoparticles as anticancer agents.

PubMed

Sarkar, Arindam

2018-01-01

Since the approval of cisplatin in 1979, platinum-based drugs have been regularly used in cancer chemotherapy as a first-line treatment or with the combination of other nonplatinum drugs. Subsequent approval of second- and third-generation drugs such as carboplatin and oxaliplatin respectively, has widened the therapeutic achievement of platinum compounds. There are few other platinum drugs approved recently and many other new drugs as well as the formulations of the old ones are going through clinical trials now. Considering the astonishing achievement of these drugs, analyses on the overall scenario of the patent applications on platinum compounds have become the priority to the scientific community. This review summarizes the published patent applications on the novel platinum anticancer compounds from 2012 to 2017 (August).

Markers of Oxidative Stress and Inflammation in Ascites and Plasma in Patients with Platinum-Sensitive, Platinum-Resistant, and Platinum-Refractory Epithelial Ovarian Cancer

PubMed Central

Cantón-Romero, Juan Carlos; Bañuelos-Ramírez, Jose Luis; Sifuentes-Franco, Sonia; Castellanos-González, José Alberto

2017-01-01

Diverse proinflammatory biomarkers and oxidative stress are strongly associated with advanced epithelial ovarian cancer (EOC). Objective. To determine the behavior of markers of oxidative stress and inflammation in plasma and ascites fluid in patients with platinum-sensitive, platinum-resistant, and platinum-refractory EOC. Methods. A prospective cohort study. The colorimetric method was used to determine levels of the markers 8-isoprostanes (8-IP), lipid peroxidation products (LPO), and total antioxidant capacity (TAC) in plasma and ascites fluid; and with ELISA, the levels of interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α) were determined in patients with EOC. Results. In ascites fluid, a significant increase in 8-IP versus baseline plasma levels was found (p = 0.002). There was an important leakage of the TAC levels in ascites fluid versus baseline plasma levels (p < 0.001). The IL-6 was elevated in ascites fluid versus baseline plasma levels (p = 0.003), and there were diminished levels of TNF-α in ascites fluid versus baseline plasma levels (p = 0.001). Discussion. We hypothesize that the ascites fluid influences the behavior and dissemination of the tumor. Deregulation between oxidants, antioxidants, and the proinflammatory cytokines was found to vary among platinum-sensitive, platinum-resistant, and platinum-refractory patients. PMID:28848618

Platinum Publications, June 1–June 30, 2016 | Poster

Cancer.gov

Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from among the most recently published Platinum Publications.

Platinum Publications, September 30–October 27, 2016 | Poster

Cancer.gov

Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from among the most recently published Platinum Publications.

Platinum Publications, March 27 – April 30, 2015 | Poster

Cancer.gov

Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from among the most recently published Platinum Publications.

Platinum Publications, September 26 – October 29, 2014 | Poster

Cancer.gov

Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from among the most recently published Platinum Publications.

Platinum Publications, July 31–September 30, 2015 | Poster

Cancer.gov

Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from among the most recently published Platinum Publications.

Platinum Publications, July 29–September 29, 2016 | Poster

Cancer.gov

Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from among the most recently published Platinum Publications.

Platinum Publications, October 28–November 30, 2016 | Poster

Cancer.gov

Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from among the most recently published Platinum Publications.

Platinum Publications, July 1–July 28, 2016 | Poster

Cancer.gov

Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from among the most recently published Platinum Publications.

Platinum Publications, January 1–March 31, 2016 | Poster

Cancer.gov

Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from among the most recently published Platinum Publications.

Platinum Publications, June 26–July 30, 2015 | Poster

Cancer.gov

Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from among the most recently published Platinum Publications.

Platinum Publications, May 1 – June 25, 2015 | Poster

Cancer.gov

Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from among the most recently published Platinum Publications.

Investigation of a combined platinum and electron lifetime control treatment for silicon

NASA Astrophysics Data System (ADS)

Jia, Yunpeng; Cui, Zhihang; Yang, Fei; Zhao, Bao; Zou, Shikai; Liang, Yongsheng

2017-02-01

In silicon, the effect of Combined Lifetime Treatment (CLT) involving platinum diffusion and subsequent electron irradiation is different from the separate treatments of platinum diffusion and electron irradiation, even the treatment of electron irradiation followed by platinum diffusion. In this paper, we investigated the experimental behavior of different kinds of lifetime treated samples. We found that the reverse leakage current (Irr) increases with the increasing platinum diffusion temperature or electron irradiation dose in the separate treatments. Conversely, Irr of the CLT samples decreased with rising platinum diffusion temperature at the same dose of subsequent electron irradiation. By deep-level transient spectroscopy (DLTS), a new energy level E7 (Ec -0.376 eV) was found in our CLT samples. The new level E7 suppresses the dominance of the deeper level E8 (Ec -0.476 eV), which is caused by electron irradiation directly and results in Irr's increase. The formation of the level E7 comes from the complex defect-combined effect between platinum atoms and silicon vacancies, and it affects device's characteristics finally. These research will be helpful to the development of platinum-diffused devices used in intense electron irradiation environments.

Selective hydrogenation of 1,3-butadiene on platinum–copper alloys at the single-atom limit

DOE PAGES

Lucci, Felicia R.; Liu, Jilei; Marcinkowski, Matthew D.; ...

2015-10-09

Platinum is ubiquitous in the production sectors of chemicals and fuels; however, its scarcity in nature and high price will limit future proliferation of platinum-catalysed reactions. One definite approach to conserve platinum involves understanding the smallest number of platinum atoms needed to catalyse a reaction, then designing catalysts with the minimal platinum ensembles. Here we design and test a new generation of platinum–copper nanoparticle catalysts for the selective hydrogenation of 1,3-butadiene,, an industrially important reaction. Isolated platinum atom geometries enable hydrogen activation and spillover but are incapable of C–C bond scission that leads to loss of selectivity and catalyst deactivation.more » γ-Alumina-supported single-atom alloy nanoparticle catalysts with <1 platinum atom per 100 copper atoms are found to exhibit high activity and selectivity for butadiene hydrogenation to butenes under mild conditions, demonstrating transferability from the model study to the catalytic reaction under practical conditions.« less

High performance platinum single atom electrocatalyst for oxygen reduction reaction

NASA Astrophysics Data System (ADS)

Liu, Jing; Jiao, Menggai; Lu, Lanlu; Barkholtz, Heather M.; Li, Yuping; Wang, Ying; Jiang, Luhua; Wu, Zhijian; Liu, Di-Jia; Zhuang, Lin; Ma, Chao; Zeng, Jie; Zhang, Bingsen; Su, Dangsheng; Song, Ping; Xing, Wei; Xu, Weilin; Wang, Ying; Jiang, Zheng; Sun, Gongquan

2017-07-01

For the large-scale sustainable implementation of polymer electrolyte membrane fuel cells in vehicles, high-performance electrocatalysts with low platinum consumption are desirable for use as cathode material during the oxygen reduction reaction in fuel cells. Here we report a carbon black-supported cost-effective, efficient and durable platinum single-atom electrocatalyst with carbon monoxide/methanol tolerance for the cathodic oxygen reduction reaction. The acidic single-cell with such a catalyst as cathode delivers high performance, with power density up to 680 mW cm-2 at 80 °C with a low platinum loading of 0.09 mgPt cm-2, corresponding to a platinum utilization of 0.13 gPt kW-1 in the fuel cell. Good fuel cell durability is also observed. Theoretical calculations reveal that the main effective sites on such platinum single-atom electrocatalysts are single-pyridinic-nitrogen-atom-anchored single-platinum-atom centres, which are tolerant to carbon monoxide/methanol, but highly active for the oxygen reduction reaction.

Flow Injection Analysis with Electrochemical Detection for Rapid Identification of Platinum-Based Cytostatics and Platinum Chlorides in Water

PubMed Central

Kominkova, Marketa; Heger, Zbynek; Zitka, Ondrej; Kynicky, Jindrich; Pohanka, Miroslav; Beklova, Miroslava; Adam, Vojtech; Kizek, Rene

2014-01-01

Platinum-based cytostatics, such as cisplatin, carboplatin or oxaliplatin are widely used agents in the treatment of various types of tumors. Large amounts of these drugs are excreted through the urine of patients into wastewaters in unmetabolised forms. This phenomenon leads to increased amounts of platinum ions in the water environment. The impacts of these pollutants on the water ecosystem are not sufficiently investigated as well as their content in water sources. In order to facilitate the detection of various types of platinum, we have developed a new, rapid, screening flow injection analysis method with electrochemical detection (FIA-ED). Our method, based on monitoring of the changes in electrochemical behavior of analytes, maintained by various pH buffers (Britton-Robinson and phosphate buffer) and potential changes (1,000, 1,100 and 1,200 mV) offers rapid and cheap selective determination of platinum-based cytostatics and platinum chlorides, which can also be present as contaminants in water environments. PMID:24499878

Stable platinum nanoclusters on genomic DNA–graphene oxide with a high oxygen reduction reaction activity

PubMed Central

Tiwari, Jitendra N.; Nath, Krishna; Kumar, Susheel; Tiwari, Rajanish N.; Kemp, K. Christian; Le, Nhien H.; Youn, Duck Hyun; Lee, Jae Sung; Kim, Kwang S.

2013-01-01

Nanosize platinum clusters with small diameters of 2–4 nm are known to be excellent catalysts for the oxygen reduction reaction. The inherent catalytic activity of smaller platinum clusters has not yet been reported due to a lack of preparation methods to control their size (<2 nm). Here we report the synthesis of platinum clusters (diameter ≤1.4 nm) deposited on genomic double-stranded DNA–graphene oxide composites, and their high-performance electrocatalysis of the oxygen reduction reaction. The electrochemical behaviour, characterized by oxygen reduction reaction onset potential, half-wave potential, specific activity, mass activity, accelerated durability test (10,000 cycles) and cyclic voltammetry stability (10,000 cycles) is attributed to the strong interaction between the nanosize platinum clusters and the DNA–graphene oxide composite, which induces modulation in the electronic structure of the platinum clusters. Furthermore, we show that the platinum cluster/DNA–graphene oxide composite possesses notable environmental durability and stability, vital for high-performance fuel cells and batteries. PMID:23900456

Amorphous nickel boride membrane on a platinum-nickel alloy surface for enhanced oxygen reduction reaction.

PubMed

He, Daping; Zhang, Libo; He, Dongsheng; Zhou, Gang; Lin, Yue; Deng, Zhaoxiang; Hong, Xun; Wu, Yuen; Chen, Chen; Li, Yadong

2016-08-09

The low activity of the oxygen reduction reaction in polymer electrolyte membrane fuel cells is a major barrier for electrocatalysis, and hence needs to be optimized. Tuning the surface electronic structure of platinum-based bimetallic alloys, a promising oxygen reduction reaction catalyst, plays a key role in controlling its interaction with reactants, and thus affects the efficiency. Here we report that a dealloying process can be utilized to experimentally fabricate the interface between dealloyed platinum-nickel alloy and amorphous nickel boride membrane. The coating membrane works as an electron acceptor to tune the surface electronic structure of the platinum-nickel catalyst, and this composite catalyst composed of crystalline platinum-nickel covered by amorphous nickel boride achieves a 27-times enhancement in mass activity relative to commercial platinum/carbon at 0.9 V for the oxygen reduction reaction performance. Moreover, this interactional effect between a crystalline surface and amorphous membrane can be readily generalized to facilitate the 3-times higher catalytic activity of commercial platinum/carbon.

High performance platinum single atom electrocatalyst for oxygen reduction reaction

PubMed Central

Liu, Jing; Jiao, Menggai; Lu, Lanlu; Barkholtz, Heather M.; Li, Yuping; Wang, Ying; Jiang, Luhua; Wu, Zhijian; Liu, Di-jia; Zhuang, Lin; Ma, Chao; Zeng, Jie; Zhang, Bingsen; Su, Dangsheng; Song, Ping; Xing, Wei; Xu, Weilin; Wang, Ying; Jiang, Zheng; Sun, Gongquan

2017-01-01

For the large-scale sustainable implementation of polymer electrolyte membrane fuel cells in vehicles, high-performance electrocatalysts with low platinum consumption are desirable for use as cathode material during the oxygen reduction reaction in fuel cells. Here we report a carbon black-supported cost-effective, efficient and durable platinum single-atom electrocatalyst with carbon monoxide/methanol tolerance for the cathodic oxygen reduction reaction. The acidic single-cell with such a catalyst as cathode delivers high performance, with power density up to 680 mW cm−2 at 80 °C with a low platinum loading of 0.09 mgPt cm−2, corresponding to a platinum utilization of 0.13 gPt kW−1 in the fuel cell. Good fuel cell durability is also observed. Theoretical calculations reveal that the main effective sites on such platinum single-atom electrocatalysts are single-pyridinic-nitrogen-atom-anchored single-platinum-atom centres, which are tolerant to carbon monoxide/methanol, but highly active for the oxygen reduction reaction. PMID:28737170

Chemistry and biological activity of platinum amidine complexes.

PubMed

Michelin, Rino A; Sgarbossa, Paolo; Sbovata, Silvia Mazzega; Gandin, Valentina; Marzano, Cristina; Bertani, Roberta

2011-07-04

Platinum amidine complexes represent a new class of potential antitumor drugs that contain the imino moiety HN=C(sp(2)) bonded to the platinum center. They can be related to the iminoether derivatives, which were recently shown to be the first Pt(II) compounds with a trans configuration endowed with anticancer activity. The chemical and biological properties of platinum amidine complexes, and more generally of platinum imino derivatives, can be rationally modified through suitable synthetic procedures with the aim of improving their cytotoxicity and antitumor activity. The addition of protic nucleophiles to nitriles coordinated to platinum in various oxidation states can offer a wide variety of complexes with chemical, structural, and physical properties specifically tuned for a more efficacious biological response. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Research on rechargeable oxygen electrodes

NASA Technical Reports Server (NTRS)

Giner, J.; Malachesky, P. A.; Holleck, G.

1971-01-01

Studies were carried out on a number of factors which may influence the behavior of the platinum electrocatalyst of oxygen electrodes for use in rechargeable metal-oxygen batteries or hydrogen-oxygen fuel cells. The effects of pretreatments for various potentials and added ionic species, which could be present in such systems, were studied with reguard to: (1) the state of surface oxidation, (2) platinum dissolution, (3) the kinetics of oxygen evolution and reduction (including the role of hydrogen peroxide), and (4) changes in porous electrode structure. These studies were carried out on smooth platinum, platinized platinum, and Teflon-bonded platinum black electrodes in carefully purified electrolyte solutions. The main factors which appear to affect rechargeable oxygen electrode performance and life are: (1) the buildup of a refractory anodic layer on extended cycling, and (2) the dissolution of platinum.

Photoactive platinum diimine complexes showing induced cancer cell death by apoptosis.

PubMed

Zhang, Zhigang; Dai, Ruihui

2017-02-01

Photoinduced cytotoxicity mediated by a triphenylenamine-modified platinum diimine complex in human breast adenocarcinoma cells has been studied by cell viability assay. The triphenylenamine-modified platinum diimine complex showed more potent cytotoxicity in light than its carboxylate-modified analogue. To gain insights into the mechanism of photodynamic activity of this class of platinum diimine complexes, flow cytometric analyses were performed. The results suggest that upon irradiation the two platinum diimine complexes studied could induce cell cycle arrest in G 2 /M or S phase, and both of them could induce cancer cell death by apoptosis.

Shaped platinum nanoparticles directly synthesized inside mesoporous silica supports

NASA Astrophysics Data System (ADS)

Kim, Jiwhan; Bae, Youn-Sang; Lee, Hyunjoo

2014-10-01

It is difficult to deposit shape-controlled nanoparticles into a mesoporous framework while preserving the shape. For shaped platinum nanoparticles, which are typically 5-10 nm in size, capillary inclusion by sonication or the formation of a mesoporous framework around the shaped platinum nanoparticles has been attempted, but the nanoparticles aggregated or their shapes were degraded easily. In this work, we directly nucleated platinum on the surface inside a mesoporous silica support and controlled the overgrowth step, producing cubic shaped nanoparticles. Mercaptopropyltrimethoxysilane was used as an anchoring agent causing nucleation at the silica surface, and it also helped to shape the nanoparticles. Platinum nanocubes, which were synthesized with polymeric capping agents separately, were deposited inside the mesoporous silica by sonication, but most of the nanoparticles were clogged at the entrance to the pores, and the surface of the platinum had very few sites that were catalytically active, as evidenced by the small H2 uptake. Unshaped platinum nanoparticles, which were prepared by conventional wet impregnation, showed a similar amount of H2 uptake as the in situ shaped platinum cubes, but the selectivity for pyrrole hydrogenation was poorer towards the production of pyrrolidine. The mesoporosity and the residual thiol groups on the surface of the in situ shaped Pt nanocubes might cause a high selectivity for pyrrolidine.It is difficult to deposit shape-controlled nanoparticles into a mesoporous framework while preserving the shape. For shaped platinum nanoparticles, which are typically 5-10 nm in size, capillary inclusion by sonication or the formation of a mesoporous framework around the shaped platinum nanoparticles has been attempted, but the nanoparticles aggregated or their shapes were degraded easily. In this work, we directly nucleated platinum on the surface inside a mesoporous silica support and controlled the overgrowth step, producing cubic shaped nanoparticles. Mercaptopropyltrimethoxysilane was used as an anchoring agent causing nucleation at the silica surface, and it also helped to shape the nanoparticles. Platinum nanocubes, which were synthesized with polymeric capping agents separately, were deposited inside the mesoporous silica by sonication, but most of the nanoparticles were clogged at the entrance to the pores, and the surface of the platinum had very few sites that were catalytically active, as evidenced by the small H2 uptake. Unshaped platinum nanoparticles, which were prepared by conventional wet impregnation, showed a similar amount of H2 uptake as the in situ shaped platinum cubes, but the selectivity for pyrrole hydrogenation was poorer towards the production of pyrrolidine. The mesoporosity and the residual thiol groups on the surface of the in situ shaped Pt nanocubes might cause a high selectivity for pyrrolidine. Electronic supplementary information (ESI) available: Fig. S1-S9. See DOI: 10.1039/c4nr03951c

Nanoscale investigation of platinum nanoparticles on strontium titanium oxide grown via physical vapor deposition and atomic layer deposition

NASA Astrophysics Data System (ADS)

Christensen, Steven Thomas

This dissertation examines growth of platinum nanoparticles from vapor deposition on SrTiO3 using a characterization approach that combines imaging techniques and X-ray methods. The primary suite of characterization probes includes atomic force microscopy (AFM), grazing-incidence small-angle X-ray scattering (GISAXS), X-ray fluorescence (XRF), scanning electron microscopy (SEM), and X-ray absorption spectroscopy (XAS). The vapor deposition techniques include physical vapor deposition (PVD) by evaporation and atomic layer deposition (ALD). For the PVD platinum study, AFM/XRF showed ˜10 nm nanoparticles separated by an average of 100 nm. The combination of AFM, GISAXS, and XRF indicated that the nanoparticles observed with AFM were actually comprised of closely spaced, smaller nanoparticles. These conclusions were supported by high-resolution SEM. The unusual behavior of platinum nanoparticles to aggregate without coalescence or sintering was observed previously by other researchers using transmissision electron microscopy (TEM). Platinum nanoparticle growth was also investigated on SrTiO3 (001) single crystals using ALD to nucleate nanoparticles that subsequently grew and coalesced into granular films as the ALD progresses. The expected growth rate for the early stages of ALD showed a two-fold increase which was attributed to the platinum deposition occurring faster on the bare substrate. Once the nanoparticles had coalesced into a film, steady state ALD growth proceeded. The formation of nanoparticles was attributed to the atomic diffusion of platinum atoms on the surface in addition to direct growth from the ALD precursor gases. The platinum ALD nanoparticles were also studied on SrTiO3 nanocube powders. The SrTiO3 nanocubes average 60 nm on a side and the cube faces have a {001} orientation. The ALD proceeded in a similar fashion as on the single crystal substrates where the deposition rate was twice as fast as the steady state growth rate. The Pt nanoparticle size increased linearly starting at ˜0.7 nm for 1 ALD cycle to ˜3 nm for 5 ALD cycles. The platinum chemical state was also investigated using X-ray absorption spectroscopy. Platinum nanoparticles ˜1 nm or smaller tended to be oxidized. For larger nanoparticles, the platinum state systematically approached that of bulk platinum metal as the size (number of ALD cycles) increased. The platinum loading was exceptionally low, ˜10 -3 mg cm-2.

Repeating platinum/bevacizumab in recurrent or progressive cervical cancer yields marginal survival benefits.

PubMed

Zamorano, Abigail S; Wan, Leping; Powell, Matthew A; Massad, L Stewart

2017-11-01

Our objective was to assess overall survival of cervical cancer patients following prior platinum/bevacizumab chemotherapy, comparing retreatment with platinum/bevacizumab with alternative therapies. A retrospective analysis was performed of women who received platinum/bevacizumab (PB) chemotherapy for cervical cancer at Washington University between July 1, 2005 and December 31, 2015. Wilcoxon rank-sum exact test and Fisher's exact test were used to compare the treatment groups, and Kaplan Meier curves were generated. Cox regression analyses were performed, with treatment free interval and prior therapy response included as covariates. Of 84 patients who received PB chemotherapy, 59 (70%) received no second line chemotherapy, as they did not recur, progressed without further chemotherapy, were lost to follow up, or expired. Of the remaining 25 patients, 9 were retreated with the combination of platinum/bevacizumab (PB), 6 were retreated with a platinum regimen without bevacizumab (P), and 10 were retreated with neither (not-P). The only long-term survivor was in the not-P group and was treated with an immunotherapy agent. Median overall survival of all patients was 7.1 months. There was a marginal difference in survival between women in the PB and not-PB groups (11.8 versus 5.7 months; HR 3.02, 95% CI, 0.98-9.28). There was no difference in survival based on platinum interval (HR 0.81; 95% CI, 0.27-2.45). Outcomes are grim for women retreated after platinum/bevacizumab therapy and are only marginally improved by retreatment with a platinum/bevacizumab regimen. Rather than additional PB therapy, women with cervical cancer who recur after platinum/bevacizumab should consider supportive care or clinical trials.

Neoadjuvant Chemotherapy Followed by Interval Debulking Surgery and the Risk of Platinum Resistance in Epithelial Ovarian Cancer.

PubMed

da Costa, Alexandre A B A; Valadares, Camila V; Baiocchi, Glauco; Mantoan, Henrique; Saito, Augusto; Sanches, Solange; Guimarães, Andréia P; Achatz, Maria Isabel W

2015-12-01

Interval debulking surgery (IDS) is an option for treating patients with advanced ovarian carcinoma. Two randomized trials have shown similar survival rates for primary debulking surgery (PDS) and IDS. One of the concerns with IDS is the potentially higher risk of inducing platinum resistance when treating patients with greater disease volume. A retrospective review of data on 237 patients with stage IIIC and IV ovarian carcinoma who were treated at a single institution from 2000 to 2013. We analyzed the association of IDS with time to first platinum resistant relapse (TTPR); platinum-resistant disease at first relapse, defined as a platinum-free interval (PFI) after first-line chemotherapy of <6 months; and overall response rate (ORR) to chemotherapy at first platinum-sensitive relapse. The TTPR was 60 months, and the median TTPR was longer for the PDS (80.8 months) versus IDS group (39.3 months; p = 0.012) and for patients with residual disease (RD) ≤10 mm (80.8 months) compared with those with RD >10 mm (26.1 months; p < 0.001). In the multivariate analysis, IDS [hazard ratio (HR) 1.92; p = 0.009] and RD >10 mm (HR 1.65; p < 0.001) retained an increased risk of developing platinum-resistant disease. IDS was not associated with a greater risk of PFI <6 months at first relapse, and the ORR to platinum-based chemotherapy at first platinum-sensitive relapse was 87.2 % for patients who were treated with PDS compared with 68.0 % for those who underwent IDS (p = 0.051). IDS correlates with a higher risk of the development of platinum resistance.

Treatment patterns and cost-effectiveness of first line treatment of advanced non-squamous non-small cell lung cancer in Medicare patients.

PubMed

Gilden, Daniel M; Kubisiak, Joanna M; Pohl, Gerhardt M; Ball, Daniel E; Gilden, David E; John, William J; Wetmore, Stewart; Winfree, Katherine B

2017-02-01

To assess the cost-effectiveness of first-line pemetrexed/platinum and other commonly administered regimens in a representative US elderly population with advanced non-squamous non-small cell lung cancer (NSCLC). This study utilized the Surveillance Epidemiology and End Results (SEER) cancer registry linked to Medicare claims records. The study population included all SEER-Medicare patients diagnosed in 2008-2009 with advanced non-squamous NSCLC (stages IIIB-IV) as their only primary cancer and who started chemotherapy within 90 days of diagnosis. The study evaluated the four most commonly observed first-line regimens: paclitaxel/carboplatin, platinum monotherapy, pemetrexed/platinum, and paclitaxel/carboplatin/bevacizumab. Overall survival and total healthcare cost comparisons as well as incremental cost-effectiveness ratios (ICERs) were calculated for pemetrexed/platinum vs each of the other three. Unstratified analyses and analyses stratified by initial disease stage were conducted. The final study population consisted of 2,461 patients. Greater administrative censorship of pemetrexed recipients at the end of the study period disproportionately reduced the observed mean survival for pemetrexed/platinum recipients. The disease stage-stratified ICER analysis found that the pemetrexed/platinum incurred total Medicare costs of $536,424 and $283,560 per observed additional year of life relative to platinum monotherapy and paclitaxel/carboplatin, respectively. The pemetrexed/platinum vs triplet comparator analysis indicated that pemetrexed/platinum was associated with considerably lower total Medicare costs, with no appreciable survival difference. Limitations included differential censorship of the study regimen recipients and differential administration of radiotherapy. Pemetrexed/platinum yielded either improved survival at increased cost or similar survival at reduced cost relative to comparator regimens in the treatment of advanced non-squamous NSCLC. Limitations in the study methodology suggest that the observed pemetrexed survival benefit was likely conservative.

Growth and characterization of Pt-Si droplets for silicon nanowires synthesis

NASA Astrophysics Data System (ADS)

Khumalo, Z. M.; Topić, M.; Mtshali, C. B.; Blumenthal, M.

2018-02-01

The formation of platinum silicide phases as a function of the annealing temperature was investigated using in-situ real-time Rutherford backscattering spectrometry. The in-situ real-time RBS revealed the reaction of platinum and silicon to start at about 220 °C to form platinum silicide phases, Pt2Si and PtSi in sequence. Scanning electron microscope revealed the morphological change in the platinum layer (formation of droplets) at 800 °C. The particle induced X-ray emission analysis showed the variation of platinum intensity, in the droplets areas, between 1600 and 2000 counts. The surrounding areas are left almost uncovered due to platinum film dewetting. In-plane as well as out-of-plane silicon nanowires were observed to form at 800 °C and 1000 °C using pulsed laser ablation and thermal annealing techniques, respectively.

Platinum adlayered ruthenium nanoparticles, method for preparing, and uses thereof

DOEpatents

Tong, YuYe; Du, Bingchen

2015-08-11

A superior, industrially scalable one-pot ethylene glycol-based wet chemistry method to prepare platinum-adlayered ruthenium nanoparticles has been developed that offers an exquisite control of the platinum packing density of the adlayers and effectively prevents sintering of the nanoparticles during the deposition process. The wet chemistry based method for the controlled deposition of submonolayer platinum is advantageous in terms of processing and maximizing the use of platinum and can, in principle, be scaled up straightforwardly to an industrial level. The reactivity of the Pt(31)-Ru sample was about 150% higher than that of the industrial benchmark PtRu (1:1) alloy sample but with 3.5 times less platinum loading. Using the Pt(31)-Ru nanoparticles would lower the electrode material cost compared to using the industrial benchmark alloy nanoparticles for direct methanol fuel cell applications.

Determination of platinum in waste platinum-loaded carbon catalyst samples using microwave-assisted sample digestion and ICP-OES

NASA Astrophysics Data System (ADS)

Ma, Yinbiao; Wei, Xiaojuan

2017-04-01

A novel method for the determination of platinum in waste platinum-loaded carbon catalyst samples was established by inductively coupled plasma optical emission spectrometry after samples digested by microwave oven with aqua regia. Such experiment conditions were investigated as the influence of sample digestion methods, digestion time, digestion temperature and interfering ions on the determination. Under the optimized conditions, the linear range of calibration graph for Pt was 0 ˜ 200.00 mg L-1, and the recovery was 95.67% ˜ 104.29%. The relative standard deviation (RSDs) for Pt was 1.78 %. The proposed method was applied to determine the same samples with atomic absorption spectrometry with the results consistently, which is suitable for the determination of platinum in waste platinum-loaded carbon catalyst samples.

Influence of dose on particle size and optical properties of colloidal platinum nanoparticles.

PubMed

Gharibshahi, Elham; Saion, Elias

2012-11-12

Attempts to produce colloidal platinum nanoparticles by using steady absorption spectra with various chemical-based reduction methods often resulted in the fast disappearance of the absorption maxima leaving reduced platinum nanoparticles with little information on their optical properties. We synthesized colloidal platinum nanoparticles in an aqueous solution of polyvinyl pyrrolidone by gamma radiolytic reduction method, which produced steady absorption spectra of fully reduced and highly pure platinum nanoparticles free from by-product impurities or reducing agent contamination. The average particle size was found to be in the range of 3.4–5.3 nm and decreased with increasing dose due to the domination of nucleation over ion association in the formation of metal nanoparticles by the gamma radiolytic reduction method. The platinum nanoparticles exhibit optical absorption spectra with two absorption peaks centered at about 216 and 264 nm and the peaks blue shifted to lower wavelengths with decreasing particle size. The absorption spectra of platinum nanoparticles were also calculated using quantum mechanical treatment and coincidently a good agreement was obtained between the calculated and measured absorption peaks at various particle sizes. This indicates that the 216 and 264-nm absorption peaks of platinum nanoparticles conceivably originated from the intra-band transitions of conduction electrons of (n = 5, l = 2) and (n = 6, l = 0) energy states respectively to higher energy states. The absorption energies, i.e., conduction band energies of platinum nanoparticles derived from the absorption peaks increased with increasing dose and decreased with increasing particle size.

Influence of Dose on Particle Size and Optical Properties of Colloidal Platinum Nanoparticles

PubMed Central

Gharibshahi, Elham; Saion, Elias

2012-01-01

Attempts to produce colloidal platinum nanoparticles by using steady absorption spectra with various chemical-based reduction methods often resulted in the fast disappearance of the absorption maxima leaving reduced platinum nanoparticles with little information on their optical properties. We synthesized colloidal platinum nanoparticles in an aqueous solution of polyvinyl pyrrolidone by gamma radiolytic reduction method, which produced steady absorption spectra of fully reduced and highly pure platinum nanoparticles free from by-product impurities or reducing agent contamination. The average particle size was found to be in the range of 3.4–5.3 nm and decreased with increasing dose due to the domination of nucleation over ion association in the formation of metal nanoparticles by the gamma radiolytic reduction method. The platinum nanoparticles exhibit optical absorption spectra with two absorption peaks centered at about 216 and 264 nm and the peaks blue shifted to lower wavelengths with decreasing particle size. The absorption spectra of platinum nanoparticles were also calculated using quantum mechanical treatment and coincidently a good agreement was obtained between the calculated and measured absorption peaks at various particle sizes. This indicates that the 216 and 264-nm absorption peaks of platinum nanoparticles conceivably originated from the intra-band transitions of conduction electrons of (n = 5, l = 2) and (n = 6, l = 0) energy states respectively to higher energy states. The absorption energies, i.e., conduction band energies of platinum nanoparticles derived from the absorption peaks increased with increasing dose and decreased with increasing particle size. PMID:23203091

Influence of platinum nanoparticles orally administered to rats evaluated by systemic gene expression profiling.

PubMed

Katao, Kazuo; Honma, Reiko; Kato, Satoko; Watanabe, Shinya; Imai, Jun-ichi

2011-01-01

Platinum is recognized as a harmless metal and is widely used in many industrial products. Recent studies have proposed that platinum in the form of nanoparticles has antioxidant properties, suggesting potential uses for platinum nanoparticles as additives in foods and cosmetics, with direct exposure consequences for humans. However, the influence of platinum nanoparticles on humans has not been sufficiently evaluated, thus far. Therefore, to investigate the influence of platinum nanoparticles on a living body, we comprehensively examined the expression profiles of genes obtained from 25 organs and tissues of rats after oral administration of platinum nanoparticles by gavage. Comparative analysis revealed that the expression levels of 18 genes were altered in 12 organs and tissues after the administration (approximately 0.17% of all the genes examined). Of the tissues examined, those of the glandular stomach, which were most directly exposed to the orally administered platinum nanoparticles, showed altered expression levels of genes associated with inflammation. In subcutaneous adipose tissue, the expression levels of genes whose products exhibited ATPase activity were altered. Real-time reverse transcription polymerase chain reaction (real-time RT-PCR) analysis confirmed the alteration in the expression levels of these genes in these 2 different tissues. Our findings indicate that orally administered platinum nanoparticles do not have a marked effect on systemic gene expression levels, except on a small number of genes expressed in rat tissues, including peripheral tissues indirectly exposed to the orally administered nanoparticles.

Coulometric Study of Rates of Oxalic Acid Adsorption at a Polycrystalline Platinum Electrode

DTIC Science & Technology

2012-09-01

Coulometric Study of Rates of Oxalic Acid Adsorption at a Polycrystalline Platinum Electrode by Sol Gilman ARL-TR-6165 September 2012...6165 September 2012 Coulometric Study of Rates of Oxalic Acid Adsorption at a Polycrystalline Platinum Electrode Sol Gilman Sensors and...3. DATES COVERED (From - To) 4. TITLE AND SUBTITLE Coulometric Study of Rates of Oxalic Acid Adsorption at a Polycrystalline Platinum Electrode

Determination of platinum in mineral raw materials by switching chronoamperometry

NASA Astrophysics Data System (ADS)

Pakrieva, E.; Oskina, Y.; Ustinova, E.

2014-08-01

The technique of platinum (IV) determination in mineral raw materials with the application of switching chronoamperometry has been offered. The graphite electrode impregnated with polyethylene was used as the working electrode. The hydrolytic precipitation method with 3% NaOH solution has been developed to separate platinum from the sample matrix. The use of switching chronoamperometry applied to the assessment of the platinum content in geological objects has been demonstrated.

The impact of whole human blood on the kinetic inertness of platinum(iv) prodrugs - an HPLC-ICP-MS study.

PubMed

Theiner, Sarah; Grabarics, Márkó; Galvez, Luis; Varbanov, Hristo P; Sommerfeld, Nadine S; Galanski, Markus; Keppler, Bernhard K; Koellensperger, Gunda

2018-04-17

The potential advantage of platinum(iv) complexes as alternatives to classical platinum(ii)-based drugs relies on their kinetic stability in the body before reaching the tumor site and on their activation by reduction inside cancer cells. In this study, an analytical workflow has been developed to investigate the reductive biotransformation and kinetic inertness of platinum(iv) prodrugs comprising different ligand coordination spheres (respectively, lipophilicity and redox behavior) in whole human blood. The distribution of platinum(iv) complexes in blood pellets and plasma was determined by inductively coupled plasma-mass spectrometry (ICP-MS) after microwave digestion. An analytical approach based on reversed-phase (RP)-ICP-MS was used to monitor the parent compound and the formation of metabolites using two different extraction procedures. The ligand coordination sphere of the platinum(iv) complexes had a significant impact on their accumulation in red blood cells and on their degree of kinetic inertness in whole human blood. The most lipophilic platinum(iv) compound featuring equatorial chlorido ligands showed a pronounced penetration into blood cells and a rapid reductive biotransformation. In contrast, the more hydrophilic platinum(iv) complexes with a carboplatin- and oxaliplatin-core exerted kinetic inertness on a pharmacologically relevant time scale with notable amounts of the compound accumulated in the plasma fraction.

Electron Beam Welder Used to Braze Sapphire to Platinum

NASA Technical Reports Server (NTRS)

Forsgren, Roger C.; Vannuyen, Thomas

1998-01-01

A new use for electron beam brazing was recently developed by NASA Lewis Research Center's Manufacturing Engineering Division. This work was done to fabricate a fiberoptic probe (developed by Sentec Corporation) that could measure high temperatures less than 600 deg C of vibrating machinery, such as in jet engine combustion research. Under normal circumstances, a sapphire fiber would be attached to platinum by a ceramic epoxy. However, no epoxies can adhere ceramic fibers to platinum under such high temperatures and vibration. Also, since sapphire and platinum have different thermal properties, the epoxy bond is subjected to creep over time. Therefore, a new method had to be developed that would permanently and reliably attach a sapphire fiber to platinum. Brazing a sapphire fiber to a platinum shell. The fiber-optic probe assembly consists of a 0.015-in.-diameter sapphire fiber attached to a 0.25-in.-long, 0.059-in.-diameter platinum shell. Because of the small size of this assembly, electron beam brazing was chosen instead of conventional vacuum brazing. The advantage of the electron beam is that it can generate a localized heat source in a vacuum. Gold reactive braze was used to join the sapphire fiber and the platinum. Consequently, the sapphire fiber was not affected by the total heat needed to braze the components together.

Monitoring of platinum surface contamination in seven Dutch hospital pharmacies using inductively coupled plasma mass spectrometry

PubMed Central

Huitema, A. D. R.; Bakker, E. N.; Douma, J. W.; Schimmel, K. J. M.; van Weringh, G.; de Wolf, P. J.; Schellens, J. H. M.; Beijnen, J. H.

2007-01-01

Objective: To develop, validate, and apply a method for the determination of platinum contamination, originating from cisplatinum, oxaliplatinum, and carboplatinum. Methods: Inductively coupled plasma mass spectrometry (ICP-MS) was used to determine platinum in wipe samples. The sampling procedure and the analytical conditions were optimised and the assay was validated. The method was applied to measure surface contamination in seven Dutch hospital pharmacies. Results: The developed method allowed reproducible quantification of 0.50 ng l−1 platinum (5 pg/wipe sample). Recoveries for stainless steel and linoleum surfaces ranged between 50.4 and 81.4% for the different platinum compounds tested. Platinum contamination was reported in 88% of the wipe samples. Although a substantial variation in surface contamination of the pharmacies was noticed, in most pharmacies, the laminar-airflow (LAF) hoods, the floor in front of the LAF hoods, door handles, and handles of service hatches showed positive results. This demonstrates that contamination is spread throughout the preparation rooms. Conclusion: We developed and validated an ultra sensitive and reliable ICP-MS method for the determination of platinum in surface samples. Surface contamination with platinum was observed in all hospital pharmacies sampled. The interpretation of these results is, however, complicated. PMID:17377802

Recovery of Platinum from Dilute Chloride Media Using Biosorbents

NASA Astrophysics Data System (ADS)

Zeytuncu, B.; Morcali, M. H.; Yucel, O.

Pistachio nut shells and Rice husk, a biomass residue, were investigated as adsorbents for the platinum uptake from synthetically prepared dilute chloroplatinic acid solutions. The effects of the different uptake parameters on platinum uptake (%) were studied in detail on a batch sorption. Before the pistachio nut shell material was activated, platinum uptake (%) was poor compared with rice husk. However, after the pistachio nut shell material was activated at 1000°C under an argon atmosphere, the platinum uptake (%) increased two-fold. The pistachio nut shell (inactivated and activated) and rice husk were characterized by Attenuated Total Reflection-Fourier transform infrared spectroscopy (ATR-FTIR).

Synthesis and characterization of potential iron–platinum drugs and supplements by laser liquid photolysis

PubMed Central

Nkosi, Steven S; Mwakikunga, Bonex W; Sideras-Haddad, Elias; Forbes, Andrew

2012-01-01

Highly crystalline nanospherical iron–platinum systems were produced by 248 nm laser irradiation of a liquid precursor at different laser fluences, ranging from 100–375 mJ/cm2. The influence of laser intensity on particle size, iron composition, and structure was systematically investigated. Different nanostructures of iron–platinum alloy and chemically disordered iron–platinum L10 phase were obtained without annealing. The prepared precursor solution underwent deep photolysis to polycrystalline iron–platinum nanoalloys through Fe(III) acetylacetonate and Pt(II) acetylacetonate. Fe(II) and Pt(I) acetylacetone decomposed into Fe0 and Pt0 nanoparticles. We found that the (001) diffraction peak shifted linearly to a lower angle, with the last peak shifting in opposition to the others. This caused the face-centered cubic L10 structure to change its composition according to laser fluence. The nanostructures were shown to contain iron and platinum only by energy-dispersive spectroscopy at several spots. The response of these iron–platinum nanoparticles to infrared depends on their stoichiometric composition, which is controlled by laser fluence. PMID:24198494

Concurrent cetuximab versus platinum-based chemoradiation for the definitive treatment of locoregionally advanced head and neck cancer.

PubMed

Tang, Chad; Chan, Cato; Jiang, Wen; Murphy, James D; von Eyben, Rie; Colevas, A Dimitrios; Pinto, Harlan; Lee-Enriquez, Nancy; Kong, Christina; Le, Quynh-Thu

2015-03-01

The purpose of this study was to present our experience utilizing cetuximab and platinum-based concurrent chemoradiotherapy for the definitive treatment of head and neck squamous cell carcinoma (HNSCC). Patients (n = 177) who received definitive concurrent chemoradiotherapy for HNSCC were stratified into 3 groups: receiving cetuximab monotherapy (n = 24), cetuximab and chemotherapy combination (n = 33), or platinum-based chemotherapy without cetuximab (n = 120). Primary endpoints were freedom from relapse, event-free survival, and overall survival (OS). Patients receiving cetuximab monotherapy were older with lower Karnofsky performance status (KPS) and higher Charlson comorbidity scores compared with those treated with combination cetuximab and chemotherapy or platinum-based concurrent chemoradiotherapy. Patients treated with platinum-based concurrent chemoradiotherapy exhibited significantly better freedom from relapse, event-free survival, and OS compared with those receiving cetuximab monotherapy or cetuximab and chemotherapy combination therapies (all p < .05). Differences between patients receiving cetuximab monotherapy and platinum-based concurrent chemoradiotherapy held on multivariate Cox regression. This study suggests that platinum-based concurrent chemoradiotherapy is superior to cetuximab-based monotherapy for the definitive treatment of HNSCC. © 2014 Wiley Periodicals, Inc.

High performance platinum single atom electrocatalyst for oxygen reduction reaction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Jing; Jiao, Menggai; Lu, Lanlu

For the large-scale sustainable implementation of polymer electrolyte membrane fuel cells in vehicles, high-performance electrocatalysts with low platinum consumption are desirable for use as cathode material during the oxygen reduction reaction in fuel cells. Here we report a carbon black-supported cost-effective, efficient and durable platinum single-atom electrocatalyst with carbon monoxide/methanol tolerance for the cathodic oxygen reduction reaction. The acidic single-cell with such a catalyst as cathode delivers high performance, with power density up to 680 mW cm –2 at 80 °C with a low platinum loading of 0.09 mgPt cm –2, corresponding to a platinum utilization of 0.13 gPt kWmore » –1 in the fuel cell. Good fuel cell durability is also observed. As a result, theoretical calculations reveal that the main effective sites on such platinum single-atom electrocatalysts are single-pyridinic-nitrogen-atom-anchored single-platinum-atom centres, which are tolerant to carbon monoxide/methanol, but highly active for the oxygen reduction reaction.« less

High performance platinum single atom electrocatalyst for oxygen reduction reaction

DOE PAGES

Liu, Jing; Jiao, Menggai; Lu, Lanlu; ...

2017-07-24

For the large-scale sustainable implementation of polymer electrolyte membrane fuel cells in vehicles, high-performance electrocatalysts with low platinum consumption are desirable for use as cathode material during the oxygen reduction reaction in fuel cells. Here we report a carbon black-supported cost-effective, efficient and durable platinum single-atom electrocatalyst with carbon monoxide/methanol tolerance for the cathodic oxygen reduction reaction. The acidic single-cell with such a catalyst as cathode delivers high performance, with power density up to 680 mW cm –2 at 80 °C with a low platinum loading of 0.09 mgPt cm –2, corresponding to a platinum utilization of 0.13 gPt kWmore » –1 in the fuel cell. Good fuel cell durability is also observed. As a result, theoretical calculations reveal that the main effective sites on such platinum single-atom electrocatalysts are single-pyridinic-nitrogen-atom-anchored single-platinum-atom centres, which are tolerant to carbon monoxide/methanol, but highly active for the oxygen reduction reaction.« less

Sulfur tolerant zeolite supported platinum catalysts for aromatics hydrogenation

DOT National Transportation Integrated Search

1997-04-01

An experimental study of sulfur tolerant zeolite platinum catalysts for aormatics hydrogenation. Platinum catalysts supported on Y-zeolite have been prepared and characterized in various ways, including the hydrogenation of toluene in a high pressure...

Cross-reactivity of Halogenated Platinum Salts

EPA Science Inventory

Halogenated platinum (Pt) salts are well-known respiratory sensitizers associated with the development of asthma. People may be exposed to a variety of platinum compounds in different contexts (e.g. occupationally, automobile exhaust). Published reports suggest that sensitizati...

Optimum Platinum Loading In Pt/SnO2 CO-Oxidizing Catalysts

NASA Technical Reports Server (NTRS)

Schryer, David R.; Upchurch, Billy T.; Davis, Patricia P.; Brown, Kenneth G.; Schryer, Jacqueline

1991-01-01

Platinum on tin oxide (Pt/SnO2) good catalyst for oxidation of carbon monoxide at or near room temperature. Catalytic activity peaks at about 17 weight percent Pt. Catalysts with platinum loadings as high as 46 percent fabricated by technique developed at Langley Research Center. Work conducted to determine optimum platinum loading for this type of catalyst. Major application is removal of unwanted CO and O2 in CO2 lasers.

Platinum particle size and support effects in NO(x) mediated carbon oxidation over platinum catalysts.

PubMed

Villani, Kenneth; Vermandel, Walter; Smets, Koen; Liang, Duoduo; van Tendeloo, Gustaaf; Martens, Johan A

2006-04-15

Platinum metal was dispersed on microporous, mesoporous, and nonporous support materials including the zeolites Na-Y, Ba-Y, Ferrierite, ZSM-22, ETS-10, and AIPO-11, alumina, and titania. The oxidation of carbon black loosely mixed with catalyst powder was monitored gravimetrically in a gas stream containing nitric oxide, oxygen, and water. The carbon oxidation activity of the catalysts was found to be uniquely related to the Pt dispersion and little influenced by support type. The optimum dispersion is around 3-4% corresponding to relatively large Pt particle sizes of 20-40 nm. The carbon oxidation activity reflects the NO oxidation activity of the platinum catalyst, which reaches an optimum in the 20-40 nm Pt particle size range. The lowest carbon oxidation temperatures were achieved with platinum loaded ZSM-22 and AIPO-11 zeolite crystallites bearing platinum of optimum dispersion on their external surfaces.

Our Expedition in Linear Neutral Platinum-Acetylide Complexes: The Preparation of Micro/nanostructure Materials, Complicated Topologies, and Dye-Sensitized Solar Cells.

PubMed

Xu, Lin; Yang, Hai-Bo

2016-06-01

During the past few decades, the construction of various kinds of platinum-acetylide complexes has attracted considerable attention, because of their wide applications in photovoltaic cells, non-linear optics, and bio-imaging materials. Among these platinum-acetylide complexes, the linear neutral platinum-acetylide complexes, due to their attractive properties, such as well-defined linear geometry, synthetic accessibility, and intriguing photoproperties, have emerged as a rising star in this field. In this personal account, we will discuss how we entered the field of linear neutral platinum-acetylide chemistry and what we found in this field. The preparation of various types of linear neutral platinum-acetylide complexes and their applications in the areas of micro/nanostructure materials, complicated topologies, and dye-sensitized solar cells will be summarized in this account. © 2016 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effect of the platinum content on the microstructure and micropore size distribution of Pt/alumina-pillared clays.

PubMed

Barrera-Vargas, M; Valencia-Rios, J; Vicente, M A; Korili, S A; Gil, A

2005-12-15

The aim of this work is to study the effect of the platinum content (0-1.8 wt % Pt) on the microstructure of an alumina-pillared clay. For this purpose, the nitrogen physisorption data at -196 degrees C, the micropore size distributions of the supported platinum catalysts, and the hydrogen chemisorption results at 30 degrees C have been analyzed and compared. The preparation of the catalysts has modified the textural properties of the Al-pillared clay support, giving rise to a loss of surface area and micropore volume. After reduction at 420 degrees C, the presence of dispersed metallic platinum with mean crystallite size in the 22-55 A range has been found by hydrogen adsorption. Comparison of all results reveals that the platinum species block the micropore entrances by steric hindrance to nitrogen access as the platinum content increases.

Development of Platinum(iv) Complexes as Anticancer Prodrugs: the Story so Far

NASA Astrophysics Data System (ADS)

Wong, Daniel Yuan Qiang; Ang, Wee Han

2012-06-01

The serendipitous discovery of the antitumor properties of cisplatin by Barnett Rosenberg some forty years ago brought about a paradigm shift in the field of medicinal chemistry and challenged conventional thinking regarding the role of potentially toxic heavy metals in drugs. Platinum(II)-based anticancer drugs have since become some of the most effective and widely-used drugs in a clinician's arsenal and have saved countless lives. However, they are limited by high toxicity, severe side-effects and the incidence of drug resistance. In recent years, attention has shifted to stable platinum(IV) complexes as anticancer prodrugs. By exploiting the unique chemical and structural attributes of their scaffolds, these platinum(IV) prodrugs offer new strategies of targeting and killing cancer cells. This review summarizes the development of anticancer platinum(IV) prodrugs to date and some of the exciting strategies that utilise the platinum(IV) construct as targeted chemotherapeutic agents against cancer.

Electrodeposition of platinum and silver into chemically modified microporous silicon electrodes

PubMed Central

2012-01-01

Electrodeposition of platinum and silver into hydrophobic and hydrophilic microporous silicon layers was investigated using chemically modified microporous silicon electrodes. Hydrophobic microporous silicon enhanced the electrodeposition of platinum in the porous layer. Meanwhile, hydrophilic one showed that platinum was hardly deposited within the porous layer, and a film of platinum on the top of the porous layer was observed. On the other hand, the electrodeposition of silver showed similar deposition behavior between these two chemically modified electrodes. It was also found that the electrodeposition of silver started at the pore opening and grew toward the pore bottom, while a uniform deposition from the pore bottom was observed in platinum electrodeposition. These electrodeposition behaviors are explained on the basis of the both effects, the difference in overpotential for metal deposition on silicon and on the deposited metal, and displacement deposition rate of metal. PMID:22720690

Developments in platinum anticancer drugs

NASA Astrophysics Data System (ADS)

Tylkowski, Bartosz; Jastrząb, Renata; Odani, Akira

2018-01-01

Platinum compounds represent one of the great success stories of metals in medicine. Following the unexpected discovery of the anticancer activity of cisplatin (Fig. 1) in 1965 by Prof. Rosenberg [1], a large number of its variants have been prepared and tested for their ability to kill cancer cells and inhibit tumor growth. Although cisplatin has been in use for over four decades, new and more effective platinum-based therapeutics are finally on the horizon. A wide introduction to anticancer studies is given by the authors of the previous chapter. This chapter aims at providing the readers with a comprehensive and in-depth understanding of recent developments of platinum anticancer drugs and to review the state of the art. The chapter is divided into two parts. In the first part we present a historical aspect of platinum and its complexes, while in the second part we give an overview of developments in the field of platinum anticancer agents.

Biological synthesis of platinum nanoparticles with apoferritin.

PubMed

Deng, Q Y; Yang, B; Wang, J F; Whiteley, C G; Wang, X N

2009-10-01

A novel biological method for the synthesis of platinum nanoparticles using the horse spleen apoferritin (HSAF) is reported. When HSAF was incubated with K(2)PtCl(6) at 23 degrees C) for 48 h followed by subsequent reduction with NaBH(4) it resulted in the formation of spherical platinum nanoparticles, size 4.7 +/- 0.9 nm, with narrow particle size distribution confirmed by transmission electron microscopy and energy dispersive X-ray analysis. As the initial platinum concentration increased through 0.155, 0.31, 0.465 to 0.62 mM the efficiency of its removal from solution by the apoferritin was 99, 99, 84 and 71% respectively. The maximum uptake of platinum salt per mM apoferritin was estimated at 12.7 mmol l(-1) h(-1). These results clearly indicate that the HSAF protein cage can successfully serve as a suitable size-constrained support matrix for the biological synthesis of platinum nanoparticles.

A rapid and practical strategy for the determination of platinum, palladium, ruthenium, rhodium, iridium and gold in large amounts of ultrabasic rock by inductively coupled plasma optical emission spectrometry combined with ultrasound extraction

NASA Astrophysics Data System (ADS)

Zhang, Gai; Tian, Min

2015-04-01

This proposed method regulated the determination of platinum, palladium, ruthenium, rhodium, iridium and gold in platinum-group ores by nickel sulfide fire assay—inductively coupled plasma optical emission spectrometry (ICP-OES) combined with ultrasound extraction for the first time. The quantitative limits were 0.013-0.023μg/g. The samples were fused to separate the platinum-group elements from matrix. The nickel sulfide button was then dissolved with hydrochloric acid and the insoluble platinum-group sulfide residue was dissolved with aqua regia by ultrasound bath and finally determined by ICP-OES. The proposed method has been applied into the determination of platinum-group element and gold in large amounts of ultrabasic rocks from the Great Dyke of Zimbabwe.

Electrochemical Reconstitution of Biomolecules for Applications as Electrocatalysts for the Bionanofuel Cell

NASA Technical Reports Server (NTRS)

Kim, Jae-Woo; Choi, Sang H.; Lillehei, Peter T.; King, Glen C.; Watt, Gerald D.; Chu, Sang-Hyon; Park, Yeonjoon; Thibeault, Sheila

2004-01-01

Platinum-cored ferritins were synthesized as electrocatalysts by electrochemical biomineralization of immobilized apoferritin with platinum. The platinum cored ferritin was fabricated by exposing the immobilized apoferritin to platinum ions at a reduction potential. On the platinum-cored ferritin, oxygen is reduced to water with four protons and four electrons generated from the anode. The ferritin acts as a nano-scale template, a biocompatible cage, and a separator between the nanoparticles. This results in a smaller catalyst loading of the electrodes for fuel cells or other electrochemical devices. In addition, the catalytic activity of the ferritin-stabilized platinum nanoparticles is enhanced by the large surface area and particle size phenomena. The work presented herein details the immobilization of ferritin with various surface modifications, the electrochemical biomineralization of ferritin with different inorganic cores, and the fabrication of self-assembled 2-D arrays with thiolated ferritin.

Role of platinum DNA damage-induced transcriptional inhibition in chemotherapy-induced neuronal atrophy and peripheral neurotoxicity.

PubMed

Yan, Fang; Liu, Johnson J; Ip, Virginia; Jamieson, Stephen M F; McKeage, Mark J

2015-12-01

Platinum-based anticancer drugs cause peripheral neurotoxicity by damaging sensory neurons within the dorsal root ganglia (DRG), but the mechanisms are incompletely understood. The roles of platinum DNA binding, transcription inhibition and altered cell size were investigated in primary cultures of rat DRG cells. Click chemistry quantitative fluorescence imaging of RNA-incorporated 5-ethynyluridine showed high, but wide ranging, global levels of transcription in individual neurons that correlated with their cell body size. Treatment with platinum drugs reduced neuronal transcription and cell body size to an extent that corresponded to the amount of preceding platinum DNA binding, but without any loss of neuronal cells. The effects of platinum drugs on neuronal transcription and cell body size were inhibited by blocking platinum DNA binding with sodium thiosulfate, and mimicked by treatment with a model transcriptional inhibitor, actinomycin D. In vivo oxaliplatin treatment depleted the total RNA content of DRG tissue concurrently with altering DRG neuronal size. These findings point to a mechanism of chemotherapy-induced peripheral neurotoxicity, whereby platinum DNA damage induces global transcriptional arrest leading in turn to neuronal atrophy. DRG neurons may be particularly vulnerable to this mechanism of toxicity because of their requirements for high basal levels of global transcriptional activity. Findings point to a new stepwise mechanism of chemotherapy-induced peripheral neurotoxicity, whereby platinum DNA damage induces global transcriptional arrest leading in turn to neuronal atrophy. Dorsal root ganglion neurons may be particularly vulnerable to this neurotoxicity because of their high global transcriptional outputs, demonstrated in this study by click chemistry quantitative fluorescence imaging. © 2015 International Society for Neurochemistry.

Aberrant DNA Damage Response Pathways May Predict the Outcome of Platinum Chemotherapy in Ovarian Cancer

PubMed Central

Stefanou, Dimitra T.; Bamias, Aristotelis; Episkopou, Hara; Kyrtopoulos, Soterios A.; Likka, Maria; Kalampokas, Theodore; Photiou, Stylianos; Gavalas, Nikos; Sfikakis, Petros P.; Dimopoulos, Meletios A.; Souliotis, Vassilis L.

2015-01-01

Ovarian carcinoma (OC) is the most lethal gynecological malignancy. Despite the advances in the treatment of OC with combinatorial regimens, including surgery and platinum-based chemotherapy, patients generally exhibit poor prognosis due to high chemotherapy resistance. Herein, we tested the hypothesis that DNA damage response (DDR) pathways are involved in resistance of OC patients to platinum chemotherapy. Selected DDR signals were evaluated in two human ovarian carcinoma cell lines, one sensitive (A2780) and one resistant (A2780/C30) to platinum treatment as well as in peripheral blood mononuclear cells (PBMCs) from OC patients, sensitive (n = 7) or resistant (n = 4) to subsequent chemotherapy. PBMCs from healthy volunteers (n = 9) were studied in parallel. DNA damage was evaluated by immunofluorescence γH2AX staining and comet assay. Higher levels of intrinsic DNA damage were found in A2780 than in A2780/C30 cells. Moreover, the intrinsic DNA damage levels were significantly higher in OC patients relative to healthy volunteers, as well as in platinum-sensitive patients relative to platinum-resistant ones (all P<0.05). Following carboplatin treatment, A2780 cells showed lower DNA repair efficiency than A2780/C30 cells. Also, following carboplatin treatment of PBMCs ex vivo, the DNA repair efficiency was significantly higher in healthy volunteers than in platinum-resistant patients and lowest in platinum-sensitive ones (t1/2 for loss of γH2AX foci: 2.7±0.5h, 8.8±1.9h and 15.4±3.2h, respectively; using comet assay, t1/2 of platinum-induced damage repair: 4.8±1.4h, 12.9±1.9h and 21.4±2.6h, respectively; all P<0.03). Additionally, the carboplatin-induced apoptosis rate was higher in A2780 than in A2780/C30 cells. In PBMCs, apoptosis rates were inversely correlated with DNA repair efficiencies of these cells, being significantly higher in platinum-sensitive than in platinum-resistant patients and lowest in healthy volunteers (all P<0.05). We conclude that perturbations of DNA repair pathways as measured in PBMCs from OC patients correlate with the drug sensitivity of these cells and reflect the individualized response to platinum-based chemotherapy. PMID:25659114

Advances in drug delivery system for platinum agents based combination therapy.

PubMed

Kang, Xiang; Xiao, Hai-Hua; Song, Hai-Qin; Jing, Xia-Bin; Yan, Le-San; Qi, Ruo-Gu

2015-12-01

Platinum-based anticancer agents are widely used as first-line drugs in cancer chemotherapy for various solid tumors. However, great side effects and occurrence of resistance remain as the major drawbacks for almost all the platinum drugs developed. To conquer these problems, new strategies should be adopted for platinum drug based chemotherapy. Modern nanotechnology has been widely employed in the delivery of various therapeutics and diagnostic. It provides the possibility of targeted delivery of a certain anticancer drug to the tumor site, which could minimize toxicity and optimize the drug efficacy. Here, in this review, we focused on the recent progress in polymer based drug delivery systems for platinum-based combination therapy.

Platinum blue staining of cells grown in electrospun scaffolds.

PubMed

Yusuf, Mohammed; Millas, Ana Luiza G; Estandarte, Ana Katrina C; Bhella, Gurdeep K; McKean, Robert; Bittencourt, Edison; Robinson, Ian K

2014-01-01

Fibroblast cells grown in electrospun polymer scaffolds were stained with platinum blue, a heavy metal stain, and imaged using scanning electron microscopy. Good contrast on the cells was achieved compared with samples that were gold sputter coated. The cell morphology could be clearly observed, and the cells could be distinguished from the scaffold fibers. Here we optimized the required concentration of platinum blue for imaging cells grown in scaffolds and show that a higher concentration causes platinum aggregation. Overall, platinum blue is a useful stain for imaging cells because of its enhanced contrast using scanning electron microscopy (SEM). In the future it would be useful to investigate cell growth and morphology using three-dimensional imaging methods.

Multifunctional platinum-based nanoparticles for biomedical applications.

PubMed

Cheng, Qinqin; Liu, Yangzhong

2017-03-01

Platinum-based anticancer drugs play a central role in current cancer therapy. However, their applicability and efficacy are limited by drug resistance and adverse effects. Nanocarrier-based platinum drug delivery systems are promising alternatives to circumvent the disadvantages of bare platinum drugs. The various properties of nanoparticle chemistry allow for the trend toward multiple functionality. Nanoparticles preferentially accumulate at the tumor site through passive targeting, and the attachment of tumor targeting moieties further enhances their tumor-specific localization as well as tumor cell uptake. The introduction of stimuli-responsive groups into drug delivery systems can further achieve spatially and temporally controlled drug release in response to specific stimuli. Combination therapy strategies have been used to promote synergetic efficacy and overcome the resistance of platinum drugs. The tumor-localized drug delivery strategies exhibit benefits for preventing local tumor recurrence. In addition, the combination of platinum drugs and imaging agents in one unity allows the cancer diagnostics for real-time monitoring the distribution of drug-loaded nanoparticles inside the body and tumor. This review discusses recent scientific advances in multifunctional nanoparticle formulations of platinum drugs, and these designs exhibit new potential of multifunctional nanoparticles for delivering platinum-based anticancer drugs. WIREs Nanomed Nanobiotechnol 2017, 9:e1410. doi: 10.1002/wnan.1410 For further resources related to this article, please visit the WIREs website. © 2016 Wiley Periodicals, Inc.

Biosorptive recovery of platinum from platinum group metal refining wastewaters by immobilised Saccharomyces cerevisiae.

PubMed

Mack, C L; Wilhelmi, B; Duncan, J R; Burgess, J E

2011-01-01

The process of platinum group metal (PGM) refining can be up to 99.99% efficient at best, and although it may seem small, the amount of valuable metal lost to waste streams is appreciable enough to warrant recovery. The method currently used to remove entrained metal ions from refinery wastewaters, chemical precipitation, is not effective for selective recovery of PGMs. The yeast Saccharomyces cerevisiae has been found capable of sorbing numerous precious and base metals, and is a cheap and abundant source of biomass. In this investigation, S. cerevisiae was immobilised using polyethyleneimine and glutaraldehyde to produce a suitable sorbent, capable of high platinum uptake (150-170 mg/g) at low pH (<2). The sorption mechanism was found to be a chemical reaction, which made effective desorption impossible. When applied to PGM refinery wastewater, two key wastewater characteristics limited the success of the sorption process; high inorganic ion content and complex speciation of the platinum ions. The results proved the concept principle of platinum recovery by immobilised yeast biosorption and indicated that a more detailed understanding of the platinum speciation within the wastewater is required before biosorption can be applied. Overall, the sorption of platinum by the S. cerevisiae sorbent was demonstrated to be highly effective in principle, but the complexity of the wastewater requires that pretreatment steps be taken before the successful application of this process to industrial wastewater.

INDUCTION OF TRISOMICS BY PLATINUM DIAMINODINITRODICHLORIDE

EPA Science Inventory

Trisomics were produced in the pollen mother cells of Pennisetum americanum (L) K. Schum plants resulting from seeds treated with M to the minus 6th power platinum diaminodinitrodichloride. On the basis of the preliminary study the relative potency of cis-Platinum diaminodinitrod...

Inhibition of the Nuclear Export Receptor XPO1 as a Therapeutic Target for Platinum-Resistant Ovarian Cancer.

PubMed

Chen, Ying; Camacho, Sandra Catalina; Silvers, Thomas R; Razak, Albiruni R A; Gabrail, Nashat Y; Gerecitano, John F; Kalir, Eva; Pereira, Elena; Evans, Brad R; Ramus, Susan J; Huang, Fei; Priedigkeit, Nolan; Rodriguez, Estefania; Donovan, Michael; Khan, Faisal; Kalir, Tamara; Sebra, Robert; Uzilov, Andrew; Chen, Rong; Sinha, Rileen; Halpert, Richard; Billaud, Jean-Noel; Shacham, Sharon; McCauley, Dilara; Landesman, Yosef; Rashal, Tami; Kauffman, Michael; Mirza, Mansoor R; Mau-Sørensen, Morten; Dottino, Peter; Martignetti, John A

2017-03-15

Purpose: The high fatality-to-case ratio of ovarian cancer is directly related to platinum resistance. Exportin-1 (XPO1) is a nuclear exporter that mediates nuclear export of multiple tumor suppressors. We investigated possible clinicopathologic correlations of XPO1 expression levels and evaluated the efficacy of XPO1 inhibition as a therapeutic strategy in platinum-sensitive and -resistant ovarian cancer. Experimental Design: XPO1 expression levels were analyzed to define clinicopathologic correlates using both TCGA/GEO datasets and tissue microarrays (TMA). The effect of XPO1 inhibition, using the small-molecule inhibitors KPT-185 and KPT-330 (selinexor) alone or in combination with a platinum agent on cell viability, apoptosis, and the transcriptome was tested in immortalized and patient-derived ovarian cancer cell lines (PDCL) and platinum-resistant mice (PDX). Seven patients with late-stage, recurrent, and heavily pretreated ovarian cancer were treated with an oral XPO1 inhibitor. Results: XPO1 RNA overexpression and protein nuclear localization were correlated with decreased survival and platinum resistance in ovarian cancer. Targeted XPO1 inhibition decreased cell viability and synergistically restored platinum sensitivity in both immortalized ovarian cancer cells and PDCL. The XPO1 inhibitor-mediated apoptosis occurred through both p53-dependent and p53-independent signaling pathways. Selinexor treatment, alone and in combination with platinum, markedly decreased tumor growth and prolonged survival in platinum-resistant PDX and mice. In selinexor-treated patients, tumor growth was halted in 3 of 5 patients, including one with a partial response, and was safely tolerated by all. Conclusions: Taken together, these results provide evidence that XPO1 inhibition represents a new therapeutic strategy for overcoming platinum resistance in women with ovarian cancer. Clin Cancer Res; 23(6); 1552-63. ©2016 AACR . ©2016 American Association for Cancer Research.

Cross-sectional study on comorbidities and adverse events in patients with advanced and recurrent ovarian cancer in France.

PubMed

Le Saux, Olivia; Taylor, Aliki; Chia, Victoria; Pillas, Demetris; Kaur, Moninder; Freyer, Gilles

2015-01-01

The purpose of this study was to evaluate the prevalence of comorbidities and adverse events (AEs), and determine the treatment patterns according to platinum-sensitivity status in patients with advanced (stage IIIB-IV) or recurrent epithelial ovarian cancer (EOC). A cross-sectional study was carried out in France with patients over 18 years, diagnosed with advanced (stage IIIB-IV) or recurrent EOC between 2009 and 2012. A total of 23 physicians (oncologists and gynecologists) participated, contributing 127 patients. Data were abstracted by participating physicians into a case report form. Of the 127 patients included, 92 (72.4%) had advanced EOC and 35 (27.6%) had recurrent EOC. A total of 73 comorbidities were reported in 44 patients (34.6%). Vascular (10.2%), metabolic (7.1%), respiratory (5.5%), and psychiatric disorders (5.5%) were the most common types of comorbidities reported. Prevalence of AEs was 74.8%, of which 12.6% were classified as serious. The most common AEs were anemia (16.5%), hematologic events (12.6%), taste change (11.8%), and headache (7.1%). Throughout the follow-up period, twelve patient deaths were reported (six due to disease progression). Of 35 patients with recurrent disease, 16 were highly platinum sensitive (recurrence >12 months after stopping platinum-based therapy), eleven were partially platinum sensitive (recurrence 6-12 months after stopping platinum-based therapy), seven were platinum resistant (recurrence within 6 months of stopping platinum-based therapy or progression while receiving second- or later-line platinum-based therapy), and one was platinum refractory (recurrence within 6 months from the start of first-line platinum-based therapy). In this cross-sectional study of advanced and metastatic ovarian cancer patients, approximately one-third of patients were diagnosed with comorbidities, and approximately three-quarters were diagnosed with AEs (12.6% with severe AEs).

Validation of a highly sensitive ICP-MS method for the determination of platinum in biofluids: application to clinical pharmacokinetic studies with oxaliplatin.

PubMed

Morrison, J G; White, P; McDougall, S; Firth, J W; Woolfrey, S G; Graham, M A; Greenslade, D

2000-12-01

ELOXATIN (Oxaliplatin) is a novel platinum containing anti-cancer agent with a diaminocyclohexane carrier ligand which has been approved in several major European countries. Clinical studies have demonstrated that the compound exhibits marked activity against colorectal cancers in combination with 5-fluorouracil (5-FU). The aim of this work was to develop and validate a highly sensitive inductively coupled plasma mass spectrometry assay for the determination of oxaliplatin-derived platinum in plasma ultrafiltrate, plasma and whole blood and to apply this technique to clinical pharmacokinetic studies with oxaliplatin. Ultratrace detection of platinum in plasma ultrafiltrate was achieved using ultrasonic nebulisation combined with ICP-MS. This technique allows detection of platinum at the 0.001 microg Pt/ml level in only 100 microl of matrix. Assays in blood and plasma utilised a standard Meinhardt nebuliser and spray chamber, achieving detection limits of 0.1 microg Pt/ml in 100 and 200 microl of matrix, respectively. The assays were validated (accuracy and precision within +/- 15%) over the concentration ranges: 0.001-0.250 microg Pt/ml in plasma ultrafiltrate and 0.1-10 microg Pt/ml for plasma and whole blood. The effect of sample digestion. dilution, long term frozen storage and quantitation in the presence of 5-FU were also investigated and validated. The method was used to monitor platinum exposure following oxaliplatin administration (130 mg/m2) to cancer patients. Following a 2 h i.v. infusion, peak platinum levels declined in a triphasic manner in all blood compartments. Free platinum was detected in plasma ultrafiltrate at low levels (0.001 0.010 microg Pt/ml) for up to 3 weeks. In conclusion, a highly sensitive and specific assay has been developed for the determination of platinum in biofluids. This method enabled characterisation of the long term exposure to platinum in patients following oxaliplatin treatment.

DNA condensing effects and sequence selectivity of DNA binding of antitumor noncovalent polynuclear platinum complexes.

PubMed

Malina, Jaroslav; Farrell, Nicholas P; Brabec, Viktor

2014-02-03

The noncovalent analogues of antitumor polynuclear platinum complexes represent a structurally discrete class of platinum drugs. Their chemical and biological properties differ significantly from those of most platinum chemotherapeutics, which bind to DNA in a covalent manner by formation of Pt-DNA adducts. In spite of the fact that these noncovalent polynuclear platinum complexes contain no leaving groups, they have been shown to bind to DNA with high affinity. We report here on the DNA condensation properties of a series of noncovalent analogues of antitumor polynuclear platinum complexes described by biophysical and biochemical methods. The results demonstrate that these polynuclear platinum compounds are capable of inducing DNA condensation at more than 1 order of magnitude lower concentrations than conventional spermine. Atomic force microscopy studies of DNA condensation confined to a mica substrate have revealed that the DNA morphologies become more compact with increasing concentration of the platinum complexes. Moreover, we also found that the noncovalent polynuclear platinum complex [{Pt(NH3)3}2-μ-{trans-Pt(NH3)2(NH2(CH2)6NH2)2}](6+) (TriplatinNC-A) binds to DNA in a sequence-dependent manner, namely, to A/T-rich sequences and A-tract regions, and that noncovalent polynuclear platinum complexes protect DNA from enzymatic cleavage by DNase I. The results suggest that mechanisms of antitumor and cytotoxic activities of these complexes may be associated with their unique ability to condense DNA along with their sequence-specific DNA binding. Owing to their high cellular accumulation, it is also reasonable to suggest that their mechanism of action is based on the competition with naturally occurring DNA condensing agents, such as polyamines spermine, spermidine, and putrescine, for intracellular binding sites, resulting in the disturbance of the correct binding of regulatory proteins initiating the onset of apoptosis.

Living supramolecular polymerization achieved by collaborative assembly of platinum(II) complexes and block copolymers

PubMed Central

Zhang, Kaka; Yeung, Margaret Ching-Lam; Leung, Sammual Yu-Lut; Yam, Vivian Wing-Wah

2017-01-01

An important feature of biological systems to achieve complexity and precision is the involvement of multiple components where each component plays its own role and collaborates with other components. Mimicking this, we report living supramolecular polymerization achieved by collaborative assembly of two structurally dissimilar components, that is, platinum(II) complexes and poly(ethylene glycol)-b-poly(acrylic acid) (PEG-b-PAA). The PAA blocks neutralize the charges of the platinum(II) complexes, with the noncovalent metal–metal and π–π interactions directing the longitudinal growth of the platinum(II) complexes into 1D crystalline nanostructures, and the PEG blocks inhibiting the transverse growth of the platinum(II) complexes and providing the whole system with excellent solubility. The ends of the 1D crystalline nanostructures have been found to be active during the assembly and remain active after the assembly. One-dimensional segmented nanostructures with heterojunctions have been produced by sequential growth of two types of platinum(II) complexes. The PAA blocks act as adapters at the heterojunctions for lattice matching between chemically and crystallographically different platinum(II) complexes, achieving heterojunctions with a lattice mismatch as large as 21%. PMID:29078381

Fourier transform infrared (FTIR) spectroscopy to monitor the cellular impact of newly synthesized platinum derivatives.

PubMed

Berger, Gilles; Gasper, Régis; Lamoral-Theys, Delphine; Wellner, Anja; Gelbcke, Michel; Gust, Ronald; Nève, Jean; Kiss, Robert; Goormaghtigh, Erik; Dufrasne, François

2010-09-01

Platinum complexes remain widely used to combat various types of cancers. Three platinum complexes, cisplatin, carboplatin and oxaliplatin, are marketed for various oncological purposes. Additionally, nedaplatin, lobaplatin and heptaplatin have gained regionally limited approval for oncology purposes. Furthermore, various platinum derivatives are currently under clinical trials. More than 40 years after their discovery, however, the precise mechanism of action of platinum antitumor complexes remains elusive, partly because these compounds display numerous intracellular targets. Structure-activity-relationship analyses are therefore difficult to conduct to optimize the synthesis of novel platinum derivatives. The aim of the present study is to illustrate the potential of using Fourier Transform Infrared (FTIR) analyses to monitor the cellular modifications induced by the new platinum derivatives that we have synthesized. We show in the present study the advantages of combining an in vitro assay to determine the IC50 growth inhibition concentrations of a series of compounds belonging to a given chemical series and FTIR analyses carried out at the IC50 concentrations for each compound to identify potential hits within this series of compounds. The original pharmacological approach proposed here could, therefore, avoid large-scale pharmacological experiments to find hits within a given chemical series.

Effect of platinum nanoparticle deposition parameters on hydrogen peroxide transduction for applications in wearable electrochemical glucose biosensors

NASA Astrophysics Data System (ADS)

Cargill, Allison A.; Neil, Kathrine M.; Hondred, John A.; McLamore, Eric S.; Claussen, Jonathan C.

2016-05-01

Enhanced interest in wearable biosensor technology over the past decade is directly related to the increasing prevalence of diabetes and the associated requirement of daily blood glucose monitoring. In this work we investigate the platinum-carbon transduction element used in traditional first-generation glucose biosensors which rely on the concentration of hydrogen peroxide produced by the glucose-glucose oxidase binding scheme. We electrodeposit platinum nanoparticles on a commercially-available screen printed carbon electrode by stepping an applied current between 0 and 7.12 mA/cm2 for a varying number of cycles. Next, we examine the trends in deposition and the effect that the number of deposition cycles has on the sensitivity of electrochemical glucose sensing. Results from this work indicate that applying platinum nanoparticles to screen printed carbon via electrodeposition from a metal salt solution improves overall biosensor sensitivity. This work also pinpoints the amount of platinum (i.e., number of deposition cycles) that maximizes biosensor sensitivity in an effort to minimize the use of the precious metals, viz., platinum, in electrode fabrication. In summary, this work quantifies the relationship between platinum electrodeposition and sensor performance, which is crucial in designing and producing cost-effective sensors.

In vitro permeation of platinum and rhodium through Caucasian skin.

PubMed

Franken, A; Eloff, F C; Du Plessis, J; Badenhorst, C J; Jordaan, A; Du Plessis, J L

2014-12-01

During platinum group metals (PGMs) refining the possibility exists for dermal exposure to PGM salts. The dermal route has been questioned as an alternative route of exposure that could contribute to employee sensitisation, even though literature has been focused on respiratory exposure. This study aimed to investigate the in vitro permeation of platinum and rhodium through intact Caucasian skin. A donor solution of 0.3mg/ml of metal, K2PtCl4 and RhCl3 respectively, was applied to the vertical Franz diffusion cells with full thickness abdominal skin. The receptor solution was removed at various intervals during the 24h experiment, and analysed with high resolution ICP-MS. Skin was digested and analysed by ICP-OES. Results indicated cumulative permeation with prolonged exposure, with a significantly higher mass of platinum permeating after 24h when compared to rhodium. The mass of platinum retained inside the skin and the flux of platinum across the skin was significantly higher than that of rhodium. Permeated and skin retained platinum and rhodium may therefore contribute to sensitisation and indicates a health risk associated with dermal exposure in the workplace. Copyright © 2014 Elsevier Ltd. All rights reserved.

Cytotoxicity of Cyclometalated Platinum Complexes Based on Tridentate NCN and CNN-coordinating ligands: Remarkable Coordination Dependence

PubMed Central

Vezzu, Dileep A. k.; Lu, Qun; Chen, Yan-Hua; Huo, Shouquan

2014-01-01

A series of cyclometalated platinum complexes with diverse coordination patterns and geometries were screened for their anticancer activity. It was discovered that the NʌCʌN-coordinated platinum complex based on 1,3-di(pyridyl)benzene displayed much higher cytotoxicity against human lung cancer cells NCI-H522, HCC827, and NCI-H1299, and human prostate cancer cell RV1 than cisplatin. In a sharp contrast, the CʌNʌN-coordinated platinum complex based on 6-phenyl-2,2′-bipyridine was ineffective on these cancer cells. This remarkable difference in cytotoxicity displayed by NʌCʌN- and CʌNʌN-coordinated platinum complexes was related to the trans effect of the carbon donor in the cyclometalated platinum complexes, which played a crucial role in facilitating the dissociation of the chloride ligand to create an active binding site. The DNA binding was studied for the NʌCʌN-coordinated platinum complex using electrophoresis and emission titration. The cellular uptake observed by fluorescent microscope showed the complex is largely concentrated in the cytoplasm. The possible pathways for the cell apoptosis was studied by western blot analysis and the activation of PARP via caspase 7 was observed. PMID:24531534

CDK6 protects epithelial ovarian cancer from platinum-induced death via FOXO3 regulation.

PubMed

Dall'Acqua, Alessandra; Sonego, Maura; Pellizzari, Ilenia; Pellarin, Ilenia; Canzonieri, Vincenzo; D'Andrea, Sara; Benevol, Sara; Sorio, Roberto; Giorda, Giorgio; Califano, Daniela; Bagnoli, Marina; Militello, Loredana; Mezzanzanica, Delia; Chiappetta, Gennaro; Armenia, Joshua; Belletti, Barbara; Schiappacassi, Monica; Baldassarre, Gustavo

2017-10-01

Epithelial ovarian cancer (EOC) is an infrequent but highly lethal disease, almost invariably treated with platinum-based therapies. Improving the response to platinum represents a great challenge, since it could significantly impact on patient survival. Here, we report that silencing or pharmacological inhibition of CDK6 increases EOC cell sensitivity to platinum. We observed that, upon platinum treatment, CDK6 phosphorylated and stabilized the transcription factor FOXO3, eventually inducing ATR transcription. Blockage of this pathway resulted in EOC cell death, due to altered DNA damage response accompanied by increased apoptosis. These observations were recapitulated in EOC cell lines in vitro , in xenografts in vivo , and in primary tumor cells derived from platinum-treated patients. Consistently, high CDK6 and FOXO3 expression levels in primary EOC predict poor patient survival. Our data suggest that CDK6 represents an actionable target that can be exploited to improve platinum efficacy in EOC patients. As CDK4/6 inhibitors are successfully used in cancer patients, our findings can be immediately transferred to the clinic to improve the outcome of EOC patients. © 2017 The Authors. Published under the terms of the CC BY 4.0 license.

Optimal chemotherapy treatment for women with recurrent ovarian cancer

PubMed Central

Fung-Kee-Fung, M.; Oliver, T.; Elit, L.; Oza, A.; Hirte, H.W.; Bryson, P.

2007-01-01

Question What is the optimal chemotherapy treatment for women with recurrent ovarian cancer who have previously received platinum-based chemotherapy? Perspectives Currently, standard primary therapy for advanced disease involves a combination of maximal cytoreductive surgery and chemotherapy with carboplatin plus paclitaxel or with carboplatin alone. Despite initial high response rates, a large proportion of patients relapse, resulting in a therapeutic challenge. Because these patients are not curable, the goal of therapy becomes improvement in both quality and length of life. The search has therefore been to find active agents for women with recurrent disease following platinum-based chemotherapy. Outcomes Outcomes of interest included any combination of tumour response rate, progression-free survival, overall survival, adverse events, and quality of life. Methodology The medline, embase, and Cochrane Library databases were systematically searched for primary articles and practice guidelines. The resulting evidence informed the development of clinical practice recommendations. The systematic review and recommendations were approved by the Report Approval Panel of the Program in Evidence-Based Care, and by the Gynecology Cancer Disease Site Group (dsg). The practice guideline was externally reviewed by a sample of practitioners from Ontario, Canada. Results Thirteen randomized trials compared various chemotherapy regimens for patients with recurrent ovarian cancer. In five of the thirteen trials in which 100% of patients were considered sensitive to platinum-containing chemotherapy, further platinum-based combination chemotherapy significantly improved response rates (two trials), progression-free survival (four trials), and overall survival (three trials) when compared with single-agent chemotherapy involving carboplatin or paclitaxel. Only two of these randomized trials compared the same chemotherapy regimens: carboplatin alone versus the combination of carboplatin and paclitaxel. Both trials were consistent in reporting improved survival outcomes with the combination of carboplatin and paclitaxel. In one trial, the combination of carboplatin and gemcitabine resulted in significantly higher response rates and improved progression-free survival when compared with carboplatin alone. Median survival with carboplatin alone ranged from 17 months to 24 months in four trials. In eight of the thirteen trials in which 35%–100% of patients had platinum-refractory or -resistant disease, one trial reported a statistically significant 2-month improvement in overall survival with liposomal doxorubicin as compared with topotecan (15 months vs. 13 months, p = 0.038; hazard ratio: 1.23; 95% confidence interval: 1.01 to 1.50). In that trial, because of the limited clinical benefit and the unusual finding that a survival difference emerged only after a year of treatment with no corresponding improvement in the rate of response or of progression-free survival, the authors concluded that further confirmation by results from randomized trials were needed to establish the superiority of one agent over another in their trial. In one trial, topotecan was superior to treosulphan in patient progression-free survival by a span of approximately 2 months (5.4 months vs. 3.0 months, p < 0.001). Toxicity was reported in all of the randomized trials, and although data on adverse events varied by treatment regimen, the observed adverse events correlated with known toxicity profiles. As expected, combination chemotherapy was associated with higher rates of adverse events. Practice Guideline Target Population This clinical recommendation applies to women with recurrent epithelial ovarian cancer who have previously received platinum-based chemotherapy. Of specific interest are women who have previously shown sensitivity to platinum therapy and those who previously were refractory or resistant to platinum-based chemotherapy. As a general categorization within what is actually a continuum, “platinum sensitivity” refers to disease recurrence 6 months or more after prior platinum-containing chemotherapy, and “platinum resistance” refers to a response to platinum-based chemotherapy followed by relapse less than 6 months after chemotherapy is stopped. “Platinum-refractory disease” refers to a lack of response or to progression while on platinum-based chemotherapy. Recommendations Although the body of evidence that informs the clinical recommendations is based on randomized trial data, those data are incomplete. Based on the available data and expert consensus opinion, the Gynecology Cancer dsg makes these recommendations: Systemic therapy for recurrent ovarian cancer is not curative. It is therefore recognized that each patient must be individually assessed to determine optimal therapy in terms of recurrence, sensitivity to platinum, toxicity, ease of administration, and patient preference. All suitable patients should be offered the opportunity to participate in randomized trials, if available. In the absence of contraindications, combination platinum-based chemotherapy should be considered for patients with prior sensitivity to platinum-containing chemotherapy. As compared with carboplatin alone, the combination of carboplatin and paclitaxel significantly improved both progression-free and overall survival. If combination platinum-based chemotherapy is not indicated, then a single platinum agent should be considered. Carboplatin has demonstrated efficacy across trials and has a manageable toxicity profile. If a single platinum agent is not being considered, then monotherapy with paclitaxel, topotecan, or pegylated liposomal doxorubicin are seen as reasonable treatment options. Some patients may be repeatedly sensitive to treatment and may benefit from multiple lines of chemotherapy. For patients with platinum-refractory or platinum-resistant disease, the goals of treatment should be to improve quality of life by extending the symptom-free interval, by reducing symptom intensity, and by increasing progression-free interval, and, if possible, to prolong life. With non-platinum agents, monotherapy should be considered because no advantage appears to accrue to the use of non-platinum-containing combination chemotherapy in this group of patients. Single-agent paclitaxel, topotecan, or pegylated liposomal doxorubicin have demonstrated activity in this patient population and are reasonable treatment options. No evidence either supports or refutes the use of more than one line of chemotherapy in patients with platinum-refractory or platinum-resistant recurrence. Many treatment options have shown modest response rates, but their benefits over best supportive care have not been studied in clinical trials. PMID:17938703

Mouse Model of Halogenated Platinum Salt Hypersensitivity

EPA Science Inventory

Occupational exposure to halogenated platinum salts can trigger the development of asthma. Concern for increased asthma risk exists for the general population due to the use of platinum (Pt) in catalytic converters and its emerging use as a diesel fuel additive. To investigate a...

A Gene Expression Profile of BRCAness That Predicts for Responsiveness to Platinum and PARP Inhibitors

DTIC Science & Technology

2015-10-01

1 Award Number: W81XWH-10-1-0585 TITLE: A Gene Expression Profile of BRCAness That Predicts for Responsiveness to Platinum and PARP Inhibitors...TITLE AND SUBTITLE A Gene Expression Profile of BRCAness That Predicts for Responsiveness to Platinum and PARP Inhibitors 5a. CONTRACT NUMBER W81XWH...BRCAlike, i.e. not HR deficient and are resistant to PARPis but are sensitive to platinum . These tumors exhibit alterations in another DNA repair

Electrocatalyst for oxygen reduction with reduced platinum oxidation and dissolution rates

DOEpatents

Adzic, Radoslav; Zhang, Junliang; Vukmirovic, Miomir

2012-11-13

The invention relates to platinum-metal oxide composite particles and their use as electrocatalysts in oxygen-reducing cathodes and fuel cells. The invention particularly relates to methods for preventing the oxidation of the platinum electrocatalyst in the cathodes of fuel cells by use of these platinum-metal oxide composite particles. The invention additionally relates to methods for producing electrical energy by supplying such a fuel cell with an oxidant, such as oxygen, and a fuel source, such as hydrogen.

Identification of the formation of metal-vinylidene interfacial bonds of alkyne-capped platinum nanoparticles by isotopic labeling.

PubMed

Hu, Peiguang; Chen, Limei; Deming, Christopher P; Bonny, Lewis W; Lee, Hsiau-Wei; Chen, Shaowei

2016-10-07

Stable platinum nanoparticles were prepared by the self-assembly of 1-dodecyne and dodec-1-deuteroyne onto bare platinum colloid surfaces. The nanoparticles exhibited consistent core size and optical properties. FTIR and NMR measurements confirmed the formation of Pt-vinylidene (Pt[double bond, length as m-dash]C[double bond, length as m-dash]CH-) interfacial linkages rather than Pt-acetylide (Pt-C[triple bond, length as m-dash]C-) and platinum-hydride (Pt-H) bonds.

Electrocatalyst for oxygen reduction with reduced platinum oxidation and dissolution rates

DOEpatents

Adzic, Radoslav [East Setauket, NY; Zhang, Junliang [Stony Brook, NY; Vukmirovic, Miomir [Port Jefferson Station, NY

2011-11-22

The invention relates to platinum-metal oxide composite particles and their use as electrocatalysts in oxygen-reducing cathodes and fuel cells. The invention particularly relates to methods for preventing the oxidation of the platinum electrocatalyst in the cathodes of fuel cells by use of these platinum-metal oxide composite particles. The invention additionally relates to methods for producing electrical energy by supplying such a fuel cell with an oxidant, such as oxygen, and a fuel source, such as hydrogen.

IgE antibody responses to platinum group metals: a large scale refinery survey.

PubMed Central

Murdoch, R D; Pepys, J; Hughes, E G

1986-01-01

All 306 South African platinum refinery workers (116 white, 190 coloured) accepted for employment on grounds of absence of evidence of atopy were investigated using the skin prick test and RAST to detect sensitivity to platinum, palladium, and rhodium salts. RAST studies were made for these, together with HSA and DNP-HSA RAST. Of the 306 workers, 38 had a positive skin prick test to the platinum halide salts; of these, one gave a positive reaction to the palladium salt and six to the rhodium salt. There were no isolated positives to the rhodium and palladium halide salts. Total IgE levels were raised in 24 of the 38 (63%) platinum salt prick test positive workers compared with only 43 of the 268 (16%) prick test negative group (p less than 0.001). Positive RASTs were obtained in 62% of those with positive skin tests to the platinum salts. Four of the six giving positive rhodium salt skin tests gave a positive RAST to rhodium salt. Of these, two gave positive RASTS to HSA and all four to DNP-HSA. The palladium salt RAST was negative in the single skin test reactor. In the platinum salt skin test positive group a raised HSA RAST was obtained in 10.5% compared with only 2.5% in the skin negative group. Twenty one per cent of the platinum salt skin positive group had a raised RAST score to DNP-HSA with only 3.5% (4/116) in the skin test negative group, of whom three also had a raised HSA RAST. The latter findings are suggestive of IgE antibody production to new antigenic determinants in HSA produced by conjugation with the platinum salts. PMID:2936374

Selection of a platinum-binding sequence in a loop of a four-helix bundle protein.

PubMed

Yagi, Sota; Akanuma, Satoshi; Kaji, Asumi; Niiro, Hiroya; Akiyama, Hayato; Uchida, Tatsuya; Yamagishi, Akihiko

2018-02-01

Protein-metal hybrids are functional materials with various industrial applications. For example, a redox enzyme immobilized on a platinum electrode is a key component of some biofuel cells and biosensors. To create these hybrid materials, protein molecules are bound to metal surfaces. Here, we report the selection of a novel platinum-binding sequence in a loop of a four-helix bundle protein, the Lac repressor four-helix protein (LARFH), an artificial protein in which four identical α-helices are connected via three identical loops. We created a genetic library in which the Ser-Gly-Gln-Gly-Gly-Ser sequence within the first inter-helical loop of LARFH was semi-randomly mutated. The library was then subjected to selection for platinum-binding affinity by using the T7 phage display method. The majority of the selected variants contained the Tyr-Lys-Arg-Gly-Tyr-Lys (YKRGYK) sequence in their randomized segment. We characterized the platinum-binding properties of mutant LARFH by using quartz crystal microbalance analysis. Mutant LARFH seemed to interact with platinum through its loop containing the YKRGYK sequence, as judged by the estimated exclusive area occupied by a single molecule. Furthermore, a 10-residue peptide containing the YKRGYK sequence bound to platinum with reasonably high affinity and basic side chains in the peptide were crucial in mediating this interaction. In conclusion, we have identified an amino acid sequence, YKRGYK, in the loop of a helix-loop-helix motif that shows high platinum-binding affinity. This sequence could be grafted into loops of other polypeptides as an approach to immobilize proteins on platinum electrodes for use as biosensors among other applications. Copyright © 2017 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Characterization of long-term elution of platinum from carboplatin-impregnated calcium sulfate hemihydrate beads in vitro by two distinct sample collection methods.

PubMed

Tulipan, Rachel J; Phillips, Heidi; Garrett, Laura D; Dirikolu, Levent; Mitchell, Mark A

2017-05-01

OBJECTIVE To characterize long-term elution of platinum from carboplatin-impregnated calcium sulfate hemihydrate (CI-CSH) beads in vitro by comparing 2 distinct sample collection methods designed to mimic 2 in vivo environments. SAMPLES 162 CI-CSH beads containing 4.6 mg of carboplatin (2.4 mg of platinum/bead). PROCEDURES For method 1, which mimicked an in vivo environment with rapid and complete fluid exchange, each of 3 plastic 10-mL conical tubes contained 3 CI-CSH beads and 5 mL of PBS solution. Eluent samples were obtained by evacuation of all fluid at 1, 2, 3, 6, 9, and 12 hours and 1, 2, 3, 6, 9, 12, 15, 18, 22, 26, and 30 days. Five milliliters of fresh PBS solution was then added to each tube. For method 2, which mimicked an in vivo environment with no fluid exchange, each of 51 tubes (ie, 3 tubes/17 sample collection times) contained 3 CI-CSH beads and 5 mL of PBS solution. Eluent samples were obtained from the assigned tubes for each time point. All samples were analyzed for platinum content by inductively coupled plasma-mass spectrometry. RESULTS Platinum was released from CI-CSH beads for 22 to 30 days. Significant differences were found in platinum concentration and percentage of platinum eluted from CI-CSH beads over time for each method. Platinum concentrations and elution percentages in method 2 samples were significantly higher than those of method 1 samples, except for the first hour measurements. CONCLUSIONS AND CLINICAL RELEVANCE Sample collection methods 1 and 2 may provide estimates of the minimum and maximum platinum release, respectively, from CI-CSH beads in vivo.

SO2-Binding Properties of Cationic η6,η1-NCN-Pincer Arene Ruthenium Platinum Complexes: Spectroscopic and Theoretical Studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bonnet, Sylvestre A.; Van Lenthe, Joop H.; van Dam, Hubertus JJ

2011-03-01

The SO2-binding properties of a series of η6,η1-NCN-pincer ruthenium platinum complexes have been studied by both UV-visible spectroscopy, and theoretical calculations. When an electronwithdrawing [Ru(C5R5)]+ fragment (R = H or Me) is η6-coordinated to the phenyl ring of the NCNpincer platinum fragment (cf. [2]+ and [3]+, see scheme 1), the characteristic orange coloration (pointing to η1- SO2 binding to Pt) of a solution of the parent NCN-pincer platinum complex 1 in dichloromethane upon SO2-bubbling is not observed. However, when the ruthenium center is η6- coordinated to a phenyl substituent linked in para-position to the carbon-to-platinum bond, i.e. complex [4]+, themore » SO2-binding property of the NCN-platinum center seems to be retained, as bubbling SO2 into a solution of the latter complex produces the characteristic orange color. We performed theoretical calculations at the MP2 level of approximation and TD-DFT studies, which enabled us to interpret the absence of color change in the case of [2]+ as an absence of coordination of SO2 to platinum. We analyze this absence or weaker SO2-coordination in dichloromethane to be a consequence of the relative electron-poorness of the platinum center in the respective η6- ruthenium coordinated NCN-pincer platinum complexes, that leads to a lower binding energy and an elongated calculated Pt-S bond distance. We also discuss the effects of electrostatic interactions in these cationic systems, which also seems to play a destabilizing role for complex [2(SO2)]+.« less

Association between in vitro platinum resistance in the EDR assay and clinical outcomes for ovarian cancer patients.

PubMed

Holloway, Robert W; Mehta, Rita S; Finkler, Neil J; Li, Kuo-Tung; McLaren, Christine E; Parker, Ricardo J; Fruehauf, John P

2002-10-01

The initial clinical response to platinum is a major determinant of outcome for patients with ovarian cancer. This retrospective study was undertaken to correlate the response and survival of newly diagnosed advanced ovarian cancer patients who received platinum-based therapy with in vitro drug response to cisplatin or carboplatin measured as percentage cell inhibition (PCI) in the in vitro Extreme Drug Resistance (EDR) assay. Outcomes for newly diagnosed ovarian cancer patients with tumor specimens submitted in a serial fashion for the EDR assay were studied. EDR assay results for cisplatin and carboplatin were correlated with clinical outcome for 79 evaluable chemotherapy nai;ve cases who presented with advanced (stages IIC, III, and IV) ovarian cancer. Stage IV and suboptimally debulked stage IIIc accounted for 16 cases, while 63 cases were optimally debulked Stage III/IIc. All patients were treated with platinum-based combination chemotherapy at a single institution. In vitro results for patient tumors were classified as low drug resistance (PCI > median), intermediate drug resistance [PCI between the median and 1 standard deviation (SD) below the median], or extreme drug resistance (PCI more than 1 SD below the median). For the purpose of this analysis, in vitro EDR to either cisplatin or carboplatin was considered to represent extreme resistance to platinum (EDRP), while the absence of EDR to either cisplatin or carboplatin was considered to represent low resistance to platinum (LDRP). Patients demonstrating relative in vitro resistance to paclitaxel and non-cross-resistance to cyclophosphamide and/or doxorubicin received cyclophosphamide plus platinum (CP); cyclophosphamide, doxorubicin, and platinum (CAP); or platinum alone in place of paclitaxel plus platinum (TP). Progression-free survival (PFS) and overall survival (OS) were correlated with EDR assay results. Median PFS was 6 months for the 17 cases exhibiting EDRP, compared to 24 months for the 62 cases exhibiting LDRP in vitro [relative risk (RR) 3.78, confidence intervals (CI) 1.82-7.83], adjusted for stage, debulking status, in vitro response to 3-OH-cyclophosphamide, and histological grade. Estimated overall 5-year survival was 19% for patients with tumors showing EDRP, compared to 68% for patients with tumors showing LDRP (RR 2.32, CI 1.06-5.07). Patients treated with CP (n = 20) showed no significant difference in OS compared to patients treated with TP (n = 54), CAP (n = 4), or cisplatin (n = 1) alone. In vitro platinum response remained an independent predictor of PFS and OS in multivariate analyses adjusted for CP versus TP, CAP, or platinum administration, and adjusted for debulking status. Median PFS for all 79 patients was 22 months, with an estimated 5-year survival of 57%. Patients with tumors demonstrating in vitro EDR to platinum were at significantly increased risk for progression and death when treated with standard platinum-based regimens. Such patients may therefore benefit from entry onto trials with novel agents or combinations.

Controllable deposition of platinum nanoparticles on single-wall carbon nanohorns as catalyst for direct methanol fuel cells.

PubMed

Niu, Ben; Xu, Wei; Guo, Zhengduo; Zhou, Nengzhi; Liu, Yang; Shi, Zujin; Lian, Yongfu

2012-09-01

Uniform and well dispersed platinum nanoparticles were successfully deposited on single-walled carbon nanohorns with the assistance of 4,4-dipydine and ion liquids, respectively. In particular, the size of platinum nanoparticles could be controlled in a very narrow range (2.2 to 2.5 nm) when ion liquids were applied. The crystalline nature of these platinum nanoparticles was confirmed by high resolution transmission electron microscopy observation and X-ray power diffraction analysis, and two species of platinum Pt(0) and Pt(II) were detected by X-ray photoelectron spectroscopy. Electrochemical studies revealed that thus obtained nanocomposites had much better electrocatalytic activity for the methanol oxidation than those prepared with carbon nanotubes as supporter.

Research Advances in Resistance to Platinum-based Chemotherapy in Lung Cancer.

PubMed

Zhang, Yajuan; Chang, De; Zhang, Jianpeng

2017-02-20

Platinum-based chemotherapy is the the cornerstone of treatment of many cancers. Combinations of platinum drugs with other agents are still the mainstream therapies for non-small cell lung cancer,showing significant effectiveness in an early phase. Along with the treatment,the tumor cells can become resistant to chemotherapy drugs,which affect the efficacy and prognosis. The mechanisms of drug resistance are complicated,including abnormal expressions of membrane proteins,enhanced DNA repair functions,abnormal regulation mechanisms of apoptosis,and enhanced cellular detoxification function. In this article we summarize some of the main mechanisms of platinum resistance in lung cancer cells,with an attempt to identify new potential target analogues or inhibitors and improve the efficacies of the combined use of platinum-based drugs.

Investigating the performance of catalyst layer micro-structures with different platinum loadings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khakaz-Baboli, Moben; Harvey, David; Pharoah, Jon

In this study a four-phase micro-structure of a PEFC catalyst layer was reconstructed by randomly placing overlapping spheres for each solid catalyst phase. The micro-structure was mirrored to make a micro-structure. A body-fit computational mesh was produced for the reconstructed micro-structure in OpenFOAM. Associated conservation equations were solved within all the phases with electrochemical reaction as the boundary condition at the interface between ionomer and platinum phases. The study is focused on the platinum loading of CL. The polarization curves of the micro-structure performance have been compared for different platinum loadings. This paper gives increased insight into the relatively greatermore » losses at decreased platinum loadings.« less

Bioinspired hierarchical nanotubular titania immobilized with platinum nanoparticles for photocatalytic hydrogen production.

PubMed

Liu, Xiaoyan; Li, Jiao; Zhang, Yiming; Huang, Jianguo

2015-05-11

A bioinspired nanocomposite composed of platinum nanoparticles and nanotubular titania was fabricated in which the titania matter was templated by natural cellulose substance. The composite possesses three- dimensional hierarchical structures, and ultrafine metallic platinum particles with sizes of ca. 2 nm were immobilized uniformly on the surfaces of the titania nanotubes. Such a nanocomposite with 1.06 wt % of platinum content shows the optimal photocatalytic hydrogen production activity from water splitting of 16.44 mmol h(-1)  g(-1) , and excessive loading of platinum results in poorer photocatalytic performance. The structural integrity of the nanocomposite upon cyclic water-splitting processes results in its sufficient photocatalytic stability. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Stabilizing platinum in phosphoric acid fuel cells

NASA Technical Reports Server (NTRS)

Remick, R. J.

1981-01-01

The cathode of the phosphoric acid fuel cell uses a high surface area platinum catalyst supported on a carbon substrate. During operation, the small platinum crystallites sinter, causing loss in cell performance. A support was developed that stabilizes platinum in the high surface area condition by retarding or preventing the sintering process. The approach is to form etch pits in the carbon by oxidizing the carbon in the presence of a metal oxide catalyst, remove the metal oxide by an acid wash, and then deposit platinum in these pits. Results confirm the formation of etch pits in each of the three supports chosen for investigation: Vulcan XC-72R, Vulcan XC-72 that was graphized at 2500 C, and Shawinigan Acetylene Black.

Monochloramine-sensitive amperometric microelectrode: optimization of gold, platinum, and carbon fiber sensing materials for removal of dissolved oxygen interference

EPA Science Inventory

Amperometric monochloramine detection using newly fabricated gold, platinum, and carbon-fiber microsensors was investigated to optimize sensor operation and eliminate oxygen interference. Gold and platinum microsensors exhibited no oxygen interference during monochloramine measu...

Surface engineering of hierarchical platinum-cobalt nanowires for efficient electrocatalysis

DOE PAGES

Bu, Lingzheng; Guo, Shaojun; Zhang, Xu; ...

2016-06-29

Despite intense research in past decades, the lack of high-performance catalysts for fuel cell reactions remains a challenge in realizing fuel cell technologies for transportation applications. Here we report a facile strategy for synthesizing hierarchical platinum-cobalt nanowires with high-index, platinum-rich facets and ordered intermetallic structure. These structural features enable unprecedented performance for the oxygen reduction and alcohol oxidation reactions. The specific/mass activities of the platinum-cobalt nanowires for oxygen reduction reaction are 39.6/33.7 times higher than commercial Pt/C catalyst, respectively. Density functional theory simulations reveal that the active threefold hollow sites on the platinum-rich high-index facets provide an additional factor inmore » enhancing oxygen reduction reaction activities. The nanowires are stable in the electrochemical conditions and also thermally stable. Furthermore, this work may represent a key step towards scalable production of high performance platinum-based nanowires for applications in catalysis and energy conversion.« less

On the mobility of carbon-supported platinum nanoparticles towards unveiling cathode degradation in water electrolysis

NASA Astrophysics Data System (ADS)

Paciok, Paul; Schalenbach, Maximilian; Carmo, Marcelo; Stolten, Detlef

2017-10-01

This study investigates the influence of the hydrogen evolution reaction (HER) overpotential on the mobility of carbon-supported platinum particles. The migration of the platinum over the carbon support was analyzed by means of identical location transmission electron microscopy (IL-TEM). While at potentials of 0.1 and 0 V vs. reversible hydrogen electrode (RHE), no changes to the Pt/C material were observed. With a decrease of the overpotential to -0.1 V vs. RHE, an increase in the quantity of migrating platinum particles took place. At -0.2 V vs. RHE, a further rise in the particle migration was observed. The effect of the overpotential on the migration was explained by a higher hydrogen generation rate, the formation of a hydrogen monolayer on the platinum and the resulting changes of the platinum support distance. The mechanisms revealed in this study could describe a relevant source of degradation of PEM water electrolyzers.

Chemotherapy in advanced ovarian cancer: four systematic meta-analyses of individual patient data from 37 randomized trials. Advanced Ovarian Cancer Trialists' Group.

PubMed Central

Aabo, K.; Adams, M.; Adnitt, P.; Alberts, D. S.; Athanazziou, A.; Barley, V.; Bell, D. R.; Bianchi, U.; Bolis, G.; Brady, M. F.; Brodovsky, H. S.; Bruckner, H.; Buyse, M.; Canetta, R.; Chylak, V.; Cohen, C. J.; Colombo, N.; Conte, P. F.; Crowther, D.; Edmonson, J. H.; Gennatas, C.; Gilbey, E.; Gore, M.; Guthrie, D.; Yeap, B. Y.

1998-01-01

The purpose of this systematic study was to provide an up to date and reliable quantitative summary of the relative benefits of various types of chemotherapy (non-platinum vs platinum, single-agent vs combination and carboplatin vs cisplatin) in the treatment of advanced ovarian cancer. Also, to investigate whether well-defined patient subgroups benefit more or less from cisplatin- or carboplatin-based therapy. Meta-analyses were based on updated individual patient data from all available randomized controlled trials (published and unpublished), including 37 trials, 5667 patients and 4664 deaths. The results suggest that platinum-based chemotherapy is better than non-platinum therapy, show a trend in favour of platinum combinations over single-agent platinum, and suggest that cisplatin and carboplatin are equally effective. There is no good evidence that cisplatin is more or less effective than carboplatin in any particular subgroup of patients. Images Figure 1 Figure 2 Figure 3 PMID:9836481

Synthesis and Analysis of the Structure, Diffusion and Cytotoxicity of Heterocyclic Platinum(IV) Complexes.

PubMed

Macias, Freddy J; Deo, Krishant M; Pages, Benjamin J; Wormell, Paul; Clegg, Jack K; Zhang, Yingjie; Li, Feng; Zheng, Gang; Sakoff, Jennette; Gilbert, Jayne; Aldrich-Wright, Janice R

2015-11-16

We have developed six dihydroxidoplatinum(IV) compounds with cytotoxic potential. Each derived from active platinum(II) species, these complexes consist of a heterocyclic ligand (HL) and ancillary ligand (AL) in the form [Pt(HL)(AL)(OH)2](2+), where HL is a methyl-functionalised variant of 1,10-phenanthroline and AL is the S,S or R,R isomer of 1,2-diaminocyclohexane. NMR characterisation and X-ray diffraction studies clearly confirmed the coordination geometry of the octahedral platinum(IV) complexes. The self-stacking of these complexes was determined using pulsed gradient stimulated echo nuclear magnetic resonance. The self-association behaviour of square planar platinum(II) complexes is largely dependent on concentration, whereas platinum(IV) complexes do not aggregate under the same conditions, possibly due to the presence of axial ligands. The cytotoxicity of the most active complex, exhibited in several cell lines, has been retained in the platinum(IV) form. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Palladium–platinum core-shell icosahedra with substantially enhanced activity and durability towards oxygen reduction

DOE PAGES

Wang, Xue; Choi, Sang-Il; Roling, Luke T.; ...

2015-07-02

Conformal deposition of platinum as ultrathin shells on facet-controlled palladium nanocrystals offers a great opportunity to enhance the catalytic performance while reducing its loading. Here we report such a system based on palladium icosahedra. Owing to lateral confinement imposed by twin boundaries and thus vertical relaxation only, the platinum overlayers evolve into a corrugated structure under compressive strain. For the core-shell nanocrystals with an average of 2.7 platinum overlayers, their specific and platinum mass activities towards oxygen reduction are enhanced by eight- and sevenfold, respectively, relative to a commercial catalyst. Density functional theory calculations indicate that the enhancement can bemore » attributed to the weakened binding of hydroxyl to the compressed platinum surface supported on palladium. After 10,000 testing cycles, the mass activity of the core-shell nanocrystals is still four times higher than the commercial catalyst. Ultimately, these results demonstrate an effective approach to the development of electrocatalysts with greatly enhanced activity and durability.« less

Microstructural Study on Oxidation Resistance of Nonmodified and Platinum Modified Aluminide Coating

NASA Astrophysics Data System (ADS)

Zagula-Yavorska, Maryana; Sieniawski, Jan

2014-03-01

Platinum electroplating layers (3 and 7 μm thick) were deposited on the surface of the Inconel 713 LC, CMSX 4, and Inconel 625 Ni-base superalloys. Diffusion treatment at 1050°C for 2 h under argon atmosphere was performed after electroplating. Diffusion treated samples were aluminized according to the low activity CVD process at 1050°C for 8 h. The nonmodified aluminide coatings consist of NiAl phase. Platinum modification let to obtain the (Ni,Pt)Al phase in coatings. The coated samples were subjected to cyclic oxidation testing at 1100°C. It was discovered that increase of the platinum electroplating thickness from 3 to 7 μm provides the improvement of oxidation resistance of aluminide coatings. Increase of the platinum thickness causes decreases in weight change and decreases in parabolic constant during oxidation. The platinum provides the pure Al2O3 oxide formation, slow growth oxide layer, and delay the oxide spalling during heating-cooling thermal cycles.

Biomonitoring of traffic police officers exposed to airborne platinum

PubMed Central

Iavicoli, I; Bocca, B; Petrucci, F; Senofonte, O; Carelli, G; Alimonti, A; Caroli, S

2004-01-01

Background: Over the past two decades there has been a substantial increase in environmental levels of palladium, platinum, and rhodium, the platinum group elements (PGEs), due to the widespread use of catalytic converters for automotive traction. Aim: To evaluate urinary platinum levels in occupationally exposed subjects. Methods: A total of 161 employees from the Rome City Police Force were studied; 103 were traffic police involved in controlling streets with an average flow of vehicles, while the remaining 58 were control subjects engaged only in office work. Platinum quantification in the urine samples of these subjects was carried out by sector field inductively coupled plasma mass spectrometry. Results: There were no statistically significant differences between platinum levels in the group of subjects engaged in traffic control and the control group (4.45 (2.42) ng/l v 4.56 (2.84) ng/l, respectively). Conclusions: Urinary levels were found to be higher than those reported for other urban populations, thus showing a progressive increase in human exposure to Pt. PMID:15208381

Synthesis of platinum nanowire networks using a soft template.

PubMed

Song, Yujiang; Garcia, Robert M; Dorin, Rachel M; Wang, Haorong; Qiu, Yan; Coker, Eric N; Steen, William A; Miller, James E; Shelnutt, John A

2007-12-01

Platinum nanowire networks have been synthesized by chemical reduction of a platinum complex using sodium borohydride in the presence of a soft template formed by cetyltrimethylammonium bromide in a two-phase water-chloroform system. The interconnected polycrystalline nanowires possess the highest surface area (53 +/- 1 m2/g) and electroactive surface area (32.4 +/- 3.6 m2/g) reported for unsupported platinum nanomaterials; the high surface area results from the small average diameter of the nanowires (2.2 nm) and the 2-10 nm pores determined by nitrogen adsorption measurements. Synthetic control over the network was achieved simply by varying the stirring rate and reagent concentrations, in some cases leading to other types of nanostructures including wormlike platinum nanoparticles. Similarly, substitution of a palladium complex for platinum gives palladium nanowire networks. A mechanism of formation of the metal nanowire networks is proposed based on confined metal growth within a soft template consisting of a network of swollen inverse wormlike micelles.

DNA polymerase η modulates replication fork progression and DNA damage responses in platinum-treated human cells

NASA Astrophysics Data System (ADS)

Sokol, Anna M.; Cruet-Hennequart, Séverine; Pasero, Philippe; Carty, Michael P.

2013-11-01

Human cells lacking DNA polymerase η (polη) are sensitive to platinum-based cancer chemotherapeutic agents. Using DNA combing to directly investigate the role of polη in bypass of platinum-induced DNA lesions in vivo, we demonstrate that nascent DNA strands are up to 39% shorter in human cells lacking polη than in cells expressing polη. This provides the first direct evidence that polη modulates replication fork progression in vivo following cisplatin and carboplatin treatment. Severe replication inhibition in individual platinum-treated polη-deficient cells correlates with enhanced phosphorylation of the RPA2 subunit of replication protein A on serines 4 and 8, as determined using EdU labelling and immunofluorescence, consistent with formation of DNA strand breaks at arrested forks in the absence of polη. Polη-mediated bypass of platinum-induced DNA lesions may therefore represent one mechanism by which cancer cells can tolerate platinum-based chemotherapy.

Polymer Nanocarriers to Enhance the Efficiency of Platinum-Based Chemotherapeutics

NASA Astrophysics Data System (ADS)

Callari, Manuela

The aim of this Thesis was to design and prepare polymer nanocarriers capable of encapsulating, carrying and delivering platinum-based chemotherapeutics. Polymer nanocarrier have been widely studied and employed as platinum drug delivery systems with the primary scope to overcome limitations presented by platinum-based chemotherapeutics. The conjugation of platinum onto polymers, however, presents some challenges, and, although there has been great progress in the field of drug delivery in the past years, to date only three polymer nanocarriers for platinum drugs have found their way to the clinic. In this Thesis, hydrophilic block copolymers were synthesised via reversible addition fragmentation chain transfer (RAFT) polymerisation or N-carboxyanhydride ring-opening polymerization (NCA-ROP). Upon attachment of a hydrophobic platinum drug the block copolymer becomes amphiphilic and can self-assemble in aqueous media into nanoparticles of different morphology depending on the block copolymer features. Spherical micelles consisting of a poly(methacrylic acid) core which conjugates and encapsulates the platinum chemotherapeutic and a hydrophilic shell made of sugar blocks were prepared and their biological activities compared in vitro. Among the sugars considered here, fructose based micelles showed promising results in terms of their targeting ability towards breast cancer cells. Consequently, fructose-shelled micelles were selected to explore the effect of different loading quantities of platinum drug. It was discovered that the amount of platinum in the core of the micelle highly influences the internal morphology of the micelle which, in turn, affects the micelle-cell interactions. Micelles with low dual drug loading had better cellular uptake and higher toxicity than the micelles with high drug loading, despite having the same fructose-based outer shell. Interestingly, this aspect had been neglected by literature so far, and is important to explore. Micelles made of a fructose shell were then compared to micelles with a non-targeting hydrophilic shell made of poly(ethylene glycol) methyl ether methacrylate (PEGMEMA). The aim was to compare the process of cellular uptake and the mechanism of platinum release inside the cell. For this scope, a fluorescent platinum drug was synthesised as a probing tool. Finally, a polymer vesicle based on PEG and poly(glutamic acid) was designed to co-deliver a platinum drug and the cancer inhibitor, paclitaxel, simultaneously. The two drugs have a synergistic effect when used in combination or co-delivered by the vesicles. Moreover, a viability study using multicellular tumour spheroids (MCTS) showed a significant decrease in cell proliferation when the MCTS were treated with single drug, a combination of free drugs and dual-drug loaded vesicles compared with untreated MCTS. An improvement is observed in the case of the dual-drug vesicles.

Bio-inspired routes for synthesizing efficient nanoscale platinum electrocatalysts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cha, Jennifer N.; Wang, Joseph

2014-08-31

The overall objective of the proposed research is to use fundamental advances in bionanotechnology to design powerful platinum nanocrystal electrocatalysts for fuel cell applications. The new economically-viable, environmentally-friendly, bottom-up biochemical synthetic strategy will produce platinum nanocrystals with tailored size, shape and crystal orientation, hence leading to a maximum electrochemical reactivity. There are five specific aims to the proposed bio-inspired strategy for synthesizing efficient electrocatalytic platinum nanocrystals: (1) isolate peptides that both selectively bind particular crystal faces of platinum and promote the nucleation and growth of particular nanocrystal morphologies, (2) pattern nanoscale 2-dimensional arrays of platinum nucleating peptides from DNA scaffolds,more » (3) investigate the combined use of substrate patterned peptides and soluble peptides on nanocrystal morphology and growth (4) synthesize platinum crystals on planar and large-area carbon electrode supports, and (5) perform detailed characterization of the electrocatalytic behavior as a function of catalyst size, shape and morphology. Project Description and Impact: This bio-inspired collaborative research effort will address key challenges in designing powerful electrocatalysts for fuel cell applications by employing nucleic acid scaffolds in combination with peptides to perform specific, environmentally-friendly, simultaneous bottom-up biochemical synthesis and patterned assembly of highly uniform and efficient platinum nanocrystal catalysts. Bulk synthesis of nanoparticles usually produces a range of sizes, accessible catalytic sites, crystal morphologies, and orientations, all of which lead to inconsistent catalytic activities. In contrast, biological systems routinely demonstrate exquisite control over inorganic syntheses at neutral pH and ambient temperature and pressures. Because the orientation and arrangement of the templating biomolecules can be precisely controlled, the nanocrystals boast a defined shape, morphology, orientation and size and are synthesized at benign reaction conditions. Adapting the methods of biomineralization towards the synthesis of platinum nanocrystals will allow effective control at a molecular level of the synthesis of highly active metal electrocatalysts, with readily tailored properties, through tuning of the biochemical inputs. The proposed research will incorporate many facets of biomineralization by: (1) isolating peptides that selectively bind particular crystal faces of platinum (2) isolating peptides that promote the nucleation and growth of particular nanocrystal morphologies (3) using two-dimensional DNA scaffolds to control the spatial orientation and density of the platinum nucleating peptides, and (4) combining bio-templating and soluble peptides to control crystal nucleation, orientation, and morphology. The resulting platinum nanocrystals will be evaluated for their electrocatalytic behavior (on common carbon supports) to determine their optimal size, morphology and crystal structure. We expect that such rational biochemical design will lead to highly uniform and efficient platinum nanocrystal catalysts for fuel cell applications.« less

[Forensic Application of HuaxiaTM Platinum Kit].

PubMed

Wang, Y L; Sheng, X; Li, M; Chen, Y L; Lin, Y; Chen, L Q

2017-04-01

To investigate the genetic polymorphism of 23 autosomal STR loci of Huaxia™ Platinum kit in Chinese Han population, and to evaluate the forensic efficiency of Huaxia™ Platinum kit. A total of 500 unrelated healthy individuals from Han population were genotyped with Huaxia™ Platinum kit. The frequency distribution and the parameter of population genetics of STR loci were analysed statistically. Huaxia™ Platinum kit was compared with other 7 commercial STR kits commonly seen at home and abroad in the number of STR loci, interior label, fluorescent mark, total number of alleles in Ladder and system effectiveness. All the 23 autosomal STR loci were consistent with Hardy-Weinberg equilibrium （ P >0.05）. The discrimination power was 0.791 5-0.986 2. The polymorphism information content （PIC） was 0.559 0-0.914 0. The combined discrimination power （CDP） was 1-4.1×10⁻²⁸, while combined probability of paternity exclusion in trio （CPET） and in duo （CPED） were 1-4.1×10⁻¹⁰ and 1-8.4×10⁻⁷, respectively. Compared with other 7 kits, Huaxia™ Platinum kit contained the most number of alleles within the Ladder. All the 23 autosomal STR loci of Huaxia™ Platinum kit with highly polymorphic in Han population can be used for paternity testing and individual identification. Compared with other 7 kits, it appears that Huaxia™ Platinum kit can provide more genetic information. Copyright© by the Editorial Department of Journal of Forensic Medicine

ENVIRONMENTAL TECHNOLOGY VERIFICATION REPORT, HVLP COATING EQUIPMENT, SHARPE MANUFACTURING COMPANY PLATINUM 2012 HVLP SPRAY GUN

EPA Science Inventory

This report presents the results of the verification test of the Sharpe Platinum 2013 high-volume, low-pressure gravity-feed spray gun, hereafter referred to as the Sharpe Platinum, which is designed for use in automotive refinishing. The test coating chosen by Sharpe Manufacturi...

Measurements of thermoelectric power in annealed and quenched gold-platinum alloys

NASA Technical Reports Server (NTRS)

Baarle, C. V.; Huebener, R. P.

1969-01-01

Report gives measurements of absolute thermoelectric powers of dilute gold-platinum alloys and influence of quenched-in lattice vacancies on their thermoelectric powers. It investigates phonon-drag component of thermoelectric power as a function of platinum concentration, and change in phonon-drag thermoelectric power by lattice vacancies.

C-H activation of imidazolium salts by Pt(0) at ambient temperature: synthesis of hydrido platinum bis(carbene) compounds.

PubMed

Duin, Marcel A; Clement, Nicolas D; Cavell, Kingsley J; Elsevier, Cornelis J

2003-02-07

A zerovalent platinum(carbene) complex with two monoalkene ligands, which is able to activate C-H bonds of imidazolium salts at room temperature to yield isolable hydrido platinum(II) bis(carbene) compounds, has been synthesised for the first time.

78 FR 11954 - Revised Pricing Grid for Gold and Platinum Products

Federal Register 2010, 2011, 2012, 2013, 2014

2013-02-20

... DEPARTMENT OF THE TREASURY United States Mint Revised Pricing Grid for Gold and Platinum Products AGENCY: United States Mint, Department of the Treasury. ACTION: Notice. SUMMARY: The United States Mint is announcing a revised pricing grid for 2013 gold and platinum products. Please see the grid...

Exhaust system having a gold-platinum group metal catalyst

DOEpatents

Ragle, Christie Susan [Havana, IL; Silver, Ronald G [Peoria, IL; Zemskova, Svetlana Mikhailovna [Edelstein, IL; Eckstein, Colleen J [Metamora, IL

2011-12-06

A method of providing an exhaust treatment device is disclosed. The method includes applying a catalyst including gold and a platinum group metal to a particulate filter. The concentration of the gold and the platinum group metal is sufficient to enable oxidation of carbon monoxide and nitric oxide.

78 FR 60270 - Platinum Energy, LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes Request...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-10-01

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. ER13-2436-000] Platinum Energy, LLC; Supplemental Notice That Initial Market- Based Rate Filing Includes Request for Blanket Section 204 Authorization This is a supplemental notice in the above-referenced proceeding, of Platinum...

Exhaust system having a gold-platinum group metal catalyst

DOEpatents

Ragle, Christie Susan; Silver, Ronald G.; Zemskova, Svetlana Mikhailovna; Eckstein, Colleen J.

2012-08-07

A method of providing an exhaust treatment device is disclosed. The method includes applying a catalyst including gold and a platinum group metal to a particulate filter. The concentration of the gold and the platinum group metal is sufficient to enable oxidation of carbon monoxide and nitric oxide.

Evaluation of novel trans-sulfonamide platinum complexes against tumor cell lines.

PubMed

Pérez, Carlos; Díaz-García, C Vanesa; Agudo-López, Alba; del Solar, Virginia; Cabrera, Silvia; Agulló-Ortuño, M Teresa; Navarro-Ranninger, Carmen; Alemán, José; López-Martín, José A

2014-04-09

Platinum-based drugs, mainly cisplatin, are employed for the treatment of solid malignancies. However, cisplatin treatment often results in the development of chemoresistance, leading to therapeutic failure. Here, the antitumor activity of different trans-sulfonamide platinum complexes in a panel of human cell lines is presented. The cytotoxicity profiles and cell cycle analyses of these platinum sulfonamide complexes were different from those of cisplatin. These studies showed that complex 2b with cyclohexyldiamine and dansyl moieties had the best antitumoral activities. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

Improving Platinum Efficiency:. Nanoformulations

NASA Astrophysics Data System (ADS)

Carmona, Rolando; Liang, Xing-Jie

2013-09-01

Platinum-based drugs continue being the support of therapy for many different kinds of cancer. Cancer patients often present irreversible resistance to platinum after repeated treatment in clinic. Despite of the great efforts, chemoresistance (intrinsic or acquired) already is a major limitation in the management of this disease. In this review, the last current research on cancer characteristic and cancer chemical resistance is summarized, the major and novel strategies to reverse resistance to platinum- based drugs are discussed and this article mainly emphasizes the contribution of nanotechnology and combination therapies to target sites and reduce the cancer chemoresistance.

The RSC Faraday prize lecture of 1989 on platinum.

PubMed

Thomas, John Meurig

2017-08-25

In 1861, Michael Faraday gave one of his last Friday Evening Discourses at the Royal Institution of Great Britain, London, on platinum, which he described as "this beautiful, magnificent and valuable metal". More than a hundred and twenty years later (in 1989), the author re-enacted, at the Royal Institution, many of the demonstrations that Faraday carried out in his memorable Discourse. This article outlines many of Faraday's views on, and experiments with, platinum. It also describes the continuing importance and utilization of platinum, both as perceived in 1989 and from present perspectives.

Evolution of platinum resistance in high-grade serous ovarian cancer.

PubMed

Cooke, Susanna L; Brenton, James D

2011-11-01

High-grade serous ovarian cancers account for most ovarian-cancer mortality. Although this disease initially responds well to platinum-based chemotherapy, relapse and progression to chemotherapy resistance are frequently seen. Time to relapse after first-line therapy is a predictor of response to secondary platinum treatment: more than 12 months is associated with high chance of a secondary response, whereas relapses within 6 months generally indicate platinum resistance. In this Personal View we discuss whether patterns of response, relapse, and the development of drug resistance in high-grade serous ovarian cancers are related to distinct underlying molecular and cellular biological characteristics. In particular, we propose that rapid relapse with platinum-resistant disease is due to minor subpopulations of intrinsically resistant cancer cells at presentation. Copyright © 2011 Elsevier Ltd. All rights reserved.

Fluoropyrimidine and platinum toxicity pharmacogenetics: an umbrella review of systematic reviews and meta-analyses.

PubMed

Campbell, Jared M; Bateman, Emma; Peters, Micah Dj; Bowen, Joanne M; Keefe, Dorothy M; Stephenson, Matthew D

2016-03-01

Fluoropyrimidine (FU) and platinum-based chemotherapies are greatly complicated by their associated toxicities. This umbrella systematic review synthesized all systematic reviews that investigated associations between germline variations and toxicity, with the aim of informing personalized medicine. Systematic reviews are important in pharmacogenetics where false positives are common. Four systematic reviews were identified for FU-induced toxicity and three for platinum. Polymorphisms of DPYD and TYMS, but not MTHFR, were statistically significantly associated with FU-induced toxicity (although only DPYD had clinical significance). For platinum, GSTP1 was found to not be associated with toxicity. This umbrella systematic review has synthesized the best available evidence on the pharmacogenetics of FU and platinum toxicity. It provides a useful reference for clinicians and identifies important research gaps.

Cytotoxicity of cyclometalated platinum complexes based on tridentate NCN and CNN-coordinating ligands: remarkable coordination dependence.

PubMed

Vezzu, Dileep A K; Lu, Qun; Chen, Yan-Hua; Huo, Shouquan

2014-05-01

A series of cyclometalated platinum complexes with diverse coordination patterns and geometries were screened for their anticancer activity. It was discovered that the N^C^N-coordinated platinum complex based on 1,3-di(pyridyl)benzene displayed much higher cytotoxicity against human lung cancer cells NCI-H522, HCC827, and NCI-H1299, and human prostate cancer cell RV1 than cisplatin. In a sharp contrast, the C^N^N-coordinated platinum complex based on 6-phenyl-2,2'-bipyridine was ineffective on these cancer cells. This remarkable difference in cytotoxicity displayed by N^C^N- and C^N^N-coordinated platinum complexes was related to the trans effect of the carbon donor in the cyclometalated platinum complexes, which played a crucial role in facilitating the dissociation of the chloride ligand to create an active binding site. The DNA binding was studied for the N^C^N-coordinated platinum complex using electrophoresis and emission titration. The cellular uptake observed by fluorescent microscope showed that the complex is largely concentrated in the cytoplasm. The possible pathways for the cell apoptosis were studied by western blot analysis and the activation of PARP via caspase 7 was observed. Copyright © 2014 Elsevier Inc. All rights reserved.

Water-gas shift reaction on alumina-supported Pt-CeO x catalysts prepared by supercritical fluid deposition

DOE PAGES

Deal, Jacob W.; Le, Phong; Corey, C. Blake; ...

2016-08-25

Alumina-supported platinum catalysts, both with and without ceria, were prepared by supercritical fluid deposition and evaluated for activity for water-gas shift reaction. The organometallic precursor, platinum(II) acetylacetonate, was deposited from solution in supercritical carbon dioxide. Analysis of the catalysts by high resolution scanning transmission electron microscopy indicated that platinum was present in the form of highly dispersed metal nanoparticles. Pretreatment of the alumina-supported ceria in hydrogen prior to the deposition of the platinum precursor resulted in more platinum nucleated on ceria than non-pretreated alumina-supported ceria but varied in both particle size and structure. The ceria-containing catalyst that was not pretreatedmore » exhibited a more uniform particle size, and the Pt particles were encapsulated in crystalline ceria. Reaction rate measurements showed that the catalyst was more active for water-gas shift, with reaction rates per mass of platinum that exceeded most literature values for water-gas shift reaction on Pt-CeO x catalysts. The high activity was attributed to the significant fraction of platinum/ceria interfacial contact. We found that these results show the promise of supercritical fluid deposition as a scalable means of synthesizing highly active supported metal catalysts that offer efficient utilization of precious metals.« less

Irradiation of DNA loaded with platinum containing molecules by fast atomic ions C(6+) and Fe(26+).

PubMed

Usami, N; Kobayashi, K; Furusawa, Y; Frohlich, H; Lacombe, S; Sech, C Le

2007-09-01

In order to study the role of the Linear Energy Transfer (LET) of fast atomic ions in platinum-DNA complexes inducing breaks, DNA Plasmids were irradiated by C(6+) and Fe(26+) ions. DNA Plasmids (pBR322) loaded with different amounts of platinum contained in a terpyridine-platinum molecule (PtTC) were irradiated by C(6+) ions and Fe(26+) ions. The LET values ranged between 13.4 keV/microm and 550 keV/microm. In some experiments, dimethyl sulfoxide (DMSO) was added. In all experiments, a significant increase in DNA strand breaks was observed when platinum was present. The yield of breaks induced per Gray decreased when the LET increased. The yield of single and double strand breaks per plasmid per track increased with the LET, indicating that the number of DNA breaks per Gray was related to the number of tracks through the medium. These findings show that more DNA breaks are induced by atomic ions when platinum is present. This effect increases for low LET heavy atoms. As DSB induction may induce cell death, these results could open new perspectives with the association of hadrontherapy and chemotherapy. Thus the therapeutic index might be improved by loading the tumour with platinum salts.

Ferroxidase activity of apoferritin is increased in the presence of platinum nanoparticles.

PubMed

Sennuga, Afolake; van Marwijk, Jacqueline; Whiteley, Chris G

2012-01-27

The ferroxidase activity of horse spleen apoferritin (HSAF) is increased by nine-fold in the presence of platinum nanoparticles. HSAF was mixed with varying concentrations of K2PtCl4 followed by a 20-fold concentration of sodium borohydride to afford Pt:HSAF nanoparticle complexes in a ratio of between 1:250 and 1:4000. Typical colour changes, from colourless or pale yellow to brown, occurred that were dependent on the amount of platinum present. These complexes were characterized by UV/vis, inductively coupled plasma optical emission spectroscopy, Fourier transform infrared, transmission electron microscopy and energy dispersive x-ray spectroscopy. Transmission electron microscopy analysis revealed that the size of nanoparticles increased as the molar ratio of platinum to HSAF increased with an average size diameter of 2-6 nm generated with HSAF:platinum molar ratios of 1:250-1:4000. Fourier transform infrared spectroscopy (FTIR) spectra showed no distinct changes in the structure of HSAF but confirmed that the nanoparticles were attached to the protein. The effect of platinum nanoparticles on the ferroxidase activity of HSAF showed a specific activity of 360 ρmol min(-1) mg(-1), (nine-fold increase over the control) at the molar ratio of HSAF:platinum nanoparticles of 1:1000.

Exosomes as mediators of platinum resistance in ovarian cancer.

PubMed

Crow, Jennifer; Atay, Safinur; Banskota, Samagya; Artale, Brittany; Schmitt, Sarah; Godwin, Andrew K

2017-02-14

Exosomes have been implicated in the cell-cell transfer of oncogenic proteins and genetic material. We speculated this may be one mechanism by which an intrinsically platinum-resistant population of epithelial ovarian cancer (EOC) cells imparts its influence on surrounding tumor cells. To explore this possibility we utilized a platinum-sensitive cell line, A2780 and exosomes derived from its resistant subclones, and an unselected, platinum-resistant EOC line, OVCAR10. A2780 cells demonstrate a ~2-fold increase in viability upon treatment with carboplatin when pre-exposed to exosomes from platinum-resistant cells as compared to controls. This coincided with increased epithelial to mesenchymal transition (EMT). DNA sequencing of EOC cell lines revealed previously unreported somatic mutations in the Mothers Against Decapentaplegic Homolog 4 (SMAD4) within platinum-resistant cells. A2780 cells engineered to exogenously express these SMAD4 mutations demonstrate up-regulation of EMT markers following carboplatin treatment, are more resistant to carboplatin, and release exosomes which impart a ~1.7-fold increase in resistance in naive A2780 recipient cells as compared to controls. These studies provide the first evidence that acquired SMAD4 mutations enhance the chemo-resistance profile of EOC and present a novel mechanism in which exchange of tumor-derived exosomes perpetuates an EMT phenotype, leading to the development of subpopulations of platinum-refractory cells.

Mannose-conjugated platinum complexes reveals effective tumor targeting mediated by glucose transporter 1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Ran; Li, Hong; Gao, Xiangqian

Despite numerous studies that report the glucose derived glycoconjugates as antitumor candidates, using mannose as sugar motif for specific tumor targeting remains less studied. In this research, two novel mannose-conjugated platinum complexes 4a and 4b that target the Warburg effect were designed, synthesized and evaluated for their antitumor activities in vitro and in vivo. Compared with oxaliplatin, both complexes exhibited substantial enhancement in water solubility as well as excellent or comparative cytotoxicity in six human cancer cell lines. Cytotoxicity assessments on Glucose transporter 1 (GLUT1) down-regulated or overexpressed cells and platinum accumulation study demonstrated that cellular uptake of compound 4a was regulatedmore » by GLUT1. In particular, 4a induced apoptosis in HT29 cells by suppressing expression of Bcl-2 and Bcl-XL, which preliminary explained the mechanism origin of antitumor effect. As indicated by its maximum tolerated dose-finding assay and in vivo anticancer activity, compound 4a exhibits better safety and efficacy profile than oxaliplatin. The findings of this study indicate the possibility of subjecting mannose-conjugated platinum complexes as lead compounds for further preclinical evaluation. - Highlights: • Mannose-conjugated platinum complexes were designed and synthesized to target glucose transporter 1(GLUT1). • Mannose-conjugated platinum complex 4a transport across cancer cells through GLUT1. • Mannose-conjugated platinum complex 4a induce apoptosis in HT29 cells. • Mannose-conjugated platinum complex 4a antitumor activities were more potent than those of oxaliplatin.« less

Rationally designed oxaliplatin-nanoparticle for enhanced antitumor efficacy

PubMed Central

Paraskar, Abhimanyu; Soni, Shivani; Roy, Bhaskar; Papa, Anne-Laure; Sengupta, Shiladitya

2012-01-01

Nanoscale drug delivery vehicles have been extensively studied as carriers for cancer chemotherapeutics. However the formulation of platinum chemotherapeutics in nanoparticles has been a challenge arising from their physicochemical properties. There are only few reports describing oxaliplatin nanoparticles. In this study, we derivatized the monomeric units of a polyisobutylene maleic acid copolymer with glucosamine, which chelates trans-1,2-diaminocyclohexane (DACH) platinum (II) through a novel monocarboxylato and O→Pt coordination linkage. At a specific polymer to platinum ratio, the complex self assembled into a nanoparticle, where the polymeric units act as the leaving group, releasing DACH-platinum in sustained pH-dependent manner. Sizing was done using dynamic light scatter and electron microscopy. The nanoparticles were evaluated for efficacy in vitro and in vivo. Biodistribution was quantified using inductive-coupled plasma-atomic absorption spectroscopy (ICP-AAS). The PIMA-GA-DACH-platinum nanoparticle was found to be more active than free oxaliplatin in vitro. In vivo, the nanoparticles resulted in greater tumor inhibition than oxaliplatin (equivalent to 5mg/kg platinum dose) with minimal nephrotoxicity or body weight loss. ICP-AAS revealed significant preferential tumor accumulation of platinum with reduced biodistribution to the kidney or liver following PIMA-GA-DACH-platinum nanoparticle administration as compared with free oxaliplatin. These results indicate that the rational engineering of a novel polymeric nanoparticle inspired by the bioactivation of oxaliplatin results in increased antitumor potency with reduced systemic toxicity compared with the parent cytotoxic. Rational design can emerge as an exciting strategy in the synthesis of nanomedicines for cancer chemotherapy. PMID:22275055

Collective Behavior of Water on Platinum

NASA Astrophysics Data System (ADS)

Limmer, David; Willard, Adam; Chandler, David

2012-02-01

We present the results of molecular dynamics simulations of a interface between water and a platinum electrode. Using importance sampling techniques we probe a variety of collective phenomenon that emerge at the interface. We consider platinum electrodes with two different geometries and discuss how different behaviors result from a competition between geometrical frustration and favorable local interactions.

Platinum Publications, November 27, 2014 – February 26, 2015 | Poster

Cancer.gov

Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from

Platinum Publications as of March 6, 2014 | Poster

Cancer.gov

Platinum Publications are selected from articles by NCI at Frederick scientists published in 21 prestigious science journals. This list represents new publications generated from PubMed as of the date shown above. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from among the most

Platinum Publications, October 30 – November 26, 2014 | Poster

Cancer.gov

Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from

Platinum Publications, June 1–June 30, 2016 | Poster

Cancer.gov

Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from

Platinum Publications, March 27 – April 30, 2015 | Poster

Cancer.gov

Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from

Platinum Publications, January 1–March 31, 2016 | Poster

Cancer.gov

Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from

Failure mechanism characterization of platinum alloy

NASA Technical Reports Server (NTRS)

Rosen, J. M.; Mcfarlen, W. T.

1986-01-01

This article describes procedures and results of testing performed on a platinum/10-percent rhodium, thin-wall tubular product. The purpose of the testing was to develop exemplar SEM fractographs to be used to characterize failures under various environmental conditions. Conditions evaluated for the platinum alloys included high temperature, hydrogen environment, braze metal contamination, and cyclic loading.

Platinum Publications as of September 25, 2014 | Poster

Cancer.gov

Platinum Publications are selected from articles by NCI at Frederick scientists published in 21 prestigious science journals. This list represents new publications generated from PubMed as of the date shown above. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from among the most

Platinum Publications as of December 3, 2013 | Poster

Cancer.gov

Platinum Publications are selected from articles by NCI at Frederick scientists published in 21 prestigious science journals. This list represents new publications generated from PubMed as of the date shown above. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from among the most

Platinum Publications as of May 29, 2014 | Poster

Cancer.gov

Platinum Publications are selected from articles by NCI at Frederick scientists published in 21 prestigious science journals. This list represents new publications generated from PubMed as of the date shown above. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from among the most

Platinum Publications as of April 30, 2014 | Poster

Cancer.gov

Platinum Publications are selected from articles by NCI at Frederick scientists published in 21 prestigious science journals. This list represents new publications generated from PubMed as of the date shown above. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from among the most

Platinum Publications as of June 25, 2014 | Poster

Cancer.gov

Platinum Publications are selected from articles by NCI at Frederick scientists published in 21 prestigious science journals. This list represents new publications generated from PubMed as of the date shown above. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from among the most

76 FR 8627 - Revision of Class E Airspace; Platinum, AK

Federal Register 2010, 2011, 2012, 2013, 2014

2011-02-15

...-1105; Airspace Docket No. 10-AAL-20] Revision of Class E Airspace; Platinum, AK AGENCY: Federal... Platinum, AK, to accommodate the addition of a Standard Instrument Approach Procedure (SIAP), at the... 7th Avenue, Box 14, Anchorage, AK 99513-7587; telephone number (907) 271-5898; fax: (907) 271-2850; e...

Platinum Publications, May 1 – June 25, 2015 | Poster

Cancer.gov

Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from

Platinum Publications, October 30–December 31, 2015 | Poster

Cancer.gov

Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from

Platinum Publications, February 27 – March 26, 2015 | Poster

Cancer.gov

Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from

Platinum Publications, July 29–September 29, 2016 | Poster

Cancer.gov

Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from

Platinum Publications, July 1–July 28, 2016 | Poster

Cancer.gov

Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from

Platinum Publications, July 31–September 30, 2015 | Poster

Cancer.gov

Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from

Platinum Publications, October 28–November 30, 2016 | Poster

Cancer.gov

Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from

Platinum Publications, June 26–July 30, 2015 | Poster

Cancer.gov

Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from

Platinum Publications, September 26 – October 29, 2014 | Poster

Cancer.gov

Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from

Platinum Publications, September 30–October 27, 2016 | Poster

Cancer.gov

Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from

Platinum Publications, October 1–29, 2015 | Poster

Cancer.gov

Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from

The Chemical and Biological Effects of cis-Dichlorodiammineplatinum (II), an Antitumor Agent, on DNA

PubMed Central

Munchausen, Linda L.

1974-01-01

cis-Dichlorodiammineplatinum (II) binds irreversibly to the bases in DNA; the amount of platinum complex bound can be determined from changes in the ultraviolet absorption spectrum. As the ratio of platinum to phosphate is increased, an increasing inactivation of bacterial transforming DNA is observed. At a ratio that corresponds to spectrometric saturation, transforming activity is inactivated >105-fold. The trans isomer of the platinum complex, which is not effective against tumors, induces a similar inactivation of transforming DNA but with half the efficiency, indicating a different mode of binding. The sensitivity to inactivation by cis isomer varies slightly with the genetic marker assayed but is not dependent on the excision repair system. Uptake of DNA by competent cells is unaffected by bound platinum complex; however, integration of platinum-bound transforming DNA into the host genome decreases as the mole fraction of platinum increases. This loss of integration parallels the decreased transforming activity of the DNA. Although the drug induces interstrand crosslinks in DNA in vitro, these crosslinks are relatively rare events and cannot account for the observed inactivation. PMID:4548188

Clinical development of platinum complexes in cancer therapy: an historical perspective and an update.

PubMed

Lebwohl, D; Canetta, R

1998-09-01

The vast amount of basic research on platinum coordination complexes has produced, over the past 25 years, several thousand new molecules for preclinical screening and 28 compounds which have entered clinical development. The goals of these research activities have been to identify compounds with superior efficacy, reduced toxicity, lack of cross-resistance or improved pharmacological characteristics as compared with the parent compound, cisplatin. After the remarkable therapeutic effects of cisplatin had been established, only a few other platinum compounds succeeded in reaching general availability. Whereas carboplatin is an analogue with an improved therapeutic index (mostly driven by reduced organ toxicity) over that of cisplatin, new compounds clearly more active than or non-cross-resistant with cisplatin have not yet been identified. The platinum analogues that remain under investigation are focusing on expanding the utilisation of platinum therapy to tumour types not usually treated with, or responsive to, cisplatin or carboplatin. In addition, novel routes of administration constitute another avenue of research. The clinical development of platinum coordination complexes, with emphasis on those compounds still under active development, is reviewed.

Structures of 38-atom gold-platinum nanoalloy clusters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ong, Yee Pin; Yoon, Tiem Leong; Lim, Thong Leng

2015-04-24

Bimetallic nanoclusters, such as gold-platinum nanoclusters, are nanomaterials promising wide range of applications. We perform a numerical study of 38-atom gold-platinum nanoalloy clusters, Au{sub n}Pt{sub 38−n} (0 ≤ n ≤ 38), to elucidate the geometrical structures of these clusters. The lowest-energy structures of these bimetallic nanoclusters at the semi-empirical level are obtained via a global-minimum search algorithm known as parallel tempering multi-canonical basin hopping plus genetic algorithm (PTMBHGA), in which empirical Gupta many-body potential is used to describe the inter-atomic interactions among the constituent atoms. The structures of gold-platinum nanoalloy clusters are predicted to be core-shell segregated nanoclusters. Gold atomsmore » are observed to preferentially occupy the surface of the clusters, while platinum atoms tend to occupy the core due to the slightly smaller atomic radius of platinum as compared to gold’s. The evolution of the geometrical structure of 38-atom Au-Pt clusters displays striking similarity with that of 38-atom Au-Cu nanoalloy clusters as reported in the literature.« less

A brief review of the management of platinum-resistant-platinum-refractory ovarian cancer.

PubMed

Oronsky, Bryan; Ray, Carolyn M; Spira, Alexander I; Trepel, Jane B; Carter, Corey A; Cottrill, Hope M

2017-06-01

Ovarian cancer, which ranks fifth in cancer deaths among women, is the most lethal gynecologic malignancy. Epithelial ovarian cancer (EOC) is the most common histologic type, with the 5-year survival for all stages estimated at 45.6%. This rate increases to more than 70% in the minority of patients who are diagnosed at an early stage, but declines to 35% in the vast majority of patients diagnosed at advanced stage. Recurrent EOC is incurable. Platinum sensitivity (or lack thereof) is a major determinant of prognosis. The current standard treatment is primary surgery followed by platinum-based chemotherapy. In recurrent platinum-resistant/platinum-refractory EOC, sequential single-agent salvage chemotherapy is superior to multiagent chemotherapy. Multiagent regimens increase toxicity without clear benefit; however, no preferred sequence of single agents is recommended. The impact of targeted therapies and immunotherapies on progression-free survival and overall survival, which remains dismal, is under active investigation. Currently, clinical trials offer the best hope for the development of a new treatment paradigm in this recalcitrant disease.

Influence of Pb 2+ ions in the H 2 oxidation on Pt catalyzed hydrogen diffusion anodes in sulfuric acid: presence of oscillatory phenomena

NASA Astrophysics Data System (ADS)

Expósito, E.; Sánchez-Sánchez, C. M.; Solla-Gullón, J.; Montiel, V.

The influence of Pb 2+ ions in sulfuric acid medium on the behavior of a platinum catalyzed hydrogen diffusion electrode (HDE) in a filter press reactor has been studied. A voltammetric study of the H 2 oxidation reaction on a polyoriented platinum electrode and a platinum rotating disk electrode (RDE) in presence of lead ions in solution has also been carried out. Potential oscillations were found in galvanostatic experiments of H 2 oxidation using a HDE catalyzed with platinum when Pb 2+ ions are present in solution. This oscillatory phenomenon was also observed when hydrogen oxidation was carried out in presence of Pb 2+ ions using a platinum RDE. The oscillatory behavior observed has been attributed to an adsorption-oxidation-desorption process of lead on the platinum surface. Due to the low solubility of Pb 2+ in sulfuric acid, at high values of coverage, lead is oxidised to insoluble lead sulfate that blocks the Pt surface. The coupling of the dissolution of lead sulfate and the Pb electrochemical adsorption-oxidation processes cause the oscillatory phenomenon.

Role of bonding mechanisms during transfer hydrogenation reaction on heterogeneous catalysts of platinum nanoparticles supported on zinc oxide nanorods

NASA Astrophysics Data System (ADS)

Al-Alawi, Reem A.; Laxman, Karthik; Dastgir, Sarim; Dutta, Joydeep

2016-07-01

For supported heterogeneous catalysis, the interface between a metal nanoparticle and the support plays an important role. In this work the dependency of the catalytic efficiency on the bonding chemistry of platinum nanoparticles supported on zinc oxide (ZnO) nanorods is studied. Platinum nanoparticles were deposited on ZnO nanorods (ZnO NR) using thermal and photochemical processes and the effects on the size, distribution, density and chemical state of the metal nanoparticles upon the catalytic activities are presented. The obtained results indicate that the bonding at Pt-ZnO interface depends on the deposition scheme which can be utilized to modulate the surface chemistry and thus the activity of the supported catalysts. Additionally, uniform distribution of metal on the catalyst support was observed to be more important than the loading density. It is also found that oxidized platinum Pt(IV) (platinum hydroxide) provided a more suitable surface for enhancing the transfer hydrogenation reaction of cyclohexanone with isopropanol compared to zero valent platinum. Photochemically synthesized ZnO supported nanocatalysts were efficient and potentially viable for upscaling to industrial applications.

Platinum-ruthenium-palladium fuel cell electrocatalyst

DOEpatents

Gorer, Alexander

2006-02-07

A catalyst suitable for use in a fuel cell, especially as an anode catalyst, that contains platinum at a concentration that is between about 20 and about 60 atomic percent, ruthenium at a concentration that is between about 20 and about 60 atomic percent, palladium at a concentration that is between about 5 and about 45 atomic percent, and having an atomic ratio of platinum to ruthenium that is between about 0.7 and about 1.2. Alternatively, the catalyst may contain platinum at a concentration that is between about 25 and about 50 atomic percent, ruthenium at a concentration that is between about 25 and about 55 atomic percent, palladium at a concentration that is between about 5 and about 45 atomic percent, and having a difference between the concentrations of ruthenium and platinum that is no greater than about 20 atomic percent.

Non-traditional platinum compounds for improved accumulation, oral bioavailability, and tumor targeting.

PubMed

Lovejoy, Katherine S; Lippard, Stephen J

2009-12-28

The five platinum anticancer compounds currently in clinical use conform to structure-activity relationships formulated (M. J. Cleare and J. D. Hoeschele, Bioinorg. Chem., 1973, 2, 187-210) shortly after the discovery that cis-diamminedichloroplatinum(II), cisplatin, has antitumor activity in mice. These compounds are neutral platinum(II) species with two am(m)ine ligands or one bidentate chelating diamine and two additional ligands that can be replaced by water through aquation reactions. The resulting cations ultimately form bifunctional adducts on DNA. Information about the chemistry of these platinum compounds and correlations of their structures with anticancer activity have provided guidance for the design of novel anticancer drug candidates based on the proposed mechanisms of action. This article discusses advances in the synthesis and evaluation of such non-traditional platinum compounds, including cationic and tumor-targeting constructs.

Synthesis of platinum nanowheels using a bicellar template.

PubMed

Song, Yujiang; Dorin, Rachel M; Garcia, Robert M; Jiang, Ying-Bing; Wang, Haorong; Li, Peng; Qiu, Yan; van Swol, Frank; Miller, James E; Shelnutt, John A

2008-09-24

Disk-like surfactant bicelles provide a unique meso-structured reaction environment for templating the wet-chemical reduction of platinum(II) salt by ascorbic acid to produce platinum nanowheels. The Pt wheels are 496 +/-55 nm in diameter and possess thickened centers and radial dendritic nanosheets (about 2-nm in thickness) culminating in flared dendritic rims. The structural features of the platinum wheels arise from confined growth of platinum within the bilayer that is also limited at edges of the bicelles. The size of CTAB/FC7 bicelles is observed to evolve with the addition of Pt(II) complex and ascorbic acid. Synthetic control is demonstrated by varying the reaction parameters including metal salt concentration, temperature, and total surfactant concentration. This study opens up opportunities for the use of other inhomogeneous soft templates for synthesizing metals, metal alloys, and possibly semiconductors with complex nanostructures.

Population differences in platinum toxicity as a means to identify novel genetic susceptibility variants

PubMed Central

O'Donnell, Peter H.; Gamazon, Eric; Zhang, Wei; Stark, Amy L.; Kistner-Griffin, Emily O.; Huang, R. Stephanie; Dolan, M. Eileen

2010-01-01

Objectives Clinical studies show that Asians (ASN) are more susceptible to toxicities associated with platinum-containing regimens. We hypothesized that studying ASN as an `enriched phenotype' population could enable the discovery of novel genetic determinants of platinum susceptibility. Methods Using well-genotyped lymphoblastoid cell lines from the HapMap, we determined cisplatin and carboplatin cytotoxicity phenotypes (IC50s) for ASN, Caucasians (CEU), and Africans (YRI). IC50s were used in genome-wide association studies. Results ASN were most sensitive to platinums, corroborating clinical findings. ASN genome-wide association studies produced 479 single-nucleotide polymorphisms (SNPs) associating with cisplatin susceptibility and 199 with carboplatin susceptibility (P<10−4). Considering only the most significant variants (P< 9.99 × 10−6), backwards elimination was then used to identify reduced-model SNPs, which robustly described the drug phenotypes within ASN. These SNPs comprised highly descriptive genetic signatures of susceptibility, with 12 SNPs explaining more than 95% of the susceptibility phenotype variation for cisplatin, and eight SNPs approximately 75% for carboplatin. To determine the possible function of these variants in ASN, the SNPs were tested for association with differential expression of target genes. SNPs were highly associated with the expression of multiple target genes, and notably, the histone H3 family was implicated for both drugs, suggesting a platinum-class mechanism. Histone H3 has repeatedly been described as regulating the formation of platinum-DNA adducts, but this is the first evidence that specific genetic variants might mediate these interactions in a pharmacogenetic manner. Finally, to determine whether any ASN-identified SNPs might also be important in other human populations, we interrogated all 479/199 SNPs for association with platinum susceptibility in an independent combined CEU/YRI population. Three unique SNPs for cisplatin and 10 for carboplatin replicated in CEU/YRI. Conclusion Enriched `platinum susceptible' populations can be used to discover novel genetic determinants governing interindividual platinum chemotherapy susceptibility. PMID:20393316

Impact of Long-Term Serum Platinum Concentrations on Neuro- and Ototoxicity in Cisplatin-Treated Survivors of Testicular Cancer

PubMed Central

Sprauten, Mette; Darrah, Thomas H.; Peterson, Derick R.; Campbell, M. Ellen; Hannigan, Robyn E.; Cvancarova, Milada; Beard, Clair; Haugnes, Hege S.; Fosså, Sophie D.; Oldenburg, Jan; Travis, Lois B.

2012-01-01

Purpose Cisplatin-induced neurotoxicity and ototoxicity (NTX) are important adverse effects after chemotherapy for testicular cancer (TC). Although serum platinum is measurable years after therapy, its impact on NTX has not been evaluated. Patients and Methods In all, 169 cisplatin-treated survivors of TC provided blood samples at Survey I and reported NTX during Survey I (1998-2002) and Survey II (2007-2008). Serum platinum was quantified by inductively coupled plasma mass spectrometry. Patient-reported outcomes were evaluated with the Scale for Chemotherapy-Induced Neurotoxicity (SCIN), regarding the extent of symptom bother as 0, “not at all”; 1, “a little”; 2, “quite a bit”; or 3, “very much.” Summing the six symptom scores yielded a total SCIN score of 0 to 18. Categorizing total SCIN scores into quartiles yielded similar-sized groups with increasing symptoms. Multivariate ordinal logistic regression analyses evaluated associations between NTX and long-term serum platinum levels, adjusting for cisplatin dose, dosing schedule, and age. Results At Survey I, a significant four- to five-fold association with total SCIN score emerged for the highest serum platinum quartile (odds ratio [OR], 4.69; 95% CI, 1.82 to 12.08). Paresthesias and Raynaud's syndrome (hands and feet) showed significant two- to four-fold increased risks with the highest platinum quartile. At Survey II, total SCIN score remained significantly associated with the highest platinum quartile (OR, 4.28; 95% CI, 1.36 to 13.48). Paresthesias (hands and feet) and tinnitus showed significant three- to four-fold increased risks for the highest platinum quartile. Cumulative cisplatin dose was not associated with total SCIN score or individual SCIN symptoms in multivariate analyses. Conclusion Here we document a significant relationship between increasing levels of residual serum platinum and NTX severity after adjusting for initial cisplatin dose. PMID:22184390

Some Effects of Exposure to Exhaust-gas Streams on Emittance and Thermoelectric Power of Bare-wire Platinum Rhodium - Platinum Thermocouples

NASA Technical Reports Server (NTRS)

Glawe, George E; Shepard, Charles E

1954-01-01

Thermocouples were exposed to exhaust gases from the combustion of propane, 72-octane gasoline, and JP-4 fuel. Exposure increased the emissivity of the thermocouple wire, which increased its radiation error. Two methods are presented for determining the emittance of the wires. The emissivity of a clean platinum rhodium-platinum thermocouple was approximately 0.2 in the temperature range investigated, while the emittance of an exposed thermocouple coated with exhaust residue was about 0.5. The exposure caused negligible change in the thermoelectric power of the thermocouples.

Platinum nanoparticles: a non-toxic, effective and thermally stable alternative plasmonic material for cancer therapy and bioengineering.

PubMed

Samadi, Akbar; Klingberg, Henrik; Jauffred, Liselotte; Kjær, Andreas; Bendix, Poul Martin; Oddershede, Lene B

2018-05-17

Absorption of near infrared (NIR) light by metallic nanoparticles can cause extreme heating and is of interest for instance in cancer treatment since NIR light has a relatively large penetration depth into biological tissue. Here, we quantify the extraordinary thermoplasmonic properties of platinum nanoparticles and demonstrate their efficiency in photothermal cancer therapy. Although platinum nanoparticles are extensively used for catalysis, they are much overlooked in a biological context. Via direct measurements based on a biological matrix we show that individual irradiated platinum nanoparticles with diameters of 50-70 nm can easily reach surface temperatures up to 900 K. In contrast to gold nanoshells, which are often used for photothermal purposes, we demonstrate that the platinum particles remain stable at these extreme temperatures. The experiments are paralleled by finite element modeling confirming the experimental results and establishing a theoretical understanding of the particles' thermoplasmonic properties. At extreme temperatures it is likely that a vapor layer will form around the plasmonic particle, and we show this scenario to be consistent with direct measurements and simulations. Viability studies demonstrate that platinum nanoparticles themselves are non-toxic at therapeutically relevant concentrations, however, upon laser irradiation we show that they efficiently kill human cancer cells. Therefore, platinum nanoparticles are highly promising candidates for thermoplasmonic applications in the life sciences, in nano-medicine, and for bio-medical engineering.

Exposure of the German general population to platinum and rhodium - Urinary levels and determining factors.

PubMed

Munker, Sven; Kilo, Sonja; Röß, Christoph; Jeitner, Peter; Schierl, Rudolf; Göen, Thomas; Drexler, Hans

2016-11-01

In this study the exposure of the general population in Germany to platinum and rhodium and its determinants was investigated in 259 participants (subdivided in three groups) by urine analyses and assessment of the dental status. Complementary, an interview including questions characterising possible exposure to traffic exhaust was conducted. The median excretion was 2.42ng platinum/g creatinine and 7.27ng rhodium/g creatinine. The detailed analysis of the collected data showed significant higher platinum excretion values with increasing number of surfaces covered with restorations containing precious metals (R=0.389; p<0.001), but also higher values for habitants of urban areas (median=3.43ng/g creatinine; 95th percentile=25.2ng/g) compared with those of rural areas (median=2.06ng/g creatinine; 95th percentile=20.0ng/g). Also, participants working in urban areas showed higher platinum excretion values (median=3.27ng/g; 95th percentile=19.6ng/g). Male participants living and working next to highly frequented roads showed higher rhodium excretion values (median=7.27ng/g; 95th percentile=13.5 ng/g). In summary, the study showed that exhaust emissions have an influence on platinum and rhodium excretion, but for platinum this influence is rather low compared to the influence of precious metals containing restorations. Copyright © 2016 Elsevier GmbH. All rights reserved.

Inhibition of nuclear factor kappaB proteins-platinated DNA interactions correlates with cytotoxic effectiveness of the platinum complexes

PubMed Central

Brabec, Viktor; Kasparkova, Jana; Kostrhunova, Hana; Farrell, Nicholas P.

2016-01-01

Nuclear DNA is the target responsible for anticancer activity of platinum anticancer drugs. Their activity is mediated by altered signals related to programmed cell death and the activation of various signaling pathways. An example is activation of nuclear factor kappaB (NF-κB). Binding of NF-κB proteins to their consensus sequences in DNA (κB sites) is the key biochemical activity responsible for the biological functions of NF-κB. Using gel-mobility-shift assays and surface plasmon resonance spectroscopy we examined the interactions of NF-κB proteins with oligodeoxyribonucleotide duplexes containing κB site damaged by DNA adducts of three platinum complexes. These complexes markedly differed in their toxic effects in tumor cells and comprised highly cytotoxic trinuclear platinum(II) complex BBR3464, less cytotoxic conventional cisplatin and ineffective transplatin. The results indicate that structurally different DNA adducts of these platinum complexes exhibit a different efficiency to affect the affinity of the platinated DNA (κB sites) to NF-κB proteins. Our results support the hypothesis that structural perturbations induced in DNA by platinum(II) complexes correlate with their higher efficiency to inhibit binding of NF-κB proteins to their κB sites and cytotoxicity as well. However, the full generalization of this hypothesis will require to evaluate a larger series of platinum(II) complexes. PMID:27574114

Supramolecular PEGylated Dendritic Systems as pH/Redox Dual-Responsive Theranostic Nanoplatforms for Platinum Drug Delivery and NIR Imaging.

PubMed

Li, Yunkun; Li, Yachao; Zhang, Xiao; Xu, Xianghui; Zhang, Zhijun; Hu, Cheng; He, Yiyan; Gu, Zhongwei

2016-01-01

Recently, self-assembling small dendrimers into supramolecular dendritic systems offers an alternative strategy to develop multifunctional nanoplatforms for biomedical applications. We herein report a dual-responsive supramolecular PEGylated dendritic system for efficient platinum-based drug delivery and near-infrared (NIR) tracking. With a refined molecular/supramolecular engineering, supramolecular dendritic systems were stabilized by bioreducible disulfide bonds and endowed with NIR fluorescence probes, and PEGylated platinum derivatives coordinated onto the abundant peripheral groups of supramolecular dendritic templates to generate pH/redox dual-responsive theranostic supramolecular PEGylated dendritic systems (TSPDSs). TSPDSs markedly improved the pharmacokinetics and biodistribution of platinum-based drugs, owing to their stable nanostructures and PEGylated shells during the blood circulation. Tumor intracellular environment (low pH value and high glutathione concentration) could trigger the rapid disintegration of TSPDSs due to acid-labile coordination bonds and redox-cleavable disulfide linkages, and then platinum-based drugs were delivered into the nuclei to exert antitumor activity. In vivo antitumor treatments indicated TSPDSs not only provided high antitumor efficiency which was comparable to clinical cisplatin, but also reduced renal toxicity of platinum-based drugs. Moreover, NIR fluorescence of TSPDSs successfully visualized in vitro and in vivo fate of nanoplatforms and disclosed the intracellular platinum delivery and pharmacokinetics. These results confirm tailor-made supramolecular dendritic system with sophisticated nanostructure and excellent performance is a promising candidate as smart theranostic nanoplatforms.

Inhibition of nuclear factor kappaB proteins-platinated DNA interactions correlates with cytotoxic effectiveness of the platinum complexes.

PubMed

Brabec, Viktor; Kasparkova, Jana; Kostrhunova, Hana; Farrell, Nicholas P

2016-08-30

Nuclear DNA is the target responsible for anticancer activity of platinum anticancer drugs. Their activity is mediated by altered signals related to programmed cell death and the activation of various signaling pathways. An example is activation of nuclear factor kappaB (NF-κB). Binding of NF-κB proteins to their consensus sequences in DNA (κB sites) is the key biochemical activity responsible for the biological functions of NF-κB. Using gel-mobility-shift assays and surface plasmon resonance spectroscopy we examined the interactions of NF-κB proteins with oligodeoxyribonucleotide duplexes containing κB site damaged by DNA adducts of three platinum complexes. These complexes markedly differed in their toxic effects in tumor cells and comprised highly cytotoxic trinuclear platinum(II) complex BBR3464, less cytotoxic conventional cisplatin and ineffective transplatin. The results indicate that structurally different DNA adducts of these platinum complexes exhibit a different efficiency to affect the affinity of the platinated DNA (κB sites) to NF-κB proteins. Our results support the hypothesis that structural perturbations induced in DNA by platinum(II) complexes correlate with their higher efficiency to inhibit binding of NF-κB proteins to their κB sites and cytotoxicity as well. However, the full generalization of this hypothesis will require to evaluate a larger series of platinum(II) complexes.

Exosomes as mediators of platinum resistance in ovarian cancer

PubMed Central

Crow, Jennifer; Atay, Safinur; Banskota, Samagya; Artale, Brittany; Schmitt, Sarah; Godwin, Andrew K

2017-01-01

Exosomes have been implicated in the cell-cell transfer of oncogenic proteins and genetic material. We speculated this may be one mechanism by which an intrinsically platinum-resistant population of epithelial ovarian cancer (EOC) cells imparts its influence on surrounding tumor cells. To explore this possibility we utilized a platinum-sensitive cell line, A2780 and exosomes derived from its resistant subclones, and an unselected, platinum-resistant EOC line, OVCAR10. A2780 cells demonstrate a ~2-fold increase in viability upon treatment with carboplatin when pre-exposed to exosomes from platinum-resistant cells as compared to controls. This coincided with increased epithelial to mesenchymal transition (EMT). DNA sequencing of EOC cell lines revealed previously unreported somatic mutations in the Mothers Against Decapentaplegic Homolog 4 (SMAD4) within platinum-resistant cells. A2780 cells engineered to exogenously express these SMAD4 mutations demonstrate up-regulation of EMT markers following carboplatin treatment, are more resistant to carboplatin, and release exosomes which impart a ~1.7-fold increase in resistance in naive A2780 recipient cells as compared to controls. These studies provide the first evidence that acquired SMAD4 mutations enhance the chemo-resistance profile of EOC and present a novel mechanism in which exchange of tumor-derived exosomes perpetuates an EMT phenotype, leading to the development of subpopulations of platinum-refractory cells. PMID:28060758

Efficacy and safety of platinum combination chemotherapy re-challenge for relapsed patients with non-small-cell lung cancer after postoperative adjuvant chemotherapy of cisplatin plus vinorelbine.

PubMed

Imai, Hisao; Shukuya, Takehito; Yoshino, Reiko; Muraki, Keiko; Mori, Keita; Ono, Akira; Akamatsu, Hiroaki; Taira, Tetsuhiko; Kenmotsu, Hirotsugu; Naito, Tateaki; Murakami, Haruyasu; Tomizawa, Yoshio; Takahashi, Toshiaki; Takahashi, Kazuhisa; Saito, Ryusei; Yamamoto, Nobuyuki

2013-01-01

There is no standard therapy for relapsed patients who have received postoperative platinum-based adjuvant chemotherapy for resected non-small-cell lung cancer (NSCLC). We investigated the efficacy and safety of platinum combination chemotherapy re-challenge for such patients. Medical records from 3 institutes from April 2005 to July 2012 were retrospectively reviewed. Patients who underwent complete surgical resection were eligible if they received postoperative adjuvant chemotherapy consisting of cisplatin plus vinorelbine once and then re-challenge with platinum combination chemotherapy. Sixteen patients were enrolled in this study. After re-challenge with platinum combination chemotherapy, we observed an overall response rate of 31.2% (5/16) and a disease control rate of 81.2% (13/16). Median progression-free survival and overall survival from the start of the re-administration of platinum combination chemotherapy were 6.5 and 28.0 months, respectively. Frequently observed severe adverse events (≥grade 3) included neutropenia (31.2%), thrombocytopenia (31.2%), leukopenia (12.5%) and hyponatremia (12.5%). Frequently observed non-hematological toxicities (≥grade 2) were anorexia (37.5%) and nausea (37.5%). Re-challenge with platinum combination chemotherapy was effective and safe; therefore, this therapy should be considered as a treatment option for relapsed patients after postoperative cisplatin-based adjuvant chemotherapy for resected NSCLC. © 2014 S. Karger AG, Basel.

Recycling Metals from Spent Screen-Printed Electrodes While Learning the Fundamentals of Electrochemical Sensing

ERIC Educational Resources Information Center

González-Sánchez, María-Isabel; Gómez-Monedero, Beatriz; Agrisuelas, Jerónimo; Valero, Edelmira

2018-01-01

A laboratory experiment in which students recycle silver and platinum selectively from spent screen-printed platinum electrodes is described. The recovered silver in solution is used to show its spontaneous redox reaction with a copper sheet. The recovered platinum is electrodeposited onto a screen-printed carbon electrode to develop a sensor for…

A Change to the Platinum Publications | Poster

Cancer.gov

Please be advised that the Poster will no longer publish the “Platinum Publications” series listing recent NCI at Frederick publications. All published research represents a valuable addition to the fight against cancer, AIDS, and infectious diseases—thus, the “Platinum Publications” did not adequately commend all of the important work done by NCI at Frederick researchers.

40 CFR 421.262 - Effluent limitations guidelines representing the degree of effluent reduction attainable by the...

Code of Federal Regulations, 2011 CFR

2011-07-01

... Within the range of 7.5 to 10.0 at all times. (i) Platinum precipitation and filtration. BPT Limitations... Maximum for monthly average mg/troy ounce of platinum precipitated Copper 9.880 5.200 Cyanide (total) 1... times. (k) Other platinum group metals precipitation and filtration. BPT Limitations for the Secondary...

40 CFR 421.262 - Effluent limitations guidelines representing the degree of effluent reduction attainable by the...

Code of Federal Regulations, 2012 CFR

2012-07-01

... Within the range of 7.5 to 10.0 at all times. (i) Platinum precipitation and filtration. BPT Limitations... Maximum for monthly average mg/troy ounce of platinum precipitated Copper 9.880 5.200 Cyanide (total) 1... times. (k) Other platinum group metals precipitation and filtration. BPT Limitations for the Secondary...

40 CFR 421.262 - Effluent limitations guidelines representing the degree of effluent reduction attainable by the...

Code of Federal Regulations, 2013 CFR

2013-07-01

... Within the range of 7.5 to 10.0 at all times. (i) Platinum precipitation and filtration. BPT Limitations... Maximum for monthly average mg/troy ounce of platinum precipitated Copper 9.880 5.200 Cyanide (total) 1... times. (k) Other platinum group metals precipitation and filtration. BPT Limitations for the Secondary...

40 CFR 421.262 - Effluent limitations guidelines representing the degree of effluent reduction attainable by the...

Code of Federal Regulations, 2014 CFR

2014-07-01

... Within the range of 7.5 to 10.0 at all times. (i) Platinum precipitation and filtration. BPT Limitations... Maximum for monthly average mg/troy ounce of platinum precipitated Copper 9.880 5.200 Cyanide (total) 1... times. (k) Other platinum group metals precipitation and filtration. BPT Limitations for the Secondary...

Bimetallic alloy electrocatalysts with multilayered platinum-skin surfaces

DOEpatents

Stamenkovic, Vojislav R.; Wang, Chao; Markovic, Nenad M.

2016-01-26

Compositions and methods of preparing a bimetallic alloy having enhanced electrocatalytic properties are provided. The composition comprises a PtNi substrate having a surface layer, a near-surface layer, and an inner layer, where the surface layer comprises a nickel-depleted composition, such that the surface layer comprises a platinum skin having at least one atomic layer of platinum.

Baseline clinical predictors of antitumor response to the PARP inhibitor olaparib in germline BRCA1/2 mutated patients with advanced ovarian cancer.

PubMed

Rafii, Saeed; Gourley, Charlie; Kumar, Rajiv; Geuna, Elena; Ern Ang, Joo; Rye, Tzyvia; Chen, Lee-May; Shapira-Frommer, Ronnie; Friedlander, Michael; Matulonis, Ursula; De Greve, Jacques; Oza, Amit M; Banerjee, Susana; Molife, L Rhoda; Gore, Martin E; Kaye, Stan B; Yap, Timothy A

2017-07-18

The PARP inhibitor olaparib was recently granted Food and Drug Administration (FDA) accelerated approval in patients with advanced BRCA1/2 mutation ovarian cancer. However, antitumor responses are observed in only approximately 40% of patients and the impact of baseline clinical factors on response to treatment remains unclear. Although platinum sensitivity has been suggested as a marker of response to PARP inhibitors, patients with platinum-resistant disease still respond to olaparib. 108 patients with advanced BRCA1/2 mutation ovarian cancers were included. The interval between the end of the most recent platinum chemotherapy and PARPi (PTPI) was used to predict response to olaparib independent of conventional definition of platinum sensitivity. RECIST complete response (CR) and partial response (PR) rates were 35% in patients with platinum-sensitive versus 13% in platinum-resistant (p<0.005). Independent of platinum sensitivity status, the RECIST CR/PR rates were 42% in patients with PTPI greater than 52 weeks and 18% in patients with PTPI less than 52 weeks (p=0.016). No association was found between baseline clinical factors such as FIGO staging, debulking surgery, BRCA1 versus BRCA2 mutations, prior history of breast cancer and prior chemotherapy for breast cancer, and the response to olaparib. We conducted an international multicenter retrospective study to investigate the association between baseline clinical characteristics of patients with advanced BRCA1/2 mutation ovarian cancers from eight different cancer centers and their antitumor response to olaparib. PTPI may be used to refine the prediction of response to PARP inhibition based on the conventional categorization of platinum sensitivity.

Pemetrexed Singlet Versus Nonpemetrexed-Based Platinum Doublet as Second-Line Chemotherapy after First-Line Epidermal Growth Factor Receptor (EGFR) Tyrosine Kinase Inhibitor Failure in Non-small Cell Lung Cancer Patients with EGFR Mutations.

PubMed

Park, Sehhoon; Keam, Bhumsuk; Kim, Se Hyun; Kim, Ki Hwan; Kim, Yu Jung; Kim, Jin-Soo; Kim, Tae Min; Lee, Se-Hoon; Kim, Dong-Wan; Lee, Jong Seok; Heo, Dae Seog

2015-10-01

Platinum-based doublet chemotherapy is the treatment of choice for patients with non-small cell lung cancer (NSCLC); however, the role of a platinum-based doublet as second-line therapy after failure of an epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) for NSCLC patients has not yet been elucidated. The purpose of this study was to compare the clinical efficacy of pemetrexed versus a platinum-based doublet as second-line therapy after failure of EGFR TKI used as first-line therapy for NSCLC patients with EGFR mutations. We designed a multicenter retrospective cohort study of 314 NSCLC patients with EGFR mutations who received an EGFR TKI as first-line palliative chemotherapy. Our analysis included 83 patients who failed EGFR TKI therapy and received second-line cytotoxic chemotherapy. Forty-six patients were treated using a platinum-based doublet and 37 patients were treated using singlet pemetrexed. The overall response rates of patients receiving a platinum-based doublet and patients receiving pemetrexed were17.4% and 32.4%, respectively (p=0.111). The median progression-free survival (PFS) of patients receiving pemetrexed was significantly longer than that of patients receiving a platinum-based doublet (4.2 months vs. 2.7 months, respectively; p=0.008). The hazard ratio was 0.54 (95% confidence interval, 0.34 to 0.86; p=0.009). Our retrospective analysis found that second-line pemetrexed singlet therapy provided significantly prolonged PFS compared to second-line platinum-based doublet chemotherapy for NSCLC patients with EGFR mutations who failed first-line EGFR TKI. Conduct of prospective studies for confirmation of our results is warranted.

In vitro effects of platinum compounds on renal cellular respiration in mice.

PubMed

Almarzooqi, Saeeda-S; Alfazari, Ali-S; Abdul-Kader, Hidaya-M; Saraswathiamma, Dhanya; Albawardi, Alia-S; Souid, Abdul-Kader

2015-01-01

Cisplatin, carboplatin and oxaliplatin are structurally-related compounds, which are commonly used in cancer therapy. Cisplatin (Platinol(®)) has Boxed Warning stating: "Cumulative renal toxicity associated with PLATINOL is severe", while carboplatin and oxaliplatin are less nephrotoxic. These drugs form platinum adducts with cellular DNA. Their bindings to cellular thiols (e.g., glutathione and metallothionein) are known to contribute to drug resistance while thiol depletion augments platinum toxicity. Using phosphorescence oxygen analyzer, this study investigated the effects of platinum drugs on renal cellular respiration (mitochondrial O2 consumption) in the presence and absence of the thiol blocking agent N-ethylmaleimide (used here as a model for thiol depletion). Renal cellular ATP was also determined. Kidney fragments from C57BL/6 mice were incubated at 37 °C in Krebs-Henseleit buffer (gassed with 95% O2:5% CO2) with and without 100 μM platinum drug in the presence and absence of 100 μM N-ethylmaleimide for ≤ 6 h. Platinum drugs alone had no effects on cellular respiration (P ≥ 0.143) or ATP (P ≥ 0.161). N-ethylmaleimide lowered cellular respiration (P ≤ 0.114) and ATP (P = 0.008). The combination of platinum drug and N-ethylmaleimide significantly lowered both cellular respiration (P ≤ 0.006) and ATP (P ≤ 0.003). Incubations with N-ethylmaleimide alone were associated with moderate-to-severe tubular necrosis. Incubations with cisplatin+N-ethylmaleimide vs. cisplatin alone produced similar severities of tubular necrosis. Tubular derangements were more prominent in carboplatin+N-ethylmaleimide vs. carboplatin alone and in oxaliplatin+N-ethylmaleimide vs. oxaliplatin alone. These results demonstrate the adverse events of thiol depletion on platinum-induced nephrotoxicities. The results suggest cellular bioenergetics is a useful surrogate biomarker for assessing drug-induced nephrotoxicities.

Hole doping, hybridization gaps, and electronic correlation in graphene on a platinum substrate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hwang, Jinwoong; Hwang, Hwihyeon; Kim, Min-Jeong

The interaction between graphene and substrates provides a viable route to enhance the functionality of both materials. Depending on the nature of electronic interaction at the interface, the electron band structure of graphene is strongly influenced, allowing us to make use of the intrinsic properties of graphene or to design additional functionalities in graphene. In this paper, we present an angle-resolved photoemission study on the interaction between graphene and a platinum substrate. The formation of an interface between graphene and platinum leads to a strong deviation in the electronic structure of graphene not only from its freestanding form but alsomore » from the behavior observed on typical metals. Finally, the combined study on the experimental and theoretical electron band structure unveils the unique electronic properties of graphene on a platinum substrate, which singles out graphene/platinum as a model system investigating graphene on a metallic substrate with strong interaction.« less

Hole doping, hybridization gaps, and electronic correlation in graphene on a platinum substrate

DOE PAGES

Hwang, Jinwoong; Hwang, Hwihyeon; Kim, Min-Jeong; ...

2017-08-02

The interaction between graphene and substrates provides a viable route to enhance the functionality of both materials. Depending on the nature of electronic interaction at the interface, the electron band structure of graphene is strongly influenced, allowing us to make use of the intrinsic properties of graphene or to design additional functionalities in graphene. In this paper, we present an angle-resolved photoemission study on the interaction between graphene and a platinum substrate. The formation of an interface between graphene and platinum leads to a strong deviation in the electronic structure of graphene not only from its freestanding form but alsomore » from the behavior observed on typical metals. Finally, the combined study on the experimental and theoretical electron band structure unveils the unique electronic properties of graphene on a platinum substrate, which singles out graphene/platinum as a model system investigating graphene on a metallic substrate with strong interaction.« less

Biotinylated platinum(IV) complexes designed to target cancer cells.

PubMed

Zhao, Jian; Hua, Wuyang; Xu, Gang; Gou, Shaohua

2017-11-01

Three biotinylated platinum(IV) complexes (1-3) were designed and synthesized. The resulting platinum(IV) complexes exhibited effective cytotoxicity against the tested cancer cell lines, especially complex 1, which was 2.0-9.6-fold more potent than cisplatin. These complexes were found to be rapidly reduced to their activated platinum(II) counterparts by glutathione or ascorbic acid under biologically relevant condition. Additional molecular docking studies revealed that the biotin moieties of all Pt(IV) complexes can effectively bind with the streptavidin through the noncovalent interactions. Besides, introduction of the biotin group can obviously promote the cancer cell uptake of platinum when treated with complex 1, particularly in cisplatin-resistant SGC-7901/Cis cancer cells. Further mechanistic studies on complex 1 indicated that it activated the expression of Bax, and induced cytochrome c release from the mitochondria, and finally activated caspase-3. Copyright © 2017 Elsevier Inc. All rights reserved.

Internalization of Ineffective Platinum Complex in Nanocapsules Renders It Cytotoxic.

PubMed

Vrana, Oldrich; Novohradsky, Vojtech; Medrikova, Zdenka; Burdikova, Jana; Stuchlikova, Olga; Kasparkova, Jana; Brabec, Viktor

2016-02-18

Anticancer therapy by platinum complexes, based on nanocarrier-based delivery, may offer a new approach to improve the efficacy and tolerability of the platinum family of anticancer drugs. The original rules for the design of new anticancer platinum drugs were affected by the fact that, although cisplatin (cis-[PtCl2 (NH3)2) was an anticancer drug, its isomer transplatin was not cytotoxic. For the first time, it is demonstrated that simple encapsulation of an inactive platinum compound in phospholipid bilayers transforms it into an efficient cytotoxic agent. Notably, the encapsulation of transplatin makes it possible to overcome the resistance mechanisms operating in cancer cells treated with cisplatin and prevents inactivation of transplatin in the extracellular environment. It is also shown that transplatin delivered to the cells in nanocapsules, in contrast to free (nonencapsulated) complex, forms cytotoxic cross-links on DNA. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

CVD aluminiding process for producing a modified platinum aluminide bond coat for improved high temperature performance

NASA Technical Reports Server (NTRS)

Nagaraj, Bangalore A. (Inventor); Williams, Jeffrey L. (Inventor)

2003-01-01

A method of depositing by chemical vapor deposition a modified platinum aluminide diffusion coating onto a superalloy substrate comprising the steps of applying a layer of a platinum group metal to the superalloy substrate; passing an externally generated aluminum halide gas through an internal gas generator which is integral with a retort, the internal gas generator generating a modified halide gas; and co-depositing aluminum and modifier onto the superalloy substrate. In one form, the modified halide gas is hafnium chloride and the modifier is hafnium with the modified platinum aluminum bond coat comprising a single phase additive layer of platinum aluminide with at least about 0.5 percent hafnium by weight percent and about 1 to about 15 weight percent of hafnium in the boundary between a diffusion layer and the additive layer. The bond coat produced by this method is also claimed.

Photoinduced DNA damage and cytotoxicity by a triphenylamine-modified platinum-diimine complex.

PubMed

Zhang, Zhigang; Dai, Ruihui; Ma, Jiajia; Wang, Shuying; Wei, Xuehong; Wang, Hongfei

2015-02-01

Many planar photosensitizers tend to self-aggregate via van der Waals interactions between π-conjugated systems. The self-aggregation of the photosensitizer may reduce the efficiency of the photosensitizer to generate singlet oxygen, thereby diminishing its photodynamic activity. Efforts have been made to improve the photodynamic activity of bis-(o-diiminobenzosemiquinonato)platinum(II) which has planar geometry by the introduction of the sterically hindered triphenylamine moiety into the ligand. Herein we report the photoinduced DNA damage and cytotoxicity by a triphenylamine-modified platinum-diimine complex in red light studied by fluorescence spectra, agarose gel assay and cell viability assay. The results suggest that the triphenylamine-modified platinum-diimine complex has better capability to generate singlet oxygen than bis-(o-diiminobenzosemiquinonato)platinum(II), and it can induce DNA damage in red light, causing high photocytotoxicity in HepG-2 cells in vitro. Copyright © 2014 Elsevier Inc. All rights reserved.

Platinum(II) acetate complexes in hydrogenation of unsaturated compounds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berenblyum, A.S.; Goranskaya, T.P.; Mund, S.L.

1979-12-20

In order to further elucidate the effect of the ligand environment in the complexes of group VIII metals on the activity of H/sub 2/, the catalytic properties of Pt(II) compounds with oxygen-containing acido ligands was studied. The platinum(II) acetate complexes with aniline and triphenylphosphine were synthesized. IR spectral studies indicated that platinum(II) acetate formed complexes with either of the other compounds singly or together. Dimethylformamide(DMF) solutions of platinum acetate and its complexes with aniline and/or triphenylphosphine all absorb H/sub 2/ in the temperature range of 20 to 90/sup 0/C and at a H/sub 2/ pressure of 1 atm. After themore » absorption of H/sub 2/, the DMF solutions of (aniline)(triphenylphosphine)platinum(II)diacetate complex were found to catalyze the hydrogenaton of O/sub 2/ and 1,3-pentadiene.« less

Electro-architected porous platinum on metallic multijunction nanolayers to optimize their optical properties for infrared sensor application

NASA Astrophysics Data System (ADS)

Stanca, Sarmiza Elena; Hänschke, Frank; Zieger, Gabriel; Dellith, Jan; Dellith, Andrea; Ihring, Andreas; Belkner, Johannes; Meyer, Hans-Georg

2018-03-01

Tailoring the physicochemical properties of the metallic multijunction nanolayers is a prerequisite for the development of microelectronics. From this perspective, a desired lower reflectance of infrared radiation was achieved by an electrochemical deposition of porous platinum in nonaqueous media on silver mirror supported nickel-chrome and nickel-titanium metallic films with incremental decreasing thicknesses from 80-10 nm. The electro-assembled architectures were examined by means of scanning electron microscopy and Fourier transform infrared spectroscopy and it was observed that the layer and sublayer thicknesses and resistivities have a substantial effect upon the porous platinum morphology and its optical properties. It is here reported that the augmentation of the metallic layer electrical conductivity determines the electroformation of more compact platinum nanolayers. Moreover, the platinum black coating of metallic nanolayers causes a considerable decrease of the reflectance in the region from 1000-8000 cm-1.

Atomically flat platinum films grown on synthetic mica

NASA Astrophysics Data System (ADS)

Tanaka, Hiroyuki; Taniguchi, Masateru

2018-04-01

Atomically flat platinum thin films were heteroepitaxially grown on synthetic fluorophlogopite mica [KMg3(AlSi3O10)F2] by van der Waals epitaxy. Platinum films deposited on a fluorophlogopite mica substrate by inductively coupled plasma-assisted sputtering with oxygen introduction on a synthetic mica substrate resulted in the growth of twin single-crystalline epitaxial Pt(111) films.

Structure of matrix metalloproteinase-3 with a platinum-based inhibitor.

PubMed

Belviso, Benny Danilo; Caliandro, Rocco; Siliqi, Dritan; Calderone, Vito; Arnesano, Fabio; Natile, Giovanni

2013-06-18

An X-ray investigation has been performed with the aim of characterizing the binding sites of a platinum-based inhibitor (K[PtCl3(DMSO)]) of matrix metalloproteinase-3 (stromelysin-1). The platinum complex targets His224 in the S1' specificity loop, representing the first step in the selective inhibition process (PDB ID code 4JA1).

Oxidation performance of platinum-clad Mo-47Re alloy

NASA Technical Reports Server (NTRS)

Clark, Ronald K.; Wallace, Terryl A.

1994-01-01

The alloy Mo-47Re has favorable mechanical properties at temperatures above 1400 C, but it undergoes severe oxidation when used in air with no protective coating. To shield the alloy from oxidation, platinum cladding has been evaluated. The unprotected alloy undergoes catastrophic oxidation under static and dynamic oxidation conditions. The platinum cladding provides good protection from static and dynamic oxidation for moderate times at 1260 C. Samples tested for longer times under static oxidation conditions experienced severe oxidation. The data suggest that oxidation results from the transport of oxygen through the grain boundaries and through the pinhole defects of the platinum cladding.

Photo-stimulated low electron temperature high current diamond film field emission cathode

DOEpatents

Shurter,; Roger Philips, Devlin [Los Alamos, NM; David James, Moody [Santa Fe, NM; Nathan Andrew, Taccetti [Los Alamos, NM; Jose Martin, Russell [Santa Fe, NM; John, Steven [Los Alamos, NM

2012-07-24

An electron source includes a back contact surface having a means for attaching a power source to the back contact surface. The electron source also includes a layer comprising platinum in direct contact with the back contact surface, a composite layer of single-walled carbon nanotubes embedded in platinum in direct contact with the layer comprising platinum. The electron source also includes a nanocrystalline diamond layer in direct contact with the composite layer. The nanocrystalline diamond layer is doped with boron. A portion of the back contact surface is removed to reveal the underlying platinum. The electron source is contained in an evacuable container.

Concentrations of platinum group elements in 122 U.S. coal samples

USGS Publications Warehouse

Oman, C.L.; Finkelman, R.B.; Tewalt, S.J.

1997-01-01

Analysis of more than 13,000 coal samples by semi-quantitative optical emission spectroscopy (OES) indicates that concentrations of the platinum group elements (iridium, palladium, platinum, osmium, rhodium, and ruthenium) are less than 1 ppm in the ash, the limit of detection for this method of analysis. In order to accurately determine the concentration of the platinum group elements (PGE) in coal, additional data were obtained by inductively coupled plasma mass spectroscopy, an analytical method having part-per-billion (ppb) detection limits for these elements. These data indicate that the PGE in coal occur in concentrations on the order of 1 ppb or less.

Recent strikes in South Africa’s platinum-group metal mines: effects upon world platinum-group metal supplies

USGS Publications Warehouse

Yager, Thomas R.; Soto-Viruet, Yadira; Barry, James J.

2012-01-01

The recent labor disputes over wages and working conditions that have affected South Africa’s three leading platinum-group metal (PGM) producers have affected an industry already plagued by market pressures and labor unrest and raised the specter of constraints in the world’s supply of these metals. Although low demand for these metals in 2011 and 2012 helped to offset production losses of recent years, and particularly those losses caused by the strikes in 2012, a prolonged resumption of strikes could cause severe shortages of iridium, platinum, rhodium, ruthenium, and, to a lesser extent, palladium.

A monofunctional platinum(II)-based anticancer agent from a salicylanilide derivative: Synthesis, antiproliferative activity, and transcription inhibition.

PubMed

Wang, Beilei; Wang, Zhigang; Ai, Fujin; Tang, Wai Kin; Zhu, Guangyu

2015-01-01

Cationic monofunctional platinum(II)-based anticancer agents with a general formula of cis-[Pt(NH3)2(N-donor)Cl](+) have recently drawn significant attention due to their unique mode of action, distinctive anticancer spectrum, and promising antitumor activity both in vitro and in vivo. Understanding the mechanism of action of novel monofunctional platinum compounds through rational drug design will aid in the further development of active agents. In this study, we synthesized and evaluated a monofunctional platinum-based anticancer agent SA-Pt containing a bulky salicylanilide moiety. The antiproliferative activity of SA-Pt was close to that of cisplatin. Mechanism studies revealed that SA-Pt entered HeLa cells more efficiently than cisplatin, blocked the cell cycle at the S-phase, and induced apoptosis. The compound bound to DNA as effectively as cisplatin, but did not block RNA polymerase II-mediated transcription as strongly as cisplatin, indicating that once the compound formed Pt-DNA lesions, the salicylanilide group was more easily recognized and removed. This study not only enriches the family of monofunctional platinum-based anticancer agents but also guides the design of more potent monofunctional platinum complexes. Copyright © 2014 Elsevier Inc. All rights reserved.

Evaluation of the antitumor activity of platinum nanoparticles in the treatment of hepatocellular carcinoma induced in rats.

PubMed

Medhat, Amina; Mansour, Somaya; El-Sonbaty, Sawsan; Kandil, Eman; Mahmoud, Mustafa

2017-07-01

This study aimed to evaluate the antitumor activity of platinum nanoparticles compared with cis-platin both in vitro and in vivo in the treatment of hepatocellular carcinoma induced in rats. The treatment efficacy of platinum nanoparticles was evaluated by measuring antioxidant activities against oxidative stress caused by diethylnitrosamine in liver tissue. The measurements included reduced glutathione content and superoxide dismutase activity, as well as malondialdehyde level. Liver function tests were also determined, in addition to the evaluation of serum alpha-fetoprotein, caspase-3, and cytochrome c in liver tissue. Total RNA extraction from liver tissue samples was also done for the relative quantification of B-cell lymphoma 2, matrix metallopeptidase 9, and tumor protein p53 genes. Histopathological examination was also performed for liver tissue. Results showed that platinum nanoparticles are more potent than cis-platin in treatment of hepatocellular carcinoma induced by diethylnitrosamine in rats as it ameliorated the investigated parameters toward normal control animals. These findings were well appreciated with histopathological studies of diethylnitrosamine group treated with platinum nanoparticles, suggesting that platinum nanoparticles can serve as a good therapeutic agent for the treatment of hepatocellular carcinoma which should attract further studies.

Facile one-pot synthesis of platinum nanoparticles decorated nitrogen-graphene with high electrocatalytic performance for oxygen reduction and anodic fuels oxidation

NASA Astrophysics Data System (ADS)

Navaee, Aso; Salimi, Abdollah; Soltanian, Saeid; Servati, Peyman

2015-03-01

Due to exceptional electronic properties of graphene (Gr) and nitrogen doped graphene (N-Gr), they are considered as superior supporting platforms for novel metal nanoparticle decorations. Here, we report, a novel one-step electrochemical method for synthesis of Nitrogen-doped graphene sheets uniformly decorated with platinum nanoparticles (Pt/N-Gr). A graphite rod and platinum wire are respectively used for graphene and platinum nanoparticles production. The potential is cycled from -3V to +3V in acetonitrile solution as a nitrogen dopant source. By increasing the number of cycles the nitrogen-doped graphene/platinum nanoparticles composite is generated. After heat-treating the composite is characterized with various techniques such as FTIR, Raman, XPS, SEM and TEM. The electrocatalytic activity of the prepared composite toward the reduction of O2 and the oxidation of usual anodic fuels such as methanol, ethanol, hydrazine and formic acid is investigated using cyclic voltammetry technique. In comparison to commercial platinum/carbon, the onset potentials and the current densities for both O2 reduction and fuels oxidation are remarkably improved. Furthermore, the modified electrode by this composite shows good long-term stability and poisoning tolerance.

Platinum salt sensitivity in refinery workers: incidence and effects of smoking and exposure.

PubMed Central

Calverley, A E; Rees, D; Dowdeswell, R J; Linnett, P J; Kielkowski, D

1995-01-01

OBJECTIVE--To measure the incidence of platinum salt sensitivity (PSS) in refinery workers and examine the influence of cigarette smoking and exposure to platinum salts on sensitisation. DESIGN--A prospective cohort study with examination of workers at quarterly intervals for 18 months, and again at 24 months. SETTING--A South African primary platinum refinery. SUBJECTS--78 new recruits, selected by the refinery's usual procedure, without apparent atopy and in good respiratory health. RESULTS--After 24 months 32 (41%) subjects had been diagnosed PSS and were subsequently medically separated. Twenty two (28%) cases were confirmed by positive skin prick test to platinum salts, 10 (13%) cases were symptomatic but skin prick negative. Incidence of cases per 100 person-months was 1.9 skin prick positive and 0.8 negative. Risk of sensitisation was about eight times greater for smokers than non-smokers, and six times greater for high exposure than low exposure. CONCLUSION--Smoking and intensity of exposure were definitely associated with development of PSS. Positive responses to platinum salt skin prick test had a 100% positive predictive value for symptoms and signs of PSS if exposure continued. PMID:7489056

Preparation of Carbon-Platinum-Ceria and Carbon-Platinum-Cerium catalysts and its application in Polymer Electrolyte Fuel Cell: Hydrogen, Methanol, and Ethanol

NASA Astrophysics Data System (ADS)

Guzman Blas, Rolando Pedro

This thesis is focused on fuel cells using hydrogen, methanol and ethanol as fuel. Also, in the method of preparation of catalytic material for the anode: Supercritical Fluid Deposition (SFD) and impregnation method using ethylenediaminetetraacetic acid (EDTA) as a chelating agent. The first part of the thesis describes the general knowledge about Hydrogen Polymer Exchange Membrane Fuel Cell (HPEMFC),Direct Methanol Fuel Cell (DMFC) and Direct Ethanol Fuel Cell (DEFC), as well as the properties of Cerium and CeO2 (Ceria). The second part of the thesis describes the preparation of catalytic material by Supercritical Fluid Deposition (SFD). SFD was utilized to deposit Pt and ceria simultaneously onto gas diffusion layers. The Pt-ceria catalyst deposited by SFD exhibited higher methanol oxidation activity compared to the platinum catalyst alone. The linear sweep traces of the cathode made for the methanol cross over study indicate that Pt-Ceria/C as the anode catalyst, due to its better activity for methanol, improves the fuel utilization, minimizing the methanol permeation from anode to cathode compartment. The third and fourth parts of the thesis describe the preparation of material catalytic material Carbon-Platinum-Cerium by a simple and cheap impregnation method using EDTA as a chelating agent to form a complex with cerium (III). This preparation method allows the mass production of the material catalysts without additional significant cost. Fuel cell polarization and power curves experiments showed that the Carbon-Platinum-Cerium anode materials exhibited better catalytic activity than the only Vulcan-Pt catalysts for DMFC, DEFC and HPEMFC. In the case of Vulcan-20%Pt-5%w Cerium, this material exhibits better catalytic activity than the Vulcan-20%Pt in DMFC. In the case of Vulcan-40% Pt-doped Cerium, this material exhibits better catalytic activity than the Vulcan-40% Pt in DMFC, DEFC and HPEMFC. Finally, I propose a theory that explains the reason why the carbon-platinum-cerium has better catalytic activity than platinum-carbon. Due to the hybridization behavior of C and Ce could arise charge transfer, both carbon and cerium to the Platinum. Ce-C→Pt charge transfer could occur at the Ce-C/Pt interface. Thus, results in an increase in the catalytic activity of platinum-cerium-carbon when compared with carbon-platinum.

Supramolecular PEGylated Dendritic Systems as pH/Redox Dual-Responsive Theranostic Nanoplatforms for Platinum Drug Delivery and NIR Imaging

PubMed Central

Li, Yunkun; Li, Yachao; Zhang, Xiao; Xu, Xianghui; Zhang, Zhijun; Hu, Cheng; He, Yiyan; Gu, Zhongwei

2016-01-01

Recently, self-assembling small dendrimers into supramolecular dendritic systems offers an alternative strategy to develop multifunctional nanoplatforms for biomedical applications. We herein report a dual-responsive supramolecular PEGylated dendritic system for efficient platinum-based drug delivery and near-infrared (NIR) tracking. With a refined molecular/supramolecular engineering, supramolecular dendritic systems were stabilized by bioreducible disulfide bonds and endowed with NIR fluorescence probes, and PEGylated platinum derivatives coordinated onto the abundant peripheral groups of supramolecular dendritic templates to generate pH/redox dual-responsive theranostic supramolecular PEGylated dendritic systems (TSPDSs). TSPDSs markedly improved the pharmacokinetics and biodistribution of platinum-based drugs, owing to their stable nanostructures and PEGylated shells during the blood circulation. Tumor intracellular environment (low pH value and high glutathione concentration) could trigger the rapid disintegration of TSPDSs due to acid-labile coordination bonds and redox-cleavable disulfide linkages, and then platinum-based drugs were delivered into the nuclei to exert antitumor activity. In vivo antitumor treatments indicated TSPDSs not only provided high antitumor efficiency which was comparable to clinical cisplatin, but also reduced renal toxicity of platinum-based drugs. Moreover, NIR fluorescence of TSPDSs successfully visualized in vitro and in vivo fate of nanoplatforms and disclosed the intracellular platinum delivery and pharmacokinetics. These results confirm tailor-made supramolecular dendritic system with sophisticated nanostructure and excellent performance is a promising candidate as smart theranostic nanoplatforms. PMID:27375780

Platinum transfer from hCTR1 to Atox1 is dependent on the type of platinum complex.

PubMed

Wu, Xuelei; Yuan, Siming; Wang, Erqiong; Tong, Yang; Ma, Guolin; Wei, Kaiju; Liu, Yangzhong

2017-05-24

In spite of their wide application, the cellular uptake of platinum based anticancer drugs is still unclear. The copper transport protein, hCTR1, is proposed to facilitate the cellular uptake of cisplatin, whereas organic cation transport (OCT) is more important for oxaliplatin. It has been reported that both N-terminal and C-terminal metal binding motifs of hCTR1 are highly reactive to cisplatin, which is the initial step of protein assisted cellular uptake of cisplatin. It is still unknown how the platinum drugs in hCTR1 transfer to cytoplasmic media, and whether various platinum complexes possess different activities in this process. Herein, we investigated the reaction of the platinated C-terminal metal binding motif of hCTR1 (C8) with the down-stream protein Atox1. Results show that Atox1 is highly reactive to the platinated C8 adducts of cisplatin and transplatin, whereas the oxaliplatin/C8 adduct is much less reactive. The platinum transfer from C8 to Atox1 occurs in the reaction, which results in the protein unfolding of Atox1. These results demonstrated that the platinated intracellular-domain of hCTR1 is reactive to Atox1, and the reactivity is dependent on the ligand and the coordination structure of platinum complexes. The different reactivity is consistent with the hypothesis that hCTR1 is more significant in the transport of cisplatin than that of oxaliplatin.

Platinum anticancer agents and antidepressants: desipramine enhances platinum-based cytotoxicity in human colon cancer cells

PubMed Central

Kabolizadeh, Peyman; Engelmann, Brigitte J.; Pullen, Nicholas; Stewart, Jennifer K.; Ryan, John J.

2011-01-01

A unique synergistic effect on platinum drug cytotoxicity is noted in the presence of the tricyclic anti-depressant desipramine. Desipramine is used for treating neuropathic pain, particularly in prostate cancer patients. The clinically used drugs cisplatin (cis-[PtCl2(NH3)2]), oxaliplatin [1,2-diaminocyclohexaneoxalatoplatinum(II)], and the cationic trinuclear agent BBR3464 [{trans-PtCl(NH3)2}2-μ-(trans-Pt(NH3)2(H2N(CH2)6NH2)2)]4+, which has undergone evaluation in phase II clinical trials for activity in lung and ovarian cancers, were evaluated. Surprisingly, desipramine greatly augments the cytotoxicity of all the platinum-based chemotherapeutics in HCT116 colorectal carcinoma cell lines. Desipramine enhanced cellular accumulation of cisplatin, but had no effect on the accumulation of oxaliplatin or BBR3464, suggesting that enhanced accumulation could not be a consistent means by which desipramine altered the platinum-drug-mediated cytotoxicity. The desipramine/cisplatin combination resulted in increased levels of p53 as well as mitochondrial damage, caspase activation, and poly(ADP ribose) polymerase cleavage, suggesting that desipramine may synergize with cisplatin more than with other platinum chemotherapeutics partly by activating distinct apoptotic pathways. The study argues that desipramine may be a means of enhancing chemoresponsiveness of platinum drugs and the results warrant further investigation. The results emphasize the importance of understanding the differential pharmacological action of adjuvants employed in combinations with cancer chemotherapeutics. PMID:21918844

Differential nephrotoxicity of cisplatin and a novel series of traditional Chinese medicine-platinum anticancer agents correlates with their chemical reactivity towards sulfur-containing nucleophiles.

PubMed

To, Kenneth K W; Au-Yeung, Steve C F; Ho, Yee-Ping

2006-07-01

A series of novel traditional Chinese medicine-platinum compounds has been found to be active against a number of murine and human cancers both in vitro and in vivo. Their high potency and the lack of cisplatin cross-resistance are believed to be due to the inclusion of the protein phosphatase 2A-inhibiting demethylcantharidin in the novel structures. A simple reversed-phase high-performance liquid chromatographic method was developed and validated as a stability-indicating assay for the platinum compounds. Using cisplatin and carboplatin as reference compounds, the stability study agrees well with the literature-reported findings. The novel traditional Chinese medicine-platinum compounds were more stable than cisplatin in water and dextrose, but became unstable in normal saline, a characteristic similar to that of carboplatin. The developed assay was further applied to study the chemical reactivity of the novel platinum compounds towards physiologically important nucleophiles such as glutathione and cysteine. The novel compounds were considerably less reactive to the sulfur-containing nucleophiles than cisplatin. In-vitro cytotoxicity assay was performed in a porcine kidney LLC-PK1 cell line model to investigate the nephrotoxicity potential of the platinum compounds. The lower rate of hydrolysis and the decreased reactivity of the novel traditional Chinese medicine-platinum compounds towards sulfur-containing bionucleophiles appear to have reduced their toxicity when compared with cisplatin, yet the antitumor activities of the novel compounds have not been compromised.

Iridium Interfacial Stack (IRIS)

NASA Technical Reports Server (NTRS)

Spry, David James (Inventor)

2015-01-01

An iridium interfacial stack ("IrIS") and a method for producing the same are provided. The IrIS may include ordered layers of TaSi.sub.2, platinum, iridium, and platinum, and may be placed on top of a titanium layer and a silicon carbide layer. The IrIS may prevent, reduce, or mitigate against diffusion of elements such as oxygen, platinum, and gold through at least some of its layers.

Urinary excretion of platinum, arsenic and selenium of cancer patients from the Antofagasta region in Chile treated with platinum-based drugs

PubMed Central

2012-01-01

Background Arsenic exposure increases the risk of non-cancerous and cancerous diseases. In the Antofagasta region in Chile, an established relationship exists between arsenic exposure and the risk of cancer of the bladder, lung and skin. Platinum-based drugs are first-line treatments, and many works recognise selenium as a cancer-fighting nutrient. We characterised the short-term urinary excretion amounts of arsenic, selenium and platinum in 24-h urine samples from patients with lung cancer and those with cancer other than lung treated with cisplatin or/and carboplatin. As - Se - Pt inter-element relationships were also investigated. Results The amounts of platinum excreted in urine were not significantly different between patients with lung cancer and those with other cancers treated with cisplatin, despite the significant variation in platinum amounts supplied from platinum-based drugs. In general, the analytical amounts of excreted selenium were greater than those for arsenic, which could imply that platinum favours the excretion of selenium. For other types of cancers treated with drugs without platinum, excretion of selenium was also greater than that of arsenic, suggesting an antagonist selenium-anti-cancer drug relationship. Conclusions Regards the baseline status of patients, the analytical amounts of excreted Se is greater than those for As, particularly, for cisplatin chemotherapy. This finding could imply that for over the As displacement Pt favours the excretion of Se. The analytical amounts of excreted Se were greater than those for As, either with and without Pt-containing drugs, suggesting an antagonist Se-anti-cancer drug relationship. However, it seemed that differences existed between As - Se - Pt inter-element associations in patients treated for lung cancer in comparison with those treated for cancer other than lung. Therefore, knowledge obtained in this work, can contribute to understanding the arsenic cancer mechanism and the As - Se - Pt inter-element association for lung cancer and other types of cancer, which in some cases respond at a linear mathematical model. PMID:22546077

Relationships between hydrophobicity, reactivity, accumulation and peripheral nerve toxicity of a series of platinum drugs

PubMed Central

Screnci, D; McKeage, M J; Galettis, P; Hambley, T W; Palmer, B D; Baguley, B C

2000-01-01

Previous work has shown platinum drugs to differ in their effects on the peripheral nervous system. To test whether their differential toxicity was due to differences in their partitioning into the peripheral nervous system, we correlated the hydrophobicity, reactivity, tissue accumulation and neurotoxicity of a series of eight platinum analogues. Neurotoxicity was detected by measuring sensory nerve conduction velocity (SNCV) in Wistar rats treated twice per week at the maximum tolerated dose. Tissue platinum concentrations were measured by inductively coupled plasma mass spectrometry. Hydrophobicity (log P) was measured using an octanol-aqueous shake-flask method. The half-life of platinum drug binding to plasma proteins in vitro was determined. The cumulative dose causing altered SNCV ranged from 15 to > 2050 μmol kg−1. Ranking of the compounds by their neurotoxic potency in rats (oxaliplatin >R,R -(DACH)PtC4> ormaplatin >S,S -(DACH)PtCl4>S,S -(DACH)Pt oxalato > cisplatin > carboplatin > JM216) correlated with the frequency of neurotoxicity in patients (r> 0.99;P< 0.05). Ranking the compounds by their peripheral nerve accumulation was cisplatin > carboplatin > oxaliplatin >R,R -(DACH)PtCl4≈S,S -(DACH)PtCl4and did not correlate with neurotoxicity. Log P ranged from – 2.53 to –0.16 but did not correlate with neurotoxicity. Log P correlated inversely with platinum accumulation in dorsal root ganglia (r2= 0.99;P = 0.04), sural nerve (r2= 0.85;P = 0.025), sciatic nerve (r2= 0.98;P = 0.0012), spinal cord (r2= 0.97, P = 0.018) and brain (r2= 0.98, P = 0.001). Reactivity correlated with neurotoxicity potency in rats (r2= 0.89, P = 0.0005) and with the frequency of neurotoxicity in patients (r2= 0.99, P = 0.0002). The hydrophilicity of platinum drugs correlates with platinum sequestration in the peripheral nervous system but not with neurotoxicity. Differences in the reactivity of platinum complexes accounts for some of the variation in their neurotoxicity. © 2000 Cancer Research Campaign PMID:10732773

Thin film temperature sensor

NASA Technical Reports Server (NTRS)

Grant, H. P.; Przybyszewski, J. S.

1980-01-01

Thin film surface temperature sensors were developed. The sensors were made of platinum-platinum/10 percent rhodium thermocouples with associated thin film-to-lead wire connections and sputtered on aluminum oxide coated simulated turbine blades for testing. Tests included exposure to vibration, low velocity hydrocarbon hot gas flow to 1250 K, and furnace calibrations. Thermal electromotive force was typically two percent below standard type S thermocouples. Mean time to failure was 42 hours at a hot gas flow temperature of 1250 K and an average of 15 cycles to room temperature. Failures were mainly due to separation of the platinum thin film from the aluminum oxide surface. Several techniques to improve the adhesion of the platinum are discussed.

Research on rechargeable oxygen electrodes.

NASA Technical Reports Server (NTRS)

Giner, J.; Holleck, G.; Malachesky, P. A.

1970-01-01

A research program is described which consisted of studying the effects of electrode cycling in very pure KOH solutions, with and without controlled additions of impurities, on oxide formation, oxygen evolution kinetics, oxygen reduction kinetics (including hydrogen peroxide formation), and changes in electrode structure. Bright platinum, platinized platinum, and Teflon-bonded platinum black electrodes were studied. Three main problem areas are identified: the buildup of a refractory anodic layer on prolonged cycling, which leads to a degradation of performance; the dissolution and subsequent deposition of dendritic platinum in the separator, leading to short-circuit ing and loss of electrocatalyst; and the disruptive effect of bubbling during gas evolution on charge. Each of these problem areas is analyzed, and remedial solutions are proposed.

Nonenzymatic glucose detection by using a three-dimensionally ordered, macroporous platinum template.

PubMed

Song, Yan-Yan; Zhang, Dai; Gao, Wei; Xia, Xing-Hua

2005-03-18

A three-dimensionally ordered, macroporous, inverse-opal platinum film was synthesized electrochemically by the inverted colloidal-crystal template technique. The inverse-opal film that contains platinum nanoparticles showed improved electrocatalytic activity toward glucose oxidation with respect to the directly deposited platinum; this improvement is due to the interconnected porous structure and the greatly enhanced effective surface area. In addition, the inverse-opal Pt-film electrode responds more sensitively to glucose than to common interfering species of ascorbic acid, uric acid, and p-acetamidophenol due to their different electrochemical reaction mechanisms. Results showed that the ordered macroporous materials with enhanced selectivity and sensitivity are promising for fabrication of nonenzymatic glucose biosensors.

Chemical surface modification of polycrystalline platinum thin-films to promote preferential chemisorption of n-hexane, piperidine, and cyclohexane

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thomas, V.; Schwank, J.; Gland, J.

In this study, hard/soft Lewis acid-base (HSAB) principles are used to modify a thin-polycrystalline platinum film to promote preferential chemisorption of molecules such as piperidine, n-hexane, and cyclohexane. Specifically, the particle size and electron density distribution of the platinum surface is modified using thermal treatment and co-adsorption of electro-positive and negative species. These studies are conducted in an ultra-high vacuum chamber. The platinum surface is characterized, before and after modification protocols, using a variety of in-situ and ex-situ techniques. These include temperature programmed desorption (TPD), both resistance change and work function measurements, and both X-ray photoelectron spectroscopy and diffraction.

Nanofiber-deposited porous platinum enables glucose fuel cell anodes with high current density in body fluids

NASA Astrophysics Data System (ADS)

Frei, Maxi; Erben, Johannes; Martin, Julian; Zengerle, Roland; Kerzenmacher, Sven

2017-09-01

The poisoning of platinum anodes by body-fluid constituents such as amino acids is currently the main hurdle preventing the application of abiotic glucose fuel cells as battery-independent power supply for medical implants. We present a novel anode material that enables continuous operation of glucose oxidation anodes in horse serum for at least 30 days at a current density of (7.2 ± 1.9) μA cm-2. The fabrication process is based on the electro-deposition of highly porous platinum onto a 3-dimensional carbon nanofiber support, leading to approximately 2-fold increased electrode roughness factors (up to 16500 ± 2300). The material's superior performance is not only related to its high specific surface area, but also to an improved catalytic activity and/or poisoning resistance. Presumably, this results from the micro- and nanostructure of the platinum deposits. This represents a major step forward in the development of implantable glucose fuel cells based on long-term stable platinum electrodes.

Rapid epitaxy-free graphene synthesis on silicidated polycrystalline platinum

PubMed Central

Babenko, Vitaliy; Murdock, Adrian T.; Koós, Antal A.; Britton, Jude; Crossley, Alison; Holdway, Philip; Moffat, Jonathan; Huang, Jian; Alexander-Webber, Jack A.; Nicholas, Robin J.; Grobert, Nicole

2015-01-01

Large-area synthesis of high-quality graphene by chemical vapour deposition on metallic substrates requires polishing or substrate grain enlargement followed by a lengthy growth period. Here we demonstrate a novel substrate processing method for facile synthesis of mm-sized, single-crystal graphene by coating polycrystalline platinum foils with a silicon-containing film. The film reacts with platinum on heating, resulting in the formation of a liquid platinum silicide layer that screens the platinum lattice and fills topographic defects. This reduces the dependence on the surface properties of the catalytic substrate, improving the crystallinity, uniformity and size of graphene domains. At elevated temperatures growth rates of more than an order of magnitude higher (120 μm min−1) than typically reported are achieved, allowing savings in costs for consumable materials, energy and time. This generic technique paves the way for using a whole new range of eutectic substrates for the large-area synthesis of 2D materials. PMID:26175062

Preparation and Analysis of Platinum Thin Films for High Temperature Sensor Applications

NASA Technical Reports Server (NTRS)

Wrbanek, John D.; Laster, Kimala L. H.

2005-01-01

A study has been made of platinum thin films for application as high temperature resistive sensors. To support NASA Glenn Research Center s high temperature thin film sensor effort, a magnetron sputtering system was installed recently in the GRC Microsystems Fabrication Clean Room Facility. Several samples of platinum films were prepared using various system parameters to establish run conditions. These films were characterized with the intended application of being used as resistive sensing elements, either for temperature or strain measurement. The resistances of several patterned sensors were monitored to document the effect of changes in parameters of deposition and annealing. The parameters were optimized for uniformity and intrinsic strain. The evaporation of platinum via oxidation during annealing over 900 C was documented, and a model for the process developed. The film adhesion was explored on films annealed to 1000 C with various bondcoats on fused quartz and alumina. From this compiled data, a list of optimal parameters and characteristics determined for patterned platinum thin films is given.

Preparation and evaluation of advanced catalysts for phosphoric acid fuel cells

NASA Technical Reports Server (NTRS)

Stonehart, P.; Baris, J.; Hockmuth, J.; Pagliaro, P.

1984-01-01

The platinum electrocatalysts were characterized for their crystallite sizes and the degree of dispersion on the carbon supports. One application of these electrocatalysts was for anodic oxidation of hydrogen in hot phosphoric acid fuel cells, coupled with the influence of low concentrations of carbon monoxide in the fuel gas stream. In a similar way, these platinum on carbon electrocatalysts were evaluated for oxygen reduction in hot phosphoric acid. Binary noble metal alloys were prepared for anodic oxidation of hydrogen and noble metal-refractory metal mixtures were prepared for oxygen reduction. An exemplar alloy of platinum and palladium (50/50 atom %) was discovered for anodic oxidation of hydrogen in the presence of carbon monoxide, and patent disclosures were submitted. For the cathode, platinum-vanadium alloys were prepared showing improved performance over pure platinum. Preliminary experiments on electrocatalyst utilization in electrode structures showed low utilization of the noble metal when the electrocatalyst loading exceeded one weight percent on the carbon.

Growth of arrays of oriented epitaxial platinum nanoparticles with controlled size and shape by natural colloidal lithography

DOE PAGES

Komanicky, Vladimir; Barbour, Andi; Lackova, Miroslava; ...

2014-07-05

Here, we developed a method for production of arrays of platinum nanocrystals of controlled size and shape using templates from ordered silica bead monolayers. Silica beads with nominal sizes of 150 and 450 nm were self-assembl into monolayers over strontium titanate single crystal substrates. The monolayers were used as shadow masks for platinum metal deposition on the substrate using the three-step evaporation technique. Produced arrays of epitaxial platinum islands were transformed into nanocrystals by annealing in a quartz tube in nitrogen flow. The shape of particles is determined by the substrate crystallography, while the size of the particles and theirmore » spacing are controlled by the size of the silica beads in the mono- layer mask. As a proof of concept, arrays of platinum nanocrystals of cubooctahedral shape were prepared on (100) strontium titanate substrates. We also characterized the nanocrystal arrays by atomic force microscopy, scanning electron microscopy, and synchrotron X-ray diffraction techniques.« less

Enhancement of the reduction efficiency of soluble starch for platinum nanoparticles synthesis.

PubMed

Tongsakul, Duangta; Wongravee, Kanet; Thammacharoen, Chuchaat; Ekgasit, Sanong

2012-08-01

In this work, the efficiency of soluble starch as a reducing and a stabilizing agent in the synthesis of platinum nanoparticles under acidic-alkaline treatment is systematically studied. The degraded intermediates with reducing potential (i.e., small molecules containing aldehyde and α-hydroxy ketone moieties) are concomitantly generated when the alkaline concentration is greater than 0.025 M. The in situ generated species could completely reduce platinum ions (20 mM) and sufficiently stabilize the obtained platinum nanoparticles (5 mM) of uniform particle size (2-4 nm). The reduction is efficient and rapid as a complete conversion is achieved within 5 min. In a stronger alkaline condition, the platinum nanoparticles tend to aggregate and form a bigger domain because extensive degradation generates small starch fragments with less stabilization efficiency. This observation suggests that starch is a promising green material which could be chemically treated and transformed to a powerful reducing agent and stabilizer for the synthesis of metal nanoparticles. Copyright © 2012 Elsevier Ltd. All rights reserved.

Haemocompatibility assessment of synthesised platinum nanoparticles and its implication in biology.

PubMed

Shiny, P J; Mukherjee, Amitava; Chandrasekaran, N

2014-06-01

The growing need for advanced treatment of evolving diseases has become a motivation for this study. Among the noble metals, platinum nanoparticles are of importance because of their catalytic property, antioxidant potential, minimal toxicity and diverse applications. Biological process of synthesis has retained its significance, because it is a simple one-step process yielding stable nanoparticles. Herein, we have synthesised platinum nanoparticles through a green process using the unexplored seaweed Padina gymnospora, a brown alga. The course of synthesis was monitored and the nanoparticles were characterised using UV-visible spectroscopy. The synthesised nanoparticles were studied using TEM, XRD and FTIR. The TEM and XRD studies reveal the size of the nanoparticle to be <35 nm. The catalytic nanoparticles were capable of oxidising NADH to NAD(+). The biocompatibility was tested by haemolytic assay for the furtherance of the application of platinum nanoparticles in medicine. This is the first report on the biogenic synthesis of platinum nanoparticles using seaweed.

Catalysts for the Oxidation of Carbon Monoxide at Low Temperatures.

DTIC Science & Technology

1979-11-21

Four catalysts ( hopcalite , Whetlerite, a supported palladium, and a supported platinum) were tested for efficiency in promoting the oxidation of...carbon monoxide (CO). At room temperature and 50% RH, hopcalite has no catalytic capability and platinum has practically none. At room temperature and 15...RH, hopcalite is superior to platinum in catalyzing the oxidation of CO. Hopcalite is more efficient than either of the other three catalysts in the

Mineral resource of the month: platinum group metals

USGS Publications Warehouse

Loferski, Patricia J.

2010-01-01

The article focuses on platinum group metals (PGMs) and their properties. According to the author, PGMs, which include iridium, osmium, palladium, platinum, rhodium, and ruthenium, are among the rarest mineral commodities in the Earth's crust. PGMs are primarily used as catalytic converters that clean harmful exhaust from vehicle engines. They are also used in the chemical industry as catalysts in the production of nitric acid and in the petroleum refining industry.

Biosorption of platinum and palladium for their separation/preconcentration prior to graphite furnace atomic absorption spectrometric determination

NASA Astrophysics Data System (ADS)

Godlewska-Żyłkiewicz, Beata

2003-08-01

Inexpensive baker's yeast Saccharomyces cerevisiae and green algae Chlorella vulgaris, either free or immobilized on silica gel have been shown to selectively accumulate platinum and palladium from water samples in acidic medium (pH 1.6-1.8). Optimization of conditions of metals biosorption (sample pH, algae and yeast masses, adsorption time, temperature) was performed in batch mode. The procedure of matrix separation based on biosorption of platinum and palladium on algae C. vulgaris covalently immobilized on silica gel in flow mode was developed. The use of algae in flow procedure offers several advantages compared with its use in the batch mode. The procedure shows better reproducibility (<2%), improved efficiency of platinum retention on the column (93.3±1.6%), is less laborious and less time consuming. The best recovery of biosorbed metals from column (87.7±3.3% for platinum and 96.8±1.1 for palladium) was obtained with solution of 0.3 mol l -1 thiourea in 1 mol l -1 hydrochloric acid. The influence of thiourea on analytical signals of examined metals during GFAAS determination is discussed. The procedure has been applied for separation of noble metals from tap and waste water samples spiked with platinum and palladium.

Platinum-based anticancer agents: innovative design strategies and biological perspectives.

PubMed

Ho, Yee-Ping; Au-Yeung, Steve C F; To, Kenneth K W

2003-09-01

The impact of cisplatin on cancer chemotherapy cannot be denied. Over the past 20 years, much effort has been dedicated to discover new platinum-based anticancer agents that are superior to cisplatin or its analogue, carboplatin. Most structural modifications are based on changing one or both of the ligand types coordinated to platinum. Altering the leaving group can influence tissue and intracellular distribution of the drug, whereas the carrier ligand usually determines the structure of adducts formed with DNA. DNA-Pt adducts produced by cisplatin and many of its classical analogues are almost identical, and would explain their similar patterns of tumor sensitivity and susceptibility to resistance. Recently some highly innovative design strategies have emerged, aimed at overcoming platinum resistance and/or to introduce novel mechanisms of antitumor action. Platinum compounds bearing the 1,2-diaminocyclohexane carrier ligand; and those of multinuclear Pt complexes giving rise to radically different DNA-Pt adducts, have resulted in novel anticancer agents capable of circumventing cisplatin resistance. Other strategies have focused on integrating biologically active ligands with platinum moieties intended to selectively localizing the anticancer properties. With the rapid advance in molecular biology, combined with innovation, it is possible new Pt-based anticancer agents will materialize in the near future. Copyright 2003 Wiley Periodicals, Inc.

Efficiencies of induction of DNA double strand breaks in solution by photoabsorption at phosphorus and platinum.

PubMed

Maeda, Munetoshi; Kobayashi, Katsumi; Hieda, Kotaro

2004-01-01

This paper aims at determining and comparing the cross sections and quantum yields for DNA strand break induction by the Auger effect at the K-shell of phosphorus and at the LIII-shell of platinum. Using synchrotron radiation, free and Pt-bound pBR322 plasmid DNA were irradiated in solution with monochromatic X-rays, the energies of which were 2.153 and 2.147 keV, corresponding to "on" and "below" the phosphorus K-shell photoabsorption, and 11.566 and 11.542 keV for "above" and "below" the L(III)-shell photoabsorption of platinum, respectively. To suppress indirect effects by hydroxyl radicals, DMSO (1M) was used as a scavenger. The inner-shell photoabsorption of phosphorus and of platinum significantly increased the induction of DNA double strand breaks (DSB), whereas it had little effect on single strand break (SSB) induction. The quantum yields for the induction of DSB were calculated to be 0.017 and 1.13, in the case of phosphorus and platinum, respectively. CONCLSIONS: The value of the quantum yield for the DSB induction of platinum was about 66-fold larger than that for the phosphorus. These results clearly demonstrate that the quantum yield of DSB depends upon the magnitude of the Auger cascade.

Mammalian cells loaded with platinum-containing molecules are sensitized to fast atomic ions.

PubMed

Usami, N; Furusawa, Y; Kobayashi, K; Lacombe, S; Reynaud-Angelin, A; Sage, E; Wu, Ting-Di; Croisy, A; Guerquin-Kern, J-L; Le Sech, C

2008-07-01

This work investigates whether a synergy in cell death induction exists in combining atomic ions irradiation and addition of platinum salts. Such a synergy could be of interest in view of new cancer therapy protocol based on atomic ions--hadrontherapy--with the addition of radiosensitizing agents containing high-Z atoms. The experiment consists in irradiating by fast ions cultured cells previously exposed to dichloroterpyridine Platinum (PtTC) and analyzing cell survival by a colony-forming assay. Chinese Hamster Ovary (CHO) cells were incubated for six hours in medium containing 350 microM PtTC, and then irradiated by fast ions C(6+) and He(2+), with Linear Energy Transfer (LET) within range 2-70 keV/microm. In some experiments, dimethyl sulfoxide (DMSO) was added to investigate the role of free radicals. The intracellular localization of platinum was determined by Nano Secondary Ion Mass Spectroscopy (Nano-SIMS). For all LET examined, cell death rate is largely enhanced when irradiating in presence of PtTC. At fixed irradiation dose, cell death rate increases with increasing LET, while the platinum relative effect is larger at low LET. This finding suggests that hadrontherapy or protontherapy therapeutic index could be improved by combining irradiation procedure with concomitant chemotherapy protocols using platinum salts.

Selective speciation improves efficacy and lowers toxicity of platinum anticancer and vanadium antidiabetic drugs.

PubMed

Doucette, Kaitlin A; Hassell, Kelly N; Crans, Debbie C

2016-12-01

Improving efficacy and lowering resistance to metal-based drugs can be addressed by consideration of the coordination complex speciation and key reactions important to vanadium antidiabetic drugs or platinum anticancer drugs under biological conditions. The methods of analyses vary depending on the specific metal ion chemistry. The vanadium compounds interconvert readily, whereas the reactions of the platinum compounds are much slower and thus much easier to study. However, the vanadium species are readily differentiated due to vanadium complexes differing in color. For both vanadium and platinum systems, understanding the processes as the compounds, Lipoplatin and Satraplatin, enter cells is needed to better combat the disease; there are many cellular metabolites, which may affect processing and thus the efficacy of the drugs. Examples of two formulations of platinum compounds illustrate how changing the chemistry of the platinum will result in less toxic and better tolerated drugs. The consequence of the much lower toxicity of the drug, can be readily realized because cisplatin administration requires hospital stay whereas Lipoplatin can be done in an outpatient manner. Similarly, the properties of Satraplatin allow for development of an oral drug. These forms of platinum demonstrate that the direct consequence of more selective speciation is lower side effects and cheaper administration of the anticancer agent. Therefore we urge that as the community goes forward in development of new drugs, control of speciation chemistry will be considered as one of the key strategies in the future development of anticancer drugs. Copyright © 2016 Elsevier Inc. All rights reserved.

Convection-enhancement delivery of platinum-based drugs and Lipoplatin™ to optimize the concomitant effect with radiotherapy in F98 glioma rat model

PubMed Central

Shi, Minghan; Fortin, David; Sanche, Léon; Paquette, Benoit

2015-01-01

The prognosis for patients with glioblastoma remains poor with current treatments. Although platinum based drugs are sometimes offered at relapse, their efficacy in this setting is still disputed. In this study, we use convection-enhanced delivery (CED) to deliver the platinum-based drugs (cisplatin, carboplatin, and Lipoplatin™-liposomal formulation of cisplatin) directly into the tumor of F98 glioma-bearing rats that were subsequently treated with γ radiation (15 Gy). CED increased by factors varying between 17 and 111, the concentration of these platinum-based drugs in the brain tumor compared to intra-venous (i.v.) administration, and by 9- to 34-fold, when compared to intra-arterial (i.a.) administration. Furthermore, CED resulted in a better systemic tolerance to platinum drugs compared to their i.a. injection. Among the drugs tested, carboplatin showed the highest maximum tolerated dose (MTD). Treatment with carboplatin resulted in the best median survival time (MeST) (38.5 days), which was further increased by the addition of radiotherapy (54.0 days). Although the DNA-bound platinum adduct were higher at 4 h after CED than 24 h for carboplatin group, combination with radiotherapy led to similar improvement of median survival time. However, less toxicity was observed in animals irradiated 24 h after CED-based chemotherapy. In conclusion, CED increased the accumulation of platinum drugs in tumor, reduced the toxicity, and resulted in a higher median survival time. The best treatment was obtained in animals treated with carboplatin and irradiated 24 h later. PMID:25784204

Copper (II) complexes of bidentate ligands exhibit potent anti-cancer activity regardless of platinum sensitivity status.

PubMed

Wehbe, Mohamed; Lo, Cody; Leung, Ada W Y; Dragowska, Wieslawa H; Ryan, Gemma M; Bally, Marcel B

2017-12-01

Insensitivity to platinum, either through inherent or acquired resistance, is a major clinical problem in the treatment of many solid tumors. Here, we explored the therapeutic potential of diethyldithiocarbamate (DDC), pyrithione (Pyr), plumbagin (Plum), 8-hydroxyquinoline (8-HQ), clioquinol (CQ) copper complexes in a panel of cancer cell lines that differ in their sensitivity to platins (cisplatin/carboplatin) using a high-content imaging system. Our data suggest that the copper complexes were effective against both platinum sensitive (IC 50  ~ 1 μM platinum) and insensitive (IC 50  > 5 μM platinum) cell lines. Furthermore, copper complexes of DDC, Pyr and 8-HQ had greater therapeutic activity compared to the copper-free ligands in all cell lines; whereas the copper-dependent activities of Plum and CQ were cell-line specific. Four of the copper complexes (Cu(DDC) 2 , Cu(Pyr) 2 , Cu(Plum) 2 and Cu(8-HQ) 2 ) showed IC 50 values less than that of cisplatin in all tested cell lines. The complex copper DDC (Cu(DDC) 2 ) was selected for in vivo evaluation due to its low nano-molar range activity in vitro and the availability of an injectable liposomal formulation. Liposomal (Cu(DDC) 2 ) was tested in a fast-growing platinum-resistant A2780-CP ovarian xenograft model and was found to achieve a statistically significant reduction (50%; p < 0.05) in tumour size. This work supports the potential use of copper-based therapeutics to treat cancers that are insensitive to platinum drugs.

Convection-enhancement delivery of platinum-based drugs and Lipoplatin(TM) to optimize the concomitant effect with radiotherapy in F98 glioma rat model.

PubMed

Shi, Minghan; Fortin, David; Sanche, Léon; Paquette, Benoit

2015-06-01

The prognosis for patients with glioblastoma remains poor with current treatments. Although platinum-based drugs are sometimes offered at relapse, their efficacy in this setting is still disputed. In this study, we use convection-enhanced delivery (CED) to deliver the platinum-based drugs (cisplatin, carboplatin, and Lipoplatin(TM) - liposomal formulation of cisplatin) directly into the tumor of F98 glioma-bearing rats that were subsequently treated with γ radiation (15 Gy). CED increased by factors varying between 17 and 111, the concentration of these platinum-based drugs in the brain tumor compared to intra-venous (i.v.) administration, and by 9- to 34-fold, when compared to intra-arterial (i.a.) administration. Furthermore, CED resulted in a better systemic tolerance to platinum drugs compared to their i.a. injection. Among the drugs tested, carboplatin showed the highest maximum tolerated dose (MTD). Treatment with carboplatin resulted in the best median survival time (MeST) (38.5 days), which was further increased by the addition of radiotherapy (54.0 days). Although the DNA-bound platinum adduct were higher at 4 h after CED than 24 h for carboplatin group, combination with radiotherapy led to similar improvement of median survival time. However, less toxicity was observed in animals irradiated 24 h after CED-based chemotherapy. In conclusion, CED increased the accumulation of platinum drugs in tumor, reduced the toxicity, and resulted in a higher median survival time. The best treatment was obtained in animals treated with carboplatin and irradiated 24 h later.

Electrochemical behavior of platinum nanoparticles on a carbon xerogel support modified with a [(trifluoromethyl)-benzenesulfonyl]imide electrolyte.

PubMed

Liu, Bing; Mei, Hua; DesMarteau, Darryl; Creager, Stephen E

2014-12-11

A monoprotic [(trifluoromethyl)benzenesulfonyl]imide (SI) superacid electrolyte was used to covalently modify a mesoporous carbon xerogel (CX) support via reaction of the corresponding trifluoromethyl aryl sulfonimide diazonium zwitterion with the carbon surface. Electrolyte attachment was demonstrated by elemental analysis, acid-base titration, and thermogravimetric analysis. The ion-exchange capacity of the fluoroalkyl-aryl-sulfonimide-grafted carbon xerogel (SI-CX) was ∼0.18 mequiv g(-1), as indicated by acid-base titration. Platinum nanoparticles were deposited onto the SI-grafted carbon xerogel samples by the impregnation and reduction method, and these materials were employed to fabricate polyelectrolyte membrane fuel-cell (PEMFC) electrodes by the decal transfer method. The SI-grafted carbon-xerogel-supported platinum (Pt/SI-CX) was characterized by X-ray diffraction and transmission electron microscopy to determine platinum nanoparticle size and distribution, and the findings are compared with CX-supported platinum catalyst without the grafted SI electrolyte (Pt/CX). Platinum nanoparticle sizes are consistently larger on Pt/SI-CX than on Pt/CX. The electrochemically active surface area (ESA) of platinum catalyst on the Pt/SI-CX and Pt/CX samples was measured with ex situ cyclic voltammetry (CV) using both hydrogen adsorption/desorption and carbon monoxide stripping methods and by in situ CV within membrane electrode assemblies (MEAs). The ESA values for Pt/SI-CX are consistently lower than those for Pt/CX. Some possible reasons for the behavior of samples with and without grafted SI layers and implications for the possible use of SI-grafted carbon layers in PEMFC devices are discussed.

Platinum-Induced Ototoxicity in Children: A Consensus Review on Mechanisms, Predisposition, and Protection, Including a New International Society of Pediatric Oncology Boston Ototoxicity Scale

PubMed Central

Brock, Penelope R.; Knight, Kristin R.; Freyer, David R.; Campbell, Kathleen C.M.; Steyger, Peter S.; Blakley, Brian W.; Rassekh, Shahrad R.; Chang, Kay W.; Fligor, Brian J.; Rajput, Kaukab; Sullivan, Michael; Neuwelt, Edward A.

2012-01-01

Purpose The platinum chemotherapy agents cisplatin and carboplatin are widely used in the treatment of adult and pediatric cancers. Cisplatin causes hearing loss in at least 60% of pediatric patients. Reducing cisplatin and high-dose carboplatin ototoxicity without reducing efficacy is important. Patients and Methods This review summarizes recommendations made at the 42nd Congress of the International Society of Pediatric Oncology (SIOP) in Boston, October 21-24, 2010, reflecting input from international basic scientists, pediatric oncologists, otolaryngologists, oncology nurses, audiologists, and neurosurgeons to develop and advance research and clinical trials for otoprotection. Results Platinum initially impairs hearing in the high frequencies and progresses to lower frequencies with increasing cumulative dose. Genes involved in drug transport, metabolism, and DNA repair regulate platinum toxicities. Otoprotection can be achieved by acting on several these pathways and generally involves antioxidant thiol agents. Otoprotection is a strategy being explored to decrease hearing loss while maintaining dose intensity or allowing dose escalation, but it has the potential to interfere with tumoricidal effects. Route of administration and optimal timing relative to platinum therapy are critical issues. In addition, international standards for grading and comparing ototoxicity are essential to the success of prospective pediatric trials aimed at reducing platinum-induced hearing loss. Conclusion Collaborative prospective basic and clinical trial research is needed to reduce the incidence of irreversible platinum-induced hearing loss, and optimize cancer control. Wide use of the new internationally agreed-on SIOP Boston ototoxicity scale in current and future otoprotection trials should help facilitate this goal. PMID:22547603

GREAT-a randomized controlled trial comparing HydroSoft/HydroFrame and bare platinum coils for endovascular aneurysm treatment: procedural safety and core-lab-assessedangiographic results.

PubMed

Taschner, Christian A; Chapot, René; Costalat, Vincent; Machi, Paolo; Courthéoux, Patrick; Barreau, Xavier; Berge, Jérôme; Pierot, Laurent; Kadziolka, Kryzsztof; Jean, Betty; Blanc, Raphaël; Biondi, Alessandra; Brunel, Hervé; Gallas, Sophie; Berlis, Ansgar; Herbreteau, Denis; Berkefeld, Joachim; Urbach, Horst; El Shikh, Samer; Fiehler, Jens; Desal, Hubert; Graf, Erika; Bonafé, Alain

2016-08-01

Hybrid hydrogel-platinum coils (HydroCoil) have proven effective for endovascular aneurysm treatment. To overcome technical limitations (coil stiffness, time restriction for placement), a second generation of softer hydrogel coils has been brought to clinical practice (HydroSoft, HydroFrame). We report on procedural safety and core-lab-assessed angiographic results from an open-label multicenter randomized controlled trial. Web-based randomization occurred in 15 medical centers in France and seven in Germany between coil embolization with second-generation hydrogel coils and treatment with any bare platinum coil. Assist devices could be used as clinically required. Primary endpoint is a composite outcome including major aneurysm recurrence and poor clinical outcome at 18 months follow-up. Five hundred thirteen patients were randomized (hydrogel n = 256, bare platinum n = 257). Twenty patients were excluded for missing informed consent and nine patients for treatment related criteria. Four hundred eighty-four patients were analyzed as randomized (hydrogel n = 243, bare platinum n = 241). Two hundred eight had ruptured aneurysms (43 %). Prespecified procedural complications occurred in 58 subjects (hydrogel n = 28, bare platinum n = 30, p = 0.77). The 14-day mortality rate was 2.1 % in both arms of the study. The median calculated packing densities for aneurysms assigned to hydrogel and bare platinum were 39 and 31 % respectively (p < 0.001). No statistically significant differences were found between arms in the post procedural angiographic occlusion rate (p = 0.8). Second-generation hydrogel coils can be used in a wide spectrum of aneurysms with a risk profile equivalent to bare platinum. Packing density was significantly higher in aneurysms treated with hydrogel coils. http://www.germanctr.de , DRKS00003132.

Anti-tumour activity of platinum compounds in advanced prostate cancer-a systematic literature review.

PubMed

Hager, S; Ackermann, C J; Joerger, M; Gillessen, S; Omlin, A

2016-06-01

For men with advanced castration-resistant prostate cancer (CRPC), several treatment options are available, including androgen receptor (AR) pathway inhibitors (abiraterone acetate, enzalutamide), taxanes (docetaxel, cabazitaxel) and the radionuclide (radium-223). However, cross-resistance is a clinically relevant problem. Platinum compounds have been tested in a number of clinical trials in molecularly unselected prostate cancer patients. Advances in CRPC molecular profiling have shown that a significant proportion of patients harbour DNA repair defects, which may serve as predictive markers for sensitivity to platinum agents. To systematically identify and analyse clinical trials that have evaluated platinum agents in advanced prostate cancer patients. PubMed was searched to identify published clinical trials of platinum agents in advanced prostate cancer. The PRIMSA statement was followed for the systematic review process. Identified trials are analysed for study design, statistical plan, assessments of anti-tumour activity and the potential value of predictive biomarkers. A total of 163 references were identified by the literature search and 72 publications that met the selection criteria were included in this review; of these 33 used carboplatin, 27 cisplatin, 6 satraplatin, 4 oxaliplatin and 2 other platinum compounds. Overall, anti-tumour activity varies in the range of 10%-40% for objective response and 20%-70% for PSA decline ≥50%. Response seemed highest for the combinations of carboplatin with taxanes or oxaliplatin with gemcitabine. The interpretation of the clinical data is limited by differences in response criteria used and patient populations studied. Platinum compounds have moderate anti-tumour activity in molecularly unselected patients with advanced prostate cancer. Translational evidence of DNA repair deficiency should be leveraged in future studies to select prostate cancer patients most likely to benefit from platinum-based therapy. © The Author 2016. Published by Oxford University Press on behalf of the European Society for Medical Oncology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Encapsulation, controlled release, and antitumor efficacy of cisplatin delivered in liposomes composed of sterol-modified phospholipids

DOE PAGES

Kieler-Ferguson, Heidi M.; Chan, Darren; Sockolosky, Jonathan; ...

2017-03-03

Here, we employed a recently introduced class of sterol-modified lipids (SML) to produce m-PEG-DSPE containing liposome compositions with a range of cis-platinum content release rates. SML have a cholesterol succinate attached to the phosphatidylglycerol head group and a fatty acid at the 2 position. These compositions were compared to the well-studied liposome phospholipid compositions: mPEG-DSPE/Hydrogenated Soy PC/cholesterol or mPEG-DSPE/POPC/cholesterol to determine the effect of the cis-platinum release extent on C26 tumor proliferation in the BALB/c colon carcinoma mouse model. The release rates of cis-platinum from liposomes composed of SML are a function of the acyl chain length. SML-liposomes with shortermore » acyl chain lengths C-8 provided more rapid cisplatin release, lower in vitro IC50, and were easier to formulate compared to liposomes using traditional phospholipid compositions. Similar to other liposome cis-platinum formulations, the half-life of m-PEG-DSPE SML liposome cisplatin is substantially longer than the free drug. This resulted in a higher tumor cisplatin concentration at 48 h post-dosing compared to the free drug and higher Pt-DNA adducts in the tumor. Moreover, the maximum tolerated dose of the liposome formulations where up to four fold greater than the free drug. Using X-ray fluorescence spectroscopy on tumor sections, we compared the location of platinum, to the location of a fluorescence lipid incorporated in the liposomes. The liposome platinum co-localized with the fluorescent lipid and both were non-uniformly distributed in the tumor. Non-encapsulated Cis-platinum, albeit at a low concentration, was more uniformly distributed thorough the tumor. Three liposome formulations, including the well studied hydrogenated HSPC composition, had better antitumor activity in the murine colon 26 carcinoma model as compared to the free drug at the same dose but the SML liposome platinum formulations did not perform better than the HSPC formulation.« less

Encapsulation, controlled release, and antitumor efficacy of cisplatin delivered in liposomes composed of sterol-modified phospholipids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kieler-Ferguson, Heidi M.; Chan, Darren; Sockolosky, Jonathan

Here, we employed a recently introduced class of sterol-modified lipids (SML) to produce m-PEG-DSPE containing liposome compositions with a range of cis-platinum content release rates. SML have a cholesterol succinate attached to the phosphatidylglycerol head group and a fatty acid at the 2 position. These compositions were compared to the well-studied liposome phospholipid compositions: mPEG-DSPE/Hydrogenated Soy PC/cholesterol or mPEG-DSPE/POPC/cholesterol to determine the effect of the cis-platinum release extent on C26 tumor proliferation in the BALB/c colon carcinoma mouse model. The release rates of cis-platinum from liposomes composed of SML are a function of the acyl chain length. SML-liposomes with shortermore » acyl chain lengths C-8 provided more rapid cisplatin release, lower in vitro IC50, and were easier to formulate compared to liposomes using traditional phospholipid compositions. Similar to other liposome cis-platinum formulations, the half-life of m-PEG-DSPE SML liposome cisplatin is substantially longer than the free drug. This resulted in a higher tumor cisplatin concentration at 48 h post-dosing compared to the free drug and higher Pt-DNA adducts in the tumor. Moreover, the maximum tolerated dose of the liposome formulations where up to four fold greater than the free drug. Using X-ray fluorescence spectroscopy on tumor sections, we compared the location of platinum, to the location of a fluorescence lipid incorporated in the liposomes. The liposome platinum co-localized with the fluorescent lipid and both were non-uniformly distributed in the tumor. Non-encapsulated Cis-platinum, albeit at a low concentration, was more uniformly distributed thorough the tumor. Three liposome formulations, including the well studied hydrogenated HSPC composition, had better antitumor activity in the murine colon 26 carcinoma model as compared to the free drug at the same dose but the SML liposome platinum formulations did not perform better than the HSPC formulation.« less

Platinum Monolayer Shell on Non-Noble Metal Core Electrocatalysts for the Hydrogen Oxidation Reaction

NASA Astrophysics Data System (ADS)

Teeluck, Krishani Malini

According to the United States Environmental Protection Agency, as of 2015, transportation accounted for 32% of the carbon dioxide emissions in the United States (and all carbon dioxide emissions in the U.S. accounted for 82.2% of all greenhouse gases from human activity). A hydrogen fuel cell is a device that efficiently produces electrical energy directly from a chemical reaction, with zero carbon emissions, and therefore holds great promise in alleviating our dependence on harmful use of energy sources. Due to their clean emissions and high efficiencies, there has been focus on the hydrogen fuel cell for vehicle applications using proton exchange membrane and alkaline fuel cells. Although the proton exchange membrane fuel cell is currently being used in vehicles, their high cost limits their feasibility in the market. This has inspired the development of the alkaline fuel cell whose efficiency and simplicity suggest the possibility of manufacturing high power fuel cell vehicles at a low cost, since the electrocatalysts in the alkaline fuel cell can be made from non-noble metals. Although the hydrogen oxidation reaction is one of the fastest electrochemical reactions in acidic media, it is two orders of magnitude slower in alkaline media, which hinders the overall efficiency of the alkaline fuel cell. Pure platinum is currently the best catalyst for the hydrogen oxidation reaction, but platinum’s high cost and rarity yields economic issues, rendering the technology futile if it cannot be commercialized. Furthermore, platinum’s hydrogen binding energy is slightly stronger than the optimal hydrogen binding energy. As the hydrogen oxidation reaction happens only on the surface of the catalyst, there is no need for platinum content beyond the exterior. Since tungsten and nickel are cheap, as well as abundant, they are ideal elements to replace the core of the catalyst with, while leaving a platinum shell surrounding this core. The activity of the hydrogen oxidation reaction when using a platinum monolayer shell on a nickel tungsten core electrocatalyst is explored, and it was found that the novel catalyst created here exhibits kinetics that rival pure platinum, but at less than half the platinum content, suggesting that nickel and tungsten modify the electronic properties of platinum in a way that enhances its activity for the hydrogen oxidation reaction. Furthermore, the hydrogen binding energy of this novel electrocatalyst was found to be weaker than the optimal binding energy (rather than stronger, as seen in pure platinum), indicating the possibility of modifying the electronic properties of platinum for a more optimal hydrogen binding energy.

Bi-metallic nanoparticles as cathode electrocatalysts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lu, Jun; Amine, Khalil; Wang, Xiaoping

A lithium-air battery cathode catalyst includes core-shell nanoparticles on a carbon support, wherein: a core of the core-shell nanoparticles is platinum metal; and a shell of the core-shell nanoparticles is copper metal; wherein: the core-shell nanoparticles have a weight ratio of the copper metal to the platinum metal from about 4% to about 6% copper to from about 2% to about 12% platinum, with a remaining percentage being the carbon support.

Correlation of Electrode Kinetics with Surface Structure.

DTIC Science & Technology

1980-09-01

platinum and gold electrodes is sufficiently strong so that monolayers are formed upon contact even with small (millimolar) bulk iodide concentrations...transition-metal reactants, we have monitored the effects of altering the electrode material from mercury to silver, platinum, and gold upon the...strikingly different behavior for the reduction of Co III(NH3)5X and Co II(en)2X2 at platinum and gold electrodes. 1 0 For halide bridging ligands (X

High frequency reference electrode

DOEpatents

Kronberg, J.W.

1994-05-31

A high frequency reference electrode for electrochemical experiments comprises a mercury-calomel or silver-silver chloride reference electrode with a layer of platinum around it and a layer of a chemically and electrically resistant material such as TEFLON around the platinum covering all but a small ring or halo' at the tip of the reference electrode, adjacent to the active portion of the reference electrode. The voltage output of the platinum layer, which serves as a redox electrode, and that of the reference electrode are coupled by a capacitor or a set of capacitors and the coupled output transmitted to a standard laboratory potentiostat. The platinum may be applied by thermal decomposition to the surface of the reference electrode. The electrode provides superior high-frequency response over conventional electrodes. 4 figs.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sukri, Shahratul Ain Mohd; Heng, Lee Yook; Karim, Nurul Huda Abd

A platinum (II) salphen complex was synthesised by condensation reaction of 2,4-dihydroxylbenzaldehyde and o-phenylenediamine with potassium tetrachloroplatinate to obtain N,N′-Bis-4-(hydroxysalicylidene)-phenylenediamine-platinum (II). The structure of the complex was confirmed by {sup 1}H and {sup 13}C NMR spectroscopy, FTIR spectroscopy, CHN elemental analyses and ESI-MS spectrometry. The platinum (II) salphen complex with four donor atoms N{sub 2}O{sub 2} from its salphen ligand coordinated to platinum (II) metal centre were determined. The binding mode and interaction of this complex with calf thymus DNA was determined by UV/Vis DNA titration and emission titration. The intercalation between the DNA bases by π-π stacking due tomore » its square planar geometry and aromatic rings structures was proposed.« less

High frequency reference electrode

DOEpatents

Kronberg, James W.

1994-01-01

A high frequency reference electrode for electrochemical experiments comprises a mercury-calomel or silver-silver chloride reference electrode with a layer of platinum around it and a layer of a chemically and electrically resistant material such as TEFLON around the platinum covering all but a small ring or "halo" at the tip of the reference electrode, adjacent to the active portion of the reference electrode. The voltage output of the platinum layer, which serves as a redox electrode, and that of the reference electrode are coupled by a capacitor or a set of capacitors and the coupled output transmitted to a standard laboratory potentiostat. The platinum may be applied by thermal decomposition to the surface of the reference electrode. The electrode provides superior high-frequency response over conventional electrodes.

Phosphorus adlayers on Platinum (110)

NASA Astrophysics Data System (ADS)

Heikkinen, Olli; Riihimäki, Ari; Sainio, Jani; Lahtinen, Jouko

2017-10-01

Platinum is a metal utilized in many applications. Its catalytic activity can be decreased due to chemical poisoning caused e.g. by phosphorus. To gain more understanding of its poisoning, we present a study of phosphorus adsorption on a platinum (110) single crystal surface. Using X-ray photoelectron spectroscopy, we have found that the adsorbate coverage saturates at around 3 monolayers. Annealing the phosphorus-covered platinum surface at 750 °C gives rise to three different ordered adlayer structures, with symmetries of 2 × 3, 11 × 4 and √{ 2} × 1 , from the lowest to the highest coverage, detected with low-energy electron diffraction. We have studied the sample topography with scanning tunnelling microscopy. We also present a tentative model for the observed structures and their evolution.

Preparation of low-sulfur platinum and platinum aluminide layers in thermal barrier coatings

NASA Technical Reports Server (NTRS)

Spitsberg, Irene T. (Inventor); Walston, William S. (Inventor); Schaeffer, Jon C. (Inventor)

2003-01-01

A method for preparing a coated nickel-base superalloy article reduces the sulfur content of the surface region of the metallic coating layers to low levels, thereby improving the adhesion of the coating layers to the article. The method includes depositing a first layer of platinum overlying the surface of a substrate, depositing a second layer of aluminum over the platinum, and final desulfurizing the article by heating the article to elevated temperature, preferably in hydrogen, and removing a small amount of material from the surface that was exposed during the step of heating. A ceramic layer may be deposited over the desulfurized article. The article may also be similarly desulfurized at other points in the fabrication procedure.

Effects of para-substituents of styrene derivatives on their chemical reactivity on platinum nanoparticle surfaces

NASA Astrophysics Data System (ADS)

Hu, Peiguang; Chen, Limei; Deming, Christopher P.; Lu, Jia-En; Bonny, Lewis W.; Chen, Shaowei

2016-06-01

Stable platinum nanoparticles were successfully prepared by the self-assembly of para-substituted styrene derivatives onto the platinum surfaces as a result of platinum-catalyzed dehydrogenation and transformation of the vinyl groups to the acetylene ones, forming platinum-vinylidene/-acetylide interfacial bonds. Transmission electron microscopic measurements showed that the nanoparticles were well dispersed without apparent aggregation, suggesting sufficient protection of the nanoparticles by the organic capping ligands, and the average core diameter was estimated to be 2.0 +/- 0.3 nm, 1.3 +/- 0.2 nm, and 1.1 +/- 0.2 nm for the nanoparticles capped with 4-tert-butylstyrene, 4-methoxystyrene, and 4-(trifluoromethyl)styrene, respectively, as a result of the decreasing rate of dehydrogenation with the increasing Taft (polar) constant of the para-substituents. Importantly, the resulting nanoparticles exhibited unique photoluminescence, where an increase of the Hammett constant of the para-substituents corresponded to a blue-shift of the photoluminescence emission, suggesting an enlargement of the HOMO-LUMO band gap of the nanoparticle-bound acetylene moieties. Furthermore, the resulting nanoparticles exhibited apparent electrocatalytic activity towards oxygen reduction in acidic media, with the best performance among the series of samples observed with the 4-tert-butylstyrene-capped nanoparticles due to an optimal combination of the nanoparticle core size and ligand effects on the bonding interactions between platinum and oxygen species.Stable platinum nanoparticles were successfully prepared by the self-assembly of para-substituted styrene derivatives onto the platinum surfaces as a result of platinum-catalyzed dehydrogenation and transformation of the vinyl groups to the acetylene ones, forming platinum-vinylidene/-acetylide interfacial bonds. Transmission electron microscopic measurements showed that the nanoparticles were well dispersed without apparent aggregation, suggesting sufficient protection of the nanoparticles by the organic capping ligands, and the average core diameter was estimated to be 2.0 +/- 0.3 nm, 1.3 +/- 0.2 nm, and 1.1 +/- 0.2 nm for the nanoparticles capped with 4-tert-butylstyrene, 4-methoxystyrene, and 4-(trifluoromethyl)styrene, respectively, as a result of the decreasing rate of dehydrogenation with the increasing Taft (polar) constant of the para-substituents. Importantly, the resulting nanoparticles exhibited unique photoluminescence, where an increase of the Hammett constant of the para-substituents corresponded to a blue-shift of the photoluminescence emission, suggesting an enlargement of the HOMO-LUMO band gap of the nanoparticle-bound acetylene moieties. Furthermore, the resulting nanoparticles exhibited apparent electrocatalytic activity towards oxygen reduction in acidic media, with the best performance among the series of samples observed with the 4-tert-butylstyrene-capped nanoparticles due to an optimal combination of the nanoparticle core size and ligand effects on the bonding interactions between platinum and oxygen species. Electronic supplementary information (ESI) available: TGA curves and additional voltammograms. See DOI: 10.1039/c6nr02296k

Combination Platinum-based and DNA Damage Response-targeting Cancer Therapy: Evolution and Future Directions

PubMed Central

Basourakos, Spyridon P.; Li, Likun; Aparicio, Ana M.; Corn, Paul G.; Kim, Jeri; Thompson, Timothy C.

2017-01-01

Maintenance of genomic stability is a critical determinant of cell survival and is necessary for growth and progression of malignant cells. Interstrand crosslinking (ICL) agents, including platinum-based agents, are first-line chemotherapy treatment for many solid human cancers. In malignant cells, ICL triggers the DNA damage response (DDR). When the damage burden is high and lesions cannot be repaired, malignant cells are unable to divide and ultimately undergo cell death either through mitotic catastrophe or apoptosis. The activities of ICL agents, in particular platinum-based therapies, establish a “molecular landscape,” i.e., a pattern of DNA damage that can potentially be further exploited therapeutically with DDR-targeting agents. If the molecular landscape created by platinum-based agents could be better defined at the molecular level, a systematic, mechanistic rationale(s) could be developed for the use of DDR-targeting therapies in combination/maintenance protocols for specific, clinically advanced malignancies. New therapeutic drugs such as poly(ADP-ribose) polymerase (PARP) inhibitors are examples of DDR-targeting therapies that could potentially increase the DNA damage and replication stress imposed by platinum-based agents in tumor cells and provide therapeutic benefit for patients with advanced malignancies. Recent studies have shown that the use of PARP inhibitors together with platinum-based agents is a promising therapy strategy for ovarian cancer patients with ”BRCAness”, i.e., a phenotypic characteristic of tumors that not only can involve loss-of-function mutations in either BRCA1 or BRCA2, but also encompasses the molecular features of BRCA-mutant tumors. On the basis of these promising results, additional mechanism-based studies focused on the use of various DDR-targeting therapies in combination with platinum-based agents should be considered. This review discusses, in general, (1) ICL agents, primarily platinum-based agents, that establish a molecular landscape that can be further exploited therapeutically; (2) multiple points of potential intervention after ICL agent–induced crosslinking that further predispose to cell death and can be incorporated into a systematic, therapeutic rationale for combination/maintenance therapy using DDR-targeting agents; and (3) available agents that can be considered for use in combination/maintenance clinical protocols with platinum-based agents for patients with advanced malignancies. PMID:27978798

Combination Platinum-based and DNA Damage Response-targeting Cancer Therapy: Evolution and Future Directions.

PubMed

Basourakos, Spyridon P; Li, Likun; Aparicio, Ana M; Corn, Paul G; Kim, Jeri; Thompson, Timothy C

2017-01-01

Maintenance of genomic stability is a critical determinant of cell survival and is necessary for growth and progression of malignant cells. Interstrand crosslinking (ICL) agents, including platinum-based agents, are first-line chemotherapy treatment for many solid human cancers. In malignant cells, ICL triggers the DNA damage response (DDR). When the damage burden is high and lesions cannot be repaired, malignant cells are unable to divide and ultimately undergo cell death either through mitotic catastrophe or apoptosis. The activities of ICL agents, in particular platinum-based therapies, establish a "molecular landscape," i.e., a pattern of DNA damage that can potentially be further exploited therapeutically with DDR-targeting agents. If the molecular landscape created by platinum-based agents could be better defined at the molecular level, a systematic, mechanistic rationale(s) could be developed for the use of DDR-targeting therapies in combination/maintenance protocols for specific, clinically advanced malignancies. New therapeutic drugs such as poly(ADP-ribose) polymerase (PARP) inhibitors are examples of DDR-targeting therapies that could potentially increase the DNA damage and replication stress imposed by platinum-based agents in tumor cells and provide therapeutic benefit for patients with advanced malignancies. Recent studies have shown that the use of PARP inhibitors together with platinum-based agents is a promising therapy strategy for ovarian cancer patients with "BRCAness", i.e., a phenotypic characteristic of tumors that not only can involve loss-of-function mutations in either BRCA1 or BRCA2, but also encompasses the molecular features of BRCA-mutant tumors. On the basis of these promising results, additional mechanism-based studies focused on the use of various DDR-targeting therapies in combination with platinum-based agents should be considered. This review discusses, in general, (1) ICL agents, primarily platinum-based agents, that establish a molecular landscape that can be further exploited therapeutically; (2) multiple points of potential intervention after ICL agent-induced crosslinking that further predispose to cell death and can be incorporated into a systematic, therapeutic rationale for combination/ maintenance therapy using DDR-targeting agents; and (3) available agents that can be considered for use in combination/maintenance clinical protocols with platinum-based agents for patients with advanced malignancies. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Activity of chemotherapy in mucinous ovarian cancer with a recurrence free interval of more than 6 months: results from the SOCRATES retrospective study

PubMed Central

Pignata, Sandro; Ferrandina, Gabriella; Scarfone, Giovanna; Scollo, Paolo; Odicino, Franco; Cormio, Gennaro; Katsaros, Dionyssios; Villa, Antonella; Mereu, Liliana; Ghezzi, Fabio; Manzione, Luigi; Lauria, Rossella; Breda, Enrico; Alletti, Desiderio Gueli; Ballardini, Michela; Lombardi, Alessandra Vernaglia; Sorio, Roberto; Mangili, Giorgia; Priolo, Domenico; Magni, Giovanna; Morabito, Alessandro

2008-01-01

Background Mucinous ovarian carcinoma have a poorer prognosis compared with other histological subtypes. The aim of this study was to evaluate, retrospectively, the activity of chemotherapy in patients with platinum sensitive recurrent mucinous ovarian cancer. Methods The SOCRATES study retrospectively assessed the pattern of care of a cohort of patients with recurrent platinum-sensitive ovarian cancer observed in the years 2000–2002 in 37 Italian centres. Data were collected between April and September 2005. Patients with recurrent ovarian cancer with > 6 months of platinum free interval were considered eligible. Results Twenty patients with mucinous histotype and 388 patients with other histotypes were analyzed. At baseline, mucinous tumours differed from the others for an higher number of patients with lower tumor grading (p = 0.0056) and less advanced FIGO stage (p = 0.025). At time of recurrence, a statistically significant difference was found in performance status (worse in mucinous, p = 0.024). About 20% of patients underwent secondary cytoreduction in both groups, but a lower number of patients were optimally debulked in the mucinous group (p = 0.03). Patients with mucinous cancer received more frequently single agent platinum than platinum based-combination therapy or other non-platinum schedules as second line therapy (p = 0.026), with a response rate lower than in non-mucinous group (36.4% vs 62.6%, respectively, p = 0.04). Median time to progression and overall survival were worse for mucinous ovarian cancer. Finally, mucinous cancer received a lower number of chemotherapy lines (p = 0.0023). Conclusion This analysis shows that platinum sensitive mucinous ovarian cancer has a poor response to chemotherapy. Studies dedicated to this histological subgroup are needed. PMID:18761742

Density Functional Theory Study of Oxygen Reduction Activity on Ultrathin Platinum Nanotubes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matanovic, Ivana; Kent, Paul; Garzon, Fernando

2012-07-13

The structure, stability, and catalytic activity of a number of single- and double-wall platinum (n,m) nanotubes ranging in diameter from 0.3 to 2.0 nm were studied using plane-wave based density functional theory in the gas phase and water environment. The change in the catalytic activity toward the oxygen reduction reaction (ORR) with the size and chirality of the nanotube was studied by calculating equilibrium adsorption potentials for ORR intermediates and by constructing free energy diagrams in the ORR dissociative mechanism network. In addition, the stability of the platinum nanotubes is investigated in terms of electrochemical dissolution potentials and by determiningmore » the most stable state of the material as a function of pH and potential, as represented in Pourbaix diagrams. Our results show that the catalytic activity and the stability toward electrochemical dissolution depend greatly on the diameter and chirality of the nanotube. On the basis of the estimated overpotentials for ORR, we conclude that smaller, approximately 0.5 nm in diameter single-wall platinum nanotubes consistently show a huge, up to 400 mV larger overpotential than platinum, indicating very poor catalytic activity toward ORR. This is the result of substantial structural changes induced by the adsorption of any chemical species on these tubes. Single-wall n = m platinum nanotubes with a diameter larger than 1 nm have smaller ORR overpotentials than bulk platinum for up to 180 mV and thus show improved catalytic activity relative to bulk. We also predict that these nanotubes can endure the highest cell potentials but dissolution potentials are still for 110 mV lower than for the bulk, indicating a possible corrosion problem.« less

Coating Carbon Fibers With Platinum

NASA Technical Reports Server (NTRS)

Effinger, Michael R.; Duncan, Peter; Coupland, Duncan; Rigali, Mark J.

2007-01-01

A process for coating carbon fibers with platinum has been developed. The process may also be adaptable to coating carbon fibers with other noble and refractory metals, including rhenium and iridium. The coated carbon fibers would be used as ingredients of matrix/fiber composite materials that would resist oxidation at high temperatures. The metal coats would contribute to oxidation resistance by keeping atmospheric oxygen away from fibers when cracks form in the matrices. Other processes that have been used to coat carbon fibers with metals have significant disadvantages: Metal-vapor deposition processes yield coats that are nonuniform along both the lengths and the circumferences of the fibers. The electrical resistivities of carbon fibers are too high to be compatible with electrolytic processes. Metal/organic vapor deposition entails the use of expensive starting materials, it may be necessary to use a furnace, and the starting materials and/or materials generated in the process may be hazardous. The present process does not have these disadvantages. It yields uniform, nonporous coats and is relatively inexpensive. The process can be summarized as one of pretreatment followed by electroless deposition. The process consists of the following steps: The surfaces of the fiber are activated by deposition of palladium crystallites from a solution. The surface-activated fibers are immersed in a solution that contains platinum. A reducing agent is used to supply electrons to effect a chemical reduction in situ. The chemical reduction displaces the platinum from the solution. The displaced platinum becomes deposited on the fibers. Each platinum atom that has been deposited acts as a catalytic site for the deposition of another platinum atom. Hence, the deposition process can also be characterized as autocatalytic. The thickness of the deposited metal can be tailored via the duration of immersion and the chemical activity of the solution.

Basophil Activation Test is a Relevant Biomarker of the Outcome of Rapid Desensitization in Platinum Compounds-Allergy.

PubMed

Giavina-Bianchi, Pedro; Galvão, Violeta Régnier; Picard, Matthieu; Caiado, Joana; Castells, Mariana C

Rapid drug desensitization (RDD) has become a cornerstone in the management of immediate drug hypersensitivity reactions (DHRs) to chemotherapeutic agents. Because of the inherent risk of anaphylaxis during RDD, biomarkers to predict patients at risk of developing such severe reactions are needed. The basophil activation test (BAT) has been used in DHRs as a diagnostic tool. We evaluated basophil CD63 and CD203c expression (BAT) as a biomarker to assess the safety and effectiveness of RDD in platinum compounds-allergic patients. Patients allergic to platinum compounds (n = 15) undergoing RDD were assessed through clinical history, skin testing, serum tryptase levels, and BAT. BAT was performed immediately before RDD, assessing CD203c and CD63 expression on basophils. BAT was also performed in 6 patients tolerant to platinum compounds and in 6 healthy volunteers. BAT was positive to CD203c or CD63 in 11 out of 15 patients allergic to platinum compounds (73%), with increased expression of CD203c and CD63 in 11 (73%) and 6 (40%) patients, respectively. Increased CD63 expression tended to be associated with more severe initial reactions. All controls had negative test results. Reactions during RDD were associated with BAT positivity and increased tryptase levels. Only 1 of 4 patients with negative BAT had a mild reaction during RDD. BAT remained positive in multiple sequential RDD. BAT identified patients allergic to platinum compounds with an increased risk of reactions during desensitization and higher CD63 expression was observed in severe reactions. Multiple RDDs to platinum compounds did not induce persistent hyporesponsiveness on basophils. BAT is a potential biomarker for RDD. Copyright © 2016 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.

Environmental and biological monitoring of platinum-containing drugs in two hospital pharmacies using positive air pressure isolators.

PubMed

Kopp, Bettina; Crauste-Manciet, Sylvie; Guibert, Agnès; Mourier, Wilhelmine; Guerrault-Moro, Marie-Noelle; Ferrari, Sylvie; Jomier, Jean-Yves; Brossard, Denis; Schierl, Rudolf

2013-04-01

Environmental and biological monitoring of platinum containing drugs was implemented in two French hospital pharmacies using positive air pressure isolators and having similar working procedures when preparing antineoplastic drugs. Wipe sampling of surfaces, gloves, and vials was performed in the preparation room and in storage areas. All employees involved in the preparation of antineoplastic drugs were tested for urinary platinum on Monday before work and Friday after shift. Only traces of platinum were detected on surfaces in the preparation room outside the isolators (less than 1.61 pg cm(-2)). However, in one center, significant contamination was found in the storage area of the drug vials, which can most likely be linked to the rupture of a platinum vial and due to inefficient cleaning procedures. Surfaces inside the isolators were found to be contaminated (maximum: 198.4 pg cm(-2)). A higher level of contamination was detected in one pharmacy and could be explained by the lack of overgloving with regular changes during the preparation process. Nitrile gloves used during drug handling outside the isolator showed the highest platinum concentration (maximum: 5.86 ng per pair). With regards to platinum urine concentration, no significant difference was found between exposed and unexposed pharmacy personnel. Isolator technology combined with individual protective measures seems to be efficient to protect workers from occupational exposure to antineoplastic drugs, whereas specific individual protective procedures implemented were focussing on the risk of handling vials outside the isolator (e.g. high frequency of glove changing). Moreover, overgloving inside the isolator would contribute to substantially decrease inner surface contamination and should be recommended in order to limit the transfer of chemical contamination to the end products.

RANDOMIZED TRIAL OF PEGYLATED LIPOSOMAL DOXORUBICIN (PLD) PLUS CARBOPLATIN VERSUS CARBOPLATIN IN PLATINUM-SENSITIVE (PS) PATIENTS WITH RECURRENT EPITHELIAL OVARIAN OR PERITONEAL CARCINOMA AFTER FAILURE OF INITIAL PLATINUM-BASED CHEMOTHERAPY (SOUTH WEST ONCOLOGY GROUP PROTOCOL S0200)

PubMed Central

Alberts, David S.; Liu, P. Y.; Wilczynski, Sharon P.; Clouser, Mary C.; Lopez, Ana Maria; Michelin, David P.; Lanzotti, Victor J.; Markman, Maurie

2008-01-01

Objective Because debate continues over the role of combination, platinum-based chemotherapy for platinum sensitive (PS), recurrent ovarian cancer (OC), we compared overall survival (OS), progression-free survival (PFS), confirmed complete response rate and time to treatment failure in this population. Methods Patients with recurrent stage III or IV OC, a progression-free and platinum-free interval of 6- 24 months after first-line platinum-based chemotherapy and up to 12 courses of a non-platinum containing consolidation treatment were eligible. Patients were randomized to IV pegylated liposomal doxorubicin (PLD) (30 mg/m2) plus IV carboplatin (AUC=5 mg/mL × min) once every 4 weeks (PLD arm) or IV carboplatin alone (AUC=5mg/mL × min) once every 4 weeks. Results The PLD arm enrolled 31 patients and the carboplatin alone arm 30 for a total of 61 patients out of 900 planned. Response rates were 67% for the PLD arm and 32% for the carboplatin only arm (Fisher’s exact p=0.02). The estimated median PFS was 12 and 8 months for PLD versus carboplatin alone. The estimated median OS on the PLD arm was 26 months and 18 months on the carboplatin only arm (p=0.02). Twenty-six percent of the patients on the PLD arm reported grade 4 toxicities, all hematological in nature. Conclusion This study was closed early because of slow patient accrual. The response rate, median PFS and OS results are intriguing. These data suggest that there may be an advantage to the PLD plus carboplatin combination treatment in patients with PS, recurrent OC. The regimen should be further tested. PMID:17949799

Predicting 6- and 12-Month Risk of Mortality in Patients With Platinum-Resistant Advanced-Stage Ovarian Cancer: Prognostic Model to Guide Palliative Care Referrals.

PubMed

Foote, Jonathan; Lopez-Acevedo, Micael; Samsa, Gregory; Lee, Paula S; Kamal, Arif H; Alvarez Secord, Angeles; Havrilesky, Laura J

2018-02-01

Predictive models are increasingly being used in clinical practice. The aim of the study was to develop a predictive model to identify patients with platinum-resistant ovarian cancer with a prognosis of less than 6 to 12 months who may benefit from immediate referral to hospice care. A retrospective chart review identified patients with platinum-resistant epithelial ovarian cancer who were treated at our institution between 2000 and 2011. A predictive model for survival was constructed based on the time from development of platinum resistance to death. Multivariate logistic regression modeling was used to identify significant survival predictors and to develop a predictive model. The following variables were included: time from diagnosis to platinum resistance, initial stage, debulking status, number of relapses, comorbidity score, albumin, hemoglobin, CA-125 levels, liver/lung metastasis, and the presence of a significant clinical event (SCE). An SCE was defined as a malignant bowel obstruction, pleural effusion, or ascites occurring on or before the diagnosis of platinum resistance. One hundred sixty-four patients met inclusion criteria. In the regression analysis, only an SCE and the presence of liver or lung metastasis were associated with poorer short-term survival (P < 0.001). Nine percent of patients with an SCE or liver or lung metastasis survived 6 months or greater and 0% survived 12 months or greater, compared with 85% and 67% of patients without an SCE or liver or lung metastasis, respectively. Patients with platinum-resistant ovarian cancer who have experienced an SCE or liver or lung metastasis have a high risk of death within 6 months and should be considered for immediate referral to hospice care.

Rapid total volatile organic carbon quantification from microbial fermentation using a platinum catalyst and proton transfer reaction-mass spectrometry.

PubMed

Schoen, Heidi R; Peyton, Brent M; Knighton, W Berk

2016-12-01

A novel analytical system was developed to rapidly and accurately quantify total volatile organic compound (VOC) production from microbial reactor systems using a platinum catalyst and a sensitive CO 2 detector. This system allows nearly instantaneous determination of total VOC production by utilizing a platinum catalyst to completely and quantitatively oxidize headspace VOCs to CO 2 in coordination with a CO 2 detector. Measurement of respiratory CO 2 by bypassing the catalyst allowed the total VOC content to be determined from the difference in the two signals. To the best of our knowledge, this is the first instance of a platinum catalyst and CO 2 detector being used to quantify the total VOCs produced by a complex bioreactor system. Continuous recording of these CO 2 data provided a record of respiration and total VOC production throughout the experiments. Proton transfer reaction-mass spectrometry (PTR-MS) was used to identify and quantify major VOCs. The sum of the individual compounds measured by PTR-MS can be compared to the total VOCs quantified by the platinum catalyst to identify potential differences in detection, identification and calibration. PTR-MS measurements accounted on average for 94 % of the total VOC carbon detected by the platinum catalyst and CO 2 detector. In a model system, a VOC producing endophytic fungus Nodulisporium isolate TI-13 was grown in a solid state reactor utilizing the agricultural byproduct beet pulp as a substrate. Temporal changes in production of major volatile compounds (ethanol, methanol, acetaldehyde, terpenes, and terpenoids) were quantified by PTR-MS and compared to the total VOC measurements taken with the platinum catalyst and CO 2 detector. This analytical system provided fast, consistent data for evaluating VOC production in the nonhomogeneous solid state reactor system.

Anti-Candida Activity of a New Platinum Derivative

PubMed Central

Watanabe, T.; Takano, M.; Ogasawara, A.; Mikami, T.; Kobayashi, T.; Watabe, M.; Matsumoto, T.

2000-01-01

A new platinum derivative of the form H[Pt(IV)(Hdigly)Cl2(OH)2] (Hdigly⩵glycylglycine) damaged the Candida albicans cell membrane and inhibited the growth of the cells. The cytotoxic activity of H[Pt(IV)(Hdigly)Cl2(OH)2] on mammalian cells was 10-fold lower than that of cis-diammine-dichloroplatinum (cisplatin). Substitution of platinum for peptides is effective for enhancement of antifungal activity and reduction of the toxicity to mammalian cells. PMID:10991871

Stabilizing platinum in phosphoric acid fuel cells

NASA Technical Reports Server (NTRS)

Remick, R. J.

1982-01-01

Platinum sintering on phosphoric acid fuel cell cathodes is discussed. The cathode of the phosphoric acid fuel cell uses a high surface area platinum catalyst dispersed on a conductive carbon support to minimize both cathode polarization and fabrication costs. During operation, however, the active surface area of these electrodes decreases, which in turn leads to decreased cell performance. This loss of active surface area is a major factor in the degradation of fuel cell performance over time.

Electrocatalysts having gold monolayers on platinum nanoparticle cores, and uses thereof

DOEpatents

Adzic, Radoslav; Zhang, Junliang

2010-04-27

The invention relates to gold-coated particles useful as fuel cell electrocatalysts. The particles are composed of an electrocatalytically active core at least partially encapsulated by an outer shell of gold or gold alloy. The invention more particularly relates to such particles having a noble metal-containing core, and more particularly, a platinum or platinum alloy core. In other embodiments, the invention relates to fuel cells containing these electrocatalysts and methods for generating electrical energy therefrom.

Thermochemical analyses of the oxidative vaporization of metals and oxides by oxygen molecules and atoms

NASA Technical Reports Server (NTRS)

Kohl, F. J.; Leisz, D. M.; Fryburg, G. C.; Stearns, C. A.

1977-01-01

Equilibrium thermochemical analyses are employed to describe the vaporization processes of metals and metal oxides upon exposure to molecular and atomic oxygen. Specific analytic results for the chromium-, platinum-, aluminum-, and silicon-oxygen systems are presented. Maximum rates of oxidative vaporization predicted from the thermochemical considerations are compared with experimental results for chromium and platinum. The oxidative vaporization rates of chromium and platinum are considerably enhanced by oxygen atoms.

Mild in situ growth of platinum nanoparticles on multiwalled carbon nanotube-poly (vinyl alcohol) hydrogel electrode for glucose electrochemical oxidation

NASA Astrophysics Data System (ADS)

Liu, Shumin; Zheng, Yudong; Qiao, Kun; Su, Lei; Sanghera, Amendeep; Song, Wenhui; Yue, Lina; Sun, Yi

2015-12-01

This investigation describes an effective strategy to fabricate an electrochemically active hybrid hydrogel made from platinum nanoparticles that are highly dense, uniformly dispersed, and tightly embedded throughout the conducting hydrogel network for the electrochemical oxidation of glucose. A suspension of multiwalled carbon nanotubes and polyvinyl alcohol aqueous was coated on glassy carbon electrode by electrophoretic deposition and then physically crosslinked to form a three-dimensional porous conductive hydrogel network by a process of freezing and thawing. The network offered 3D interconnected mass-transport channels (around 200 nm) and confined nanotemplates for in situ growth of uniform platinum nanoparticles via the moderate reduction agent, ascorbic acid. The resulting hybrid hydrogel electrode membrane demonstrates an effective method for loading platinum nanoparticles on multiwalled carbon nanotubes by the electrostatic adsorption between multiwalled carbon nanotubes and platinum ions within porous hydrogel network. The average diameter of platinum nanoparticles is 37 ± 14 nm, which is less than the particle size by only using the moderate reduction agent. The hybrid hydrogel electrode membrane-coated glassy carbon electrode showed excellent electrocatalytic activity and good long-term stability toward glucose electrochemical oxidation. The glucose oxidation current exhibited a linear relationship with the concentration of glucose in the presence of chloride ions, promising for potential applications of implantable biofuel cells, biosensors, and electronic devices.

Tuning Frustration in Rare Earth Pyrochlores by Platinum Substitution

NASA Astrophysics Data System (ADS)

Hallas, Alannah; Gaudet, Jonathan; Sharma, Arzoo; Wilson, Murray; Cai, Yipeng; Tachibana, Makoto; Wiebe, Chris; Gaulin, Bruce; Luke, Graeme

A successful mechanism for exploring the rich physics of rare earth pyrochlores, R2B2O7, is to substitute the non-magnetic B-site. Varying the ionic radius of the B-site induces an internal chemical pressure. Some rare earths are robust to substitutions; for example, the holmium-based pyrochlores all exhibit a dipolar spin ice state. In the case of other rare earths such as ytterbium, the ground states are remarkably fragile to chemical pressure. In this talk, I will introduce two materials with a new non-magnetic B-site: platinum. The ionic radius of platinum is comparable to that of titanium, which occupies the B-site in the most well-studied family of pyrochlores. Thus, platinum does not induce a strong chemical pressure on the lattice. Nevertheless, using Gd2Pt2O7 and Er2Pt2O7 as examples, I will show that platinum does affect a dramatic change on the magnetic properties. We trace this effect to platinum's empty eg orbitals, which mediate superexchange pathways not available in other rare earth pyrochlores. In Gd2Pt2O7, this results in a striking 160% enhancement of TN as compared to other Gd-based pyrochlores. In Er2Pt2O7, the ordering temperature is strongly suppressed and the ground state is altered.

Electron transfer processes occurring on platinum neural stimulating electrodes: pulsing experiments for cathodic-first/charge-balanced/biphasic pulses for 0.566 ≤ k ≤ 2.3 in oxygenated and deoxygenated sulfuric acid.

PubMed

Kumsa, Doe W; Montague, Fred W; Hudak, Eric M; Mortimer, J Thomas

2016-10-01

The application of a train of cathodic-first/charge-balanced/biphasic pulses applied to a platinum electrode resulted in a positive creep of the anodic phase potential that increases with increasing charge injection but reaches a steady-state value before 1000 pulses have been delivered. The increase follows from the fact that charge going into irreversible reactions occurring during the anodic phase must equal the charge going into irreversible reactions during the cathodic phase for charge-balanced pulses. In an oxygenated electrolyte the drift of the measured positive potential moved into the platinum oxidation region of the i(V e) profile when the charge injection level exceeds k = 1.75. Platinum dissolution may occur in this region and k = 1.75 defines a boundary between damaging and non-damaging levels on the Shannon Plot. In a very low oxygen environment, the positive potential remained below the platinum oxidation region for the highest charge injection values studied, k = 2.3. The results support the hypothesis that platinum dissolution is the defining factor for the Shannon limit, k = 1.75. Numerous instrumentation issues were encountered in the course of making measurements. The solutions to these issues are provided.

Development and Validation of an Inductively Coupled Plasma Mass Spectrometry (ICP-MS) Method for Quantitative Analysis of Platinum in Plasma, Urine, and Tissues.

PubMed

Zhang, Ti; Cai, Shuang; Forrest, Wai Chee; Mohr, Eva; Yang, Qiuhong; Forrest, M Laird

2016-09-01

Cisplatin, a platinum chemotherapeutic, is one of the most commonly used chemotherapeutic agents for many solid tumors. In this work, we developed and validated an inductively coupled plasma mass spectrometry (ICP-MS) method for quantitative determination of platinum levels in rat urine, plasma, and tissue matrices including liver, brain, lungs, kidney, muscle, heart, spleen, bladder, and lymph nodes. The tissues were processed using a microwave accelerated reaction system (MARS) system prior to analysis on an Agilent 7500 ICP-MS. According to the Food and Drug Administration guidance for industry, bioanalytical validation parameters of the method, such as selectivity, accuracy, precision, recovery, and stability were evaluated in rat biological samples. Our data suggested that the method was selective for platinum without interferences caused by other presenting elements, and the lower limit of quantification was 0.5 ppb. The accuracy and precision of the method were within 15% variation and the recoveries of platinum for all tissue matrices examined were determined to be 85-115% of the theoretical values. The stability of the platinum-containing solutions, including calibration standards, stock solutions, and processed samples in rat biological matrices was investigated. Results indicated that the samples were stable after three cycles of freeze-thaw and for up to three months. © The Author(s) 2016.

Development and Validation of an Inductively Coupled Plasma Mass Spectrometry (ICP-MS) Method for Quantitative Analysis of Platinum in Plasma, Urine, and Tissues

PubMed Central

Zhang, Ti; Cai, Shuang; Forrest, Wai Chee; Mohr, Eva; Yang, Qiuhong; Forrest, M. Laird

2016-01-01

Cisplatin, a platinum chemotherapeutic, is one of the most commonly used chemotherapeutic agents for many solid tumors. In this work, we developed and validated an inductively coupled plasma mass spectrometry (ICP-MS) method for quantitative determination of platinum levels in rat urine, plasma, and tissue matrices including liver, brain, lungs, kidney, muscle, heart, spleen, bladder, and lymph nodes. The tissues were processed using a microwave accelerated reaction system (MARS) system prior to analysis on an Agilent 7500 ICP-MS. According to the Food and Drug Administration guidance for industry, bioanalytical validation parameters of the method, such as selectivity, accuracy, precision, recovery, and stability were evaluated in rat biological samples. Our data suggested that the method was selective for platinum without interferences caused by other presenting elements, and the lower limit of quantification was 0.5 ppb. The accuracy and precision of the method were within 15% variation and the recoveries of platinum for all tissue matrices examined were determined to be 85–115% of the theoretical values. The stability of the platinum-containing solutions, including calibration standards, stock solutions, and processed samples in rat biological matrices was investigated. Results indicated that the samples were stable after three cycles of freeze–thaw and for up to three months. PMID:27527103

The role of the equatorial ligands for the redox behavior, mode of cellular accumulation and cytotoxicity of platinum(IV) prodrugs.

PubMed

Göschl, Simone; Varbanov, Hristo P; Theiner, Sarah; Jakupec, Michael A; Galanski, Markus; Keppler, Bernhard K

2016-07-01

The current study aims to elucidate the possible reasons for the significantly different pharmacological behavior of platinum(IV) complexes with cisplatin-, carboplatin- or nedaplatin-like cores and how this difference can be related to their main physicochemical properties. Chlorido-containing complexes are reduced fast (within hours) by ascorbate and are able to unwind plasmid DNA in the presence of ascorbate, while their tri- and tetracarboxylato analogs are generally inert under the same conditions. Comparison of the lipophilicity, cellular accumulation and cytotoxicity of the investigated platinum compounds revealed the necessity to define new structure-property/activity relationships (SPRs and SARs). The higher activity and improved accumulation of platinum(IV) complexes bearing Cl(-) in equatorial position cannot only be attributed to passive diffusion facilitated by their lipophilicity. Therefore, further platinum accumulation experiments under conditions where active/facilitated transport mechanisms are suppressed were performed. Under hypothermic conditions (4°C), accumulation of dichloridoplatinum(IV) complexes is reduced down to 10% of the amount determined at 37°C. These findings suggest the involvement of active and/or facilitated transport in cellular uptake of platinum(IV) complexes with a cisplatin-like core. Studies with ATP depletion mediated by oligomycin and low glucose partially confirmed these observations, but their feasibility was severely limited in the adherent cell culture setting. Copyright © 2016 Elsevier Inc. All rights reserved.

Surface modification of platinum by laser-produced X-rays

NASA Astrophysics Data System (ADS)

Latif, Hamid; Shahid Rafique, M.; Khaleeq-ur-Rahaman, M.; Sattar, Abdul; Anjum, S.; Usman, A.; Zaheer, S.; Rawat, R. S.

2014-11-01

Laser-induced plasma is used as an X-ray source for the growth of hillocks like nanostructures on platinum surface. To generate X-rays, plasma is produced by Nd:YAG laser, which is operated at second harmonics (λ = 532 nm, E = 400 mJ). Analytical grade 5 N pure Al, Cu and W are used as laser targets for X-rays production. X-rays produced from Al, Cu and W plasmas are used to irradiate three analytical grade (5 N pure) platinum substrates, respectively, under the vacuum ∼10-4 torr. XRD analysis shows considerable structural changes in the exposed platinum. The decrement in reflection intensities, increment in dislocation line density, change in d-spacing and disturbance in the periodicity of planes evidently prove these structural changes. Atomic force microscope AFM topographic analysis of the platinum exposed to X-rays emitted from Al, Cu and W targets showed that nanometer-size hillocks are produced on the platinum surface irrespective of the source. It has also been observed that due to these hillocks, the roughness of the surface has increased. Conductivity of hillocks produced from X-rays produced by Al, Cu and W targets is compared and it is shown that the hillocks produced by Al target X-rays have better conductivity compared to the hillocks produced by X-rays from Cu and W targets.

Smoking and occupational allergy in workers in a platinum refinery.

PubMed Central

Venables, K. M.; Dally, M. B.; Nunn, A. J.; Stevens, J. F.; Stephens, R.; Farrer, N.; Hunter, J. V.; Stewart, M.; Hughes, E. G.; Newman Taylor, A. J.

1989-01-01

OBJECTIVE--To test the hypothesis that smoking increases the risk of sensitisation by occupational allergens. DESIGN--Historical prospective cohort study. SETTING--Platinum refinery. SUBJECTS--91 Workers (86 men) who started work between 1 January 1973 and 31 December 1974 and whose smoking habit and atopic state (on skin prick testing with common allergens) had been noted at joining. MAIN OUTCOME MEASURES--Results of skin prick tests with platinum salts carried out routinely every three to six months and records of any respiratory symptoms noted by the refinery's occupational health service. Follow up was until 1980 or until leaving refinery work, whichever was earlier. RESULTS--57 Workers smoked and 29 were atopic; 22 developed a positive result on skin testing with platinum salts and 49 developed symptoms, including all 22 whose skin test result was positive. Smoking was the only significant predictor of a positive result on skin testing with platinum salts and its effect was greater than that of atopy; the estimated relative risks (95% confidence interval) when both were included in the regression model were: smokers versus non-smokers 5.05 (1.68 to 15.2) and atopic versus non-atopic 2.29 (0.88 to 5.99). Number of cigarettes smoked per day was the only significant predictor of respiratory symptoms. CONCLUSION--Smokers are at increased risk of sensitisation by platinum salts. PMID:2508944

Effects of para-substituents of styrene derivatives on their chemical reactivity on platinum nanoparticle surfaces.

PubMed

Hu, Peiguang; Chen, Limei; Deming, Christopher P; Lu, Jia-En; Bonny, Lewis W; Chen, Shaowei

2016-06-09

Stable platinum nanoparticles were successfully prepared by the self-assembly of para-substituted styrene derivatives onto the platinum surfaces as a result of platinum-catalyzed dehydrogenation and transformation of the vinyl groups to the acetylene ones, forming platinum-vinylidene/-acetylide interfacial bonds. Transmission electron microscopic measurements showed that the nanoparticles were well dispersed without apparent aggregation, suggesting sufficient protection of the nanoparticles by the organic capping ligands, and the average core diameter was estimated to be 2.0 ± 0.3 nm, 1.3 ± 0.2 nm, and 1.1 ± 0.2 nm for the nanoparticles capped with 4-tert-butylstyrene, 4-methoxystyrene, and 4-(trifluoromethyl)styrene, respectively, as a result of the decreasing rate of dehydrogenation with the increasing Taft (polar) constant of the para-substituents. Importantly, the resulting nanoparticles exhibited unique photoluminescence, where an increase of the Hammett constant of the para-substituents corresponded to a blue-shift of the photoluminescence emission, suggesting an enlargement of the HOMO-LUMO band gap of the nanoparticle-bound acetylene moieties. Furthermore, the resulting nanoparticles exhibited apparent electrocatalytic activity towards oxygen reduction in acidic media, with the best performance among the series of samples observed with the 4-tert-butylstyrene-capped nanoparticles due to an optimal combination of the nanoparticle core size and ligand effects on the bonding interactions between platinum and oxygen species.

The nature of thrombosis induced by platinum and tungsten coils in saccular aneurysms.

PubMed

Byrne, J V; Hope, J K; Hubbard, N; Morris, J H

1997-01-01

To compare the efficacy and biocompatability of electrolytic and mechanically detachable embolization coils of two metal types. Experimental saccular aneurysms in pigs were used to assess embolization induced by platinum or tungsten coils. Longitudinal angiographic and histologic studies were performed on treated and untreated (control) aneurysms to compare thrombosis and cellular responses after embolization with electrolytically detachable platinum coils and with mechanically detached tungsten coils. Fewer tungsten than platinum coils were needed to induce thrombosis. The inflammatory response within the aneurysmal lumen was more florid in embolized aneurysms than in control aneurysms. No difference was found in the timing or extent of accumulation of eosinophils, lymphocytes, or polymorphs between the two coils used. Giant cell responses were more marked in treated aneurysms; tungsten coils more than platinum coils. The amount of collagen and fibrosis present increased over the study period and was similar in treated and control aneurysms. The coil type influenced the initial cellular response but had little effect on the rate or degree to which blood clot within the aneurysm was replaced by fibrous tissue.

What can platinum offer yet in the treatment of PS2 NSCLC patients? A systematic review and meta-analysis.

PubMed

Bronte, Giuseppe; Rolfo, Christian; Passiglia, Francesco; Rizzo, Sergio; Gil-Bazo, Ignacio; Fiorentino, Eugenio; Cajozzo, Massimo; Van Meerbeeck, Jan P; Lequaglie, Cosimo; Santini, Daniele; Pauwels, Patrick; Russo, Antonio

2015-09-01

Randomized phase III trials showed interesting, but conflicting results, regarding the treatment of NSCLC, PS2 population. This meta-analysis aims to review all randomized trials comparing platinum-based doublets and single-agents in NSCLC PS2 patients. Data from all published randomized trials, comparing efficacy and safety of platinum-based doublets to single agents in untreated NSCLC, PS2 patients, were collected. Pooled ORs were calculated for the 1-year Survival-Rate (1y-SR), Overall Response Rate (ORR), and grade 3-4 (G3-4) hematologic toxicities. Six eligible trials (741 patients) were selected. Pooled analysis showed a significant improvement in ORR (OR: 3.243; 95% CI: 1.883-5.583) and 1y-SR (OR: 1.743; 95% CI: 1.203-2.525) in favor of platinum-based doublets. G3-4 hematological toxicities were also more frequent in this group. This meta-analysis suggests that platinum-combination regimens are superior to singleagent both in terms of ORR and survival-rate with increase of severe hematological toxicities. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Antibacterial activity of microstructured sacrificial anode thin films by combination of silver with platinum group elements (platinum, palladium, iridium).

PubMed

Köller, Manfred; Bellova, Petri; Javid, Siyamak Memar; Motemani, Yahya; Khare, Chinmay; Sengstock, Christina; Tschulik, Kristina; Schildhauer, Thomas A; Ludwig, Alfred

2017-05-01

Five different Ag dots arrays (16 to 400dots/mm 2 ) were fabricated on a continuous platinum, palladium, or iridium thin film and for comparison also on titanium film by sputter deposition and photolithographic patterning. To analyze the antibacterial activity of these microstructured films Staphylococcus aureus (S. aureus) were placed onto the array surfaces and cultivated overnight. To analyze the viability of planktonic as well as surface adherent bacteria, the applied bacterial fluid was subsequently aspirated, plated on blood agar plates and adherent bacteria were detected by fluorescence microscopy. A particular antibacterial effect towards S. aureus was induced by Ag dot arrays on each of the platinum group thin film (sacrificial anode system for Ag) in contrast to Ag dot arrays fabricated on the Ti thin films (non-sacrificial anode system for Ag). Among platinum group elements the Ir-Ag system exerted the highest antibacterial activity which was accompanied by most advanced dissolution of the Ag dots and Ag ion release compared to Ag dots on Pt or Pd. Copyright © 2016 Elsevier B.V. All rights reserved.

Association of a Platinum Complex to a G-Quadruplex Ligand Enhances Telomere Disruption.

PubMed

Charif, Razan; Granotier-Beckers, Christine; Bertrand, Hélène Charlotte; Poupon, Joël; Ségal-Bendirdjian, Evelyne; Teulade-Fichou, Marie-Paule; Boussin, François D; Bombard, Sophie

2017-08-21

Telomeres protect the ends of chromosomes against illegitimate recombination and repair. They can be targets for G-quadruplex ligands and platinum complexes due to their repeated G-rich sequences. Protection of telomeres is ensured by a complex of six proteins, including TRF2, which inhibits the DNA damage response pathway. We analyzed telomere modifications induced in cancer cells by the experimental hybrid platinum complex, Pt-MPQ, comprising both an ethylene diamine monofunctional platinum complex and a G-quadruplex recognition moiety (MPQ). Pt-MPQ promotes the displacement of two telomeric proteins (TRF2 and TRF1) from telomeres, as well as the formation of telomere damage and telomere sister losses, whereas the control compound MPQ does not. This suggests that the platinum moiety potentiates the targeting of the G-quadruplex ligand to telomeres, opening a new perspective for telomere biology and anticancer therapy. Interestingly, the chemotherapy drug cisplatin, which has no specific affinity for G-quadruplex structures, partially induces the TRF2 delocalization from telomeres but produces less telomeric DNA damage, suggesting that this TRF2 displacement could be independent of G-quadruplex recognition.

Carbon Nanotubes as Support in the Platinum-Catalyzed Hydrolytic Dehydrogenation of Ammonia Borane.

PubMed

Chen, Wenyao; Duan, Xuezhi; Qian, Gang; Chen, De; Zhou, Xinggui

2015-09-07

We report remarkable support effects for carbon nanotubes (CNTs) in the Pt/CNT-catalyzed hydrolytic dehydrogenation of ammonia borane. The origin of the support-dependent activity and durability is elucidated by combining the catalytic and durability testing with characterization by a range of spectroscopy and high-angle annular dark-field scanning transmission electron microscopy techniques and ICP analysis. The effects mainly arise from different electronic properties and different abilities for the adsorption of boron-containing species on platinum surfaces and changes in size and shape of the platinum particles during the reaction. Defect-rich CNTs in particular are a promising support material, as it not only enhances the platinum binding energy, leading to the highest hydrogen generation rate, but also inhibits the adsorption of boron-containing species and stabilizes the platinum nanoparticles to resist the agglomeration during the reaction, leading to the highest durability. The insights revealed herein may pave the way for the rational design of highly active and durable metal/carbon catalysts for the hydrolytic dehydrogenation of ammonia borane. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

First Principle Calculation : Investigation on interaction of Pt/Graphene as Catalyst

NASA Astrophysics Data System (ADS)

Anugrah Putri Namari, Nuning; Suprijadi

2017-07-01

The increasing in energy needs and the lack of non-renewable energy sources becomes a challenge for the human being to be able to use renewable energy sources. One of the devices to process renewable energy is Polymer Electrolyte Membrane Fuel Cell (PEMFC) . PEMFC use hydrogen and Oxygen as an energy sources . The most important reaction in fuel cell is Oxidation and reduction process. Therefore, a catalyst is needed to help the OR process. Study of catalyst shows that the most effective fuel cell for now is Platinum. Many fuel cell have use platinum as the catalyst. However, Platinum is a rare and expensive element. Therefore, to reduce the cost of fuel cell fabrication, we need to increase the activity of platinum. In this research, we use graphene as a support material. Then, we will study about the interaction of platinum on graphene and analyze its morphological change and electronic properties.The research conduct using Density Functional Theory (DFT). The calculation result shows that Pt/graphene can break H2 into H+ and the binding between Pt cluster is stronger than binding with the substrate.

Intermediate stages of electrochemical oxidation of single-crystalline platinum revealed by in situ Raman spectroscopy

PubMed Central

Huang, Yi-Fan; Kooyman, Patricia J.; Koper, Marc T. M.

2016-01-01

Understanding the atomistic details of how platinum surfaces are oxidized under electrochemical conditions is of importance for many electrochemical devices such as fuel cells and electrolysers. Here we use in situ shell-isolated nanoparticle-enhanced Raman spectroscopy to identify the intermediate stages of the electrochemical oxidation of Pt(111) and Pt(100) single crystals in perchloric acid. Density functional theory calculations were carried out to assist in assigning the experimental Raman bands by simulating the vibrational frequencies of possible intermediates and products. The perchlorate anion is suggested to interact with hydroxyl phase formed on the surface. Peroxo-like and superoxo-like two-dimensional (2D) surface oxides and amorphous 3D α-PtO2 are sequentially formed during the anodic polarization. Our measurements elucidate the process of the electrochemical oxidation of platinum single crystals by providing evidence for the structure-sensitive formation of a 2D platinum-(su)peroxide phase. These results may contribute towards a fundamental understanding of the mechanism of degradation of platinum electrocatalysts. PMID:27514695

Specific cationic emission of cisplatin following ionization by swift protons

NASA Astrophysics Data System (ADS)

Moretto-Capelle, Patrick; Champeaux, Jean-Philippe; Deville, Charlotte; Sence, Martine; Cafarelli, Pierre

2016-05-01

We have investigated collision-induced ionization and fragmentation by 100 keV protons of the radio sensitizing molecule cisplatin, which is used in cancer treatments. A large emission of HCl+ and NH2+ is observed, but surprisingly, no cationic fragments containing platinum are detected, in contrast to ionization-dissociation induced by electronic collision. Theoretical investigations show that the ionization processes take place on platinum and on chlorine atoms. We propose new ionization potentials for cisplatin. Dissociation limits corresponding to the measured fragmentation mass spectrum have been evaluated and the theoretical results show that the non-observed cationic fragments containing platinum are mostly associated with low dissociation energies. We have also investigated the reaction path for the hydrogen transfer from the NH3 group to the Cl atom, as well as the corresponding dissociation limits from this tautomeric form. Here again the cations containing platinum correspond to lower dissociation limits. Thus, the experimental results suggest that excited states, probably formed via inner-shell ionization of the platinum atom of the molecule, correlated to higher dissociation limits are favored.

Efficacy of tegafur-uracil in advanced urothelial cancer patients after the treatment failure of platinum-based chemotherapy.

PubMed

Maolake, Aerken; Izumi, Kouji; Takahashi, Rie; Itai, Shingo; Machioka, Kazuaki; Yaegashi, Hiroshi; Nohara, Takahiro; Kitagawa, Yasuhide; Kadono, Yoshifumi; Konaka, Hiroyuki; Mizokami, Atsushi; Namiki, Mikio

2015-03-01

Platinum-based chemotherapy is the first-line treatment for advanced urinary tract urothelial cancers. However, the optimal second-line treatment is unclear. Although tegafur-uracil is sometimes used for advanced urothelial cancer patients after the treatment failure of platinum-based chemotherapy, there is little evidence regarding its use as a second-line treatment. Advanced urothelial cancer patients previously treated with platinum-based chemotherapy were retrospectively analyzed. Overall survival (OS) was compared between patients with and without tegafur-uracil treatment. Thirty-one patients (27 and 4 patients with and without tegafur-uracil treatment, respectively) were analyzed. OS from the last day of the final chemotherapy course was better in patients with tegafur-uracil treatment than in those without (p<0.001, 358 and 66.5 days of the median survival time, respectively). Tegafur-uracil may be a candidate for the secondary treatment of advanced urothelial cancer patients after the treatment failure of platinum-based chemotherapy. Copyright© 2015 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

VB Platinum Tile & Carpet, Inc. Information Sheet

EPA Pesticide Factsheets

VB Platinum Tile & Carpet, Inc. (the Company) is located in Bristow, Virginia. The settlement involves renovation activities conducted at a property constructed prior to 1978, located in Washington, DC.

The Role of Near-Earth Asteroids in Long-Term Platinum Supply

NASA Astrophysics Data System (ADS)

Blair, B. R.

2000-01-01

High-grade platinum-group metal concentrations have been identified in an abundant class of near-Earth asteroids known as LL Chondrites. The potential existence of a high-value asteroid-derived mineral product is examined from an economic perspective to assess the possible impacts on long-term precious metal supply. It is hypothesized that extraterrestrial sources of platinum group metals will become available in the global marketplace in a 20-year time frame, based on current trends of growth in technology and increasing levels of human activities in near-Earth space. Current and projected trends in platinum supply and demand are cited from the relevant literature to provide an economic context and provide an example for evaluating the economic potential of future asteroid-derived precious and strategic metals.

Thermally stable single-atom platinum-on-ceria catalysts via atom trapping

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jones, John; Xiong, Haifeng; DelaRiva, Andrew

2016-07-08

Catalysts based on single atoms of scarce precious metals can lead to more efficient use through enhanced reactivity and selectivity. However, single atoms on catalyst supports can be mobile and aggregate into nanoparticles when heated at elevated temperatures. High temperatures are detrimental to catalyst performance unless these mobile atoms can be trapped. We used ceria powders having similar surface areas but different exposed surface facets. When mixed with a platinum/ aluminum oxide catalyst and aged in air at 800°C, the platinum transferred to the ceria and was trapped. Polyhedral ceria and nanorods were more effective than ceria cubes at anchoringmore » the platinum. Performing synthesis at high temperatures ensures that only the most stable binding sites are occupied, yielding a sinter-resistant, atomically dispersed catalyst.« less

Dynamic wet-ETEM observation of Pt/C electrode catalysts in a moisturized cathode atmosphere.

PubMed

Yoshida, Kenta; Bright, Alexander N; Ward, Michael R; Lari, Leonardo; Zhang, Xudong; Hiroyama, Tomoki; Boyes, Edward D; Gai, Pratibha L

2014-10-24

The gas injection line of the latest spherical aberration-corrected environmental transmission electron microscope has been modified for achieving real-time/atomic-scale observations in moisturised gas atmospheres for the first time. The newly developed Wet-TEM system is applied to platinum carbon electrode catalysts to investigate the effect of water molecules on the platinum/carbon interface during deactivation processes such as sintering and corrosion. Dynamic in situ movies obtained in dry and 24% moisturised nitrogen environments visualize the rapid rotation, migration and agglomeration of platinum nanoparticles due to the physical adsorption of water and the hydroxylation of the carbon surface. The origin of the long-interconnected aggregation of platinum nanoparticles was discovered to be a major deactivation process in addition to conventional carbon corrosion.

Active targeting of cancer cells using folic acid-conjugated platinum nanoparticles.

PubMed

Teow, Yiwei; Valiyaveettil, Suresh

2010-12-01

Interaction of nanoparticles with human cells is an interesting topic for understanding toxicity and developing potential drug candidates. Water soluble platinum nanoparticles were synthesized via reduction of hexachloroplatinic acid using sodium borohydride in the presence of capping agents. The bioactivity of folic acid and poly(vinyl pyrrolidone) capped platinum nanoparticles (Pt-nps) has been investigated using commercially available cell lines. In the cell viability experiments, PVP-capped nanoparticles were found to be less toxic (>80% viability), whereas, folic acid-capped platinum nanoparticles showed a reduced viability down to 24% after 72 h of exposure at a concentration of 100 μg ml(-1) for MCF7 breast cancer cells. Such toxicity, combined with the possibility to incorporate functional organic molecules as capping agents, can be used for developing new drug candidates.

New Pt/Alumina model catalysts for STM and in situ XPS studies

NASA Astrophysics Data System (ADS)

Nartova, Anna V.; Gharachorlou, Amir; Bukhtiyarov, Andrey V.; Kvon, Ren I.; Bukhtiyarov, Valerii I.

2017-04-01

The new Pt/alumina model catalysts for STM and in situ XPS studies based on thin alumina film formed over the conductive substrate are proposed. Procedure of platinum deposition developed for porous alumina was adapted for the model alumina support. The set of Pt/AlOx-film samples with the different mean platinum particle size was prepared. Capabilities of in situ XPS investigations of the proposed catalysts were demonstrated in study of NO decomposition on platinum nanoparticles. It is shown that proposed model catalysts behave similarly to Pt/γ-Al2O3 and provide the new opportunities for the instrumental studies of platinum catalysts due to resolving several issues (charging, heating, screening) that are typical for the investigation of the porous oxide supported catalysts.

Platinum-Resistor Differential Temperature Sensor

NASA Technical Reports Server (NTRS)

Kolbly, R. B.; Britcliffe, M. J.

1985-01-01

Platinum resistance elements used in bridge circuit for measuring temperature difference between two flowing liquids. Temperature errors with circuit are less than 0.01 degrees C over range of 100 degrees C.

Pt(110)(1×1) surfaces prepared by low temperature platinum deposition: surface characterization and stability

NASA Astrophysics Data System (ADS)

Alnot, M.; Ehrhardt, J. J.

1993-05-01

Adsorption of platinum atoms on Pt(110)(1×2) at low temperature has been studied by LEED, photoemission of adsorbed xenon (PAX) and Δφ measurements. Deposition of half a monolayer of platinum at 150 K produces a sharp (1×1) LEED pattern. A possible structural disorder of the as-grown surface is discussed. The (1×1) → (1×2) reconstruction is observed after annealing at a temperature slightly higher than 300 K.

Atlas of the Spectrum of a Platinum/Neon Hollow-Cathode Lamp in the Region 1130-4330 Å

National Institute of Standards and Technology Data Gateway

SRD 112 Atlas of the Spectrum of a Platinum/Neon Hollow-Cathode Lamp in the Region 1130-4330 Å (Web, free access)   Atlas of the Spectrum of a Platinum/Neon Hollow-Cathode Lamp in the Region 1130-4330 Å contains wavelengths and intensities for about 5600 lines in the region 4330 Å. An atlas plot of the spectrum is given, with the spectral lines marked and their intensities, wavelengths, and classifications listed.

Isolation of homoleptic platinum oxyanionic complexes with doubly protonated diazacrown cation

NASA Astrophysics Data System (ADS)

Vasilchenko, Danila; Tkachev, Sergey; Baidina, Iraida; Romanenko, Galina; Korenev, Sergey

2017-02-01

Doubly protonated diazacrown ether cation (1,4,10,13-tetraoxa-7,16-diazoniacyclooctadecane DCH22+) was used for the efficient isolation of the homoleptic platinum complexes [Pt(NO3)6]2- and [Pt(C2O4)2]2- to crystalline solid phases from solutions containing mixtures of related platinum complexes. DCH22+ molecules in nitric acid solution were shown to prevent the condensation of mononuclear [Pt(H2O)n(NO3)6-n]n-2 species.

High temperature sorbents for oxygen

NASA Technical Reports Server (NTRS)

Sharma, Pramod K. (Inventor)

1994-01-01

A sorbent capable of removing trace amounts of oxygen (ppt) from a gas stream at a high temperature above 200 C comprising a porous alumina silicate support, such as zeolite, containing from 1 to 10 percent by weight of ion exchanged transition metal, such as copper or cobalt ions, and 0.05 to 1.0 percent by weight of an activator selected from a platinum group metal such as platinum is described. The activation temperature, oxygen sorption, and reducibility are all improved by the presence of the platinum activator.

Electron-Transfer Kinetics of Redox Centers Anchored to Metal Surfaces: Weak- versus Strong-Overlap Reaction Pathways.

DTIC Science & Technology

1983-11-01

constants ket are presented for the one-electron electroreduction of various Co1]:I(NH3)5X complexes bound to mercury, platinum, and gold surfaces...electroreduction of various Co^^(NH𔃽)𔃿X complexes bound to mercury, platinum, and gold surfaces via either small inorganic or extended organic ligands X. t...platinum, gold , and copper, to enable values of ke* to be obtained for the one-electron reduction of the surface-Douna_redox center.2.3 These

Material and Energy Flows Associated with Select Metals in GREET 2. Molybdenum, Platinum, Zinc, Nickel, Silicon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Benavides, Pahola T.; Dai, Qiang; Sullivan, John L.

2015-09-01

In this work, we analyzed the material and energy consumption from mining to production of molybdenum, platinum, zinc, and nickel. We also analyzed the production of solar- and semiconductor-grade silicon. We described new additions to and expansions of the data in GREET 2. In some cases, we used operating permits and sustainability reports to estimate the material and energy flows for molybdenum, platinum, and nickel, while for zinc and silicon we relied on information provided in the literature.

45 CFR 156.400 - Definitions.

Code of Federal Regulations, 2013 CFR

2013-10-01

..., silver, gold, or platinum level of coverage is referred to as a standard bronze plan, a standard silver plan, a standard gold plan, and a standard platinum plan, respectively. Zero cost sharing plan...

40 CFR 421.261 - Specialized definitions.

Code of Federal Regulations, 2014 CFR

2014-07-01

... apply to this subpart. (b) The term precious metals shall mean gold, platinum, palladium, rhodium, iridium, osmium, and ruthenium. (c) The term Combined Metals, shall mean the total of gold, platinum and...

40 CFR 421.261 - Specialized definitions.

Code of Federal Regulations, 2013 CFR

2013-07-01

... apply to this subpart. (b) The term precious metals shall mean gold, platinum, palladium, rhodium, iridium, osmium, and ruthenium. (c) The term Combined Metals, shall mean the total of gold, platinum and...

40 CFR 421.261 - Specialized definitions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... apply to this subpart. (b) The term precious metals shall mean gold, platinum, palladium, rhodium, iridium, osmium, and ruthenium. (c) The term Combined Metals, shall mean the total of gold, platinum and...

40 CFR 421.261 - Specialized definitions.

Code of Federal Regulations, 2012 CFR

2012-07-01

... apply to this subpart. (b) The term precious metals shall mean gold, platinum, palladium, rhodium, iridium, osmium, and ruthenium. (c) The term Combined Metals, shall mean the total of gold, platinum and...

A tertiary care experience with paclitaxel and cetuximab as palliative chemotherapy in platinum sensitive and nonsensitive in head and neck cancers

PubMed Central

Noronha, Vanita; Patil, Vijay M.; Joshi, Amit; Bhattacharjee, Atanu; Paul, Davinder; Dhumal, Sachin; Juvekar, Shashikant; Arya, Supreeta; Prabhash, Kumar

2017-01-01

Background: The combination of paclitaxel and cetuximab (PaCe) has led to an encouraging response rate in Phase 2 setting with limited toxicity. The aim of our study was to assess the efficacy of this regimen in our setting in platinum sensitive and nonsensitive patients. Methods: This was a retrospective analysis of head and neck cancer patients treated with weekly PaCe as palliative chemotherapy between May 2010 and August 2014. The standard schedule of cetuximab along with 80 mg/m2 of weekly paclitaxel was administered till either disease progression or withdrawal of patient's consent. The toxicity and response were noted in accordance with CTCAE version 4.02 and RECIST version 1.1 criteria, respectively. The response rates between platinum sensitive and nonsensitive patients were compared by Chi-square test. Overall survival (OS) and progression-free survival (PFS) were estimated by Kaplan–Meier survival method and log-rank test was used for comparison. Cox proportional hazard model was used for identification of factors affecting PFS and OS. Results: One Hundred patients with a median age of 52 years (interquartile range: 46–56 years) were included. Forty-five patients (45%) were platinum insensitive, whereas 55 patients (55%) were platinum sensitive. In platinum insensitive patients and sensitive patients, the response rates were 38.5% and 22.2%, respectively (P = 0.104), whereas the symptomatic benefit in pain was seen in 89.5% and 71.7%, respectively (P = 0.044). The median PFS in platinum insensitive and sensitive patients were 150 and 152 days, respectively (P = 0.932), whereas the median OS was 256 days (95% confidence interval [95% CI]: 168.2–343.8 days) and 314 days (95% CI: 227.6–400.4 days), respectively (P = 0.23). Nineteen patients (19%) had grades 3–4 adverse events during chemotherapy. Conclusion: Weekly paclitaxel combined with cetuximab has promising efficacy and good tolerability in the palliative setting in advanced head and neck cancer in both platinum sensitive and insensitive patients. PMID:28413788

Multidrug Resistance-Associated Protein 2 (MRP2) Mediated Transport of Oxaliplatin-Derived Platinum in Membrane Vesicles

PubMed Central

Myint, Khine; Li, Yan; Paxton, James; McKeage, Mark

2015-01-01

The platinum-based anticancer drug oxaliplatin is important clinically in cancer treatment. However, the role of multidrug resistance-associated protein 2 (MRP2) in controlling oxaliplatin membrane transport, in vivo handling, toxicity and therapeutic responses is unclear. In the current study, preparations of MRP2-expressing and control membrane vesicles, containing inside-out orientated vesicles, were used to directly characterise the membrane transport of oxaliplatin-derived platinum measured by inductively coupled plasma mass spectrometry. Oxaliplatin inhibited the ATP-dependent accumulation of the model MRP2 fluorescent probe, 5(6)-carboxy-2,'7'-dichlorofluorescein, in MRP2-expressing membrane vesicles. MRP2-expressing membrane vesicles accumulated up to 19-fold more platinum during their incubation with oxaliplatin and ATP as compared to control membrane vesicles and in the absence of ATP. The rate of ATP-dependent MRP2-mediated active transport of oxaliplatin-derived platinum increased non-linearly with increasing oxaliplatin exposure concentration, approaching a plateau value (Vmax) of 2680 pmol Pt/mg protein/10 minutes (95%CI, 2010 to 3360 pmol Pt/mg protein/10 minutes), with the half-maximal platinum accumulation rate (Km) at an oxaliplatin exposure concentration of 301 μM (95% CI, 163 to 438 μM), in accordance with Michaelis-Menten kinetics (r2 = 0.954). MRP2 inhibitors (myricetin and MK571) reduced the ATP-dependent accumulation of oxaliplatin-derived platinum in MRP2-expressing membrane vesicles in a concentration-dependent manner. To identify whether oxaliplatin, or perhaps a degradation product, was the likely substrate for this active transport, HPLC studies were undertaken showing that oxaliplatin degraded slowly in membrane vesicle incubation buffer containing chloride ions and glutathione, with approximately 95% remaining intact after a 10 minute incubation time and a degradation half-life of 2.24 hours (95%CI, 2.08 to 2.43 hours). In conclusion, MRP2 mediates the ATP-dependent active membrane transport of oxaliplatin-derived platinum. Intact oxaliplatin and its anionic monochloro oxalate ring-opened intermediate appear likely candidates as substrates for MRP2-mediated transport. PMID:26131551

Functionalization of Platinum Complexes for Biomedical Applications.

PubMed

Wang, Xiaoyong; Wang, Xiaohui; Guo, Zijian

2015-09-15

Platinum-based anticancer drugs are the mainstay of chemotherapy regimens in clinic. Nevertheless, the efficacy of platinum drugs is badly affected by serious systemic toxicities and drug resistance, and the pharmacokinetics of most platinum drugs is largely unknown. In recent years, a keen interest in functionalizing platinum complexes with bioactive molecules, targeting groups, photosensitizers, fluorophores, or nanomaterials has been sparked among chemical and biomedical researchers. The motivation for functionalization comes from some of the following demands: to improve the tumor selectivity or minimize the systemic toxicity of the drugs, to enhance the cellular accumulation of the drugs, to overcome the tumor resistance to the drugs, to visualize the drug molecules in vitro or in vivo, to achieve a synergistic anticancer effect between different therapeutic modalities, or to add extra functionality to the drugs. In this Account, we present different strategies being used for functionalizing platinum complexes, including conjugation with bisphosphonates, peptides, receptor-specific ligands, polymers, nanoparticles, magnetic resonance imaging contrast agents, metal chelators, or photosensitizers. Among them, bisphosphonates, peptides, and receptor-specific ligands are used for actively targeted drug delivery, polymers and nanoparticles are for passively targeted drug delivery, magnetic resonance imaging contrast agents are for theranostic purposes, metal chelators are for the treatment or prevention of Alzheimer's disease (AD), and photosensitizers are for photodynamic therapy of cancers. The rationales behind these designs are explained and justified at the molecular or cellular level, associating with the requirements for diagnosis, therapy, and visualization of biological processes. To illustrate the wide range of opportunities and challenges that are emerging in this realm, representative examples of targeted drug delivery systems, anticancer conjugates, anticancer theranostic agents, and anti-AD compounds relevant to functionalized platinum complexes are provided. All the examples exhibit new potential of platinum complexes for future applications in biomedical areas. The emphases of this Account are placed on the functionalization for targeted drug delivery and theranostic agents. In the end, a general assessment of various strategies has been made according to their major shortcomings and defects. The original information in this Account comes entirely from literature appearing since 2010.

Multidrug Resistance-Associated Protein 2 (MRP2) Mediated Transport of Oxaliplatin-Derived Platinum in Membrane Vesicles.

PubMed

Myint, Khine; Li, Yan; Paxton, James; McKeage, Mark

2015-01-01

The platinum-based anticancer drug oxaliplatin is important clinically in cancer treatment. However, the role of multidrug resistance-associated protein 2 (MRP2) in controlling oxaliplatin membrane transport, in vivo handling, toxicity and therapeutic responses is unclear. In the current study, preparations of MRP2-expressing and control membrane vesicles, containing inside-out orientated vesicles, were used to directly characterise the membrane transport of oxaliplatin-derived platinum measured by inductively coupled plasma mass spectrometry. Oxaliplatin inhibited the ATP-dependent accumulation of the model MRP2 fluorescent probe, 5(6)-carboxy-2,'7'-dichlorofluorescein, in MRP2-expressing membrane vesicles. MRP2-expressing membrane vesicles accumulated up to 19-fold more platinum during their incubation with oxaliplatin and ATP as compared to control membrane vesicles and in the absence of ATP. The rate of ATP-dependent MRP2-mediated active transport of oxaliplatin-derived platinum increased non-linearly with increasing oxaliplatin exposure concentration, approaching a plateau value (Vmax) of 2680 pmol Pt/mg protein/10 minutes (95%CI, 2010 to 3360 pmol Pt/mg protein/10 minutes), with the half-maximal platinum accumulation rate (Km) at an oxaliplatin exposure concentration of 301 μM (95% CI, 163 to 438 μM), in accordance with Michaelis-Menten kinetics (r2 = 0.954). MRP2 inhibitors (myricetin and MK571) reduced the ATP-dependent accumulation of oxaliplatin-derived platinum in MRP2-expressing membrane vesicles in a concentration-dependent manner. To identify whether oxaliplatin, or perhaps a degradation product, was the likely substrate for this active transport, HPLC studies were undertaken showing that oxaliplatin degraded slowly in membrane vesicle incubation buffer containing chloride ions and glutathione, with approximately 95% remaining intact after a 10 minute incubation time and a degradation half-life of 2.24 hours (95%CI, 2.08 to 2.43 hours). In conclusion, MRP2 mediates the ATP-dependent active membrane transport of oxaliplatin-derived platinum. Intact oxaliplatin and its anionic monochloro oxalate ring-opened intermediate appear likely candidates as substrates for MRP2-mediated transport.

Platinum nanowire microelectrode arrays for neurostimulation applications: Fabrication, characterization, and in-vitro retinal cell stimulation

NASA Astrophysics Data System (ADS)

Whalen, John J., III

Implantable electrical neurostimulating devices are being developed for a number of applications, including artificial vision through retinal stimulation. The epiretinal prosthesis will use a two-dimensional array microelectrodes to address individual cells of the retina. MEMS fabrication processes can produce arrays of microelectrodes with these dimensions, but there are two critical issues that they cannot satisfy. One, the stimulating electrodes are the only part of the implanted electrical device that penetrate through the water impermeable package, and must do so without sacrificing hermeticity. Two, As electrode size decreases, the current density (A cm-2 ) increases, due to increased electrochemical impedance. This reduces the amount of charge that can be safely injected into the tissue. To date, MEMS processing method, cannot produce electrode arrays with good, prolonged hermetic properties. Similarly, MEMS approaches do not account for the increased impedance caused by decreased surface area. For these reasons there is a strong motivation for the development of a water-impermeable, substrate-penetrating electrode array with low electrochemical impedance. This thesis presents a stimulating electrode array fabricated from platinum nanowires using a modified electrochemical template synthesis approach. Nanowires are electrochemically deposited from ammonium hexachloroplatinate solution into lithographically patterned nanoporous anodic alumina templates to produce microarrays of platinum nanowires. The platinum nanowires penetrating through the ceramic aluminum oxide template serve as parallel electrical conduits through the water impermeable, electrically insulating substrate. Electrode impedance can be adjusted by either controlling the nanowire hydrous platinum oxide content or by partially etching the alumina template to expose additional surface area. A stepwise approach to this project was taken. First, the electrochemistry of ammonium hexachloroplatinate solution was characterized, and physical properties of electrodeposited thin films were correlated to deposition conditions used. Second, platinum nanowires were fabricated and their properties characterized, using similar deposition conditions. Third, the feasibility of fabricating platinum nanowire stimulating electrode arrays with a variety of surface structures was demonstrated. Fourth, the enhanced charge transfer characteristics of these structures were demonstrated using electrochemical techniques. Finally, retinal cell stimulation was demonstrated using electrodes from platinum nanowire arrays.

EPA Response to RFC 11001

EPA Pesticide Factsheets

Response to Ms Randlshofer that IRIS assessment of halogenated platinum salts is not needed due to platinum fuel additived being removed from the list of registered additives for use in on-road diesel vehicles

Platinum-ruthenium-palladium alloys for use as a fuel cell catalyst

DOEpatents

Gorer, Alexander

2002-01-01

A noble metal alloy composition for a fuel cell catalyst, a ternary alloy composition containing platinum, ruthenium and palladium. The alloy shows increased activity as compared to well-known catalysts.

45 CFR 156.400 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-10-01

... to the requirements of § 156.130(a). A standard plan at the bronze, silver, gold, or platinum level..., and a standard platinum plan, respectively. Zero cost sharing plan variation means, with respect to a...

Platinum-ruthenium-nickel fuel cell electrocatalyst

DOEpatents

Gorer, Alexander

2005-07-26

A catalyst suitable for use in a fuel cell, especially as an anode catalyst, that contains platinum, ruthenium, and nickel, wherein the nickel is at a concentration that is less than about 10 atomic percent.

Electron Field Emission Properties of Textured Platinum Surfaces

NASA Technical Reports Server (NTRS)

Sovey, James S.

2002-01-01

During ground tests of electric microthrusters and space tests of electrodynamic tethers the electron emitters must successfully operate at environmental pressures possibly as high as 1x10(exp -4) Pa. High partial pressures of oxygen, nitrogen, and water vapor are expected in such environments. A textured platinum surface was used in this work for field emission cathode assessments because platinum does not form oxide films at low temperatures. Although a reproducible cathode conditioning process did not evolve from this work, some short term tests for periods of 1 to 4 hours showed no degradation of emission current at an electric field of 8 V/mm and background pressures of about 1x10(exp -6) Pa. Increases of background pressure by air flow to about 3x10(exp -4) Pa yield a hostile environment for the textured platinum field emission cathode.

Fabrication of porous noble metal thin-film electrode by reactive magnetron sputtering.

PubMed

Cho, Tae-Shin; Choi, Heonjin; Kim, Joosun

2013-06-01

Porous platinum films have been fabricated by reactive sputtering combined with subsequent thermal annealing. Using the SEM, XRD, XPS, and polarization resistance measurement techniques, the microstructural development of the film and its resultant electrochemical properties have been characterized. Pore evolution was understood as a result of the thermal grooving of platinum during annealing process. We demonstrated that crystallization should be followed by agglomeration for the evolution of porous microstructures. Furthermore, reaction sputtering affected the adhesion enhancement between the film and substrate compared to the film deposited by non-reactive sputtering. The polarization resistance of the porous platinum film was five times lower than that of the dense platinum film. At 600 degrees C the resistance of the porous film was 5.67 omega x cm2, and that of the dense film was 38 omega x cm2.

Nickel and platinum group metal nanoparticle production by Desulfovibrio alaskensis G20.

PubMed

Capeness, M J; Edmundson, M C; Horsfall, L E

2015-12-25

Desulfovibrio alaskensis G20 is an anaerobic sulfate reducing bacteria. While Desulfovibrio species have previously been shown to reduce palladium and platinum to the zero-state, forming nanoparticles in the process; there have been no reports that D. alaskensis is able to form these nanoparticles. Metal nanoparticles have properties that make them ideal for use in many industrial and medical applications, such as their size and shape giving them higher catalytic activity than the bulk form of the same metal. Nanoparticles of the platinum group metals in particular are highly sought after for their catalytic ability and herein we report the formation of both palladium and platinum nanoparticles by D. alaskensis and the biotransformation of solvated nickel ions to nanoparticle form. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

Enhanced anti-cancer efficacy to cancer cells by doxorubicin loaded water-soluble amino acid-modified β-cyclodextrin platinum complexes.

PubMed

Zhao, Mei-Xia; Zhao, Meng; Zeng, Er-Zao; Li, Yang; Li, Jin-Ming; Cao, Qian; Tan, Cai-Ping; Ji, Liang-Nian; Mao, Zong-Wan

2014-08-01

The effective targeted delivery of insoluble anticancer drugs to increase the intracellular drug concentration has become a focus in cancer therapy. In this system, two water-soluble amino acid-modified β-cyclodextrin (β-CD) platinum complexes were reported. They showed preferable binding ability to DNA and effective inhibition to cancer cells, and they could bind and unwind pBR322 DNA in a manner which was similar to cisplatin. Besides, our platinum complexes could effectively deliver the anticancer drug doxorubicin (Dox) into cells and had higher cell inhibition ratio, but less toxicity on the normal cells, compared with cancer cells. In this combination system, Dox was encapsulated into the hydrophobic cavities of β-CD at the optimum molar ratio of 1:1, which were validated by UV-visible (UV-vis) absorption spectroscopy, fluorescence spectroscopy and MTT experiments. Moreover, the combination system had higher cell inhibition ratio than free Dox and amino acid-modified β-CD platinum complexes, and the results of high content screening (HCS) showed that Dox-loaded amino acid-modified β-CD platinum complexes could permeate the cell membrane and enter cells, suggesting the efficient transport of Dox across the membranes with the aid of the β-CD. We expect that the amino acid-modified β-CD platinum complexes will deliver the antitumor drug Dox to enhance intracellular drug accumulation and such combination system showed great potential as an antitumor drug. Copyright © 2014 Elsevier Inc. All rights reserved.

Design, Synthesis of Novel Platinum(II) Glycoconjugates, and Evaluation of Their Antitumor Effects.

PubMed

Han, Jianbin; Gao, Xiangqian; Liu, Ran; Yang, Jinna; Zhang, Menghua; Mi, Yi; Shi, Ying; Gao, Qingzhi

2016-06-01

A new series of sugar-conjugated (trans-R, R-cyclohexane-1, 2-diamine)-2-halo-malonato-platinum(II) complexes were designed and synthesized to target tumor-specific glucose transporters (GLUTs). The water solubility of the sugar-conjugated platinum (II) complexes was greatly improved by average of 570-fold, 33-fold, and 94-fold, respectively, compared to cisplatin (1.0 mg/mL), carboplatin (17.1 mg/mL), and the newest generation of clinical drug oxaliplatin (6.0 mg/mL). Despite the high water solubility, the platinum(II) glycoconjugates exhibited a notable increase in cytotoxicity by a margin of 1.5- to 6.0-fold in six different human cancer cell lines with respect to oxaliplatin. The potential GLUT1 transportability of the complexes was investigated through a molecular docking study and was confirmed with GLUT1 inhibitor-mediated cytotoxicity dependency evaluation. The results showed that the sugar-conjugated platinum(II) complexes can be recognized by the glucose recognition binding site of GLUT1 and their cell killing effect depends highly on the GLUT1 inhibitor, quercetin. The research presenting a prospective concept for targeted therapy anticancer drug design, and with the analysis of the synthesis, water solubility, antitumor activity, and the transportability of the platinum(II) glycoconjugates, this study provides fundamental data supporting the inherent potential of these designed conjugates as lead compounds for GLUT-mediated tumor targeting. © 2016 John Wiley & Sons A/S.

Nomograms Predicting Platinum Sensitivity, Progression-Free Survival, and Overall Survival Using Pretreatment Complete Blood Cell Counts in Epithelial Ovarian Cancer

PubMed Central

Paik, E Sun; Sohn, Insuk; Baek, Sun-Young; Shim, Minhee; Choi, Hyun Jin; Kim, Tae-Joong; Choi, Chel Hun; Lee, Jeong-Won; Kim, Byoung-Gie; Lee, Yoo-Young; Bae, Duk-Soo

2017-01-01

Purpose This study was conducted to evaluate the prognostic significance of pre-treatment complete blood cell count (CBC), including white blood cell (WBC) differential, in epithelial ovarian cancer (EOC) patients with primary debulking surgery (PDS) and to develop nomograms for platinum sensitivity, progression-free survival (PFS), and overall survival (OS). Materials and Methods We retrospectively reviewed the records of 757 patients with EOC whose primary treatment consisted of surgical debulking and chemotherapy at Samsung Medical Center from 2002 to 2012. We subsequently created nomograms for platinum sensitivity, 3-year PFS, and 5-year OS as prediction models for prognostic variables including age, stage, grade, cancer antigen 125 level, residual disease after PDS, and pre-treatment WBC differential counts. The models were then validated by 10-fold cross-validation (CV). Results In addition to stage and residual disease after PDS, which are known predictors, lymphocyte and monocyte count were found to be significant prognostic factors for platinum-sensitivity, platelet count for PFS, and neutrophil count for OS on multivariate analysis. The area under the curves of platinum sensitivity, 3-year PFS, and 5-year OS calculated by the 10-fold CV procedure were 0.7405, 0.8159, and 0.815, respectively. Conclusion Prognostic factors including pre-treatment CBC were used to develop nomograms for platinum sensitivity, 3-year PFS, and 5-year OS of patients with EOC. These nomograms can be used to better estimate individual outcomes. PMID:27669704

Nomograms Predicting Platinum Sensitivity, Progression-Free Survival, and Overall Survival Using Pretreatment Complete Blood Cell Counts in Epithelial Ovarian Cancer.

PubMed

Paik, E Sun; Sohn, Insuk; Baek, Sun-Young; Shim, Minhee; Choi, Hyun Jin; Kim, Tae-Joong; Choi, Chel Hun; Lee, Jeong-Won; Kim, Byoung-Gie; Lee, Yoo-Young; Bae, Duk-Soo

2017-07-01

This study was conducted to evaluate the prognostic significance of pre-treatment complete blood cell count (CBC), including white blood cell (WBC) differential, in epithelial ovarian cancer (EOC) patients with primary debulking surgery (PDS) and to develop nomograms for platinum sensitivity, progression-free survival (PFS), and overall survival (OS). We retrospectively reviewed the records of 757 patients with EOC whose primary treatment consisted of surgical debulking and chemotherapy at Samsung Medical Center from 2002 to 2012. We subsequently created nomograms for platinum sensitivity, 3-year PFS, and 5-year OS as prediction models for prognostic variables including age, stage, grade, cancer antigen 125 level, residual disease after PDS, and pre-treatment WBC differential counts. The models were then validated by 10-fold cross-validation (CV). In addition to stage and residual disease after PDS, which are known predictors, lymphocyte and monocyte count were found to be significant prognostic factors for platinum-sensitivity, platelet count for PFS, and neutrophil count for OS on multivariate analysis. The area under the curves of platinum sensitivity, 3-year PFS, and 5-year OS calculated by the 10-fold CV procedure were 0.7405, 0.8159, and 0.815, respectively. Prognostic factors including pre-treatment CBC were used to develop nomograms for platinum sensitivity, 3-year PFS, and 5-year OS of patients with EOC. These nomograms can be used to better estimate individual outcomes.

Molecular pathways: the immunogenic effects of platinum-based chemotherapeutics.

PubMed

Hato, Stanleyson V; Khong, Andrea; de Vries, I Jolanda M; Lesterhuis, W Joost

2014-06-01

The platinum-based drugs cisplatin, carboplatin, and oxaliplatin belong to the most widely used chemotherapeutics in oncology, showing clinical efficacy against many solid tumors. Their main mechanism of action is believed to be the induction of cancer cell apoptosis as a response to their covalent binding to DNA. In recent years, this picture has increased in complexity, based on studies indicating that cellular molecules other than DNA may potentially act as targets, and that part of the antitumor effects of platinum drugs occurs through modulation of the immune system. These immunogenic effects include modulation of STAT signaling; induction of an immunogenic type of cancer cell death through exposure of calreticulin and release of ATP and high-mobility group protein box-1 (HMGB-1); and enhancement of the effector immune response through modulation of programmed death receptor 1-ligand and mannose-6-phosphate receptor expression. Both basic and clinical studies indicate that at least part of the antitumor efficacy of platinum chemotherapeutics may be due to immune potentiating mechanisms. Clinical studies exploiting this novel mechanism of action of these old cancer drugs have been initiated. Here, we review the literature on the immunogenic effects of platinum, summarize the clinical advances using platinum as a cytotoxic compound with immune adjuvant properties, and discuss the limitations to these studies and the gaps in our understanding of the immunologic effects of these drugs. Clin Cancer Res; 20(11); 2831-7. ©2014 AACR. ©2014 American Association for Cancer Research.

Correlation of MSH3 polymorphisms with response and survival in advanced non-small cell lung cancer patients treated with first-line platinum-based chemotherapy.

PubMed

Xu, X-L; Yao, Y-L; Xu, W-Z; Feng, J-G; Mao, W-M

2015-04-15

Mismatch repair (MMR) genes, as well as the nucleotide excision repair genes, play an important role in removing cisplatin-DNA adducts, and the mutation of MMR genes in tumors can lead to a decreased response to platinum-based therapies. We examined MutS homolog 3 (MSH3), a mismatch repair gene, and whether polymorphisms of MSH3 were associated with response and survival in advanced non-small cell lung cancer (NCSLC) patients who were treated with platinum-based chemotherapy. The peripheral blood of 180 advanced NCSLC patients who were treated with first-line platinum-based chemotherapy was collected to determine the patients' genotypes of MSH3. The three genotypes of the MSH3 polymorphisms rs26279, rs1650697 and rs1105524 were investigated. A statistically significant association was observed between the polymorphism rs26279 (Ala1054Thr) and sensitivity to platinum-based chemotherapy (P = 0.014). A significant correlation was found between rs1105524 and progression-free survival (PFS), with the G/A and A/A genotypes (median survival time: 14.27 months; 95%CI = 9.80-18.75) suffering shorter survival than patients with the G/G genotype (median survival time: 26.37 months; 95%CI = 15.03-37.71) (P = 0.04). Our results showed that single nucleotide polymorphisms in MSH3 had an impact on the chemotherapy response and prognosis of advanced NCSLC patients who were treated with platinum-based chemotherapy.

Targeting RNA polymerase I transcription machinery in cancer cells by a novel monofunctional platinum-based agent.

PubMed

Zhang, Zhen-Lei; Zhao, Chun-Lai; Chen, Qian; Xu, Kai; Qiao, Xin; Xu, Jing-Yuan

2018-06-01

Aberrant ribosome biogenesis and enlarged nucleoli have long been used by pathologists as a marker of aggressive tumors. Suppression of RNA polymerase I (Pol I) transcription machinery within the nucleolus could be a direct way to trigger the nucleolar stress and to inhibit the rapid proliferation of cancer cells. Here we modified cisplatin with an analogue of the selective inhibitor of RNA polymerase I-mediated transcription BMH-21 to develop a novel platinum-based Pol I selective inhibitor. We show that this novel monofunctional platinum-based agent, P1-B1, had enhanced antitumor activity of up to 17-fold greater than the clinical drug cisplatin in cisplatin-resistant non-small cell lung cancer cells. P1-B1 also had significantly lower cytotoxicity compared to cisplatin as well as the Pol I selective inhibitor BMH-21 in MRC-5 normal lung fibroblast cells, and the selectivity index (SI) greatly increases. Mechanistic investigations revealed that P1-B1 displayed significant nucleolar accumulation, selectively inhibited Pol I transcription, and induced nucleolar stress, leading to S-phase arrest and apoptosis. Our results suggest that the effects of P1-B1 are mechanistically distinct from those of conventional platinum agents and the recently described non-classical platinum compounds and that functionalizing platinum-based agents with directly Pol I transcription inhibition properties may represent an improved modality for cancer treatment. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

DcR3 binds to ovarian cancer via heparan sulfate proteoglycans and modulates tumor cells response to platinum with corresponding alteration in the expression of BRCA1

PubMed Central

2012-01-01

Background Overcoming platinum resistance is a major obstacle in the treatment of Epithelial Ovarian Cancer (EOC). In our previous work Decoy Receptor 3 (DcR3) was found to be related to platinum resistance. The major objective of this work was to define the cellular interaction of DcR3 with EOC and to explore its effects on platinum responsiveness. Methods We studied cell lines and primary cultures for the expression of and the cells ability to bind DcR3. Cells were cultured with DcR3 and then exposed to platinum. Cell viability was determined by MTT assay. Finally, the cells molecular response to DcR3 was studied using real time RT-PCR based differential expression arrays, standard RT-PCR, and Western blot. Results High DcR3 in the peritoneal cavity of women with EOC is associated with significantly shorter time to first recurrence after platinum based therapy (p = 0.02). None-malignant cells contribute DcR3 in the peritoneal cavity. The cell lines studied do not secrete DcR3; however they all bind exogenous DcR3 to their surface implying that they can be effected by DcR3 from other sources. DcR3s protein binding partners are minimally expressed or negative, however, all cells expressed the DcR3 binding Heparan Sulfate Proteoglycans (HSPGs) Syndecans-2, and CD44v3. DcR3 binding was inhibited by heparin and heparinase. After DcR3 exposure both SKOV-3 and OVCAR-3 became more resistant to platinum with 15% more cells surviving at high doses. On the contrary CaOV3 became more sensitive to platinum with 20–25% more cell death. PCR array analysis showed increase expression of BRCA1 mRNA in SKOV-3 and OVCAR-3 and decreased BRCA1 expression in CaOV-3 after exposure to DcR3. This was confirmed by gene specific real time PCR and Western blot analysis. Conclusions Non-malignant cells contribute to the high levels of DcR3 in ovarian cancer. DcR3 binds readily to EOC cells via HSPGs and alter their responsiveness to platinum chemotherapy. The paradoxical responses seen were related to the expression pattern of HSPGs available on the cells surface to interact with. Although the mechanism behind this is not completely known alterations in DNA repair pathways including the expression of BRCA1 appear to be involved. PMID:22583667

Synthesis of platinum nanoparticle electrocatalysts by atomic layer deposition

NASA Astrophysics Data System (ADS)

Lubers, Alia Marie

Demand for energy continues to increase, and without alternatives to fossil fuel combustion the effects on our environment will become increasingly severe. Fuel cells offer a promising improvement on current methods of energy generation; they are able to convert hydrogen fuel into electricity with a theoretical efficiency of up to 83% and interface smoothly with renewable hydrogen production. Fuel cells can replace internal combustion engines in vehicles and are used in stationary applications to power homes and businesses. The efficiency of a fuel cell is maximized by its catalyst, which is often composed of platinum nanoparticles supported on carbon. Economical production of fuel cell catalysts will promote adoption of this technology. Atomic layer deposition (ALD) is a possible method for producing catalysts at a large scale when employed in a fluidized bed. ALD relies on sequential dosing of gas-phase precursors to grow a material layer by layer. We have synthesized platinum nanoparticles on a carbon particle support (Pt/C) by ALD for use in proton exchange membrane fuel cells (PEMFCs) and electrochemical hydrogen pumps. Platinum nanoparticles with different characteristics were deposited by changing two chemistries: the carbon substrate through functionalization; and the deposition process by use of either oxygen or hydrogen as ligand removing reactants. The metal depositing reactant was trimethyl(methylcyclopentadienyl)platinum(IV). Functionalizing the carbon substrate increased nucleation during deposition resulting in smaller and more dispersed nanoparticles. Use of hydrogen produced smaller nanoparticles than oxygen, due to a gentler hydrogenation reaction compared to using oxygen's destructive combustion reaction. Synthesized Pt/C materials were used as catalysts in an electrochemical hydrogen pump, a device used to separate hydrogen fuel from contaminants. Catalysts deposited by ALD on functionalized carbon using a hydrogen chemistry were the most successful hydrogen pumping catalysts, comparable to a commercial Pt/C catalyst. Synthesized Pt/C materials were also used as PEMFC catalysts. We found the ALD catalysts with lower platinum loading to be competitive with a commercial fuel cell catalyst, especially when exhibiting similar platinum particle characteristics. The functionalized carbon helped produce smaller and more dispersed platinum particles; however, it encouraged carbon corrosion within an electrode, severing electrical connections and lowering energy production. The most suitable chemistry for competitive Pt/C catalysts was produced by platinum ALD on unmodified carbon using hydrogen as a reactant. ALD is a promising method for fabricating electrocatalysts, which could help fuel cells become an economically viable alternative to fossil fuels.

Oxygen-related 1-platinum defects in silicon: An electron paramagnetic resonance study

NASA Astrophysics Data System (ADS)

Juda, U.; Scheerer, O.; Höhne, M.; Riemann, H.; Schilling, H.-J.; Donecker, J.; Gerhardt, A.

1996-09-01

A monoclinic 1-platinum defect recently detected was investigated more thoroughly by electron paramagnetic resonance (EPR). The defect is one of the dominating defects in platinum doped silicon. With a perfect reproducibility it is observed in samples prepared from n-type silicon as well as from p-type silicon, in float zone (FZ) silicon as well as in Czochralski (Cz) silicon. Its concentration varies with the conditions of preparation and nearly reaches that of isolated substitutional platinum in Cz silicon annealed for 2 h at 540 °C after quenching from the temperature of platinum diffusion. Because of its concentration which in Cz-Si exceeds that in FZ-Si the defect is assumed to be oxygen-related though a hyperfine structure with 17O could not be resolved. The defect causes a level close to the valence band. This is concluded from variations of the Fermi level and from a discussion of the spin Hamiltonian parameters. In photo-EPR experiments the defect is coupled to recently detected acceptorlike self-interstitial related defects (SIRDs); their level position turns out to be near-midgap. These defects belong to the lifetime limiting defects in Pt-doped Si.

Platinum clusters with precise numbers of atoms for preparative-scale catalysis.

PubMed

Imaoka, Takane; Akanuma, Yuki; Haruta, Naoki; Tsuchiya, Shogo; Ishihara, Kentaro; Okayasu, Takeshi; Chun, Wang-Jae; Takahashi, Masaki; Yamamoto, Kimihisa

2017-09-25

Subnanometer noble metal clusters have enormous potential, mainly for catalytic applications. Because a difference of only one atom may cause significant changes in their reactivity, a preparation method with atomic-level precision is essential. Although such a precision with enough scalability has been achieved by gas-phase synthesis, large-scale preparation is still at the frontier, hampering practical applications. We now show the atom-precise and fully scalable synthesis of platinum clusters on a milligram scale from tiara-like platinum complexes with various ring numbers (n = 5-13). Low-temperature calcination of the complexes on a carbon support under hydrogen stream affords monodispersed platinum clusters, whose atomicity is equivalent to that of the precursor complex. One of the clusters (Pt 10 ) exhibits high catalytic activity in the hydrogenation of styrene compared to that of the other clusters. This method opens an avenue for the application of these clusters to preparative-scale catalysis.The catalytic activity of a noble metal nanocluster is tied to its atomicity. Here, the authors report an atom-precise, fully scalable synthesis of platinum clusters from molecular ring precursors, and show that a variation of only one atom can dramatically change a cluster's reactivity.

Cytotoxic properties of a new organometallic platinum(II) complex and its gold(I) heterobimetallic derivatives.

PubMed

Serratrice, Maria; Maiore, Laura; Zucca, Antonio; Stoccoro, Sergio; Landini, Ida; Mini, Enrico; Massai, Lara; Ferraro, Giarita; Merlino, Antonello; Messori, Luigi; Cinellu, Maria Agostina

2016-01-14

A novel platinum(ii) organometallic complex, [Pt(pbi)(Me)(DMSO)], bearing the 2-(2'-pyridyl)-benzimidazole (pbiH) ligand, was synthesized and fully characterized. Interestingly, the reaction of this organometallic platinum(ii) complex with two distinct gold(i) phosphane compounds afforded the corresponding heterobimetallic derivatives with the pbi ligand bridging the two metal centers. The antiproliferative properties in vitro of [Pt(pbi)(Me)(DMSO)] and its gold(i) derivatives as well as those of the known coordination platinum(ii) and palladium(ii) complexes with the same ligand, of the general formula [MCl2(pbiH)], were comparatively evaluated against A2780 cancer cells, either sensitive or resistant to cisplatin. A superior biological activity of the organometallic compound clearly emerged compared to the corresponding platinum(ii) complex; the antiproliferative effects are further enhanced upon attaching the gold(i) triphenylphosphine moiety to the organometallic Pt compound. Remarkably, these novel metal species are able to overcome nearly complete resistance to cisplatin. Significant mechanistic insight into the study compounds was gained after investigating their reactions with a few representative biomolecules by electrospray mass spectrometry and X-ray crystallography. The obtained results are comprehensively discussed.

Predictive role of repair enzymes in the efficacy of Cisplatin combinations in pancreatic and lung cancer.

PubMed

Peters, Godefridus J; Avan, Abolfazl; Ruiz, Marielle Gallegos; Orsini, Vanessa; Avan, Amir; Giovannetti, Elisa; Smit, Egbert F

2014-01-01

Platinum combinations are the mainstay of treatment for non-small cell lung cancer (NSCLC), while for pancreatic cancer platinum combinations are being given to good-performance status patients. These platinum combinations consist of cis- or carboplatin with gemcitabine, while, for non-squamous NSCLC and mesothelioma, of pemetrexed. The combination of gemcitabine and cisplatin is based on gemcitabine-induced increased formation and retention of DNA-platinum adducts, which can be explained by a decrease of excision repair cross-complementing group-1 (ERCC1)-mediated DNA repair. In these patients, survival and response is prolonged when ERCC1 has a low protein or mRNA expression. A low expression of ribonucleotide reductase (RR) is related to a better treatment outcome after both gemcitabine and gemcitabine-platinum combinations. For pemetrexed combinations, ERCC1 expression was not related to survival. For both NSCLC and pancreatic cancer, polymorphisms in ERCC1 (C118T) and Xeroderma pigmentosum group D (XPD) (A751C) were related to survival. In currently ongoing and future prospective studies, patients should be selected based on their DNA repair status, but it still has to be determined whether this should be by immunohistochemistry, mRNA expression, or a polymorphism.

2-Deoxyglucose conjugated platinum (II) complexes for targeted therapy: design, synthesis, and antitumor activity.

PubMed

Mi, Qian; Ma, Yuru; Gao, Xiangqian; Liu, Ran; Liu, Pengxing; Mi, Yi; Fu, Xuegang; Gao, Qingzhi

2016-11-01

Malignant neoplasms exhibit an elevated rate of glycolysis over normal cells. To target the Warburg effect, we designed a new series of 2-deoxyglucose (2-DG) conjugated platinum (II) complexes for glucose transporter 1 (GLUT1)-mediated anticancer drug delivery. The potential GLUT1 transportability of the complexes was investigated through a comparative molecular docking analysis utilizing the latest GLUT1 protein crystal structure. The key binding site for 2-DG as GLUT1's substrate was identified with molecular dynamics simulation, and the docking study demonstrated that the 2-DG conjugated platinum (II) complexes can be recognized by the same binding site as potential GLUT1 substrate. The conjugates were synthesized and evaluated for in vitro cytotoxicity study with seven human cancer cell lines. The results of this study revealed that 2-DG conjugated platinum (II) complexes are GLUT1 transportable substrates and exhibit improved cytotoxicities in cancer cell lines that over express GLUT1 when compared to the clinical drug, Oxaliplatin. The correlation between GLUT1 expression and antitumor effects are also confirmed. The study provides fundamental information supporting the potential of the 2-DG conjugated platinum (II) complexes as lead compounds for further pharmaceutical R&D.

Behavior of platinum(iv) complexes in models of tumor hypoxia: cytotoxicity, compound distribution and accumulation.

PubMed

Schreiber-Brynzak, Ekaterina; Pichler, Verena; Heffeter, Petra; Hanson, Buck; Theiner, Sarah; Lichtscheidl-Schultz, Irene; Kornauth, Christoph; Bamonti, Luca; Dhery, Vineet; Groza, Diana; Berry, David; Berger, Walter; Galanski, Markus; Jakupec, Michael A; Keppler, Bernhard K

2016-04-01

Hypoxia in solid tumors remains a challenge for conventional cancer therapeutics. As a source for resistance, metastasis development and drug bioprocessing, it influences treatment results and disease outcome. Bioreductive platinum(iv) prodrugs might be advantageous over conventional metal-based therapeutics, as biotransformation in a reductive milieu, such as under hypoxia, is required for drug activation. This study deals with a two-step screening of experimental platinum(iv) prodrugs with different rates of reduction and lipophilicity with the aim of identifying the most appropriate compounds for further investigations. In the first step, the cytotoxicity of all compounds was compared in hypoxic multicellular spheroids and monolayer culture using a set of cancer cell lines with different sensitivities to platinum(ii) compounds. Secondly, two selected compounds were tested in hypoxic xenografts in SCID mouse models in comparison to satraplatin, and, additionally, (LA)-ICP-MS-based accumulation and distribution studies were performed for these compounds in hypoxic spheroids and xenografts. Our findings suggest that, while cellular uptake and cytotoxicity strongly correlate with lipophilicity, cytotoxicity under hypoxia compared to non-hypoxic conditions and antitumor activity of platinum(iv) prodrugs are dependent on their rate of reduction.

SEM method for direct visual tracking of nanoscale morphological changes of platinum based electrocatalysts on fixed locations upon electrochemical or thermal treatments.

PubMed

Zorko, Milena; Jozinović, Barbara; Bele, Marjan; Hodnik, Nejc; Gaberšček, Miran

2014-05-01

A general method for tracking morphological surface changes on a nanometer scale with scanning electron microscopy (SEM) is introduced. We exemplify the usefulness of the method by showing consecutive SEM images of an identical location before and after the electrochemical and thermal treatments of platinum-based nanoparticles deposited on a high surface area carbon. Observations reveal an insight into platinum based catalyst degradation occurring during potential cycling treatment. The presence of chloride clearly increases the rate of degradation. At these conditions the dominant degradation mechanism seems to be the platinum dissolution with some subsequent redeposition on the top of the catalyst film. By contrast, at the temperature of 60°C, under potentiostatic conditions some carbon corrosion and particle aggregation was observed. Temperature treatment simulating the annealing step of the synthesis reveals sintering of small platinum based composite aggregates into uniform spherical particles. The method provides a direct proof of induced surface phenomena occurring on a chosen location without the usual statistical uncertainty in usual, random SEM observations across relatively large surface areas. Copyright © 2014 Elsevier B.V. All rights reserved.

Rapid occurrence of left ventricular thrombus associated with platinum-based chemotherapy plus cetuximab for the treatment of metastatic squamous cell carcinoma of the head and neck: A case report.

PubMed

Ikeda, Atsushi; Yamachika, Eiki; Mizutani, Masahide; Matsubara, Masakazu; Moritani, Norifumi; Nakatsuji, Kazuki; Iida, Seiji

2017-11-01

Platinum-based chemotherapy plus cetuximab represents the first-line treatment for recurrent or metastatic squamous cell carcinoma of the head and neck. The most common adverse events associated with cetuximab are infusion reactions and skin reactions, and a risk of venous thromboembolic events has also recently been reported in association with cetuximab. It is well known that thrombosis is a common complication of malignancy, and represents the second most frequent cause of mortality in cancer patients. The present study reports the case of a 79-year-old man who presented with lung and liver metastases from tongue squamous cell carcinoma, for which platinum-based chemotherapy plus cetuximab was administered. After 1 cycle, the patient showed rapid growth of a left ventricular (LV) thrombus, despite ongoing antiplatelet therapy for an old myocardial infarction. Anticoagulant therapy was administered to treat the LV thrombus, which resolved within 1 week. To the best of our knowledge, this represents the first reported case of rapidly occurring LV thrombus associated with platinum-based chemotherapy plus cetuximab. Platinum-based chemotherapy plus cetuximab may be associated with a higher risk of embolic thrombus.

In vivo multimodality imaging and cancer therapy by near-infrared light-triggered trans-platinum pro-drug-conjugated upconverison nanoparticles.

PubMed

Dai, Yunlu; Xiao, Haihua; Liu, Jianhua; Yuan, Qinghai; Ma, Ping'an; Yang, Dongmei; Li, Chunxia; Cheng, Ziyong; Hou, Zhiyao; Yang, Piaoping; Lin, Jun

2013-12-18

Controlling anticancer drug activity and release on demand is very significant in cancer therapy. The photoactivated platinum(IV) pro-drug is stable in the dark and can be activated by UV light. In this study, we develop a multifunctional drug delivery system combining upconversion luminescence/magnetic resonance/computer tomography trimodality imaging and NIR-activated platinum pro-drug delivery. We use the core-shell structured upconversion nanoparticles to convert the absorbed NIR light into UV to activate the trans-platinum(IV) pro-drug, trans,trans,trans-[Pt(N3)2(NH3)(py)(O2CCH2CH2COOH)2]. Compared with using the UV directly, the NIR has a higher tissue penetration depth and is less harmful to health. Meanwhile, the upconversion nanoparticles can effectively deliver the platinum(IV) pro-drugs into the cells by endocytosis. The mice treated with pro-drug-conjugated nanoparticles under near-infrared (NIR) irradiation demonstrated better inhibition of tumor growth than that under direct UV irradiation. This multifunctional nanocomposite could be used as multimodality bioimaging contrast agents and transducers by converting NIR light into UV for control of drug activity in practical cancer therapy.

48 CFR 252.208-7000 - Intent to furnish precious metals as Government-furnished material.

Code of Federal Regulations, 2012 CFR

2012-10-01

... Offeror shall cite the type (silver, gold, platinum, palladium, iridium, rhodium, and ruthenium) and... metal* Quantity Deliverable item (NSN and nomenclature)!!rs *If platinum or palladium, specify whether...

Fuel cell with Pt/Pd electrocatalyst electrode

DOEpatents

Stonehart, Paul

1983-01-01

An electrode for use in a phosphoric acid fuel cell comprising a graphitized or partially graphitized carbon support having a platinum/palladium electrocatalyst thereon. Preferably, the platinum/palladium catalyst comprises 20 to 65 weight percent palladium.

48 CFR 252.208-7000 - Intent to furnish precious metals as Government-furnished material.

Code of Federal Regulations, 2013 CFR

2013-10-01

... Offeror shall cite the type (silver, gold, platinum, palladium, iridium, rhodium, and ruthenium) and... metal* Quantity Deliverable item (NSN and nomenclature)!!rs *If platinum or palladium, specify whether...

48 CFR 252.208-7000 - Intent to furnish precious metals as Government-furnished material.

Code of Federal Regulations, 2011 CFR

2011-10-01

... Offeror shall cite the type (silver, gold, platinum, palladium, iridium, rhodium, and ruthenium) and... metal* Quantity Deliverable item (NSN and nomenclature)!!rs *If platinum or palladium, specify whether...

48 CFR 252.208-7000 - Intent to furnish precious metals as Government-furnished material.

Code of Federal Regulations, 2014 CFR

2014-10-01

... Offeror shall cite the type (silver, gold, platinum, palladium, iridium, rhodium, and ruthenium) and... metal* Quantity Deliverable item (NSN and nomenclature)!!rs *If platinum or palladium, specify whether...

Platinum Publications, April 1–May 27, 2016 | Poster

Cancer.gov

Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed.

Determination of palladium and platinum by atomic absorption

USGS Publications Warehouse

Schnepfe, M.M.; Grimaldi, F.S.

1969-01-01

Palladium and platinum are determined by atomic absorption after fire-assay concentration into a gold bead. The limit of determination is ~0??06 ppm in a 20-g sample. Serious depressive interelement interferences are removed by buffering the solutions with a mixture of cadmium and copper sulphates with cadmium and copper concentrations each at 0??5%. Substantial amounts of Ag, Al, Au, Bi, Ca, Co, Cr, Fe, Hg, K, La, Mg, Mn, Mo, Na, Ni, Pb, Te, Ti, V, Y, Zn, and the platinum metals do not interfere in the atomic-absorption determination. ?? 1969.

High Temperature Sorbents for Oxygen

NASA Technical Reports Server (NTRS)

Sharma, Pramod K. (Inventor)

1996-01-01

A sorbent capable of removing trace amounts of oxygen (ppt) from a gas stream at a high temperature above 200 C is introduced. The sorbent comprises a porous alumina silicate support such as zeolite containing from 1 to 10 percent by weight of ion exchanged transition metal such as copper or cobalt ions and 0.05 to 1.0 percent by weight of an activator selected from a platinum group metal such as platinum. The activation temperature, oxygen sorption and reducibility are all improved by the presence of the platinum activator.

Lead, platinum, and other heavy elements in the primary cosmic radiation: HEAO-3 results ssc wg032961 cb553097

NASA Technical Reports Server (NTRS)

Waddington, C. J.; Binns, W. R.; Brewster, N. R.; Fixsen, D. J.; Garrard, T. L.; Israel, M. H.; Klarmann, J.; Newport, B. J.; Stone, E. C.

1985-01-01

An observation of the abundances of cosmic-ray lead and platinum-group nuclei using data from the HEAO-3 Heavy Nuclei Experiment (HNE) which consisted of ion chambers mounted on both sides of a plastic Cerenkov counter is reported. Further analysis with more stringent selections, inclusion of additional data, and a calibration at the LBL Bevalac, have allowed obtaining the abundance ratio of lead and the platinum group of elements for particles that had a cutoff rigidity R sub c 5 GV.

First-principles molecular transport calculation for the benzenedithiolate molecule

NASA Astrophysics Data System (ADS)

Rumetshofer, M.; Dorn, G.; Boeri, L.; Arrigoni, E.; von der Linden, W.

2017-10-01

A first-principles approach based on density functional theory and non-equilibrium Green’s functions is used to study the molecular transport system consisting of benzenedithiolate connected with monoatomic gold and platinum electrodes. Using symmetry arguments we explain why the conductance mechanism is different for gold and platinum electrodes. We present the charge stability diagram for the benzenedithiolate connected with monoatomic platinum electrodes including many-body effects in terms of an extended Hubbard Hamiltonian and discuss how the electrodes and the many-body effects influence the transport properties of the system.

Platinum- and platinum alloy-coated palladium and palladium alloy particles and uses thereof

DOEpatents

Adzic, Radoslav; Zhang, Junliang; Mo, Yibo; Vukmirovic, Miomir Branko

2010-04-06

The present invention relates to particle and nanoparticle composites useful as oxygen-reduction electrocatalysts. The particle composites are composed of a palladium or palladium-alloy particle or nanoparticle substrate coated with an atomic submonolayer, monolayer, bilayer, or trilayer of zerovalent platinum atoms. The invention also relates to a catalyst and a fuel cell containing the particle or nanoparticle composites of the invention. The invention additionally includes methods for oxygen reduction and production of electrical energy by using the particle and nanoparticle composites of the invention.

A Novel Method for Depositing Precious Metal Films on Difficult Surfaces

NASA Technical Reports Server (NTRS)

Veitch, L. C.; Phillip, W. H.

1994-01-01

A guanidine-based vehicle was developed to deposit precious metal coatings on surfaces known to be difficult to coat. To demonstrate this method, a platinum coating was deposited on alumina fibers using a guanidine-platinum solution. X-ray diffraction confirmed that the only species present in the coating was platinum and that all of the carbon species had been removed upon heat treatment. SEM results showed that some porosity was present but that the coatings uniformly covered the fiber surface and adhered well to the finer.

Photochemical H2 evolution from water catalyzed by a dichloro(diphenylbipyridine)platinum(ii) derivative tethered to multiple viologen acceptors.

PubMed

Kitamoto, Kyoji; Sakai, Ken

2016-01-25

A new single-component photocatalyst for the reduction of water to H2, a dichloro(dpbpy)platinum(ii) derivative (dpbpy = 4,4'-diphenyl-2,2'-bipyridine) tethered to four pendant viologen acceptors (1), is shown to exhibit twice higher photocatalytic efficiency than the previously reported dichloro(bpy)-platinum(ii) analog (; bpy = 2,2'-bipyridine), consistent with the higher absorptivity of at the metal-to-ligand charge transfer ((1)MLCT) band due to the larger π-conjugation in dpbpy relative to bpy.

Thin film solar energy collector

DOEpatents

Aykan, Kamran; Farrauto, Robert J.; Jefferson, Clinton F.; Lanam, Richard D.

1983-11-22

A multi-layer solar energy collector of improved stability comprising: (1) a substrate of quartz, silicate glass, stainless steel or aluminum-containing ferritic alloy; (2) a solar absorptive layer comprising silver, copper oxide, rhodium/rhodium oxide and 0-15% by weight of platinum; (3) an interlayer comprising silver or silver/platinum; and (4) an optional external anti-reflective coating, plus a method for preparing a thermally stable multi-layered solar collector, in which the absorptive layer is undercoated with a thin film of silver or silver/platinum to obtain an improved conductor-dielectric tandem.

Electrocatalysts having platium monolayers on palladium, palladium alloy, and gold alloy core-shell nanoparticles, and uses thereof

DOEpatents

Adzic, Radoslav; Mo, Yibo; Vukmirovic, Miomir; Zhang, Junliang

2010-12-21

The invention relates to platinum-coated particles useful as fuel cell electrocatalysts. The particles are composed of a noble metal or metal alloy core at least partially encapsulated by an atomically thin surface layer of platinum atoms. The invention particularly relates to such particles having a palladium, palladium alloy, gold alloy, or rhenium alloy core encapsulated by an atomic monolayer of platinum. In other embodiments, the invention relates to fuel cells containing these electrocatalysts and methods for generating electrical energy therefrom.

Palladium, platinum, and rhodium contents of rocks near the lower margin of the Stillwater complex, Montana.

USGS Publications Warehouse

Zientek, M.L.; Foose, M.P.; Leung, Mei

1986-01-01

Statistical summaries are reported for Pd, Pt and Rh contents of rocks from the lower part of the Stillwater complex, the underlying contact-metamorphosed sediments, and post-metamorphic dykes and sills wholly within the hornfelses. Variability of the data among the rock types is attributed largely to differences in sulphide content. Non-correlation of sulphur with platinum-group assays of many rock types leads to the suggestion that the immiscible sulphide and silicate liquids did not completely equilibrate with respect to platinum-group elements. -G.J.N.

Pharmacokinetic evaluation of intrapleural perfusion with hyperthermic chemotherapy using cisplatin in patients with malignant pleural effusion.

PubMed

Sakaguchi, Hirozo; Ishida, H; Nitanda, H; Yamazaki, N; Kaneko, K; Kobayashi, Kunihiko

2017-02-01

Malignant pleural effusion (MPE) has a poor prognosis. Most patients are treated with tube thoracostomy and sclerotherapy, although its success rate is around 64%. We have investigated intrapleural perfusion with hyperthermic chemotherapy (IPHC) using cisplatin in a study with a pharmacokinetic evaluation. Patients with MPE, performance status of 0-1, possibility of good lung expansion and Cr<1.2mg/dL were treated with IPHC. The circuit was filled with 2000mL of normal saline containing cisplatin at a dose of 80mg/m 2 . Under video-assisted thoracoscopic surgery, the thoracic cavity was filled and perfused at a speed of approximately 1L/min at a temperature of 43°C for 1h. Perfusion solution and plasma samples were periodically collected, and concentrations of protein-unbound (free) platinum, which was the active derivative of cisplatin, and total platinum were determined by flameless atomic absorption spectrometry. Twenty patients with MPE (8 lung cancers, 7 mesotheliomas, and 5 others) were enrolled in this study. Rate of free platinum concentration relative to total platinum concentration in perfusion solution after 1hr IPHC at 43°C was 61.1±12.9%. Area under curve (AUC) of free platinum in the pleural space was calculated to be 26.3μg/mLxh, resulting in complete control of pleural effusion for 3 months after IHPC in all cases (95% confidence interval: 83-100%). While, absorption rate of total platinum from the pleural space was 33.8±17.0% (27.4±13.6mg/m 2 ), and the maximum concentration of total platinum in serum was low, 0.66±0.31μg/mL, resulting in controllable side effects; grade 1 renal toxicity: 6 patients, grade 1 emesis: 7 patients. IPHC with cisplatin showed favorable pharmacokinetic profiles for an optional treatment to control malignant pleural effusion. Copyright © 2016 The Author(s). Published by Elsevier B.V. All rights reserved.

Electron transfer processes occurring on platinum neural stimulating electrodes: pulsing experiments for cathodic-first, charge-balanced, biphasic pulses for 0.566  ⩽  k  ⩽  2.3 in rat subcutaneous tissues

NASA Astrophysics Data System (ADS)

Kumsa, Doe W.; Bhadra, Narendra; Hudak, Eric M.; Mortimer, J. Thomas

2017-10-01

Objective. Our mission is twofold: (1) find a way to safely inject more charge through platinum electrodes than the Shannon limit (k  =  1.75) permits and (2) nurture an interest in the neural stimulation community to understand the electron transfer process occurring on neural stimulating electrodes. Approach. We report here on measurements of the electrode potential, performed on platinum neural stimulating electrodes in the subcutaneous space of an anesthetized rat under neural stimulation conditions. Main results. The results for six platinum electrodes with areas ranging from 0.2 mm2 to 12.7 mm2 were similar to prior results in sulfuric acid, except that the measured potentials were shifted negative 0.36 V because of the pH difference between the two media. The anodic ‘end’ potential, measured at t  =  20 ms after the onset of the biphasic current pulse, was the primary focus of the data collected because previous results had shown that as charge injection crosses the Shannon limit (k  =  1.75), this potential moves into a range where platinum surface oxidation and dissolution is likely to occur. The behavior of V e(t  =  20 ms) over a range of electrode surface areas studied was consistent with our sulfuric acid study. Implicit, but little noticed, in Shannon’s formulation is that small and large platinum electrodes behave the same in terms of k value; our data supports this idea. Significance. We hypothesize that the k  =  1.75 Shannon limit for safe stimulation designates a charge-injection boundary above which platinum toxicity becomes a relevant consideration for living cells around an electrode, a possibility that can be directly tested, and is a vital step forward in mission (1).

Electron transfer processes occurring on platinum neural stimulating electrodes: pulsing experiments for cathodic-first, charge-balanced, biphasic pulses for 0.566  ⩽  k  ⩽  2.3 in rat subcutaneous tissues.

PubMed

Kumsa, Doe W; Bhadra, Narendra; Hudak, Eric M; Mortimer, J Thomas

2017-10-01

Our mission is twofold: (1) find a way to safely inject more charge through platinum electrodes than the Shannon limit (k  =  1.75) permits and (2) nurture an interest in the neural stimulation community to understand the electron transfer process occurring on neural stimulating electrodes. We report here on measurements of the electrode potential, performed on platinum neural stimulating electrodes in the subcutaneous space of an anesthetized rat under neural stimulation conditions. The results for six platinum electrodes with areas ranging from 0.2 mm 2 to 12.7 mm 2 were similar to prior results in sulfuric acid, except that the measured potentials were shifted negative 0.36 V because of the pH difference between the two media. The anodic 'end' potential, measured at t  =  20 ms after the onset of the biphasic current pulse, was the primary focus of the data collected because previous results had shown that as charge injection crosses the Shannon limit (k  =  1.75), this potential moves into a range where platinum surface oxidation and dissolution is likely to occur. The behavior of V e (t  =  20 ms) over a range of electrode surface areas studied was consistent with our sulfuric acid study. Implicit, but little noticed, in Shannon's formulation is that small and large platinum electrodes behave the same in terms of k value; our data supports this idea. We hypothesize that the k  =  1.75 Shannon limit for safe stimulation designates a charge-injection boundary above which platinum toxicity becomes a relevant consideration for living cells around an electrode, a possibility that can be directly tested, and is a vital step forward in mission (1).

Long-Term Survival for Platinum-Sensitive Recurrent Ovarian Cancer Patients Treated with Secondary Cytoreductive Surgery Plus Hyperthermic Intraperitoneal Chemotherapy (HIPEC).

PubMed

Petrillo, M; De Iaco, P; Cianci, S; Perrone, M; Costantini, B; Ronsini, C; Scambia, G; Fagotti, A

2016-05-01

To analyze the 5- and 7-year survival outcomes for women with platinum-sensitive recurrent epithelial ovarian cancer (REOC) who underwent secondary cytoreductive surgery (SCS) plus platinum-based hyperthermic intraperitoneal chemotherapy (HIPEC). From the electronic databases of the Department of Obstetrics and Gynecology at the Catholic University of the Sacred Heart of Rome and of the S. Orsola Hospital, University of Bologna, a consecutive series of REOC patients were selected using the following inclusion criteria: primary platinum-free interval (PFI-1) of 6 months or longer, completeness of secondary cytoreduction score (CC) of 1 or lower, minimum follow-up period of 48 months, Eastern Cooperative Group (ECOG) performance status at recurrence of 1 or less, and platinum-based HIPEC. Progression-free survival (PFS) and post-relapse survival (PRS) were calculated as the time between SCS + HIPEC and secondary recurrence or death, respectively. The final study population included 70 women with platinum-sensitive REOC. The median follow-up time was 73 months (range 48-128 months), and the median PFI-1 was 19 months (range 6-100 months). At the time of recurrence, the median peritoneal cancer index was 7 (range 1-21), and a CC score of 0 was achieved for 62 patients (88.6 %). As the HIPEC drug, we used oxaliplatin in 17 cases (38.6 %) and cisplatin in 43 cases (61.4 %). No postoperative deaths were observed, and the complication rate for grades 3 and 4 disease was 8.6 %. The median PFS duration was 27 months (range 5-104 months), and the 5- and 7-year PRS rates were respectively 52.8 and 44.7 %, (median PRS 63 months). The current study demonstrated favorable 5- and 7-year PRS rates for platinum-sensitive REOC patients undergoing SCS + HIPEC, which encourages the inclusion of patients in randomized clinical trials for definitive conclusions to be drawn.

Effects of histidin-2-ylidene vs. imidazol-2-ylidene ligands on the anticancer and antivascular activity of complexes of ruthenium, iridium, platinum, and gold.

PubMed

Schmitt, Florian; Donnelly, Kate; Muenzner, Julienne K; Rehm, Tobias; Novohradsky, Vojtech; Brabec, Viktor; Kasparkova, Jana; Albrecht, Martin; Schobert, Rainer; Mueller, Thomas

2016-10-01

Couples of N-heterocyclic carbene complexes of ruthenium, iridium, platinum, and gold, each differing only in the carbene ligand being either 1,3-dimethylimidazol-2-ylidene (IM) or 1,3-dimethyl-N-boc-O-methylhistidin-2-ylidene (HIS), were assessed for their antiproliferative effect on seven cancer cell lines, their interaction with DNA, their cell cycle interference, and their vascular disrupting properties. In MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assays only the platinum complexes were cytotoxic at single-digit micromolar IC 50 concentrations with the (HIS)Pt complex being on average twice as active as the (IM)Pt complex. The former was highly efficacious against cisplatin-resistant HT-29 colon carcinoma cells where the latter had no effect. Both Pt complexes were accumulated by cancer cells and bound to double-helical DNA equally well. Only the (HIS)Pt complex modified the electrophoretic mobility of circular DNA in vitro due to the HIS ligand causing greater morphological changes to the DNA. Both platinum complexes induced accumulation of 518A2 melanoma cells in G2/M and S phase of the cell cycle. A disruption of blood vessels in the chorioallantoic membrane of fertilized chicken eggs was observed for both platinum complexes and the (IM)gold complex. The (HIS)platinum complex was as active as cisplatin in tumor xenografted mice while being tolerated better. We found that the HIS ligand may augment the cytotoxicity of certain antitumoral metal fragments in two ways: by acting as a transmembrane carrier increasing the cellular accumulation of the complex, and by initiating a pronounced distortion and unwinding of DNA. We identified a new (HIS)platinum complex which was highly cytotoxic against cancer cells including cisplatin-resistant ones. Copyright © 2016 Elsevier Inc. All rights reserved.

Dual mTORC1/2 Inhibition as a Novel Strategy for the Resensitization and Treatment of Platinum-Resistant Ovarian Cancer.

PubMed

Musa, Fernanda; Alard, Amandine; David-West, Gizelka; Curtin, John P; Blank, Stephanie V; Schneider, Robert J

2016-07-01

There is considerable interest in the clinical development of inhibitors of mTOR complexes mTORC1 and 2. Because mTORC1 and its downstream mRNA translation effectors may protect against genotoxic DNA damage, we investigated the inhibition of mTORC1 and mTORC1/2 in the ability to reverse platinum resistance in tissue culture and in animal tumor models of serous ovarian cancer. Cell survival, tumor growth, PI3K-AKT-mTOR pathway signaling, DNA damage and repair response (DDR) gene expression, and translational control were all investigated. We show that platinum-resistant OVCAR-3 ovarian cancer cells are resensitized to low levels of carboplatin in culture by mTOR inhibition, demonstrating reduced survival after treatment with either mTORC1 inhibitor everolimus or mTORC1/2 inhibitor PP242. Platinum resistance is shown to be associated with activating phosphorylation of AKT and CHK1, inactivating phosphorylation of 4E-BP1, the negative regulator of eIF4E, which promotes increased cap-dependent mRNA translation and increased levels of CHK1 and BRCA1 proteins. Animals with platinum-resistant OVCAR-3 tumors treated with carboplatin plus mTORC1/2 inhibition had significantly longer median survival and strikingly reduced metastasis compared with animals treated with carboplatin plus everolimus, which inhibits only mTORC1. Reduced tumor growth, metastasis, and increased survival by mTORC1/2 inhibition with carboplatin treatment was associated with reduced AKT-activating phosphorylation and increased 4E-BP1 hypophosphorylation (activation). We conclude that mTORC1/2 inhibition is superior to mTORC1 inhibition in reversing platinum resistance in tumors and strongly impairs AKT activation, DNA repair responses, and translation, promoting improved survival in the background of platinum resistance. Mol Cancer Ther; 15(7); 1557-67. ©2016 AACR. ©2016 American Association for Cancer Research.

Dual mTORC1/2 inhibition as a novel strategy for the re-sensitization and treatment of platinum-resistant ovarian cancer

PubMed Central

Musa, Fernanda; Alard, Amandine; David-West, Gizelka; Curtin, John P.; Blank, Stephanie V.; Schneider, Robert J.

2017-01-01

There is considerable interest in the clinical development of inhibitors of mTOR complexes mTORC1 and 2. Because mTORC1 and its downstream mRNA translation effectors may protect against genotoxic DNA damage, we investigated the inhibition of mTORC1 and mTORC1/2 in the ability to reverse platinum resistance in tissue culture and in animal tumor models of serous ovarian cancer. Cell survival, tumor growth, PI3K-AKT-mTOR pathway signaling, DNA damage and repair response (DDR) gene expression and translational control were all investigated. We show that platinum resistant OVCAR-3 ovarian cancer cells are re-sensitized to low levels of carboplatin in culture by mTOR inhibition, demonstrating reduced survival after treatment with either mTORC1 inhibitor everolimus or mTORC1/2 inhibitor PP242. Platinum resistance is shown to be associated with activating phosphorylation of AKT and CHK1, inactivating phosphorylation of 4E-BP1, the negative regulator of eIF4E, which promotes increased cap-dependent mRNA translation and increased levels of CHK1 and BRCA1 proteins. Animals with platinum resistant OVCAR-3 tumors treated with carboplatin plus mTORC1/2 inhibition had significantly longer median survival and strikingly reduced metastasis compared to animals treated with carboplatin plus everolimus which inhibits only mTORC1. Reduced tumor growth, metastasis and increased survival by mTORC1/2 inhibition with carboplatin treatment was associated with reduced AKT activating phosphorylation and increased 4E-BP1 hypo-phosphorylation (activation). We conclude that mTORC1/2 inhibition is superior to mTORC1 inhibition in reversing platinum resistance in tumors and strongly impairs AKT activation, DNA repair responses and translation, promoting improved survival in the background of platinum resistance. PMID:27196780

Neutrophil to lymphocyte ratio and platelet to lymphocyte ratio are predictive of chemotherapeutic response and prognosis in epithelial ovarian cancer patients treated with platinum-based chemotherapy.

PubMed

Miao, Yi; Yan, Qin; Li, Shuangdi; Li, Bilan; Feng, Youji

2016-06-07

The aim of present study was to investigate the role of preoperative neutrophil to lymphocyte ratio (NLR) and platelet to lymphocyte ratio (PLR) used as prognostic markers for predicting chemotherapeutic response and survival outcomes in patients with epithelial ovarian cancer (EOC) who are receiving platinum-based chemotherapy. A total of 344 patients diagnosed with EOC who are receiving platinum-based chemotherapy from 2005 to 2010 in the hospital were enrolled. NLR and PLR were calculated from complete blood cell count taken before operation. The patients were divided into platinum-resistant (P-R) group and platinum-sensitive (P-S) group according to chemotherapeutic response. Clinicopathologic variables and outcomes were retrospectively collected and compared among groups. We used receiver operating characteristic (ROC) curves to calculate optimal cut-off values for NLR and PLR to predict chemotherapeutic response and prognosis. The AUC, sensitivity, specificity of NLR > 3.02 to predict platinum resistance were 0.819, 75.0% and 81.45%, respectively. The corresponding values of PLR > 207 were 0.727, 60.42% and 85.48%, respectively. Patients with lower value of NLR (NLR < 3.02) or PLR (PLR < 207) had a longer progression-free survival (PFS) and overall survival (OS). In multivariate analysis, NLR and PLR showed a significant association with PFS (hazard ratio [HR], 1.733; 95%CI, 1.225-2.453, P = 0.002 and HR, 1.952; 95%CI, 1.430-2.662, P < 0.001) and OS (HR, 1.616; 95%CI, 1.138-2.297, P = 0.007, and HR, 2.167; 95%CI, 1.565-3.000, P < 0.001). These results suggest that the assessment of NLR and PLR could assist the identification of patients with poor prognosis and had potential clinical value in predicting platinum resistance in patients with EOC.

Twelve-month results of a prospective, multicentre trial to assess the everolimus-eluting coronary stent system (PROMUS Element): the PLATINUM PLUS all-comers randomised trial.

PubMed

Fajadet, Jean; Neumann, Franz-Josef; Hildick-Smith, David; Petronio, Sonia; Zaman, Azfar; Spence, Mark; Wöhrle, Jochen; Elhadad, Simon; Roberts, David; Hovasse, Thomas; Valdés, Mariano; Silber, Sigmund

2017-01-20

The aim of the study was to compare the safety and efficacy of the platinum-chromium-based everolimus-eluting stent (EES) with a cobalt-chromium EES. We performed a prospective, multicentre, single-blind non-inferiority all-comers study randomising patients with stable or unstable coronary artery disease (2:1) to treatment with the platinum-chromium EES (n=1,952) or the control cobalt-chromium EES (n=1,028) in Europe (PLATINUM PLUS trial). The primary endpoint was target vessel failure (TVF) at 12 months, a composite of target vessel-related cardiac death, myocardial infarction (MI), and ischaemia-driven target vessel revascularisation (TVR). Among 2,980 patients, 33% presented with acute coronary syndromes, and 48% with multivessel disease. At 12 months, the intention-to-treat analysis determined that the platinum-chromium EES was non-inferior to the cobalt-chromium EES for the primary endpoint (86 [4.6%] patients vs. 32 [3.2%], absolute difference 1.4%, 95% confidence interval [CI]: -0.1-2.9; upper limit of the one-sided 95% CI: 2.57%; non-inferiority p=0.012; superiority analysis: hazard ratio [HR] 1.44, 95% CI: 0.96-2.16, p=0.08). In the per protocol analysis, however, the primary endpoint was significantly more common in the platinum-chromium EES (HR 1.64, 95% CI: 1.05-2.55, p=0.03). There were no significant differences in the rates of cardiac death (1.1% vs. 1.0%, p=0.78), MI (1.6% vs. 0.8%, p=0.09), or ischaemia-driven TLR (2.0% vs. 1.6%, p=0.49). The rates of ARC definite or probable stent thrombosis were comparable between platforms (0.8% vs. 0.5%, p=0.44). At one year, the platinum-chromium EES satisfied the pre-specified criteria for non-inferiority relative to the control cobalt-chromium EES in this all-comers trial.

Platinum-Based Chemotherapy Induces Methylation Changes in Blood DNA Associated with Overall Survival in Patients with Ovarian Cancer.

PubMed

Flanagan, James M; Wilson, Angela; Koo, Chail; Masrour, Nahal; Gallon, John; Loomis, Erick; Flower, Kirsty; Wilhelm-Benartzi, Charlotte; Hergovich, Alexander; Cunnea, Paula; Gabra, Hani; Braicu, Elena Ioana; Sehouli, Jalid; Darb-Esfahani, Silvia; Vanderstichele, Adriaan; Vergote, Ignace; Kreuzinger, Caroline; Castillo-Tong, Dan Cacsire; Wisman, G Bea A; Berns, Els Mjj; Siddiqui, Nadeem; Paul, James; Brown, Robert

2017-05-01

Purpose: DNA damage repair can lead to epigenetic changes. DNA mismatch repair proteins bind to platinum DNA adducts and at sites of DNA damage can recruit the DNA methylating enzyme DNMT1, resulting in aberrant methylation. We hypothesised that DNA damage repair during platinum-based chemotherapy may cause aberrant DNA methylation in normal tissues of patients such as blood. Experimental Design: We used Illumina 450k methylation arrays and bisulphite pyrosequencing to investigate methylation at presentation and relapse in blood DNA from patients with ovarian cancer enrolled in the SCOTROC1 trial ( n = 247) and in a cohort of ovarian tumor DNA samples collected at first relapse ( n = 46). We used an ovarian cancer cell line model to investigate the role of the DNA mismatch repair gene MLH1 in platinum-induced methylation changes. Results: Specific CpG methylation changes in blood at relapse are observed following platinum-based chemotherapy and are associated with patient survival, independent of other clinical factors [hazard ratio, 3.7; 95% confidence interval, 1.8-7.6, P = 2.8 × 10 -4 ]. Similar changes occur in ovarian tumors at relapse, also associated with patient survival (hazard ratio, 2.6; 95% confidence interval, 1.0-6.8, P = 0.048). Using an ovarian cancer cell line model, we demonstrate that functional mismatch repair increases the frequency of platinum-induced methylation. Conclusions: DNA methylation in blood at relapse following chemotherapy, and not at presentation, is informative regarding survival of patients with ovarian cancer. Functional DNA mismatch repair increases the frequency of DNA methylation changes induced by platinum. DNA methylation in blood following chemotherapy could provide a noninvasive means of monitoring patients' epigenetic responses to treatment without requiring a tumor biopsy. Clin Cancer Res; 23(9); 2213-22. ©2016 AACR . ©2016 American Association for Cancer Research.

Platinum and lead markers as indicators of transportation impact.

DOT National Transportation Integrated Search

2009-08-20

The intent of this study was to provide information necessary to characterize the present concentrations of an emerging transportation related contaminant, the platinum group metals (PGM), and to provide background information necessary to explore th...

45 CFR 800.107 - Levels of coverage.

Code of Federal Regulations, 2014 CFR

2014-10-01

... to offer an MSP pursuant to a contract with OPM. (b) Bronze or platinum metal levels of coverage... coverage or the platinum level of coverage, or both, on any Exchange or SHOP in any State. (c) Child-only...

45 CFR 800.107 - Levels of coverage.

Code of Federal Regulations, 2013 CFR

2013-10-01

... to offer an MSP pursuant to a contract with OPM. (b) Bronze or platinum metal levels of coverage... coverage or the platinum level of coverage, or both, on any Exchange or SHOP in any State. (c) Child-only...

76 FR 61102 - Formations of, Acquisitions by, and Mergers of Bank Holding Companies

Federal Register 2010, 2011, 2012, 2013, 2014

2011-10-03

... Vice President) 1000 Peachtree Street, NE., Atlanta, Georgia 30309: 1. Platinum Bank Holding Company, to become a bank holding company by acquiring 100 percent of the voting shares of Platinum Bank, both...

77 FR 20022 - Formations of, Acquisitions by, and Mergers of Bank Holding Companies

Federal Register 2010, 2011, 2012, 2013, 2014

2012-04-03

... President) 1000 Peachtree Street NE., Atlanta, Georgia 30309: 1. Platinum Bank Holding Company, Brandon, Florida; to become a bank holding company by acquiring 100 percent of the voting shares of Platinum Bank...

76 FR 24884 - Formations of, Acquisitions by, and Mergers of Bank Holding Companies

Federal Register 2010, 2011, 2012, 2013, 2014

2011-05-03

... Worthy, Vice President) 2200 North Pearl Street, Dallas, Texas 75201-2272: 1. Platinum Bancshares of... shares of Platinum Bank, Lubbock, Texas. Board of Governors of the Federal Reserve System, April 28, 2011...

MEIOTIC BEHAVIOR OF PLATINUM-INDUCED ANEUPLOIDS IN PEARL MILLET

EPA Science Inventory

Cytotoxicity, measured by seed germination and seedling survival, and the clastogenic potential of platinum diaminodinitrodichloride were evaluated in pear millet (Pennisetum americanum (k) Schum). The study was conducted under controlled climatic conditions. Presoaked seed of pe...

New electrocatalysts for hydrogen-oxygen fuel cells

NASA Technical Reports Server (NTRS)

Cattabriga, R. A.; Giner, J.; Parry, J.; Swette, L. L.

1970-01-01

Platinum-silver, palladium-gold, and platinum-gold alloys serve as oxygen reduction catalysts in high-current-density cells. Catalysts were tested on polytetrafluoroethylene-bonded cathodes and a hydrogen anode at an operating cell temperature of 80 degrees C.

Nanoparticles based fiber optic SPR sensor

NASA Astrophysics Data System (ADS)

Shah, Kruti; Sharma, Navneet K.

2018-05-01

Localized surface plasmon resonance based fiber optic sensor using platinum nanoparticles is proposed and theoretically analyzed. Increase in thickness of nanoparticles layer increases the sensitivity of sensor. 50 nm thick platinum nanoparticles layer based sensor reveals highest sensitivity.

Friction behavior of members of the platinum metals group with gold

NASA Technical Reports Server (NTRS)

Buckley, D. H.

1975-01-01

The adhesion and friction behavior of the platinum metals group was examined with clean surfaces and surfaces selectively contaminated with oxygen, vinyl chloride (C2H3Cl), and methyl mercaptan (CH3SH). A pin or disk specimen configuration was used with the pin being a single crystal of gold of the (111) orientation and with the platinum metal disks also being single crystals of the (111) or (0001) orientation. Loads applied ranged from 1 to 10 g and a sliding velocity of 0.7 mm/min was employed. Results indicate adhesion and transfer of gold to all of the platinum metals. Despite this observation friction differences existed among the metals in the group. These differences are related to surface chemical activity. Adsorption of various friction reducing species was selective. With some adsorbates present strong adhesive forces between metals were still observed.

Alkali metal-refractory metal biphase electrode for AMTEC

NASA Technical Reports Server (NTRS)

Williams, Roger M. (Inventor); Bankston, Clyde P. (Inventor); Cole, Terry (Inventor); Khanna, Satish K. (Inventor); Jeffries-Nakamura, Barbara (Inventor); Wheeler, Bob L. (Inventor)

1989-01-01

An electrode having increased output with slower degradation is formed of a film applied to a beta-alumina solid electrolyte (BASE). The film comprises a refractory first metal M.sup.1 such as a platinum group metal, suitably platinum or rhodium, capable of forming a liquid or a strong surface adsorption phase with sodium at the operating temperature of an alkali metal thermoelectric converter (AMTEC) and a second refractory metal insoluble in sodium or the NaM.sup.1 liquid phase such as a Group IVB, VB or VIB metal, suitably tungsten, molybdenum, tantalum or niobium. The liquid phase or surface film provides fast transport through the electrode while the insoluble refractory metal provides a structural matrix for the electrode during operation. A trilayer structure that is stable and not subject to deadhesion comprises a first, thin layer of tungsten, an intermediate co-deposited layer of tungsten-platinum and a thin surface layer of platinum.

Say No to DMSO: Dimethylsulfoxide Inactivates Cisplatin, Carboplatin and Other Platinum Complexes

PubMed Central

Hall, Matthew D.; Telma, Katherine A.; Chang, Ki-Eun; Lee, Tobie D.; Madigan, James P.; Lloyd, John R.; Goldlust, Ian S.; Hoeschele, James D.; Gottesman, Michael M.

2014-01-01

The platinum drugs cisplatin, carboplatin and oxaliplatin are highly utilized in the clinic and as a consequence are extensively studied in the laboratory setting. In this study, we examined the literature and found a significant number of studies (11 - 34%) in prominent cancer journals utilizing cisplatin dissolved in dimethylsulfoxide (DMSO). However, dissolving cisplatin in DMSO for laboratory-based studies results in ligand displacement and changes the structure of the complex. We examined the effect of DMSO on platinum complexes, including cisplatin, carboplatin and oxaliplatin, finding that DMSO reacted with the complexes, inhibited their cytotoxicity and their ability to initiate cell death. These results render a substantial portion of the literature on cisplatin uninterpretable. Raising awareness of this significant issue in the cancer biology community is critical, and we make recommendations on appropriate solvation of platinum drugs for research. PMID:24812268

Electrical neurostimulation with imbalanced waveform mitigates dissolution of platinum electrodes

PubMed Central

Kumsa, Doe; Hudak, Eric M; Montague, Fred W; Kelley, Shawn C; Untereker, Darrel F; Hahn, Benjamin P; Condit, Chris; Cholette, Martin; Lee, Hyowon; Bardot, Dawn; Takmakov, Pavel

2017-01-01

Objective Electrical neurostimulation has traditionally been limited to the use of charge-balanced waveforms. Charge-imbalanced and monophasic waveforms are not used to deliver clinical therapy, because it is believed that these stimulation paradigms may generate noxious electrochemical species that cause tissue damage. Approach In this study, we investigated the dissolution of platinum as one of such irreversible reactions over a range of charge densities up to 160 µC cm−2 with current-controlled first phase, capacitive discharge second phase waveforms of both cathodic-first and anodic-first polarity. We monitored the concentration of platinum in solution under different stimulation delivery conditions including charge-balanced, charge-imbalanced, and monophasic pulses. Main results We observed that platinum dissolution decreased during charge-imbalanced and monophasic stimulation when compared to charge-balanced waveforms. Significance This observation provides an opportunity to re-evaluate the charge-balanced waveform as the primary option for sustainable neural stimulation. PMID:27650936

Preparation and evaluation of advanced electrocatalysts for phosphoric acid fuel cells

NASA Technical Reports Server (NTRS)

Stonehart, P.; Baris, J.; Pagliaro, P.

1980-01-01

Results are presented for hydrogen oxidation and hydrogen oxidation poisoned by carbon monoxide at levels between 0 and 30%. Due to the high activities that are now being observed for our platinum based electrocatalysts, the hydrogen concentrations were reduced to 10% levels in the gas supplies. Perturbation techniques were used to determine that a mechanism for the efficient operation of our porous gas diffusion electrodes is diffusion of the carbon monoxide out of the electrode structure through the electrolyte film on the electro-catalyst. A survey of the literature on platinum group materials (PGM) was carried out so that an identification of successful electrocatalysts could be made. Two PGM electrocatalysts were prepared and performance data for hydrogen oxidation in hot phosphoric acid in the presence of high carbon monoxide concentrations showed that they matched the best platinum on carbon electrocatalysts but with an electrocatalyst cost that was half of the platinum catalyst cost.

Photoresponsive peptide azobenzene conjugates that specifically interact with platinum surfaces

NASA Astrophysics Data System (ADS)

Dinçer, S.; Tamerler, C.; Sarıkaya, M.; Pişkin, E.

2008-05-01

The aim of this study is to prepare photoresponsive peptide-azobenzene compounds which interacts with platinum surfaces specifically, in order to create smart surfaces for further novel applications in design of smart biosensors and array platforms. Here, a water-soluble azobenzene molecule, 4-hydroxyazo benzene,4-sulfonic acid was synthesized by diazo coupling reaction. A platinum-specific peptide, originally selected by a phage display technique was chemically synthesized/purchased, and conjugated with the azobenzene compound activated with carbonyldiimidazole. Both azobenzene and its conjugate were characterized (including photoresponsive properties) by FTIR, NMR, and UV-spectrophotometer. The yield of conjugation reaction estimated by ninhydrin assay was about 65%. Peptide incorporation did not restrict the light-sensitivity of azobenzene. Adsorption of both the peptide and its azobenzene conjugate was followed by Quartz Crystal Microbalance (QCM) system. The kinetic evaluations exhibited that both molecules interact platinum surfaces, quite rapidly and strongly.

Radio- and photosensitization of DNA with compounds containing platinum and bromine atoms

NASA Astrophysics Data System (ADS)

Śmiałek, Małgorzata A.; Ptasińska, Sylwia; Gow, Jason; Vrønning Hoffmann, Søren; Mason, Nigel J.

2015-05-01

Irradiations of plasmid DNA by both X-rays and UV light in the presence and absence of compounds containing platinum and bromine atoms were performed in order to asses the sensitization potential of these compounds. Plasmid DNA pBR322 was incubated with platinum (II) bromide, hydrogen hexabromoplatinate (IV), hydrogen hexahydroxyplatinate (IV) and sodium hexahydroxyplatinate (IV). Incubation was followed by X-ray or UV irradiations. It was found that amongst the sensitizers tested, during irradiations carried out in the presence of platinum (II) bromide, the highest levels of double strand breaks formation upon X-ray treatment were recorded. In contrast much less damage was induced by UV light. Data presented here suggests that this compound may be a promising radiosensitizer for cancer treatment. Contribution to the Topical Issue "COST Action Nano-IBCT: Nano-scale Processes Behind Ion-Beam Cancer Therapy", edited by Andrey Solov'yov, Nigel Mason, Gustavo García, Eugene Surdutovich.

In Situ Biosynthesis of Fluorescent Platinum Nanoclusters: Toward Self-Bioimaging-Guided Cancer Theranostics.

PubMed

Chen, Donghua; Zhao, Chunqiu; Ye, Jing; Li, Qiwei; Liu, Xiaoli; Su, Meina; Jiang, Hui; Amatore, Christian; Selke, Matthias; Wang, Xuemei

2015-08-19

Among the noble-metal clusters, very few reports about platinum clusters were used as bioimaging probes of tumors except as a reducing catalyst. It is first established herein that the biocompatible platinum nanoclusters are spontaneously biosynthesized by cancerous cells (i.e., HepG2 (human hepatocarcinoma), A549 (lung cancer), and others) rather than noncancerous cells (i.e., L02 (human embryo liver cells)) when incubated with micromolar chloroplatinic acid solutions. These in situ biosynthesized platinum nanoclusters could be readily realized in a biological environment and emit a bright fluorescence at 460 nm, which could be further utilized to facilitate an excellent cancer-cell-killing efficiency when combined with porphyrin derivatives for photothermal treatment. This raises the possibility of providing a promising and precise bioimaging strategy for specific fluorescent self-biomarking of tumor locations and realizing fluorescence imaging-guided photothermal therapy of tumors.

Recent advances in solid polymer electrolyte fuel cell technology with low platinum loading electrodes

NASA Technical Reports Server (NTRS)

Srinivasan, Supramaniam; Manko, David J.; Koch, Hermann; Enayetullah, Mohammad A.; Appleby, A. John

1989-01-01

Of all the fuel cell systems only alkaline and solid polymer electrolyte fuel cells are capable of achieving high power densities (greater than 1 W/sq cm) required for terrestrial and extraterrestrial applications. Electrode kinetic criteria for attaining such high power densities are discussed. Attainment of high power densities in solid polymer electrolyte fuel cells has been demonstrated earlier by different groups using high platinum loading electrodes (4 mg/sq cm). Recent works at Los Alamos National Laboratory and at Texas A and M University (TAMU) demonstrated similar performance for solid polymer electrolyte fuel cells with ten times lower platinum loading (0.45 mg/sq cm) in the electrodes. Some of the results obtained are discussed in terms of the effects of type and thickness of membrane and of the methods platinum localization in the electrodes on the performance of a single cell.

Dissolution of Platinum in the Operational Range of Fuel Cells

PubMed Central

Keeley, Gareth P.; Geiger, Simon; Zeradjanin, Aleksandar R.; Hodnik, Nejc; Kulyk, Nadiia

2015-01-01

Abstract One of the most important practical issues in low‐temperature fuel‐cell catalyst degradation is platinum dissolution. According to the literature, it initiates at 0.6–0.9 VRHE, whereas previous time‐ and potential‐resolved inductively coupled plasma mass spectrometry (ICP–MS) experiments, however, revealed dissolution onset at only 1.05 VRHE. In this manuscript, the apparent discrepancy is addressed by investigating bulk and nanoparticulated catalysts. It is shown that, given enough time for accumulation, traces of platinum can be detected at potentials as low as 0.85 VRHE. At these low potentials, anodic dissolution is the dominant process, whereas, at more positive potentials, more platinum dissolves during the oxide reduction after accumulation. Interestingly, the potential and time dissolution dependence is similar for both types of electrode. Dissolution processes are discussed with relevance to fuel‐cell operation and plausible dissolution mechanisms are considered. PMID:27525206

Statistical Simulation of the Performance and Degradation of a PEMFC Membrane Electrode Assembly

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harvey, David; Bellemare-Davis, Alexander; Karan, Kunal

2012-07-01

A 1-D MEA Performance model was developed that considered transport of liquid water, agglomerate catalyst structure, and the statistical variation of the MEA characteristic parameters. The model was validated against a low surface area carbon supported catalyst across various platinum loadings and operational conditions. The statistical variation was found to play a significant role in creating noise in the validation data and that there was a coupling effect between movement in material properties with liquid water transport. Further, in studying the low platinum loaded catalyst layers it was found that liquid water played a significant role in the increasing themore » overall transport losses. The model was then further applied to study platinum dissolution via potential cycling accelerated stress tests, in which the platinum was found to dissolve nearest the membrane effectively resulting in reaction distribution shifts within the layer.« less

Precise tuning in platinum-nickel/nickel sulfide interface nanowires for synergistic hydrogen evolution catalysis

PubMed Central

Wang, Pengtang; Zhang, Xu; Zhang, Jin; Wan, Sheng; Guo, Shaojun; Lu, Gang; Yao, Jianlin; Huang, Xiaoqing

2017-01-01

Comprising abundant interfaces, multicomponent heterostructures can integrate distinct building blocks into single entities and yield exceptional functionalities enabled by the synergistic components. Here we report an efficient approach to construct one-dimensional metal/sulfide heterostructures by directly sulfuring highly composition-segregated platinum-nickel nanowires. The heterostructures possess a high density of interfaces between platinum-nickel and nickel sulfide components, which cooperate synergistically towards alkaline hydrogen evolution reaction. The platinum-nickel/nickel sulfide heterostructures can deliver a current density of 37.2 mA cm−2 at an overpotential of 70 mV, which is 9.7 times higher than that of commercial Pt/C. The heterostructures also offer enhanced stability revealed by long-term chronopotentiometry measurements. The present work highlights a potentially powerful interface-engineering strategy for designing multicomponent heterostructures with advanced performance in hydrogen evolution reaction and beyond. PMID:28239145

Recognizing Single Collisions of PtCl6(2-) at Femtomolar Concentrations on Ultramicroelectrodes by Nucleating Electrocatalytic Clusters.

PubMed

Dick, Jeffrey E; Bard, Allen J

2015-11-04

We report the electrodeposition of electrocatalytic clusters of platinum from femtomolar platinate solutions. An inert carbon fiber ultramicroelectrode (UME) was held at a potential where proton reduction was unfavorable on carbon but favorable on platinum in a 1 M sulfuric acid solution. Upon addition of femtomolar amounts of hexachloroplatinic acid, which will also reduce to Pt(0) at the applied potential on the carbon fiber UME, cathodic blips were observed in the amperometric i-t response. These blips correspond to the reduction of protons to molecular hydrogen at the small platinum clusters followed by a rapid deactivation likely due to hydrogen bubble formation. On average, these current spikes occur when five platinum atoms have been formed on the electrode, as determined by a comparative analysis of experimental cathodic blips and calculated hexachloroplatinate molecule collision frequencies.

Structural superlubricity of platinum on graphite under ambient conditions: The effects of chemistry and geometry

NASA Astrophysics Data System (ADS)

Özoǧul, Alper; Ipek, Semran; Durgun, Engin; Baykara, Mehmet Z.

2017-11-01

An investigation of the frictional behavior of platinum nanoparticles laterally manipulated on graphite has been conducted to answer the question of whether the recent observation of structural superlubricity under ambient conditions [E. Cihan, S. İpek, E. Durgun, and M. Z. Baykara, Nat. Commun. 7, 12055 (2016)] is exclusively limited to the gold-graphite interface. Platinum nanoparticles have been prepared by e-beam evaporation of a thin film of platinum on graphite, followed by post-deposition annealing. Morphological and structural characterization of the nanoparticles has been performed via scanning electron microscopy and transmission electron microscopy, revealing a crystalline structure with no evidence of oxidation under ambient conditions. Lateral manipulation experiments have been performed via atomic force microscopy under ambient conditions, whereby results indicate the occurrence of structural superlubricity at mesoscopic interfaces of 4000-75 000 nm2, with a noticeably higher magnitude of friction forces when compared with gold nanoparticles of similar contact areas situated on graphite. Ab initio simulations of sliding involving platinum and gold slabs on graphite confirm the experimental observations, whereby the higher magnitude of friction forces is attributed to stronger energy barriers encountered by platinum atoms sliding on graphite, when compared with gold. On the other hand, as predicted by theory, the scaling power between friction force and contact size is found to be independent of the chemical identity of the sliding atoms, but to be determined by the geometric qualities of the interface, as characterized by an average "sharpness score" assigned to the nanoparticles.

Study on the occurrence of platinum in Xinjie CuNi sulfide deposits by a combination of SPM and NAA

NASA Astrophysics Data System (ADS)

Li, Xiaolin; Zhu, Jieqing; Lu, Rongrong; Gu, Yingmei; Wu, Xiankang; Chen, Youhong

1997-07-01

A combination of neutron-activation analysis (NAA) and scanning proton microprobe (SPM) was used to study the distribution of platinum-group elements (PGEs) in rocks and ores from Xinjie CuNi deposit. The minimum detection limits of PGEs by NAA had been much improved by means of a nickel-sulfide fire-assay technique for pre-concentration of PGEs in the ore samples. A simple and effective method was developed for true element mapping in SPM experiments. A pair of moveable absorption filters was set up in the target chamber for high sensitivities of both major and trace elements. The bulk analysis results by NNA indicated that the PGE mineralization occurred at the base of Xinjie layered intrusion in clinopyroxenite rocks and the CuNi sulfide minerals disseminated within the rocks had high abundance level of PGEs. However, the micro-PIXE analysis of the CuNi sulfide mineral grains did not find PGEs above the MDL of 6-9 ppm for Rh, Ru and Pd, and 60 ppm for Pt. The search for platinum occurrence in sulfide minerals was followed by scanning analysis of SPM when some smaller platinum enriched grains were found in the sulfide minerals. The microscopic analysis results suggested that platinum occurred in the CuNi sulfide matrix as independent arsenide mineral grains. The chemical formula of the arsenide sperrylite was PtAs 2. The information of the platinum occurrence was helpful to future mineralogical research and mineral processing and beneficiation of the CuNi deposit.

Management of hypersensitivity to platinum- and taxane-based chemotherapy: cepo review and clinical recommendations

PubMed Central

Boulanger, J.; Boursiquot, J.N.; Cournoyer, G.; Lemieux, J.; Masse, M.S.; Almanric, K.; Guay, M.P.

2014-01-01

Background Although antineoplastic agents are critical in the treatment of cancer, they can potentially cause hypersensitivity reactions that can have serious consequences. When such a reaction occurs, clinicians can either continue the treatment, at the risk of causing a severe or a potentially fatal anaphylactic reaction, or stop the treatment, although it might be the only one available. The objective of the present work was to evaluate the effectiveness of methods used to prevent and treat hypersensitivity reactions to platinum- or taxane-based chemotherapy and to develop evidence-based recommendations. Methods The scientific literature published to December 2013, inclusive, was reviewed. Results Premedication with antihistamines, H2 blockers, and corticosteroids is not effective in preventing hypersensitivity reactions to platinum salts. However, premedication significantly reduces the incidence of hypersensitivity to taxanes. A skin test can generally be performed to screen for patients at risk of developing a severe reaction to platinum salts in the presence of grade 1 or 2 reactions, but skin testing does not appear to be useful for taxanes. A desensitization protocol allows for re-administration of either platinum- or taxane-based chemotherapy to some patients without causing severe hypersensitivity reactions. Conclusions Several strategies such as premedication, skin testing, and desensitization protocols are available to potentially allow for administration of platinum- or taxane-based chemotherapy to patients who have had a hypersensitivity reaction and for whom no other treatment options are available. Considering the available evidence, the Comité de l’évolution des pratiques en oncologie made recommendations for clinical practice in Quebec. PMID:25089112

Catalytic Activity of Platinum Monolayer on Iridium and Rhenium Alloy Nanoparticles for the Oxygen Reduction Reaction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Karan, Hiroko I.; Sasaki, Kotaro; Kuttiyiel, Kurian

2012-05-04

A new type of electrocatalyst with a core–shell structure that consists of a platinum monolayer shell placed on an iridium–rhenium nanoparticle core or platinum and palladium bilayer shell deposited on that core has been prepared and tested for electrocatalytic activity for the oxygen reduction reaction. Carbon-supported iridium–rhenium alloy nanoparticles with several different molar ratios of Ir to Re were prepared by reducing metal chlorides dispersed on Vulcan carbon with hydrogen gas at 400 °C for 1 h. These catalysts showed specific electrocatalytic activity for oxygen reduction reaction comparable to that of platinum. The activities of Pt ML/Pd ML/Ir 2Re 1,more » Pt ML/Pd 2layers/Ir 2Re 1, and Pt ML/Pd 2layers/Ir 7Re 3 catalysts were, in fact, better than that of conventional platinum electrocatalysts, and their mass activities exceeded the 2015 DOE target. Our density functional theory calculations revealed that the molar ratio of Ir to Re affects the binding strength of adsorbed OH and, thereby, the O 2 reduction activity of the catalysts. The maximum specific activity was found for an intermediate OH binding energy with the corresponding catalyst on the top of the volcano plot. The monolayer concept facilitates the use of much less platinum than in other approaches. Finally, the results with the Pt ML/Pd ML/Ir 2Re electrocatalyst indicate that it is a promising alternative to conventional Pt electrocatalysts in low-temperature fuel cells.« less

Investigation into Spectroscopic Techniques for Thermal Barrier Coating Spall Detection

NASA Technical Reports Server (NTRS)

deGroot, Wim; Opila, Beth

2001-01-01

Spectroscopic methods are proposed for detection of thermal barrier coating (TBC) spallation from engine hot zone components. These methods include absorption and emission of airborne marker species originally embedded in the TBC bond coat. In this study, candidate marker materials for this application were evaluated. Thermochemical analysis of candidate marker materials combined with additional constraints such as toxicity and uniqueness to engine environment, provided a short list of four potential species: platinum, copper oxide, zinc oxide. and indium. The melting point of indium was considered to be too low for serious consideration. The other three candidate marker materials, platinum, copper oxide, and zinc oxide were placed in a high temperature furnace and emission and absorption properties were measured over a temperature range from 800-1400 C and a spectral range from 250 to 18000 nm. Platinum did not provide the desired response, likely due to the low vapor Pressure of the metallic species and the low absorption of the oxide species. It was also found, however. that platinum caused a broadening of the carbon dioxide absorption at 4300 nm. The nature of this effect is not known. Absorption and emission caused by sodium and potassium impurities in the platinum were found in the platinum tests. Zinc oxide did not provide the desired response, again, most likely due to the low vapor pressure of the metallic species and the low absorption of the oxide species. Copper oxide generated two strongly temperature dependent absorption peaks at 324.8 and 327.4 nm. The melting point of copper oxide was determined to be too low for serious consideration as marker material.

78 FR 60269 - Combined Notice of Filings #1

Federal Register 2010, 2011, 2012, 2013, 2014

2013-10-01

.... Comments Due: 5 p.m. ET 10/15/13. Docket Numbers: ER13-2436-000. Applicants: Platinum Energy, LLC. Description: Platinum Energy, LLC Market Based Rate Tariff to be effective 10/15/2013. Filed Date: 9/24/13...

Skin Sensitizing Potency of Halogenated Platinum Salts.

EPA Science Inventory

The relationship between occupational exposure to halogenated platinum (Pt) salts and Pt-specific allergic sensitization is well-established. Although human case reports and clinical studies demonstrate that Pt salts are potent skin sensitizers, no studies have been published tha...

PKC-alpha modulation by miR-483-3p in platinum-resistant ovarian carcinoma cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arrighetti, Noemi, E-mail: Noemi.Arrighetti@istitu

The occurrence of drug resistance limits the efficacy of platinum compounds in the cure of ovarian carcinoma. Since microRNAs (miRNAs) may contribute to this phenomenon by regulating different aspects of tumor cell response, the aim of this study was to exploit the analysis of expression of miRNAs in platinum sensitive/resistant cells in an attempt to identify potential regulators of drug response. MiR-483-3p, which may participate in apoptosis and cell proliferation regulation, was found up-regulated in 4 platinum resistant variants, particularly in the IGROV-1/Pt1 subline, versus parental cells. Transfection of a synthetic precursor of miR-483-3p in IGROV-1 parental cells elicited amore » marked up-regulation of the miRNA levels. Growth-inhibition and colony-forming assays indicated that miR-483-3p over-expression reduced cell growth and conferred mild levels of cisplatin resistance in IGROV-1 cells, by interference with their proliferative potential. Predicted targets of miR-483-3p included PRKCA (encoding PKC-alpha), previously reported to be associated to platinum-resistance in ovarian carcinoma. We found that miR-483-3p directly targeted PRKCA in IGROV-1 cells. In keeping with this finding, cisplatin sensitivity of IGROV-1 cells decreased upon molecular/pharmacological inhibition of PKC-alpha. Overall, our results suggest that overexpression of miR-483-3p by ovarian carcinoma platinum-resistant cells may interfere with their proliferation, thus protecting them from DNA damage induced by platinum compounds and ultimately representing a drug-resistance mechanism. The impairment of cell growth may account for low levels of drug resistance that could be relevant in the clinical setting. - Highlights: • miR-483-3p is up-regulated in ovarian carcinoma cells resistant to platinum drugs. • Ectopic expression of miR-483-3p in IGROV-1 confers mild levels of Pt-resistance. • Overexpression of miR-483-3p down-regulates PRKCA levels in ovarian carcinoma cells. • miR 483–3p directly targets PRKCA 3′UTR in IGROV-1 cells. • The contribution of miR-483-3p to Pt-resistance is related to cell proliferation.« less

Prognostic and predictive effects of primary versus secondary platinum resistance for bevacizumab treatment for platinum-resistant ovarian cancer in the AURELIA trial.

PubMed

Trillsch, F; Mahner, S; Hilpert, F; Davies, L; García-Martínez, E; Kristensen, G; Savarese, A; Vuylsteke, P; Los, M; Zagouri, F; Gladieff, L; Sehouli, J; Khoon Lee, C; Gebski, V; Pujade-Lauraine, E

2016-09-01

Progression-free survival (PFS), objective response rate (ORR), and patient-reported outcomes (PROs) were significantly improved by adding bevacizumab to chemotherapy for platinum-resistant ovarian cancer (PROC) in the phase III AURELIA trial. We explored treatment outcomes according to primary platinum resistance (PPR) versus secondary platinum resistance (SPR). Patients were categorized as PPR (disease progression <6 months after completing first-line platinum therapy) or SPR (progression ≥6 months after first platinum but <6 months after second). The exploratory Cox and logistic regression analyses correlated PFS, ORR, overall survival (OS), and PROs with the time to development of platinum resistance. Baseline characteristics were similar in patients with PPR (n = 262; 73%) and SPR (n = 99; 27%), although ascites were more common in the PPR subgroup. In bevacizumab-treated patients (n = 179), SPR was associated with improved PFS (median 10.2 versus 5.6 months in PPR patients; P < 0.001) and OS (median 22.2 versus 13.7 months, respectively; P < 0.001) but not PROs (22% versus 22% with improved abdominal/gastrointestinal symptoms at week 8/9). In multivariate analyses, SPR remained an independent prognostic factor for better PFS [adjusted hazard ratio (HR) 0.41, 95% confidence interval (CI) 0.25-0.67; P < 0.001] and OS (HR 0.49, 95% CI 0.30-0.80; P = 0.005) in bevacizumab-treated patients, but was not statistically significant for either end point in the chemotherapy-alone subgroup. The magnitude of PFS benefit from bevacizumab appeared greater in SPR than PPR patients (HR 0.30 versus 0.55, respectively; interaction P = 0.07) with a similar direction of effect for OS (interaction P = 0.18). In bevacizumab-treated patients, PFS and OS were more favorable in SPR than PPR patients with equally improved PROs. The PFS and OS benefit from combining bevacizumab with chemotherapy was more pronounced in SPR than PPR PROC. PPR versus SPR should be a stratification factor in future trials evaluating anti-angiogenic therapy for PROC. © The Author 2016. Published by Oxford University Press on behalf of the European Society for Medical Oncology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

[Pharmacokinetic properties of platinium derivatives].

PubMed

Boisdron-Celle, M; Lebouil, A; Allain, P; Gamelin, E

2001-08-01

The three platinum derivatives currently available share many pharmacokinetic and pharmacodynamic (PK-PD) properties but present also some distinct characteristics, due to their structural differences. They result in different systemic PK-PD and metabolic behaviour and toxicity profile. Oxaliplatin is quickly transformed into dach-platinum, the active metabolite, by loosing oxalate chain. Eighty to eighty-eight per cent of platinum are bound to proteins, as for cisplatin, whereas carboplatin is less reactive. Cisplatin and oxaliplatin active metabolites, i.e. monoaquo platin and dach-platin quickly react with small proteins with sulfhydryl groups, such as glutathione, cysteine and methionine, and then with high molecular weight proteins, such as albumin and gammaglobulins through covalent link. Thus, their terminal half lives are long, about ten days, but no platinum accumulation has been reported in plasma with oxaliplatin, whereas after cisplatin administration, both total and ultrafiltrable platinum progressively accumulate in plasma. This difference may play a role in the lack of oxaliplatin nephrotoxicity and its more delayed and reversible neurotoxicity. On the other hand, carboplatin is more stable, less bound to proteins and is largely excreted inchanged in urine. This can explain that it passes more easily through the blood brain barrier. Erythrocytes represent an important deep compartment, especially for oxaliplatin, a little bit less for cisplatin. Oxaliplatin is trapped in erythrocytes through a covalent binding to globin. There, its half life is identical to that of erythrocytes. According to certain authors, this trapping would be involved in the incidence of anemia. On the contrary, carboplatin is quickly extruded from erythrocytes. The three derivatives kinetics in plasma present a wide interindividual variability, resulting in differences in term of toxicity and efficacy. For the three of them, plasma clearance is correlated to creatinine clearance, but only carboplatin dosage can be individually adjusted, based on creatinine clearance measurement, thanks to its simple renal excretion, due to exclusive glomerular filtration, and after Calvert's, Egorin's and Chatelut's population kinetics studies. Cisplatin renal excretion is more complex, combining reabsorption and secretion processes. Therefore, individual dosage adjustment needs platinum concentration measurement in plasma, but there is no general agreement on the platinum species to measure, ultrafiltrable or bound. Oxaliplatin is too recent in clinical practice and still lacks of PK-PD data. These characteristics can help us for a better knowledge of the three platinum derivatives clinical properties, both in term of kinetics, behaviour and toxicity.

Progress in catalytic ignition fabrication and modeling : fabrication part 2.

DOT National Transportation Integrated Search

2012-06-01

The ignition temperature and heat generation from oxidation of methane on a platinum catalyst were : determined experimentally. A 127 micron diameter platinum coiled wire was placed crosswise in a : quartz tube of a plug flow reactor. A source meter ...

DETERMINATION OF GOLD, PLATINUM AND PALLADIUM IN BELGIAN CONGO ORES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Crowther, A.B. et al.

1955-01-31

A survey of analytical methods for determination of gold, platinum, and palladium in urauium ore is presented. A fire assay method to obtain a silver load in which the other elements are determined appears feasible. (J.R.D.)

Method for converting UF5 to UF4 in a molten fluoride salt

DOEpatents

Bennett, Melvin R.; Bamberger, Carlos E.; Kelmers, A. Donald

1977-01-01

The reduction of UF.sub.5 to UF.sub.4 in a molten fluoride salt by sparging with hydrogen is catalyzed by metallic platinum. The reaction is also catalyzed by platinum alloyed with gold reaction equipment.

40 CFR 421.261 - Specialized definitions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... apply to this subpart. (b) The term precious metals shall mean gold, platinum, palladium, rhodium, iridium, osmium, and ruthenium. (c) The term Combined Metals, shall mean the total of gold, platinum and... AND STANDARDS NONFERROUS METALS MANUFACTURING POINT SOURCE CATEGORY Secondary Precious Metals...

Platinum Eta 2 -Disilene Complexes: Syntheses, Reactivity, and Structures

DTIC Science & Technology

1990-01-01

CP ýsq:.Prl 25 C. 7 x, ’ .P’ NSi-...H Reaction of R 2Si(H)Si(H)R.2 with Pt Complexes. PI Ih t~ Oxidative additions of monomeric silanes to platinumPhh2...thermally to product I1 2-complexes 2a,b. The reaction of tetrasubstituted 1,2-dihydridodisi- lanes (R2SiH)2 with bis(phosphine);laitinum equivalents...e.g. (diphos)PtCl2 /Li or (diphos)-. Pt(CH2 -CH2) also yielded platinum ’? 2=disilene complexes f6a (R -i-Pr), Qb (R-He), and kc (R- Ph). Reaction of

Carbon monoxide tolerant electrocatalyst with low platinum loading and a process for its preparation

DOEpatents

Adzic, Radoslav; Brankovic, Stanko; Wang, Jia

2003-12-30

An electrocatalyst is provided for use in a fuel cell that has low platinum loading and a high tolerance to carbon monoxide poisoning. The fuel cell anode includes an electrocatalyst that has a conductive support material, ruthenium nanoparticles reduced in H.sub.2 and a Group VIII noble metal in an amount of between about 0.1 and 25 wt % of the ruthenium nanoparticles, preferably between about 0.5 and 15 wt %. The preferred Group VIII noble metal is platinum. In one embodiment, the anode can also have a perfluorinated polymer membrane on its surface.

Electrolyte disorders with platinum-based chemotherapy: mechanisms, manifestations and management.

PubMed

Oronsky, Bryan; Caroen, Scott; Oronsky, Arnold; Dobalian, Vaughn E; Oronsky, Neil; Lybeck, Michelle; Reid, Tony R; Carter, Corey A

2017-11-01

Platinum chemotherapy, particularly cisplatin, is commonly associated with electrolyte imbalances, including hypomagnesemia, hypokalemia, hypophosphatemia, hypocalcemia and hyponatremia. The corpus of literature on these dyselectrolytemias is large; the objective of this review is to synthesize the literature and summarize the mechanisms responsible for these particular electrolyte disturbances in the context of platinum-based treatment as well as to present the clinical manifestations and current management strategies for oncologists and primary care physicians, since the latter are increasingly called on to provide care for cancer patients with medical comorbidities. Correct diagnosis and effective treatment are essential to improved patient outcomes.

Addition of platinum and silver nanoparticles to toughen dental porcelain.

PubMed

Fujieda, Tokushi; Uno, Mitsunori; Ishigami, Hajime; Kurachi, Masakazu; Wakamatsu, Nobukazu; Doi, Yutaka

2012-01-01

Several studies have investigated toughening porcelain that is layered over a frame or a core. The introduction of residual compressive stress to the surface of porcelain has been shown to be effective to strengthen it. In the present study, nanoparticles of precious metals of silver and platinum (rather than non-precious metals) were used to evaluate if they could increase the fracture resistance of porcelain. The addition of silver and platinum nanoparticles was found to improve the mechanical properties of porcelain since it increased both the Young's modulus and the fracture toughness of commercial porcelain.

A phase II study of sunitinib in patients with recurrent epithelial ovarian and primary peritoneal carcinoma: an NCIC Clinical Trials Group Study.

PubMed

Biagi, J J; Oza, A M; Chalchal, H I; Grimshaw, R; Ellard, S L; Lee, U; Hirte, H; Sederias, J; Ivy, S P; Eisenhauer, E A

2011-02-01

Sunitinib is a multitargeted receptor tyrosine kinase inhibitor. We conducted a two-stage phase II study to evaluate the objective response rate of oral sunitinib in recurrent epithelial ovarian cancer. Eligibility required measurable disease and one or two prior chemotherapies, at least one platinum based. Platinum-sensitive or -resistant disease was allowed. Initial dose schedule was sunitinib 50 mg daily, 4 of 6 weeks. Observation of fluid accumulations during off-treatment periods resulted in adoption of continuous 37.5 mg daily dosing in the second stage of accrual. Of 30 eligible patients, most had serous histology (67%), were platinum sensitive (73%) and had two prior chemotherapies (60%). One partial response (3.3%) and three CA125 responses (10%) were observed, all in platinum-sensitive patients using intermittent dosing. Sixteen (53%) had stable disease. Five had >30% decrease in measurable disease. Overall median progression-free survival was 4.1 months. Common adverse events included fatigue, gastrointestinal symptoms, hand-foot syndrome and hypertension. No gastrointestinal perforation occurred. Single-agent sunitinib has modest activity in recurrent platinum-sensitive ovarian cancer, but only at the 50 mg intermittent dose schedule, suggesting that dose and schedule may be vital considerations in further evaluation of sunitinib in this cancer setting.

Acute and chronic nephrotoxicity of platinum nanoparticles in mice

NASA Astrophysics Data System (ADS)

Yamagishi, Yoshiaki; Watari, Akihiro; Hayata, Yuya; Li, Xiangru; Kondoh, Masuo; Yoshioka, Yasuo; Tsutsumi, Yasuo; Yagi, Kiyohito

2013-09-01

Platinum nanoparticles are being utilized in various industrial applications, including in catalysis, cosmetics, and dietary supplements. Although reducing the size of the nanoparticles improves the physicochemical properties and provides useful performance characteristics, the safety of the material remains a major concern. The aim of the present study was to evaluate the biological effects of platinum particles less than 1 nm in size (snPt1). In mice administered with a single intravenous dose of snPt1, histological analysis revealed necrosis of tubular epithelial cells and urinary casts in the kidney, without obvious toxic effects in the lung, spleen, and heart. These mice exhibited dose-dependent elevation of blood urea nitrogen, an indicator of kidney damage. Direct application of snPt1 to in vitro cultures of renal cells induced significant cytotoxicity. In mice administered for 4 weeks with twice-weekly intraperitoneal snPt1, histological analysis of the kidney revealed urinary casts, tubular atrophy, and inflammatory cell accumulation. Notably, these toxic effects were not observed in mice injected with 8-nm platinum particles, either by single- or multiple-dose administration. Our findings suggest that exposure to platinum particles of less than 1 nm in size may induce nephrotoxicity and disrupt some kidney functions. However, this toxicity may be reduced by increasing the nanoparticle size.

Zirconia-based mixed potential sensor with Pt electrode prepared by spin-coating of polymeric precursor

NASA Astrophysics Data System (ADS)

Chrzan, A.; Woźniak, Ł.; Szymczewska, D.; Jasiński, P.

2016-11-01

Many types of yttria-stabilized zirconia (YSZ) based gas sensors have been explored extensively in recent years. Great attention have been directed to mixed-potential-type gas sensors. It is due to growing concerns with environmental issues. Not without a significance is the fact of very attractive performance of this type of sensor allowing to detect low concentration of pollutant gases. In this paper two types of YSZ based mixed-potential planar sensors were investigated, with platinum electrode painted using commercial paste and with spin coated platinum layer. Both types had second electrode in the form of porous gold. Measurements were performed at 400 °C in synthetic air and different concentrations of SO2. Gas flow was set to 100 cm3min-1 and the concentration of 50 ppm SO2 was tested. During this measurements the sensor was sintered in-situ at increasing temperatures. Sensor with 100 nm spin-coated platinum layer sintered at 700 °C was shown to exhibit two times smaller response than sensor with 5 μm porous electrode, while consisting of over 20 times smaller amount of Pt. The influence of sintering temperature on electrical conductivity of platinum films was also examined. Moreover, the platinum microstructure was investigated using SEM microscopy.

Metronomic cyclophosphamide-induced long-term remission after recurrent high-grade serous ovarian cancer: A case study

PubMed Central

de Boo, Leonora Wijnandina; Vulink, Annelie Johanna Elisabeth; Bos, Monique Elisabeth Martina Maria

2017-01-01

Metronomic oral cyclophosphamide has gained increasing interest in recent years as a promising maintenance therapy in advanced, platinum-sensitive, high-grade serous ovarian cancer (HGSOC). Metronomic treatment with cyclophosphamide refers to the frequent, usually daily, administration of a low (oral) dose of cyclophosphamide with no prolonged drug-free breaks. Main advantages of this treatment are the effective reduction of tumour activity, oral administration in an outpatient setting, low cost and the low toxicity profile. Metronomic oral cyclophosphamide can benefit patients suffering from types of cancer known to be sensitive to alkylating agents, such as platinum-sensitive HGSOC. In recent years, several publications have underlined the advantage of this regimen and possible explanations were explored. We here present a patient with multiple recurrences of metastasized HGSOC, platinum-sensitive, with an on-going complete response to monotherapy with oral cyclophosphamide. This observation supports that patients with relapsing HGSOC who responded to platinum-based chemotherapy and cannot continue platinum-based chemotherapy because of toxicity, can be offered a course of metronomic cyclophosphamide. This case may serve as a reminder that old drugs can be used successfully even in the age of new upcoming therapy such as anti-angiogenic agents (VEGF inhibitors) and poly-ADP-ribose polymerase (PARP) inhibitors. PMID:29285388

Metronomic cyclophosphamide-induced long-term remission after recurrent high-grade serous ovarian cancer: A case study.

PubMed

de Boo, Leonora Wijnandina; Vulink, Annelie Johanna Elisabeth; Bos, Monique Elisabeth Martina Maria

2017-12-01

Metronomic oral cyclophosphamide has gained increasing interest in recent years as a promising maintenance therapy in advanced, platinum-sensitive, high-grade serous ovarian cancer (HGSOC). Metronomic treatment with cyclophosphamide refers to the frequent, usually daily, administration of a low (oral) dose of cyclophosphamide with no prolonged drug-free breaks. Main advantages of this treatment are the effective reduction of tumour activity, oral administration in an outpatient setting, low cost and the low toxicity profile. Metronomic oral cyclophosphamide can benefit patients suffering from types of cancer known to be sensitive to alkylating agents, such as platinum-sensitive HGSOC. In recent years, several publications have underlined the advantage of this regimen and possible explanations were explored. We here present a patient with multiple recurrences of metastasized HGSOC, platinum-sensitive, with an on-going complete response to monotherapy with oral cyclophosphamide. This observation supports that patients with relapsing HGSOC who responded to platinum-based chemotherapy and cannot continue platinum-based chemotherapy because of toxicity, can be offered a course of metronomic cyclophosphamide. This case may serve as a reminder that old drugs can be used successfully even in the age of new upcoming therapy such as anti-angiogenic agents (VEGF inhibitors) and poly-ADP-ribose polymerase (PARP) inhibitors.

Platinum-based drugs disrupt STAT6-mediated suppression of immune responses against cancer in humans and mice.

PubMed

Lesterhuis, W Joost; Punt, Cornelis J A; Hato, Stanleyson V; Eleveld-Trancikova, Dagmar; Jansen, Bastiaan J H; Nierkens, Stefan; Schreibelt, Gerty; de Boer, Annemiek; Van Herpen, Carla M L; Kaanders, Johannes H; van Krieken, Johan H J M; Adema, Gosse J; Figdor, Carl G; de Vries, I Jolanda M

2011-08-01

Tumor microenvironments feature immune inhibitory mechanisms that prevent T cells from generating effective antitumor immune responses. Therapeutic interventions aimed at disrupting these inhibitory mechanisms have been shown to enhance antitumor immunity, but they lack direct cytotoxic effects. Here, we investigated the effect of cytotoxic cancer chemotherapeutics on immune inhibitory pathways. We observed that exposure to platinum-based chemotherapeutics markedly reduced expression of the T cell inhibitory molecule programmed death receptor-ligand 2 (PD-L2) on both human DCs and human tumor cells. Downregulation of PD-L2 resulted in enhanced antigen-specific proliferation and Th1 cytokine secretion as well as enhanced recognition of tumor cells by T cells. Further analysis revealed that STAT6 controlled downregulation of PD-L2. Consistent with these data, patients with STAT6-expressing head and neck cancer displayed enhanced recurrence-free survival upon treatment with cisplatin-based chemoradiation compared with patients with STAT6-negative tumors, demonstrating the clinical relevance of platinum-induced STAT6 modulation. We therefore conclude that platinum-based anticancer drugs can enhance the immunostimulatory potential of DCs and decrease the immunosuppressive capability of tumor cells. This dual action of platinum compounds may extend their therapeutic application in cancer patients and provides a rationale for their use in combination with immunostimulatory compounds.

Nanoscale platinum printing on insulating substrates.

PubMed

O'Connell, C D; Higgins, M J; Sullivan, R P; Jamali, S S; Moulton, S E; Wallace, G G

2013-12-20

The deposition of noble metals on soft and/or flexible substrates is vital for several emerging applications including flexible electronics and the fabrication of soft bionic implants. In this paper, we describe a new strategy for the deposition of platinum electrodes on a range of materials, including insulators and flexible polymers. The strategy is enabled by two principle advances: (1) the introduction of a novel, low temperature strategy for reducing chloroplatinic acid to platinum using nitrogen plasma; (2) the development of a chloroplatinic acid based liquid ink formulation, utilizing ethylene glycol as both ink carrier and reducing agent, for versatile printing at nanoscale resolution using dip-pen nanolithography (DPN). The ink formulation has been printed and reduced upon Si, glass, ITO, Ge, PDMS, and Parylene C. The plasma treatment effects reduction of the precursor patterns in situ without subjecting the substrate to destructively high temperatures. Feature size is controlled via dwell time and degree of ink loading, and platinum features with 60 nm dimensions could be routinely achieved on Si. Reduction of the ink to platinum was confirmed by energy dispersive x-ray spectroscopy (EDS) elemental analysis and x-ray diffraction (XRD) measurements. Feature morphology was characterized by optical microscopy, SEM and AFM. The high electrochemical activity of individually printed Pt features was characterized using scanning electrochemical microscopy (SECM).

Platinum Recovery from Synthetic Extreme Environments by Halophilic Bacteria.

PubMed

Maes, Synthia; Props, Ruben; Fitts, Jeffrey P; Smet, Rebecca De; Vilchez-Vargas, Ramiro; Vital, Marius; Pieper, Dietmar H; Vanhaecke, Frank; Boon, Nico; Hennebel, Tom

2016-03-01

Metal recycling based on urban mining needs to be established to tackle the increasing supply risk of critical metals such as platinum. Presently, efficient strategies are missing for the recovery of platinum from diluted industrial process streams, often characterized by extremely low pHs and high salt concentrations. In this research, halophilic mixed cultures were employed for the biological recovery of platinum (Pt). Halophilic bacteria were enriched from Artemia cysts, living in salt lakes, in different salt matrices (sea salt mixture and NH4Cl; 20-210 g L(-1) salts) and at low to neutral pH (pH 3-7). The main taxonomic families present in the halophilic cultures were Halomonadaceae, Bacillaceae, and Idiomarinaceae. The halophilic cultures were able to recover >98% Pt(II) and >97% Pt(IV) at pH 2 within 3-21 h (4-453 mg Ptrecovered h(-1) g(-1) biomass). X-ray absorption spectroscopy confirmed the reduction to Pt(0) and transmission electron microscopy revealed both intra- and extracellular Pt precipitates, with median diameters of 9-30 nm and 11-13 nm, for Pt(II) and Pt(IV), respectively. Flow cytometric membrane integrity staining demonstrated the preservation of cell viability during platinum recovery. This study demonstrates the Pt recovery potential of halophilic mixed cultures in acidic saline conditions.

Monitoring Interactions Inside Cells by Advanced Spectroscopies: Overview of Copper Transporters and Cisplatin.

PubMed

Lasorsa, Alessia; Natile, Giovanni; Rosato, Antonio; Tadini-Buoninsegni, Francesco; Arnesano, Fabio

2018-02-12

Resistance, either at the onset of the treatment or developed after an initial positive response, is a major limitation of antitumor therapy. In the case of platinum- based drugs, copper transporters have been found to interfere with drug trafficking by facilitating the import or favoring the platinum export and inactivation. The use of powerful spectroscopic, spectrometric and computational methods has allowed a deep structural insight into the mode of interaction of platinum drugs with the metal-binding domains of the transporter proteins. This review article focuses on the mode in which platinum drugs can compete with copper ion for binding to transport proteins and consequent structural and biological effects. Three types of transporters are discussed in detail: copper transporter 1 (Ctr1), the major responsible for Cu+ uptake; antioxidant-1 copper chaperone (Atox1), responsible for copper transfer within the cytoplasm; and copper ATPases (ATP7A/B), responsible for copper export into specific subcellular compartments and outside the cell. The body of knowledge summarized in this review can help in shaping current chemotherapy to optimize the efficacy of platinum drugs (particularly in relation to resistance) and to mitigate adverse effects on copper metabolism. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

On the enzymatic formation of platinum nanoparticles

NASA Astrophysics Data System (ADS)

Govender, Y.; Riddin, T. L.; Gericke, M.; Whiteley, C. G.

2010-01-01

A dimeric hydrogenase enzyme (44.5 and 39.4 kDa sub units) was isolated in a 39.5% yield from the fungus Fusarium oxysporum and purified 4.64-fold by ion exchange chromatography on Sephacryl S-200. Characterisation of the enzyme afforded pH and temperature optima of 7.5 and 38 °C, respectively, a half-life stability of 36 min and a V max and K m of 3.57 nmol min-1 mL-1 and 2.25 mM, respectively. This enzyme was inhibited (non-competitively) by hydrogen hexachloroplatinic acid (H2PtCl6) at 1 or 2 mM with a K i value of 118 μM. Incubation of the platinum salt with the pure enzyme under an atmosphere of hydrogen and optimum enzyme conditions (pH 7.5, 38 °C) afforded <10% bioreduction after 8 h while at conditions suitable for platinum nanoparticle formation (pH 9, 65 °C) over 90% reduction took place after the same length of time. Cell-free extract from the fungal isolates produced nearly 90% bioreduction of the platinum salt under both pH and temperature conditions. The bioreduction of the platinum salt by a hydrogenase enzyme takes place by a passive process and not an active one as previously understood.

Synthesis, structural characterization, and pro-apoptotic activity of 1-indanone thiosemicarbazone platinum(II) and palladium(II) complexes: potential as antileukemic agents.

PubMed

Gómez, Natalia; Santos, Diego; Vázquez, Ramiro; Suescun, Leopoldo; Mombrú, Alvaro; Vermeulen, Monica; Finkielsztein, Liliana; Shayo, Carina; Moglioni, Albertina; Gambino, Dinorah; Davio, Carlos

2011-08-01

In the search for alternative chemotherapeutic strategies against leukemia, various 1-indanone thiosemicarbazones, as well as eight novel platinum(II) and palladium(II) complexes, with the formula [MCl₂(HL)] and [M(HL)(L)]Cl, derived from two 1-indanone thiosemicarbazones were synthesized and tested for antiproliferative activity against the human leukemia U937 cell line. The crystal structure of [Pt(HL1)(L1)]Cl·2MeOH, where L1=1-indanone thiosemicarbazone, was solved by X-ray diffraction. Free thiosemicarbazone ligands showed no antiproliferative effect, but the corresponding platinum(II) and palladium(II) complexes inhibited cell proliferation and induced apoptosis. Platinum(II) complexes also displayed selective apoptotic activity in U937 cells but not in peripheral blood monocytes or the human hepatocellular carcinoma HepG2 cell line used to screen for potential hepatotoxicity. Present findings show that, in U937 cells, 1-indanone thiosemicarbazones coordinated to palladium(II) were more cytotoxic than those complexed with platinum(II), although the latter were found to be more selective for leukemic cells suggesting that they are promising compounds with potential therapeutic application against hematological malignancies. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Spectrometric determination of platinum with methoxypromazine maleate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thimmegowda, A.; Sankegowda, H.; Gowda, N.M.M.

1984-03-01

A simple, rapid, and sensitive spectrophotometric method has been developed for the determination of platinum in solution. The chromogenic reagent, methoxypromazine maleate, reacts with platinum(IV) almost instantaneously in phosphoric acid medium containing copper(II) catalyst to form a bluish pink 1:1 complex with an absorption maximum at 562 nm. The complexation is complete within 1 min. A 30-fold molar excess of the reagent over metal ion is necessary for completion of the reaction. Beer's law is obeyed over the concentration range of 0.4-9.8 ppm of platinum(IV) with an optimal range of 1.5-8.6 ppm. The molar absorptivity is 1.71 x 10/sub 4/more » L mol/sup -1/ cm/sup -1/ and the Sandell sensitivity is 11.4 ng cm/sup -2/. The apparent stability constant of the complex is log K = 5.58 +/- 0.1 at 27/sup 0/C. The effects of acid concentration, time, temperature, concentration of the reagent and copper, order of addition of reagents, and the interferences from various ions are investigated. The method has been used for the determination of platinum in synthetic solutions that approximate the composition of some alloys and minerals. 25 references, 1 figure, 2 tables.« less

Acute and chronic nephrotoxicity of platinum nanoparticles in mice

PubMed Central

2013-01-01

Platinum nanoparticles are being utilized in various industrial applications, including in catalysis, cosmetics, and dietary supplements. Although reducing the size of the nanoparticles improves the physicochemical properties and provides useful performance characteristics, the safety of the material remains a major concern. The aim of the present study was to evaluate the biological effects of platinum particles less than 1 nm in size (snPt1). In mice administered with a single intravenous dose of snPt1, histological analysis revealed necrosis of tubular epithelial cells and urinary casts in the kidney, without obvious toxic effects in the lung, spleen, and heart. These mice exhibited dose-dependent elevation of blood urea nitrogen, an indicator of kidney damage. Direct application of snPt1 to in vitro cultures of renal cells induced significant cytotoxicity. In mice administered for 4 weeks with twice-weekly intraperitoneal snPt1, histological analysis of the kidney revealed urinary casts, tubular atrophy, and inflammatory cell accumulation. Notably, these toxic effects were not observed in mice injected with 8-nm platinum particles, either by single- or multiple-dose administration. Our findings suggest that exposure to platinum particles of less than 1 nm in size may induce nephrotoxicity and disrupt some kidney functions. However, this toxicity may be reduced by increasing the nanoparticle size. PMID:24059288

Production of platinum radioisotopes at Brookhaven Linac Isotope Producer (BLIP)

NASA Astrophysics Data System (ADS)

Smith, Suzanne V.; McCutchan, Elizabeth; Gürdal, Gülhan; Lister, Christopher; Muench, Lisa; Nino, Michael; Sonzogni, Alexandro; Herman, Michal; Nobre, Gustavo; Cullen, Chris; Chillery, Thomas; Chowdury, Partha; Harding, Robert

2017-09-01

The accelerator production of platinum isotopes was investigated at the Brookhaven Linac Isotope Producer (BLIP). In this study high purity natural platinum foils were irradiated at 53.2, 65.7, 105.2, 151.9, 162.9 and 173.3.MeV. The irradiated foils were digested in aqua regia and then converted to their hydrochloride salt with concentrated hydrochloric acid before analyzing by gamma spectrometry periodically for at least 10 days post end of bombardment. A wide range of platinum (Pt), gold (Au) and iridium (Ir) isotopes were identified. Effective cross sections at BLIP for Pt-188, Pt-189, Pt-191 and Pt-195m were compared to literature and theoretical cross sections determined using Empire-3.2. The majority of the effective cross sections (<70 MeV) confirm those reported in the literature. While the absolute values of the theoretical cross sections were up to a factor of 3 lower, Empire 3.2 modeled thresholds and maxima correlated well with experimental values. Preliminary evaluation into a rapid separation of Pt isotopes from high levels of Ir and Au isotopes proved to be a promising approach for large scale production. In conclusion, this study demonstrated that with the use of isotopically enriched target material accelerator production of selected platinum isotopes is feasible over a wide proton energy range.

MYC RNAi-PT Combination Nanotherapy for Metastatic Prostate Cancer Treatment

DTIC Science & Technology

2016-10-01

MYC silencing in BMPC cell line-based allograft tumors by the hybrid NPs. 15. SUBJECT TERMS Nanotechnology , nanoparticle, siRNA delivery, platinum...KEYWORDS Nanotechnology , lipid, polymer, hybrid nanoparticle, siRNA delivery, platinum, MYC, prostate cancer, drug resistance, mouse model, pathology

IRIS Toxicological Review of Halogenated Platinum Salts and Platinum Compounds (External Review Draft)

EPA Science Inventory

EPA released the draft toxicological review for public comment under the Integrated Risk Information System (IRIS) Program. The original draft assessment (January 2009) has been archived but is available on this web page for the sake of transparency.

Platinum nanoparticles decorated dendrite-like gold nanostructure on glassy carbon electrodes for enhancing electrocatalysis performance to glucose oxidation

NASA Astrophysics Data System (ADS)

Jia, Hongmei; Chang, Gang; Lei, Ming; He, Hanping; Liu, Xiong; Shu, Honghui; Xia, Tiantian; Su, Jie; He, Yunbin

2016-10-01

Platinum nanoparticles decorated dendrite-like gold nanostructure, bimetal composite materials on glassy carbon electrode (Pt/DGNs/GC) for enhancing electrocatalysis to glucose oxidation was designed and successfully fabricated by a facile two-step deposition method without any templates, surfactants, or stabilizers. Dendrite-like gold nanostructure was firstly deposited on the GC electrode via the potentiostatic method, and then platinum nanoparticles were decorated on the surface of gold substrate through chemical reduction deposition. X-ray diffraction (XRD), field-emission scanning electron microscope (FE-SEM), energy-dispersive X-ray spectroscopy (EDS) were applied to characterize the evolution of morphology and structure of the as-prepared Pt/DGNs/GC. Based on electrochemical measurements such as cyclic voltammetry, linear voltammetry and chronoamperometry, Pt/DGNs/GC exhibited significantly enhanced electrocatalytic performance to glucose oxidation compared those of pure dendrite-like Au nanoparticles in our previous report. Controlling chemical reduction deposition time, the amount of platinum nanoparticles on Au surface could be regulated, which further tuned electrocatalytic properties toward glucose oxidation. The dendrite-like gold surface partially covered by platinum nanoparticles dramatically enhanced the electrocatalytic performance for the oxidation of glucose because of excellent synergetic effects between gold and platinum species and the increased electrochemical active area from Pt nanoparticles loading. The non-enzymatic glucose biosensor based on Pt/DGNs/GC showed a rapid respond time (within 2 s), wide linear range (from 0.1 mM to 14 mM), low detection limit (0.01 mM), supernal sensitivity (275.44 μA cm-2 mM-1, R = 0.993), satisfactory reproducibility and good stability for glucose sensing. It was demonstrated that Pt/DGNs/GC could work as promising candidate for factual non-enzymatic glucose detection.

Glutathione modified CdTe quantum dots as a label for studying DNA interactions with platinum based cytostatics.

PubMed

Ryvolova, Marketa; Smerkova, Kristyna; Chomoucka, Jana; Hubalek, Jaromir; Adam, Vojtech; Kizek, Rene

2013-03-01

Cisplatin, carboplatin, and oxaliplatin represent three generations of platinum based drugs applied successfully for cancer treatment. As a consequence of the employment of platinum based cytostatics in the cancer treatment, it became necessary to study the mechanism of their action. Current accepted opinion is the formation of Pt-DNA adducts, but the mechanism of their formation is still unclear. Nanomaterials, as a progressively developing branch, can offer a tool for studying the interactions of these drugs with DNA. In this study, fluorescent CdTe quantum dots (QDs, λem = 525 nm) were employed to investigate the interactions of platinum cytostatics (cisplatin, carboplatin, and oxaliplatin) with DNA fragment (500 bp, c = 25 μg/mL). Primarily, the fluorescent behavior of QDs in the presence of platinum cytostatics was monitored and major differences in the interaction of QDs with tested drugs were observed. It was found that the presence of carboplatin (c = 0.25 mg/mL) had no significant influence on QDs fluorescence; however cisplatin and oxaliplatin quenched the fluorescence significantly (average decrease of 20%) at the same concentration. Subsequently, the amount of platinum incorporated in DNA was determined by QDs fluorescence quenching. Best results were reached using oxaliplatin (9.4% quenching). Linear trend (R(2) = 0.9811) was observed for DNA platinated by three different concentrations of oxaliplatin (0.250, 0.125, and 0.063 mg/mL). Correlation with differential pulse voltammetric measurements provided linear trend (R(2) = 0.9511). As a conclusion, especially in the case of oxaliplatin-DNA adducts, the quenching was the most significant compared to cisplatin and nonquenching carboplatin. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Platinum(II)-dendrimer conjugates: synthesis and investigations on cytotoxicity, cellular distribution, platinum release, DNA, and protein binding.

PubMed

Kapp, Timo; Dullin, Anja; Gust, Ronald

2010-02-17

A set of polyamidoamine dendrimers were modified in such a way that they are able to act as carrier and drug delivery systems for cytostatics. The terminal binding of the non-proteinogenic D,L-2,3-diaminopropionic acid allowed the attachment of the cytotoxic PtX(2) moiety (X = Cl, I: A(PtI(2))(2), A(PtCl(2))(2), B(PtI(2))(2), B(PtCl(2))(2)), while the 2-carboxypentanedioic acid acted as leaving group for [meso-1,2-bis(4-fluorophenyl)ethylenediamine]platinum(II) ((m-4F-Pt)(3)C, (m-4F-Pt)(3)D). Poly(ethylene glycol) chains at C(PtI(2))(3) and C(PtCl(2))(3) as well as (m-4F-Pt)(3)C and (m-4F-Pt)(3)D mediated sufficient water solubility. Additional dansyl residues (B(PtI(2))(2) and (m-4F-Pt)(3)D) made a simultaneous determination of platinum (graphite furnace atomic absorption spectroscopy (GF-AAS)) and dendrimer (fluorimetry) possible. The ethylenediamine-terminated dendrimers were typically accumulated into MCF-7 cells in clathrin-dependent pathways and targeted the platinum moieties to the nuclear compartment. The highest intracellular platinum concentration and DNA binding caused the dendrimers A(PtX(2))(2) and B(PtX(2))(2). A coordinative DNA binding, however, is very unlikely because of low cytotoxic effects. (m-4F-Pt)(3)C and (m-4F-Pt)(3)D are labile conjugates and liberated the m-4F-Pt moiety in biological systems. The effects of these dendrimers were similar to that of the reference compounds m-4F-PtCl(2) and m-4F-Pt(H(2)O)(2).

MHD generator electrode development. Summary report, July 1, 1981-September 30, 1982

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rossing, B.R.; Buckman, R.W. Jr.; Pouchot, W.D.

Emphasis on this program was the development of and understanding wastage mechanism(s) of metallic electrodes which may be suitable alternatives to platinum anode material for use in long-term open cycle, coal-fired MHD generator operations. The laboratory tests simulate both modes of material wastage observed in MHD electrode operation; i.e., arc erosion (melting/vaporization) and electrochemical corrosion. Based on experimental results from the electrochemical tests at 1473/sup 0/K, the rank order listing of the materials tested for anode applications were platinum, E-Brite 26-1 modified with a five percent addition of platinum, chromium, IN 601, E-Brite 26-1, and 330 stainless steel ranked inmore » decreasing order. The rank order listing based on the arc erosion test was platinum, chromium, E-Brite 26-1, 330 stainless steel, and IN 601. The relative arc erosion resistance of materials based on the AVCO Mark VII generator test results gave a rank order of platinum, 330 stainless steel, IN 601, and E-Brite 26-1. Engineering tests under simulated open-cycle coal-fired MHD operating conditions were performed in the 500 kW Westinghouse Electrode System Test Facility (WESTF). Tests were conducted on candidate metallic anode materials (cold wall) and ceramic anode (hot wall) materials. A ten-hour duration cold wall slagging test was conducted on platinum, E-Brite 26-1, 330 stainless steel and IN 601 and the results were similar to those obtained for those materials in the AVCO Mark VII generator tests. Non-slagging, super hot (>1700/sup 0/C) wall hafnia-rare earth oxide electrodes were tested in a sulfurous, western coal-fired MHD environment. All four ceramic electrode pairs were destroyed. 20 references.« less

Expression and clinical implication of Beclin1, HMGB1, p62, survivin, BRCA1 and ERCC1 in epithelial ovarian tumor tissues.

PubMed

Ju, L-L; Zhao, C Y; Ye, K-F; Yang, H; Zhang, J

2016-05-01

The aim of the present study is to investigate the differential expression of Beclin1, HMGB1, p62, survivin, ERCC1 and BRCA1 protein in epithelial ovarian cancer (EOC) and to evaluate the relationship between autophagy and platinum resistance of EOC patients during platinum-based chemotherapy with the protein expression. Expression of Beclin1, HMGB1, p62, survivin, ERCC1 and BRCA1 were detected with immunohistochemistry in 60 patients, including 39 with epithelial ovarian cancer (EOC), 13 benign epithelial ovarian tumor tissue (BET) and 8 borderline ovarian tumor tissue. Beclin, p62 and ERCC1 expression was significantly higher in the EOC than the BET (p<0.05). No statistical significance was detected with HMGB1 or survivin expression among BET, borderline tumor and EOC (p>0.05). BRCA1 expression was lower in EOC than BET (p<0.05). The expression of Beclin, p62 and survivin significantly correlated with FIGO stage (p<0.05), while the expression of HMGB1 correlated with pathological type. For platinum-sensitive EOC patients, positive expression of Beclin1 and BRCA1 was lower, and positive P62 expression was higher than in platinum-resistant patients (p<0.05). BRCA1 expression was negatively correlated with Beclin1 and p62 expression (p<0.05). Inhibition of expression of beclin1 may suppress autophagy to enhance the efficiency of platinum-sensitive ovarian cancer. HMGB1, survivin and p62 are implicated in the development of ovarian cancer. ERCC1 might be a potential predictive marker for neoadjuvant treatment in the early stage of ovarian cancer, and BRCA1, Beclin1 and p62 as a biomarker to predict platinum resistance and prognosis of epithelial ovarian cancer.

Improvement of a predictive model in ovarian cancer patients submitted to platinum-based chemotherapy: implications of a GST activity profile.

PubMed

Pereira, Deolinda; Assis, Joana; Gomes, Mónica; Nogueira, Augusto; Medeiros, Rui

2016-05-01

The success of chemotherapy in ovarian cancer (OC) is directly associated with the broad variability in platinum response, with implications in patients survival. This heterogeneous response might result from inter-individual variations in the platinum-detoxification pathway due to the expression of glutathione-S-transferase (GST) enzymes. We hypothesized that GSTM1 and GSTT1 polymorphisms might have an impact as prognostic and predictive determinants for OC. We conducted a hospital-based study in a cohort of OC patients submitted to platinum-based chemotherapy. GSTM1 and GSTT1 genotypes were determined by multiplex PCR. GSTM1-null genotype patients presented a significantly longer 5-year survival and an improved time to progression when compared with GSTM1-wt genotype patients (log-rank test, P = 0.001 and P = 0.013, respectively). Multivariate Cox regression analysis indicates that the inclusion of genetic information regarding GSTM1 polymorphism increased the predictive ability of risk of death after OC platinum-based chemotherapy (c-index from 0.712 to 0.833). Namely, residual disease (HR, 4.90; P = 0.016) and GSTM1-wt genotype emerged as more important predictors of risk of death (HR, 2.29; P = 0.039; P = 0.036 after bootstrap). No similar effect on survival was observed regarding GSTT1 polymorphism, and there were no statistically significant differences between GSTM1 and GSTT1 genotypes and the assessed patients' clinical-pathological characteristics. GSTM1 polymorphism seems to have an impact in OC prognosis as it predicts a better response to platinum-based chemotherapy and hence an improved survival. The characterization of the GSTM1 genetic profile might be a useful molecular tool and a putative genetic marker for OC clinical outcome.

Gemcitabine-oxaliplatin (GEMOX) for epithelial ovarian cancer patients resistant to platinum-based chemotherapy.

PubMed

Elshebeiny, Mohamed; Almorsy, Walid

2016-09-01

Patients with platinum-resistant epithelial ovarian cancer (EOC) experience poor outcome. Currently, no clearly superior management strategy exists for platinum-resistant EOC patients. Analyze the efficacy and safety of gemcitabine-oxaliplatin (GEMOX) in platinum resistant EOC patients. Thirty-two patients with platinum-based resistant EOC were included. Studied patients had received GEM at the dose of 1000mg/m(2) on days 1 and 8 and OX 100mg/m(2) on day 1, administered over 2h 30min after GEM infusion of 3week treatment cycle. In the evaluation of tumor response, none of patients had achieved CR while PR, SD, were observed in 7 (21.9%), 9 (28.1%) respectively, clinical benefit (CR+PR+SD) was recorded in 50% of patients while PD was observed in 16 (50%) patients. In regard to survival, the median value of OS was 10.5months (range, 2.2-17.5months). The median value of PFS was 6.37months (range, 1-17.5months). The one-year OS rate was 34.4% and the one-year PFS rate was 12.5%. Concerning hematological toxicity grade 3 neutropenia was recorded in 4 (12.5%) patients while grade 4 febrile neutropenia was recorded in 2 (6.3%) patients and grade 4 anemia was represented by 3.1%. Grade 1-2 fatigue was the most common non-hematological toxicity and represented by 65.6% of patients. Grade 3 non hematological toxicity was recorded with nausea/vomiting and hepatic toxicity represented by 3.1% for both. The GEMOX combination is a regimen with a moderate therapeutic efficacy and tolerable toxic side effects in patients with platinum-resistant EOC. Copyright © 2016. Production and hosting by Elsevier B.V.

Influence of Methylenetetrahydrofolate Reductase C677T Polymorphism on the Risk of Lung Cancer and the Clinical Response to Platinum-Based Chemotherapy for Advanced Non-Small Cell Lung Cancer: An Updated Meta-Analysis

PubMed Central

Zhu, Ning; Gong, Yi; He, Jian; Xia, Jingwen

2013-01-01

Purpose Methylenetetrahydrofolate reductase (MTHFR) has been implicated in lung cancer risk and response to platinum-based chemotherapy in advanced non-small cell lung cancer (NSCLC). However, the results are controversial. We performed meta-analysis to investigate the effect of MTHFR C677T polymorphism on lung cancer risk and response to platinum-based chemotherapy in advanced NSCLC. Materials and Methods The databases of PubMed, Ovid, Wanfang and Chinese Biomedicine were searched for eligible studies. Nineteen studies on MTHFR C677T polymorphism and lung cancer risk and three articles on C677T polymorphism and response to platinum-based chemotherapy in advanced NSCLC, were identified. Results The results indicated that the allelic contrast, homozygous contrast and recessive model of the MTHFR C677T polymorphism were associated significantly with increased lung cancer risk. In the subgroup analysis, the C677T polymorphism was significantly correlated with an increased risk of NSCLC, with the exception of the recessive model. The dominant model and the variant T allele showed a significant association with lung cancer susceptibility of ever smokers. Male TT homozygote carriers had a higher susceptibility, but the allelic contrast and homozygote model had a protective effect in females. No relationship was observed for SCLC in any comparison model. In addition, MTHFR 677TT homozygote carriers had a better response to platinum-based chemotherapy in advanced NSCLC in the recessive model. Conclusion The MTHFR C677T polymorphism might be a genetic marker for lung cancer risk or response to platinum-based chemotherapy in advanced NSCLC. However, our results require further verification. PMID:24142642

Neuropilin-1-targeted gold nanoparticles enhance therapeutic efficacy of platinum(IV) drug for prostate cancer treatment.

PubMed

Kumar, Anil; Huo, Shuaidong; Zhang, Xu; Liu, Juan; Tan, Aaron; Li, Shengliang; Jin, Shubin; Xue, Xiangdong; Zhao, YuanYuan; Ji, Tianjiao; Han, Lu; Liu, Hong; Zhang, XiaoNing; Zhang, Jinchao; Zou, Guozhang; Wang, Tianyou; Tang, Suoqin; Liang, Xing-Jie

2014-05-27

Platinum-based anticancer drugs such as cisplatin, oxaliplatin, and carboplatin are some of the most potent chemotherapeutic agents but have limited applications due to severe dose-limiting side effects and a tendency for cancer cells to rapidly develop resistance. The therapeutic index can be improved through use of nanocarrier systems to target cancer cells efficiently. We developed a unique strategy to deliver a platinum(IV) drug to prostate cancer cells by constructing glutathione-stabilized (Au@GSH) gold nanoparticles. Glutathione (GSH) has well-known antioxidant properties, which lead to cancer regression. Here, we exploit the advantages of both the antioxidant properties and high surface-area-to-volume ratio of Au@GSH NPs to demonstrate their potential for delivery of a platinum(IV) drug by targeting the neuropilin-1 receptor (Nrp-1). A lethal dose of a platinum(IV) drug functionalized with the Nrp-1-targeting peptide (CRGDK) was delivered specifically to prostate cancer cells in vitro. Targeted peptide ensures specific binding to the Nrp-1 receptor, leading to enhanced cellular uptake level and cell toxicity. The nanocarriers were themselves nontoxic, but exhibited high cytotoxicity and increased efficacy when functionalized with the targeting peptide and drug. The uptake of drug-loaded nanocarriers is dependent on the interaction with Nrp-1 in cell lines expressing high (PC-3) and low (DU-145) levels of Nrp-1, as confirmed through inductively coupled plasma mass spectrometry and confocal microscopy. The nanocarriers have effective anticancer activity, through upregulation of nuclear factor kappa-B (NF-κB) protein (p50 and p65) expression and activation of NF-κB-DNA-binding activity. Our preliminary investigations with platinum(IV)-functionalized gold nanoparticles along with a targeting peptide hold significant promise for future cancer treatment.

Analysis of platinum content in biodegradable carboplatin-impregnated beads and retrospective assessment of tolerability for intralesional use of the beads in dogs following excision of subcutaneous sarcomas: 29 cases (2011-2014).

PubMed

Hess, Theresa A; Drinkhouse, Macy E; Prey, Joshua D; Miller, Jonathan M; Fettig, Arthur A; Carberry, Carol A; Brenn, Stephen H; Bailey, Dennis B

2018-02-15

OBJECTIVE To evaluate platinum content in biodegradable carboplatin-impregnated beads and retrospectively assess tolerability and outcome data for dogs treated by intralesional placement of such beads following surgical excision of subcutaneous sarcomas. DESIGN Evaluation study and retrospective case series. SAMPLE 9 carboplatin-impregnated beads and 29 client-owned dogs. PROCEDURES Platinum content in 9 carboplatin-impregnated beads from 3 lots was measured by spectrophotometry, and calculated carboplatin content was compared with the labeled content. Medical records were searched to identify dogs with subcutaneous sarcomas for which treatment included placement of carboplatin-impregnated beads between 2011 and 2014. Signalment, tumor characteristics, surgical and histologic data, adverse events, and local recurrences were recorded. Associations between variables of interest and adverse events or local disease-free interval were analyzed. RESULTS In vitro analysis identified a mean ± SD platinum content of 5.38 ± 0.97 mg/bead. Calculated carboplatin content (10.24 ± 1.84 mg/bead) was significantly greater than the labeled amount (4.6 mg/bead). Bead weight and total platinum content differed significantly among lots, but platinum content per bead weight did not. Mild-to-moderate local adverse events were reported for 11 of 29 tumors; all resolved without additional surgery. No dogs had signs of systemic toxicosis. Overall local disease-free rates 1, 2, and 3 years after surgery were 70%, 70%, and 58%, respectively, as determined by Kaplan-Meier analysis. CONCLUSIONS AND CLINICAL RELEVANCE Carboplatin-impregnated beads were well tolerated; however, results of in vitro tests indicated that caution is needed because of manufacturing inconsistencies.

P53 Is Involved in a Three-Dimensional Architecture-Mediated Decrease in Chemosensitivity in Colon Cancer.

PubMed

He, Jianming; Liang, Xi; Luo, Fen; Chen, Xuedan; Xu, Xueqing; Wang, Fengchao; Zhang, Zhenping

2016-01-01

Three-dimensional (3D) culture models represent a better approximation of solid tumor tissue architecture, especially cell adhesion, in vivo than two-dimensional (2D) cultures do. Here, we explored the role of architecture in chemosensitivity to platinum in colon cancer. Under the 3D culture condition, colon cancer cells formed multicellular spheroids, consisting of layers of cells. 3D cultures displayed significantly decreased sensitivity to platinum compared with 2D cultures. Platinum increased p53 in a dose-dependent and time-dependent manner. There was no detectable difference in basal p53 levels between 3D cultures and 2D cultures but cisplatin induced less p53 in both HCT116 3D cultures and LoVo 3D cultures. It was not due to cisplatin concentration because cisplatin induced similar γ-H2AX in 3D vs 2D. Knockdown of p53 significantly decreased sensitivity to platinum in 3D cultures. Knockdown of p53 decreased cleaved caspase 3 and apoptosis induced by cisplatin. These findings indicate that 3D architecture confers decreased chemosensitivity to platinum and p53 is involved in the mechanism. Knockdown of p53 decreased cisplatin's induction of c-Jun N-terminal kinase 1/2 (JNK1/2) activation, whereas inhibition of JNK1/2 activation increased chemosensitivity. Inhibition of p38 activation decreased cisplatin's induction of p53, but no difference in p38 activation by cisplatin was observed between 2D cultures and 3D cultures. Taken together, our results suggest that p53 is involved in a 3D architecture-mediated decrease in chemosensitivity to platinum in colon cancer. Mitogen-activated protein kinases (JNK1/2 and p38) do not play a dominant role in the mechanism.

Publications - SR 56 | Alaska Division of Geological & Geophysical Surveys

Science.gov Websites

Minerals; Iron; Jade; Jurassic; Kanayut Conglomerate; Kayak Shale; Kuskokwim Group; Lead; Limestone; Lode ; Nickel; Nikolai Greenstone; Noatak Sandstone; Nome Group; Nuggets; Orca Group; Ordovician; Ores ; Paleozoic; Palladium; Pennsylvanian; Placer; Platinum; Platinum Group Elements; Plutonic; Plutonic Hosted

Publications - SR 53 | Alaska Division of Geological & Geophysical Surveys

Science.gov Websites

Group; Lead; Limestone; Lode; Marble; Mercury; Mesozoic; Metallurgy; Metamorphic Rocks; Mineral Pluton; Nickel; Nikolai Greenstone; Noatak Sandstone; Nome Group; Nuggets; Orca Group; Ordovician; Ores ; Paleozoic; Palladium; Pennsylvanian; Placer; Platinum; Platinum Group Elements; Plutonic; Plutonic Hosted

Publications - SR 54 | Alaska Division of Geological & Geophysical Surveys

Science.gov Websites

Minerals; Iron; Jade; Jurassic; Kanayut Conglomerate; Kayak Shale; Kuskokwim Group; Lead; Limestone; Lode ; Nickel; Nikolai Greenstone; Noatak Sandstone; Nome Group; Nuggets; Orca Group; Ordovician; Ores ; Paleozoic; Palladium; Pennsylvanian; Placer; Platinum; Platinum Group Elements; Plutonic; Plutonic Hosted