Potassium Hexachloroplatinate Research Articles

Ex Vivo Electrochemical Monitoring of Cholinergic Signaling in the Mouse Colon Using an Enzyme-Based Biosensor.

Cholinergic signaling, i.e., neurotransmission mediated by acetylcholine, is involved in a host of physiological processes, including learning and memory. Cholinergic dysfunction is commonly associated with neurodegenerative diseases, including Alzheimer's disease. In the gut, acetylcholine acts as an excitatory neuromuscular signaler to mediate smooth muscle contraction, which facilitates peristaltic propulsion. Gastrointestinal dysfunction has also been associated with Alzheimer's disease. This research focuses on the preparation of an electrochemical enzyme-based biosensor to monitor cholinergic signaling in the gut and its application for measuring electrically stimulated acetylcholine release in the mouse colon ex vivo. The biosensors were prepared by platinizing Pt microelectrodes through potential cycling in a potassium hexachloroplatinate (IV) solution to roughen the electrode surface and improve adhesion of the multienzyme film. These electrodes were then modified with a permselective poly(m-phenylenediamine) polymer film, which blocks electroactive interferents from reaching the underlying substrate while remaining permeable to small molecules like H2O2. A multienzyme film containing choline oxidase and acetylcholinesterase was then drop-cast on these modified electrodes. The sensor responds to acetylcholine and choline through the enzymatic production of H2O2, which is electrochemically oxidized to produce an increase in current with increasing acetylcholine or choline concentration. Important figures of merit include a sensitivity of 190 ± 10 mA mol-1 L cm-2, a limit of detection of 0.8 μmol L-1, and a batch reproducibility of 6.1% relative standard deviation at room temperature. These sensors were used to detect electrically stimulated acetylcholine release from mouse myenteric ganglia in the presence and absence of tetrodotoxin and neostigmine, an acetylcholinesterase inhibitor.

In vitro skin permeation of potassium hexachloroplatinate and a comparison with potassium tetrachloroplatinate

Halogenated platinum salts are known respiratory sensitizers in the workplace, and occupational exposure to platinum via the respiratory system and skin has been reported. The aim of this study was to compare the permeability and skin retention of potassium hexachloroplatinate to previously published data of potassium tetrachloroplatinate. Experiments were performed using female Caucasian skin and Franz diffusion cells with the application of 0.3 mg Pt/mL in the donor solution for 24-h. After 8-h of exposure, 1.87 ng/cm2 of Pt was detected in the receptor solution with exposure to potassium hexachloroplatinate, whereas 0.47 ng/cm2 was detected with exposure to potassium tetrachloroplatinate. After 24-h of exposure the Pt retention in the skin was 1861.60 ng/cm2 and 1486.32 ng/cm2 with exposure to potassium hexa- and tetrachloroplatinate respectively. The faster rate of Pt permeation from exposure to potassium hexachloroplatinate was confirmed by the flux and permeability coefficient values. The results indicate a higher permeability and skin retention of Pt when exposed to potassium hexachloroplatinate, confirming a higher risk associated with occupational exposure to this platinum compound relative to potassium tetrachloroplatinate.

Noble-Metal Nanoparticle-Embedded Silicon Nanogratings via Single-Step Laser-Induced Periodic Surface Structuring.

Here, we show that direct femtosecond laser nanostructuring of monocrystalline Si wafers in aqueous solutions containing noble-metal precursors (such as palladium dichloride, potassium hexachloroplatinate, and silver nitrate) allows for the creation of nanogratings decorated with mono- (Pd, Pt, and Ag) and bimetallic (Pd-Pt) nanoparticles (NPs). Multi-pulse femtosecond-laser exposure was found to drive periodically modulated ablation of the Si surface, while simultaneous thermal-induced reduction of the metal-containing acids and salts causes local surface morphology decoration with functional noble metal NPs. The orientation of the formed Si nanogratings with their nano-trenches decorated with noble-metal NPs can be controlled by the polarization direction of the incident laser beam, which was justified, for both linearly polarized Gaussian and radially (azimuthally) polarized vector beams. The produced hybrid NP-decorated Si nanogratings with a radially varying nano-trench orientation demonstrated anisotropic antireflection performance, as well as photocatalytic activity, probed by SERS tracing of the paraaminothiophenol-to-dimercaptoazobenzene transformation. The developed single-step maskless procedure of liquid-phase Si surface nanostructuring that proceeds simultaneously with the localized reduction of noble-metal precursors allows for the formation of hybrid Si nanogratings with controllable amounts of mono- and bimetallic NPs, paving the way toward applications in heterogeneous catalysis, optical detection, light harvesting, and sensing.

In Vitro Monitoring of Nitric Oxide Release in the Mouse Colon Using a Boron-Doped Diamond Microelectrode Modified with Platinum Nanoparticles and Nafion.

This research reports on the preparation of a boron-doped diamond microelectrode modified with platinum nanoparticles and Nafion and its application for detecting nitric oxide (NO) in vitro in the mouse colon. Platinum nanoparticle deposition was performed potentiodynamically using a 2.0 mmol L-1 potassium hexachloroplatinate solution and cycling from -0.2 to 1.3 V vs Ag/AgCl at 0.01 V s-1 for 10 cycles. The Nafion overlayer was applied by immersion in a solution containing 2.5% (w/v) colloidal Nafion and drying overnight at 55 °C in a humid environment. The optimal microelectrode preparation conditions were chosen based on the electrode response for NO oxidation as well as rejection of nitrite (NO2-) oxidation, the main interferent in the electrochemical detection of NO in biological media. Detection figures of merit include a sensitivity of 16.7 ± 2.7 mA M-1 cm-2 (n = 3 electrodes), a detection limit of 0.5 μmol L-1 (S/N = 3), and an electrode response reproducibility of 2.5% (RSD). Electrical stimulation and continuous amperometry were used to measure NO release from myenteric ganglia in wild-type male and female mice in response to an increasing number of electrical stimuli to study nitrergic signaling in the colon. We also present preliminary data regarding the use of optogenetics to selectively stimulate nitrergic myenteric neurons using blue light stimulation with a goal of understanding how inhibitory neuromuscular signaling is involved in the myenteric plexus circuitry that controls intestinal motility.

Surface Coordination Decouples Hydrogenation Catalysis on Supported Metal Catalysts

Surface Coordination Decouples Hydrogenation Catalysis on Supported Metal Catalysts

Measurement of trace potassium hexachloroplatinate concentrations in carboplatin by HPLC-ICP-MS with valve switching

HPLC-ICP-MS method with a valve switching modality was developed for the determination of trace potassium hexachloroplatinate concentrations in carboplatin.

Studies of composite films of polyethylene oxide doped with potassium hexachloroplatinate

AbstractThe permittivity and conductivity relaxation processes of polyethylene oxide (PEO) composite along with potassium hexachloroplatinate (K2PtCl6) electrolytes additive forming PEO/K2PtCl6 complex composite have been investigated. The complex composite has been used as a model for dry‐polymer electrolytes (PEs) due to the fact that, the anion is large enough for mimicking the immobilized anion in real dry‐polymer electrolytes. Stand‐free composite films with 0%, 1%, 3%, and 5% concentrations of K2PtCl6 have been studied using broadband dielectric spectroscopy in the temperatures range from 150 K until 345 K. The microstructural dynamics revealed the α‐, β‐, and σ‐relaxations and their salient spectral characteristics at various concentrations of K2PtCl6 in PEO. The experimental ε” master curves were fitted to HN function for one and/or two relaxation peaks with and without the electrical conductivity contribution in order to investigate the relaxation time (τ), dielectric strengths (Δε), modulus formalism (M”) and the electrical conductivitie (σ). The translational and reorientational degrees of freedom of PEO/K2PtCl6 complex composites are responsible for the relaxation behavior which is predicted to be correlated to the relaxation behavior of the polymer electrolyte below and above the glass transition temperature (Tg). The relaxation time (τ) deduced from β‐relaxation follows Arrhenius‐like behavior while that deduced from α‐relaxation process follows Vogel–Tamman–Fulcher (VTF) behavior.

Single-crystal growth, structure and luminescence properties of Cs2HfCl3Br3

Single crystal of the mixed-halogen compound Cs2HfCl3Br3 was grown by the vertical Bridgman method, and we investigated its crystal structure and optical properties. Single-crystal X-ray diffraction and energy dispersive X-ray spectroscopy analyses indicated the chemical composition to be Cs2Hf(Cl0.578(6)Br0.422(6))6 (= Cs2HfCl3.47(4)Br2.53(4), approximately Cs2Hf(Cl058Br0.42)6) where the number in the parentheses denotes the estimated standard deviation in the last digit. Cs2Hf(Cl0.58Br0.42)6 was found to have a cubic Fm3‾m potassium hexachloroplatinate structure consisting of Cs+ cations and Hf(Cl0.58Br0.42)62− anions. The emission peak of Cs2HfCl3Br3 was red-shifted by Br substitution, and the photoluminescence decays of Cs2HfCl3Br3 were accelerated when compared to those of Cs2HfCl6. Cs2HfCl3Br3 had an emission peak at 450 nm under X-ray irradiation, while under UV-excitation, two photoluminescence emission peaks at 420 and 525 nm were observed. The decay profile of the 420-nm emission band had a single-exponential component with a decay time of 1.95 ± 0.01 μs under the 280-nm-excitation. On the other hand, 525-nm-emisison had two decay components of 0.28 ± 0.03 μs (11%) and 6.54 ± 0.03 μs (89%) under 305-nm-photons excitation.

Fabrication of highly sensitive non-enzymatic sensor based on Pt/PVF modified Pt electrode for detection of glucose

A novel and simple non-enzymatic glucose sensor was successfully fabricated by immobilization of platinum (Pt) particles on polyvinylferrocene-coated Pt electrode (Pt/PVF/Pt). The use of Pt/PVF composite in the development of non-enzymatic glucose sensors has been reported for the first time in this paper. The Pt particles were electrochemically incorporated in the PVF matrix through the chemical reaction between potassium hexachloroplatinate (IV) K2PtCl6 solution and PVF. The as-prepared Pt/PVF/Pt electrode was evaluated towards oxidation of glucose in alkaline media (0.1 M NaOH). The characterization and evaluation of various analytical factors such as sensitivity, selectivity, stability, reproducibility, and detection limit were investigated by cyclic voltammetry (CV) and chronoamperometry (CA) techniques. The Pt/PVF/Pt sensor showed fast response time of less than 3 s with linear glucose concentration range from 0.1 to 11.0 mM (R2 = 0.996). The sensitivity of the sensor was 327 μA mM−1 cm−2 with low detection limit of 0.026 mM. The sensor showed good stability and reproducibility along with excellent anti-interference properties to ascorbic acid, uric acid, sucrose, and fructose. Finally, the applicability of the as-prepared Pt/PVF/Pt sensor was successfully studied for detection of glucose in variety of juice samples. The results obtained for our sensor confirm that it is a promising non-enzymatic glucose sensor to be used for practical purpose.

Highly Electroactive Ni Pyrophosphate/Pt Catalyst toward Hydrogen Evolution Reaction.

Robust electrocatalysts toward the resourceful and sustainable generation of hydrogen by splitting of water via electrocatalytic hydrogen evolution reaction (HER) are a prerequisite to realize high-efficiency energy research. Highly electroactive catalysts for hydrogen production with ultralow loading of platinum (Pt) have been under exhaustive exploration to make them cutting-edge and cost-effectively reasonable for water splitting. Herein, we report the synthesis of hierarchically structured nickel pyrophosphate (β-Ni2P2O7) by a precipitation method and nickel phosphate (Ni3(PO4)2) by two different synthetic routes, namely, simple cost-effective precipitation and solution combustion processes. Thereafter, Pt-decorated nickel pyrophosphate and nickel phosphate (β-Ni2P2O7/Pt and Ni3(PO4)2/Pt) were prepared by using potassium hexachloroplatinate and ascorbic acid. The fabricated novel nickel pyrophosphate and nickel phosphate/Pt materials were utilized as potential and affordable electrocatalysts for HER by water splitting. The detailed electrochemical studies revealed that the β-Ni2P2O7/Pt (1 μg·cm-2 Pt) electrocatalyst showed excellent electrocatalytic performances for HER in acidic solution with an overpotential of 28 mV at -10 mA·cm-2, a Tafel slope of 32 mV·dec, and an exchange current density ( j0) of -1.31 mA·cm-2, which were close to the values obtained using the Vulcan/Pt (8.0 μg·cm-2 Pt), commercial benchmarking electrocatalyst with eight times higher Pt amount. Furthermore, the β-Ni2P2O7/Pt electrocatalyst maintains an excellent stability for over -0.1 V versus RHE for 12 days, keeping j0 equal after the stability test (-1.28 mA cm-2). Very well-distributed Pt NPs inside the "cages" on the β-Ni2P2O7 structure with a crystalline pattern of 0.67 nm distance to the Ni2P2O7/Pt electrocatalyst, helping the Volmer-Tafel mechanism with the Tafel reaction as a major rate-limiting step, help to liberate very fast the Pt sites after HER. The high electrocatalytic performance and remarkable durability showed the β-Ni2P2O7/Pt material to be a promising cost-effective electrocatalyst for hydrogen production.

Synthesis and Structure of Platinum Complexes with Organyltriphenylphosphonium Chlorides and DMSO

Complexes [Ph3PCH2C(O)Me][PtCl3(DMSO-S)] and [Ph3PCH2CH=CH2][PtCl3(DMSO-S)] were synthesized by the reaction of organyltriphenylphosphonium chloride with potassium tetrachloroplatinate (2 : 1) in dimethyl sulfoxide. The reaction of but-2-enylbis(triphenylphosphonim) dichloride with potassium hexachloroplatinate or hexachloroplatinic acid leads to the formation of the complex [Ph3PCH2CH=CHCH2PPh3][PtCl5(DMSO-S)]2. Phosphorus atoms in the cations of the synthesized complexes have a tetrahedral surrounding, and the anions [PtCl5(DMSO-S)]− are square in shape.

EFEK KONSENTRASI Cu PADA STRUKTUR DAN SIFAT HANTARAN LISTRIK NANOPARTIKEL CuPt

The investigation of bimetallic CuPt Nanoparticles (CuPt NPs) with average diameters in the 196.7±98 nm range have been prepared by the Liquid phase deposition methods and synthesized directly on an indium tin oxide (ITO) substrate. CuPt NPs with high surface defect grown on (ITO) surface were prepared via a simple immersion of the substrate into a solution contains 1 mM Potassium Hexachloro Platinate (K 2 PtCl 6 ), 0.2 mM Anhydrous Copper (II) Sulfate (CuSO 4 ) anhydrous, 0.01 M Sodium dodecyl sulfate (SDS) and 10 mM Formic acid for 4 h at room temperature. The modification of Cu 2+ ion precursor play a role to determine the nanoparticles geometry obtained. The simultaneous reduction of metal ions leads to either a surface enriched with one component or an alloy type of structure depending on the bimetal composition. The bimetallic CuPt NPs dispersions are characterized by FESEM, EDX Mapping, XRD, HRTEM and XPS analysis. Key words: CuPt, Liquid phase deposition, Bimetallic CuPt NPs

Spatiotemporal development of soaked protein crystal.

Crystal soaking is widely performed in biological crystallography. This paper reports time-resolved X-ray crystallographic and microtomographic analyses of tetragonal crystals of chicken egg-white lysozyme soaked in mother liquor containing potassium hexachloroplatinate. The microtomographic analysis showed that X-ray attenuation spread from the superficial layer of the crystal and then to the crystal core. The crystallographic analyses indicated that platinum sites can be classified into two groups from the temporal development of the electron densities. A soaking process consisting of binding-rate-driven and equilibrium-driven layers is proposed to describe these results. This study suggests that the composition of chemical and structural species resulting from the soaking process varies depending on the position in the crystal.

Electroless Deposition of Platinum Nanoparticles in Room-Temperature Ionic Liquids

The electroless deposition of Pt nanoparticles (Pt-NPs) could be carried out by dissolving potassium tetrachloroplatinate(II) (K2[PtCl4]) in 1-ethyl-3-methylimidazolium (EMI(+)) room-temperature ionic liquids (RTILs) containing bis(trifluoromethylsulfonyl) imide (NTf2(-)) or tetrafluoroborate (BF4(-)) anion and small cations, such as H(+), K(+), and Li(+). In this case, no deposition of Pt-NPs occurred in RTILs without such small cations. The formation of Pt-NPs was only observed in RTILs containing trifluoromethanesulfonimide (HNTf2) and protons at high temperature (≥80 °C) when potassium hexachloroplatinate(IV) (K2[PtCl6]) was dissolved in the RTILs. The obtained Pt-NPs gave a characteristic absorption spectrum of ultrasmall Pt-NPs. The ultrasmall and uniform Pt-NPs of ca. 1-4 nm in diameter were produced and the Pt-NPs/EMI(+)NTf2(-) dispersion was kept stably for several months without adding any additional stabilizers or capping molecules. The identified Fourier-transform patterns along the [0 1 1] zone axis were observed for the TEM images of Pt-NPs. On the basis of the results obtained, a probable mechanism of the electroless formation of Pt-NPs is discussed.

Evaluation of synthesized platinum nanoparticles on the MCF-7 and HepG-2 cancer cell lines

Platinum nanoparticles (PNPs) were synthesized by chemical reduction of potassium hexachloroplatinate (IV) with trisodium citrate under vigorous stirring and addition of sodium dodecyl sulfate as stabilizer reagent. Reducing agent was chosen depending on the oxidation reactions and potential values of the chemical materials used in the experiment. The aim of this study is to investigate the effects of PNPs on the different cancer cell lines and cytotoxicity study of this nanomaterial. The morphology of PNPs was investigated by scanning electron microscope (XL30, Philips Electronics, Amsterdam, The Netherlands) with the ability to perform elemental analysis by EDX. Malvern Zetasizer 3000 HSA (Malvern Instruments, Worcestershire, UK) was used to determine the distribution of particle size and zeta potential of PNPs. The cytotoxicity property of the nanoparticles was evaluated by MTT assay on MCF-7 and HepG-2 cell lines, and the cytotoxic concentration 50% values were determined for 24 h.

Reductive Dechlorination of PCBs Using Photocatalyzed UV Light

AbstractFeasibility of photocatalytic dechlorination of PCB‐138 and Aroclor‐1254 using platinum loaded TiO2 (P25) in an alkaline 2‐propanol medium has been investigated. Experiments were conducted in batch mode using a Rayonet photo‐reactor under aerated and deaerated conditions with black lamps emitting around 350 nm as light source. Two forms of platinum deposition were investigated: Photochemically loaded P25 as well as addition of potassium hexachloroplatinate into the reaction medium. Partial dechlorination of PCBs was observed after 7 h of irradiation with pure TiO2 as catalyst when the reaction vessel was kept open to air. Complete dechlorination was observed after 5 h of irradiation in a deaerated environment. Enhanced photocatalytic efficiency was observed when platinum deposited P25 was used as catalyst, with the best result being obtained when aqueous potassium hexachloroplatinate was added into the reaction medium. Lower potassium hexachloroplatinate concentration (0.1 mM) yielded better performance.

Synthesis of hollow polypyrrole-platinum complex spheres and their successful application as a catalyst for decomposition of hydrogen peroxide

Hollow pyrrole-platinumpoly (PPy-Pt) complex spheres effectively catalyze the decomposition of hydrogen peroxide to form oxygen. The method used to synthesize the catalysts employs chemical polymerization of pyrrole with potassium hexachloroplatinate(IV) as oxidant and ZSM-5 molecular sieve as a hard template removable by dissolution. ZSM-5 molecular sieve used as template has the following merits: it can be easily removed, it is inexpensive and owing to micrometer size it shows a minimal aggregation. In addition, the use of the zeolite avoids the need for non-volatile surfactants which may be adsorbed onto the synthesized PPy-Pt complex spheres and interfere with their possible applications in catalysis. The new micron-sized hollow PPy-Pt complex spheres are produced simply and cost-effectively, and they can be expected to play an important role in wastewater treatment technologies. The synthetic method may represent a novel route to prepare hollow conductive polymer spheres doped by various metals for specific applications.

Surface modified bacterial biosorbent with poly(allylamine hydrochloride): Development using response surface methodology and use for recovery of hexachloroplatinate(IV) from aqueous solution

In this study, poly(allylamine hydrochloride) (PAA/HCl) was cross-linked with fermentation bacterial waste ( Escherichia coli) in order to introduce a large amount of amine groups as binding sites for potassium hexachloroplatinate(IV), as a model anionic pollutant. The sorption performance of PAA/HCl-modified E. coli was greatly affected by the dosages of PAA/HCl and crosslinker (epichlorohydrin, ECH), and by the pH of the modification reaction medium. These factors were optimized through the response surface methodology (RSM). A three-level factorial Box-Behnken design was performed, and a second-order polynomial model was successfully used to describe the effects of PAA/HCl, ECH and the pH on the Pt(IV) uptake ( R 2 = 0.988). The optimal conditions that were obtained from the RSM were 0.49 g of PAA/HCl, 0.05 mL of ECH and pH 10.02, with 1.0 g of dried E. coli biomass. The biosorption isotherm and kinetics studies were carried out in order to evaluate the sorption potential of the PAA/HCl-modified E. coli that was prepared under the optimized conditions. The sorption performance of the developed bacterial biosorbent was 4.36 times greater than that of the raw E. coli. Desorption was carried out using 0.05 M acidified thiourea and the biosorbent was successfully regenerated and reused up to four cycles. Therefore, this simple and cost-effective method suggested here is a useful modification tool for the development of high performance biosorbents for the recovery of anionic precious metals.

Characterization and photodegradation characteristics of organic dye for Pt–titania combined multi-walled carbon nanotube composite catalysts

Multi-walled carbon nanotubes (MWCNTs), titanium(IV) isopropoxide (TIP) and potassium hexachloroplatinate(IV) (K 2PtCl 6) were used for the preparation of Pt/MWCNT/TiO 2 composites. The composites were comprehensively characterized by Brauer–Emett–Teller surface area, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, energy dispersive X-ray and UV–vis absorption spectroscopy. The photoactivity of the prepared materials under UV irradiation was tested using the conversion of methylene blue (MB) in aqueous solution. According to the results of MB removal experiment, it can be considered that the MB removal effect of the Pt/MWCNT/TiO 2 composites is affected by two kinds of effects: adsorption effect by MWCNTs and photocatalytic effect by TiO 2. Finally, the photocatalytic effect increases due to photo-induced-electron absorption effect by MWCNTs and electron trap effect by Pt metal.

Studies of the reactions of platinum halo complexes with tin(II) halides

The reaction of a dichloromethane solution of a mixture of cis,trans-[PtCl2(SMe2)2] with a tetrahydrofuran solution of SnBr2 resulted in oxidation of platinum(II) with halogen exchange producing cis,trans-[PtBr4(SMe2)2]. Reaction of a mixture of cis,trans-[PtCl2(SEt2)2], potassium tetrachloroplatinate(II) or potassium hexachloroplatinate(IV) with SnBr2 in hydrochloric acid solution resulted in formation of predominantly anionic five-coordinate trichlorostannyl platinum(II) complexes. Reaction of potassium tetrabromoplatinate(II) with SnCl2 in hydrobromic acid in the presence of tetraphenylphosphonium bromide affords cis-[PPh4]2[PtBr2(SnBr3)2]. The insertion of SnCl2 into Pt–Cl bond of platinum(II) complexes cis-[PtCl2(L2)] {L2 = (PPh3)2; (PMe3)2; {P(OMe)3}2; dppm (bis(diphenylphosphino)methane); dppa (bis(diphenylphosphino)amine); and dppe (1,2-bis(diphenylphosphino)ethane)} is described.