Polyvinylpyrrolidone Ratio Research Articles

Effect of solvent and PVP on electrode conductivity in laser-induced reduction process

Laser sintering process is a promising technique which can sinter an electrode pattern selectively without mask. In this study, metal oxide nanoparticle with several solvents and various molar ratio of polyvinylpyrrolidone (PVP) is prepared to optimize a fabrication of a copper electrode pattern. As a result, the solvent with exothermic heat flow and low absorption cross-section shows better pattern shape and higher conductivity in selective laser sintering. Additionally, PVP, a reductant, affects to the quality of electrode, too. High molar ratio and large amount of PVP make the laser sintering process window broad and the specific resistivity low.

Polyol thermolysis synthesis of TiO2 nanoparticles and its paste formulation to fabricate photoanode for dye-sensitized solar cells

Titanium dioxide (TiO2) nanoparticles (NPs) were prepared by a simple polyol thermolysis process using various mole ratios of titanium tetrachloride (TiCl4) and polyvinylpyrrolidone (PVP). The prepared TiO2 NPs were characterized by TG/DTA, XRD, SEM, and BET analysis. The TiO2 NPs obtained using 0.1 M of TiCl4 and 0.02 M of PVP have high surface area with lesser particles size than the same obtained using 0.1 M of TiCl4 with other mole ratios of PVP. The high surface area TiO2 NPs were used to formulate TiO2 paste. The impact of ethyl cellulose, terpineol, and dibutyl phthalate in the formulation of TiO2 paste was optimized with respect to standard TiO2 paste (Dyesol Ltd.) on the adsorption of dye was studied by UV–Vis spectroscopy. The photovoltaic performance of DSSCs fabricated using the formulated TiO2 paste has achieved 97.83 % of power conversion efficiency (PCE) (η = 4.5 %) with respect to the standard TiO2 paste (Dyesol Ltd.) and its PCE were found to be 4.6 % (η). This PCE value was nearly closer to that of the same DSSC fabricated using the standard TiO2 paste (Dyesol Ltd.) and higher than the P25 TiO2 (Degussa) paste and its achieved PCE were found to be 86.04 %.

Preparation and in vitro evaluation of hydrophilic fenretinide nanoparticles

Fenretinide is an effective anti-cancer drug with high in vitro cytotoxicity and low in vivo systemic toxicity. In clinical trials, fenretinide has shown poor therapeutic efficacy following oral administration – attributed to its low bioavailability and solubility. The long term goal of this project is to develop a formulation for the oral delivery of fenretinide. The purpose of this part of the study was to prepare and characterize hydrophilic nanoparticle formulations of fenretinide. Three different ratios of polyvinyl pyrrolidone (PVP) to fenretinide were used, namely, 3:1, 4:1, and 5:1. Both drug and polymer were dissolved in a mixture of methanol and dichloromethane (2:23 v/v). Rotary evaporation was used to remove the solvents, and, following reconstitution with water, a high pressure homogenizer was used to form nanoparticles. The particle size and polydispersity index were measured before and after lyophilization. The formulations were studied by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and X-ray powder diffraction (XRPD). The effectiveness of the formulations was assessed by release studies and Caco-2 cell permeability assays. As the PVP content increased, the recovered particle size following lyophilization became more consistent with the pre-lyophilization particle size, especially for those formulations with less lactose. The DSC scans of the formulations did not show any fenretinide melting endotherms, indicating that the drug was either present in an amorphous form in the formulation or that a solid solution of the drug in PVP had formed. For the release studies, the highest drug release among the formulations was 249.2±35.5ng/mL for the formulation with 4:1 polymer-to-drug. When the permeability of the formulations was evaluated in a Caco-2 cell model, the mean normalized flux for each treatment group was significantly higher (p<0.05) from the fenretinide control. The formulation containing 4:1 polymer-to-drug ratio and 6:5 lactose-to-formulation ratio emerged as the optimal choice for further evaluation as a potential oral delivery formulation for fenretinide.

The effect of PVP contents on the fiber morphology and piezoelectric characteristics of PZT nanofibers prepared by electrospinning

Lead zirconate titanate (PZT, Pb(Zr0.53Ti0.47)O3) nanofibers were prepared from a PZT precursor sol containing PVP (polyvinylpyrrolidone) by electrospinning. XRD (X-ray diffraction) measurements indicated that the concentration of the sol and the heat treatment of the as-spun nanofibers at temperatures over 650°C are essential for the growth of PZT phase. The effects of the PVP content on the viscosity of the sol, on the fiber morphology and on the piezoelectric characteristics were investigated. The mole ratio of PVP/(Ti+Zr) of 1.25 was found to be optimum for good piezoelectric characteristics.

Preparation of platinum nanoparticle catalyst for propane dehydrogenation.

Supported Pt nanoparticle catalysts were prepared by combing a chemical reduction method with an ultrasonic sonication loading method. Several techniques including transmission electron microscopy (TEM), nitrogen sorption technique and pyridine adsorption Fourier-transform infrared (Py-IR) were applied to characterize the physicochemical properties of these catalysts. The catalytic performance of catalysts was evaluated in the dehydrogenation of propane. The influence of the preparation method of Pt nanoparticles, the ratio of Polyvinyl Pyrrolidone (PVP) to Pt, loading method and different supports on the catalytic performance was investigated. PVP is useful for controlling the size of Pt nanoparticles and a PVP/Pt ratio of 15 is favorable to achieve a good catalytic performance. NaBH4 reduction is better than ethanol refluxing in preparing Pt nanoparticles. The ultrasonic sonication is effective to load the Pt nanoparticles onto the support channels. The mesoporous alumina proved to be a good catalyst support due to its high surface area and unique pore structure.

Insights into the surface property and blood compatibility of polyethersulfone/polyvinylpyrrolidone composite membranes: toward high-performance hemodialyzer

Applications of blood purification membranes are fuelled by diverse clinical needs, such as hemodialysis, hemodiafiltration, hemofiltration, plasmapheresis, and plasma collection. For clinical usage, the adding of polyvinylpyrrolidone (PVP) is the general protocol for the design of antifouling and antithrombotic properties integrated artificial membranes. In the present work, to insight into the detailed surface properties and blood compatibilities of the PVP blended composite membranes, we synthesized a series of PVP polymers with different molecular weights using reversible addition fragmentation chain transfer polymerization and designed a series of polyethersulfone (PES)/PVP composite membranes by a physically blending method. The effects of PVP molecular weights and blending ratios on the surface properties and the blood compatibilities of the composite membranes were investigated in detail. The surface attenuated total reflection Fourier transform infrared spectra and scanning electron microscopy pictures indicated that the PVP was successfully immobilized into the membranes, and the composite membranes exhibited morphology transformation from finger-like structure to sponge-like structure, which indicated that the composite membrane had tunable porosity and permeability by adding PVP. The blood compatible tests revealed that the composite membranes showed increased hydrophilicity, decreased plasma protein adsorption, suppressed platelet adhesion, and prolonged blood clotting time compared with pristine PES membrane. These results indicated that the PES/PVP composite membranes exhibited enhanced antifouling and antithrombotic properties than the pristine PES membrane. Meanwhile, the results also suggested that the composite membranes with larger molecular weight PVP and higher blending ratios might show better blood compatibility. Copyright © 2014 John Wiley & Sons, Ltd.

Microwave-assisted synthesis of size-controlled silver nanoparticles using polyvinyl pyrrolidone as a reducing agent

In this work, stable concentrated aqueous dispersions of size-controlled silver nanoparticles were prepared by microwave irradiation of silver nitrate (AgNO3)/polyvinyl pyrrolidone (PVP) solution using polyvinyl pyrrolidone (PVP) as a reducing and stabilising agent. Crystal structure, size, optical properties of the silver nanoparticles were characterised by means of X-ray diffraction (XRD), scanning electron microscope (SEM), ultraviolet visible spectroscopy (UV-vis), Fourier transform infrared (FT-IR). Quasi-spherical nanoparticles, nanocube and flake-like nanoparticles were synthesised by controlling the experimental parameters such as the ratio of PVP to AgNO3, and the particle size can be conveniently adjusted to 50 nm.

The role of light anhydrous silicic acid on physical stability of troglitazone solid dispersion under humidified conditions

The aim of this study was to confirm whether light anhydrous silicic acid (Aerosil) could exhibit a stabilizing effect on the physical stability of solid dispersion under humidified conditions. Ternary solid dispersions consist of 50% troglitazone, and various ratios of polyvinyl pyrrolidone and Aerosil were prepared using the co-milling method and then evaluated for their crystallizing behavior under storage conditions. The results showed that Aerosil has a stabilizing effect against crystallizing in the dihydrate of troglitazone under humidified conditions and has an appropriate ratio range (Troglitazone/PVP/Aerosil=50/30–20/20–30) in the ternary solid dispersion, when considering total quality satisfaction such as physical stability and dissolution. Furthermore, it was found that hydrophobized Aerosil R805 has a stronger stabilizing effect than hydrophilic Aerosil 200. The stabilizing mechanism was discussed based on the comparative results and possible molecular interaction.

Release behavior of cilostazol according to the fabrication methods and ratio of HPMC/PVP

In this study, we manufactured a polymer blend, using hydroxypropyl methylcellulose (HPMC) and polyvinylpyrrolidone (PVP), by spray drying method to improve the characteristics of polymers. This polymer blend was used to improve the drug delivery of cilostazol, a phosphodiesterase inhibitor that decreases serum triglycerides, is a direct arterial vasodilator, and inhibits platelet aggregation and smooth muscle cell proliferation. Compatibility with this drug was achieved when the polymer blend of HPMC and PVP were spray dried. Various ratios of the two ingredients were blended to determine optimum release rate of this poorly soluble drug. Cilostazol blended with different ratios of HPMC and PVP was analyzed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to confirm surface morphology and combination of drug and polymer. Differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR) were conducted to confirm thermodynamic properties and chemical structure change, respectively. Change in the drug release of cilostazol was expected by adjusting the HPMC and PVP blend ratio in gastric juice (pH 1.2). Open image in new window

Influence of water-soluble polymers on the in vitro performance of floating mucoadhesive tablets containing metformin

Context: The in vitro performance of floating mucoadhesive metformin tablets was optimized using different polymer ratios of polyvinylpyrrolidone (PVP) tamarind seed gum (TSG) and hydroxypropylmethylcellulose (HPMC).Objective: The objectives of this investigation were to investigate the combinatorial effects of PVP, TSG and HPMC; to study the work of adhesion measured on stainless steel (Wss) and on rabbit gastric mucosa (Wgm); and a comparison of hydrophilic and more hydrophobic tablets.Material and methods: In vitro performance was measured as tablet hardness (H), tablet floating lag time (FLT), time needed to release 60% of drug content (t60%), swelling thickness (S), Wss and Wgm. To compare the effects, a simplex lattice mixture design was used.Results and discussion: H, FLT, Wss and Wgm were found dependent on polymer ratio. H was increased when PVP ratio was increased. FLT, Wss and Wgm were increased when HPMC ratio was increased. The p value for the lack of fit for all models were greater than 0.05. An approximate linear correlation between Wgm and Wss was established (R2 = 0.71). The tablets containing PVP resulted in larger H, shorter FLT and t60%, whereas Wss and Wgm were enhanced.Conclusion: The different in vitro performance of tablets containing different water-soluble polymers could be explained partially by the differences in the hydrophilic properties of the polymers and the ability of PVP to interact with HPMC or TSG. An equation established is used to conclude mucoadhesion based on adhesion measurements on stainless steel.

Optical Studies of Poly (N-Carbazole) (PVK) Blending with Polyvinylpyrrolidone (PVP) Using Tauc/Davis-Mott Model

The optical absorption spectra of blended poly (N-carbazole) (PVK) with polyvinylpyrrolidone (PVP) in various compositions are investigated. A doctor blade technique was used to coat the blended polymer on a quartz substrate. The electronic parameters such as absorption edge (Ee), allowed direct band gap (Ed), allowed indirect band gap (Ei), Urbach edge (Eu) and steepness parameter (γ) were calculated using Tauc/Davis-Mott Model. The results reveal that the Ee, Ed and Ei increase with increasing of PVP ratio. There also have variation changing in Urbach energy and steepness parameter.

Effects of PVP on the preparation of nanosized Al2O3 supported Ni catalysts by polyol method for catalytic partial oxidation of methane

Small Ni metal nanoparticles (<10nm) supported on γ-Al2O3 were prepared by a simple polyol method in ethylene glycol (EG) medium. The effects of PVP (polyvinylpyrrolidone) ratio on the crystallite and particle sizes were determined by XRD and TEM analysis. The activities of the catalysts were evaluated for partial oxidation of methane (CPOM). The results indicated that in polyol process varying the ratio of PVP resulted in smaller Ni crystallite sizes, good metal dispersion and high catalytic activity. When the weight ratio of PVP to metal salt increased from 0:1 to 5:1 in the as-prepared catalyst the particle sizes decreased from 13.10nm to 8.0nm, and methane conversion increased from 69.40% to 92.00% at 800°C. The activity of the catalysts in CPOM reaction also depended on the thermal treatment. H2-pretreated catalysts exhibited higher activity than non pre- treated catalyst, suggesting that the presence of organic matrix hinders the access to the nickel active sites. Among the catalysts tested, Ni/γ-Al2O3 catalyst with a weight ratio of PVP to metal salt 5:1 exhibited the higher activity (92%) and stability with a gas hour space velocity of 157,500 (Lkg−1 h−1) at 800°C.

Synthesis and characterization of a novel wound dressing by PVP/ PAANa/chitosan with semi-interpenetrating polymer network structure

AbstractA novel hydrogel wound dressing with semi-interpenetrating polymer network structure (semi-IPN) was prepared by radical polymerization of acrylic acid with potassium persulfate (K2S2O8) as initiator and N, N'-methylenebisacrylamide (MBA) as cross-linking agent in the presence of chitosan (CTS) and polyvinyl pyrrolidone (PVP). Hydrogels were characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). SEM displayed semi- IPN hydrogels' creased surface with some scale-like wrinkles, thus improving the absorptive capability which has been considered as a most important characteristic of wound dressings. It was found that the content of cross-linking agent and the mass ratio of PVP and CTS had much influence on the mechanical properties of the hydrogel, varying from brittle plastics to elastomer due to the different degrees of cross linking. Since tensile strength is partly in inverse ratio to the hydrogel absorbent capability, the article offers an analysis of varying material proportion in order to obtain an optimum properties of the hydrogel wound dressing .

Synthesis and Conductometric Property of Sol-Gel-Derived ZnO/PVP Nano Hybrid Films

ZnO nanoparticles immobilized in polyvinylpyrrolidone (PVP) were prepared using sol-gel dip-coating technique with varying Zn2+/PVP ratios. The films were characterized using atomic force microscopy, x-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy for chemical analysis. The size and concentration of ZnO particles decreased as the Zn/PVP ratio decreased. Under low Zn2+/PVP molar ratios, ZnO particles were clearly well separated and capped in the PVP polymer matrix. Electrical resistivity of 108 Ω cm was achieved under these deposition conditions.

PMMA Modified PVDF Hollow Fiber Ultrafiltration Membranes

Polymethylmethacrylate (PMMA) modified poly(vinylidene fluoride) (PVDF) hollow fiber ultrafiltration membranes were prepared by wet spinning method using polyvinylpyrrolidone (PVP) as pore-foaming agent and mixture of dimethyl formamide (DMF)/methyl ethyl ketone (MEK) as solvent. The effects of PVDF, PMMA, PVP, and solvent ratios in the spinning solution on the permeation properties of the formed membranes were studied. The results showed that the performance of the membrane is the best with a pure water flux of 117 L/m2•h and rejection rate of 82% to bovine serum albumin (BSA), when the concentrations of PVDF, PMMA, PVP, DMF and MEK are 17, 3, 3, 60 and 17 wt%, respectively.

Synthesis of Palladium-Platinum Bimetallic Nanoparticles and their Catalytic Activity towards the Hydrogenation Reaction of Palm Olein

Bimetallic Pd-Pt catalyst was successfully prepared via conventional heating (CH), microwave (MW), and ultrasonic irradiation (US) methods. Bimetallic Pd-Pt nanoparticles stabilized with polyvinylpyrrolidone (PVP) were prepared with molar ratio of PVP to metal, 40:1. Smaller particles sizes with narrow distribution obtained after 30min and 10min with US and MW methods respectively. All the particles are spherical or near spherical in shape. The average particles size and size distribution for Pd-Pt (US) nanoparticles was 1.28 ± 0.29 nm, while for Pd-Pt (MW) nanoparticles was 1.05 ± 0.21 nm. The average particles sizes of these bimetallic nanoparticles are comparable with the classical CH method, which was 1.23 ± 0.25 nm. Based from the XPS analysis, surface compositions of Pd and Pt show that PdPt(CH) and PdPt(MW) catalyst were enriched with Pd, meanwhile PdPt (US) composition was comparable and it might be in alloy structure formation. The activity of these three catalysts for the hydrogenation reaction of palm olein was studied. The reaction conducted under ambient temperature and atmospheric pressure. A molar ratio of palm olein to catalyst of 25000:1 has been used in the hydrogenation reaction to determine the conversion of linoleate, selectivity of trans-isomer and iodine value (IV) in the hydrogenated palm olein. After 180 min of reaction, full conversion achieved with Pd-Pt (MW) catalyst, while only 91.4% and 80.6% conversion achieved with Pd-Pt (US) and Pd-Pt (CH) respectively. However, the Pd-Pt (MW) catalyst shows the highest elaidate selectivity after 180 min, which was up to 13.1%, meanwhile the elaidate selectivity of 11.82% and 8.1% for both Pd-Pt (US) and Pd-Pt (CH) respectively. Even though higher conversion of linoleate achieved in short time and lower trans selectivity produced with Pd-Pt bimetallic catalyst. The IV calculated shows that Pd-Pt (MW) catalyst has the lowest IV then followed by Pd-Pt (US) and Pd-Pt (CH) catalysts.

A novel and facile method to prepare porous hollow CuO and Cu nanofibers based on electrospinning

Here, we have introduced a novel and facile method to prepare porous hollow CuO nanofibers and Cu nanofibers via single-spinneret electrospinning of polyvinyl pyrrolidone (PVP)/copper acetate (Cu(CH3COO)2) solution followed by annealing and reduction. In this approach, the diameter and the shell thickness of the fibers can be simply adjusted by the concentration of PVP and the ratio of PVP to Cu(CH3COO)2. A possible mechanism is proposed to explain the formation of porous hollow CuO and Cu nanofiber. This method provides an new idea to prepare metal-oxide and metal fibers with a long continuous porous hollow morphology.

Slurry Nebulization-Inductively Coupled Plasma Mass Spectrometry with Solution Calibration for Determination of Ultratrace Boron in High Pure Nuclear Graphite Powder

The method of slurry nebulization-inductively coupled plasma mass spectrometry ( SN-ICP-MS) was developed for the direct determination of trace boron in high purity graphite powders. The particle size was controlled <5 mu m after the graphite powders was ground and sifted. Polyvinylpyrrolidone (PVP) was used as the dispersant in slurry preparation. The optimal mass ratio of PVP to the graphite was found to be 0.5. Well proportioned and stable slurry solution was obtained by magnetic stirrer. About 0.1 mol/L NH4OH as the aqueous medium could provide the optimal pH of 10 for the stable slurry and eliminate the memory effect of B. ICP-MS was operated in a higher resolution mode (0.6 amu) to eliminate the interference with the matrix C-12 by peak tailing. Oxygen was added into the plasma at a flow rate of 60 mL/min, to resolve carbon deposition on the sampler and skimmer cones and accelerate particle dissociation in the plasma. External calibration with aqueous solution standards was established for quantification. Beryllium was chosen as the internal standard to evaluate the efficiency of matrix effect correction. A correlation coefficient of 0.9995 for boron concentrations from 2 to 200 mu g/L was obtained with a detection limit (3s) of 0.095 mu g/g. As a practical application, with the advantage of simple, quick and low losing, the proposed method was applied to determine the trace boron in four nuclear graphite samples ( claimed 99.999% purity), with the satisfactory recoveries for the spike tests in the range of 97.2% - 103.1%.

Influence of polymer content on stabilizing milled amorphous salbutamol sulphate

The study investigates the influence of polyvinyl pyrrolidone (PVP) concentration on stabilizing the amorphous form of salbutamol sulphate (SS) before and after storage under ambient and elevated humidity conditions. Different mass ratios of SS and PVP (0–90 wt%) were co-milled using a planetary ball mill. X-ray powder diffraction (XRPD), high sensitivity differential scanning calorimetry (HSDSC), dynamic vapor sorption (DVS), infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and Raman microscopy (RM) were used to analyze the stability of the co-milled mixtures against heat and humidity treatments as well as storage at different humidity conditions. Prior storage, DSC and DVS analyses revealed that re-crystallization of amorphous SS was suppressed above PVP content of 33 wt%. Probable hydrogen bond interaction between SS and PVP was found in FT-IR analysis. XRPD diffractograms and SEM analysis showed stability against re-crystallization was achieved in the co-milled mixtures with a minimum PVP content of 80 wt% after storage. Homogeneous distribution of SS and PVP from RM analysis showed fine clustering of SS and PVP, suggesting the formation of an amorphous dispersion at molecular level. The results provide insights on the application of thermal and humidity treatments, accelerated stability testing and investigations on drug–excipient interactions to predict the minimum ratio of an excipient for stabilizing the amorphous state of a milled API.

Polymer blends used to prepare nifedipine loaded hollow microspheres for a floating-type oral drug delivery system: In vitro evaluation

The aim of this study was to investigate whether hollow microspheres prepared from polymer blends of polyvinyl pyrrolidone (PVP) and ethyl cellulose (EC) could improve the vitro release behavior of the poorly water-soluble drug nifedipine. Hollow microspheres containing nifedipine were prepared by a solvent diffusion-evaporation method using various ratios of PVP and EC codissolved with drug in ethanol/ether (5:1, v/v). The hollow microspheres could float in release medium for more than 24 h, and floating capacities were not be influenced by mixing PVP. In vitro release profiles of hollow microspheres prepared using EC along showed an initial burst release to some extent, and the cumulative release percentage was less than 55% after 24 h. But, not only the slope but also the shape of the release curves was affected by using mixture of PVP and EC. What's more important, when the ratio (PVP/EC) increased to 1.5:8.5, the cumulative release percentage could be increased to 95.8%. Furthermore, the release rate of microspheres showed a zero order approximate dynamic model and could be expressed by the following equation: Q=3.78t+8.52 (r=0.990). Consequently, hollow microspheres prepared using polymer blends of PVP and EC (1.5:8.5, w/w) could be suitable for floating-type controlled-release delivery systems for the oral administration of nifedipine.