Weight Of Polyvinylpyrrolidone Research Articles

Effect of chirality on PVP/drug interaction within binary physical mixtures of ibuprofen, ketoprofen, and naproxen: A DSC study

We report on the thermal behavior of freshly prepared binary drug/polymer physical mixtures that contained ibuprofen, ketoprofen, or naproxen as a drug, and polyvinylpyrrolidone (PVP), hydroxyethylcellulose (HEC), or methylcellulose (MC) as excipient. At 6-10 degrees C/min heating rates the DSC detected a sharp, single endotherm that corresponds to the melting of drug. On heating physical mixtures of PVP and racemic ibuprofen or ketoprofen at lower heating rates, another endotherm was registered in front of the original one. To observe the additional endotherm, specific minimal values of the heating rate and of PVP weight fraction were needed; for ibuprofen and ketoprofen they were 1.5 and 2.0 degrees C/min, and 5 and 15% (w/w), respectively. At greater PVP weight fractions the top temperatures, T(mp), of both peaks were reduced almost linearly indicating strong solid-state interfacial reaction between the drug particles and PVP matrix. The additional endotherm was abolished at greater heating rates (2 degrees C/min for ibuprofen, 3 degrees C/min for ketoprofen), by replacing the racemate with respective S+-enantiomer and by replacing PVP with HEC and MC. Hence, the possible inclusion of enantioselective component within the PVP/drug interaction, responsible for the amorphization of physical mixture over storage, is assumed.

Preparation, characterization and performance studies of polysulfone membranes using PVP as an additive

This study investigates the effect of polyvinyl pyrrolidone (PVP) of different molecular weights on the structure and permeation properties of polysulfone (PSf) membranes. The membranes were prepared by phase inversion method using PSf in two solvents, viz. N-methyl-2-pyrrolidone (NMP) and dimethyl acetamide (DMAc) separately. The surface morphology of the resulting membranes was analyzed by scanning electron microscope (SEM) and liquid displacement method. The membranes were subjected to ultrafiltration characterizations such as measurement of pure water flux (PWF), compaction factor (CF), equilibrium water content (EWC), hydraulic resistance and bovine serum albumin (BSA) rejection. Results show that the morphological parameters and flux performance of the membranes have a significant inter-relationship with the molecular weight of PVP. The membrane pore number and pore area are seen to increase with molecular weight of PVP. However, at a constant pressure, the PWF is found to decrease while BSA rejection increases significantly for the membranes prepared with both the solvents. For the membrane composition considered in this study, the solvent DMAc is found to be more suitable than NMP, in terms of BSA rejection, irrespective of the pH of the BSA solution. The maximum rejection found in this study is 76% with PSf/DMAc membrane with PVP 360,000 (at pH 9.3).

Optimization of Nanosized Silver Particle Synthesis via Experimental Design

Highly dispersed silver nanoparticles could be used as catalysts, as staining pigments for glasses and ceramics, as antimicrobial materials, in surface-enhanced Raman spectroscopy, as transparent conductive coatings, in electronics, etc. Consequently, the versatility of such particles provides strong incentives to the development of a systematic way to produce their dispersions. In this work, the optimization of the synthesis of nanosized silver particles by chemical reduction using formaldehyde in aqueous solution was studied. Effects of the possible processing variables such as the reaction temperature T, the mole ratio of [formaldehyde]/[AgNO3], [NaOH]/[AgNO3], the weight ratio of PVP/AgNO3, and the molecular weight (MW) of protective agent PVP (Polyvinyl−pyrrolidone) were considered. The data-driven model on the basis of the 44 designed experimental runs provided us the optimal conditions for closely achieving the product with the specified mean particle size and conversion of silver nitrate.

Synthesis and characterization of Rh(PVP) nanoparticles studied by XPS and NEXAFS

Rhodium nanoparticles were synthesized by the reduction of Rh 3+ ion in ethanol solvent with use of the polyvinylpyrrolidone (PVP) of various molecular weights and the solvent of different volume ratios of water to ethanol. The formed Rh(PVP) nanoparticles have been characterized by transmission electron microscopy (TEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and near edge X-ray absorption fine structure (NEXAFS) techniques. The TEM and AFM results show that the Rh(PVP) nanoparticles are monodispersed and do not agglomerate with each other. The particle size can be controlled by the molecular weight of PVP and/or the water/ethanol ratio of the solvent. The XPS and NEXAFS results indicate that the chlorine derived from RhCl 3(3H 2O) remains in the obtained nanoparticles but can be removed by heating.

P1780 Antimicrobial biodegradable composition based on high-molecular weight polyvinylpyrrolidone for the prophylaxis of experimental osteomyelitis

P1780 Antimicrobial biodegradable composition based on high-molecular weight polyvinylpyrrolidone for the prophylaxis of experimental osteomyelitis

Molecular Interaction among Probucol/PVP/SDS Multicomponent System Investigated by Solid-State NMR

Effects of polyvinylpyrrolidone (PVP) molecular weight on the solid-state intermolecular interactions among probucol/PVP/sodium dodecyl sulfate (SDS) ternary ground mixtures (GM) and the formation of nanoparticles were investigated by solid-state NMR spectroscopy. Ternary GMs of probucol were prepared with PVP (K12, K17, K30 or K90) and SDS at a weight ratio of 1:3:1 and were ground for 15, 30 and 60 min. Solid-state interactions were evaluated using powder X-ray diffraction (PXRD) and solid-state cross polarization/magic angle spinning (CP/MAS) (13)C NMR spectroscopy. A high resolution scanning electron microscopy (SEM) was employed to observe nanoparticles of probucol in the GM. The solid-state (13)C CP/MAS NMR results indicate that the low molecular weight PVP interacts with probucol and SDS more strongly than the high molecular weight PVP in the ternary GM. This finding was consistent with the result that smaller drug nanoparticles were obtained using low molecular weight of PVP. SEM images of probucol/PVP K12/SDS confirmed the presence of nanoparticles (15-25 nm) in the GM. Grinding-induced solid-state interactions among drug, PVP and SDS could be detected using solid state (13)C NMR. The interactions in both probucol-PVP and PVP-SDS should occur simultaneously to generate nanometer-sized particles of probucol.

Preparation and magnetic resonance imaging effect of polyvinylpyrrolidone‐coated iron oxide nanoparticles

Polyvinylpyrrolidone (PVP)-coated iron oxide nanoparticles were prepared by the thermal decomposition of Fe(CO)(5) (iron pentacarbonyl) in one step. X-ray diffraction (XRD), transmission electron microscopy (TEM), electrophoretic light scattering (ELS), infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) together with the variation of the molar ratio of PVP/Fe(CO)(5), solvent, and molecular weight of PVP, were used to characterize the PVP-coated iron oxide nanoparticles. Fifty to hundred nanometer-sized iron oxide nanoclusters with a spherical shape were formed in dimethylformamide (DMF), used as a solvent, and exhibited an enhanced stability in the aqueous media. Their magnetic properties were investigated by superconducting quantum interface device (SQUID). The in vitro cytotoxicity test revealed that the PVP-coated iron oxide nanoparticles exhibited excellent biocompatibility by MTT assay. Magnetic resonance imaging (MRI) effect was observed with the administration of PVP-coated iron oxide nanoparticles through the marginal vein of rabbit, resulting in improved detection of the liver lesions.

Effect of Polyvinylpyrrolidone Molecular Weight on the Critical Thickness, Crystallization, Densification and Properties of PLZT Films

ABSTRACTPLZT 9.5/65/35 ceramic films were prepared from the sol-gel solutions containing the stress-relaxing agent of polyvinylpyrrolidone(PVP) with the molecular weight of 40000, 360000 and 630000 (abbreviated as PVP40, PVP360 and PVP630) respectively. It is found that PVP40 can increase the critical thickness of the PLZT films to 0.22μm(compared with the critical thickness of 0.077μm in case of without PVP) and PVP360 and PVP630 can increase the critical thickness up to 0.49μm and 0.93μm individually. With the molecular weight of PVP increasing, the perovskite formation in the PLZT films was improved but the morphology of the films tended to be nano-porous. The films modified by PVP360 can be densified by optimizing the heat treatment conditions. When pyrolyzed at 600°C and then annealed at 700°C, the one-coating films with the thickness of 0.5μm were dense and exhibited a very slim hysteresis loop with the remnant polarization of 5.96×10−4μC/cm2 and coercive field of 21.51kV/cm, and a transmittance of around 90% and above in the wavelength of 450nm∼900nm.

Effects of chain length of polyvinylpyrrolidone for the synthesis of silver nanostructures by a microwave-polyol method

When silver nanostructures were prepared by a microwave(MW)-polyol method in the presence of polyvinylpyrrolidone (PVP) as a capping reagent, besides spherical nanoparticles, nanosheets, polygonal nanoplates, nanorods, and nanowires were synthesized within 8 min. Effects of chain length of PVP were examined by using three different molecular weights of PVPs (10, 40, and 360 k). When a short chain PVP (10 k) was used, nanosheets and nanoplates were dominantly prepared, while nanorods and nanowires were preferentially synthesized by using longer chain PVPs (40, 360 k). The maximum aspect ratios of nanorods and nanowires were ∼ 7, ∼ 130, and ∼ 200 for PVP (10, 40, 360 k), respectively. These results indicated that shape and size of Ag nanostructures can be controlled by changing chain length of PVP. On the basis of UV and visible absorption spectra of product solutions, the number density of Ag nanostructures including spherical nanoparticles increased rapidly with increasing chain length of PVP.

Stabilization and Improved in Vivo Performance of Amorphous Etoricoxib using Gelucire 50/13

Amorphous drugs have gained importance because of their advantageous biopharmaceutical properties; however, their stabilization remains a challenge. The purpose of this work was to stabilize the amorphous form of etoricoxib (ET) by using a low excipient/drug ratio to improve drug dissolution and thus bioavailability. The effect of Gelucire and polyvinylpyrrolidone (PVP) on stabilization and bioavailability of amorphous etoricoxib (AET) was studied. X-ray powder diffractometry, differential scanning calorimetry, and scanning electron microscopy were used to study the physical state of the drug. Dissolution studies were performed for melt granules of AET with Gelucire 50/13 (MG-AET) and solid dispersion with PVP (SDP) to differentiate dissolution performance. A stability study on samples was conducted for 3 months to evaluate the physical state of the drug and its dissolution in the formulation. The in vivo performance of the optimized and stable formulation of ET was evaluated in rat. Dissolution of MG-AET was significantly improved as compared to AET and SDP. Both factors, amorphization of drug and melt granulation with lipid, seemed to be important for improving dissolution. Stability data revealed that MG-AET was significantly advantageous for AET stabilization, whereas PVP was not. The amount of Gelucire required for the stabilization of one part of AET was 0.5 part (by weight), whereas even 1.5 part (by weight) of PVP failed to elicit the same result. The superior in vivo performance of MG-AET has been attributed to the altered physiochemical properties of AET and the presence of lipid in the system. Gelucire can stabilize AET and improve its biopharmaceutical performance at a low excipient/drug ratio and may provide a better alternative to conventional stabilizers such as PVP.

Preparation and catalysis of polymer-stabilized NiB catalysts on hydrogenation of carbonyl and olefinic groups

PVP-stabilized NiB catalysts were prepared using the chemical reduction method with NaBH 4, dissolving the water-soluble polymer of polyvinylpyrrolidone (PVP) in the precursor salt solution as a protective reagent. The PVP-NiB catalysts were characterized and examined for their catalysis on the hydrogenation of furfural, crotonaldehyde and citral. PVP polymer could adsorb on the nano-particles of NiB via a weak coordination bonding and stabilize it; a molecular weight of PVP of about 10,000 was suitable, and the optimal quantity of PVP (PVP/Ni) in the salt solution for preparing catalysts was around 20. The PVP-NiB samples were characterized by XRD as an amorphous structure and by TEM with a particle size distribution in the range of 3–5 nm. On catalysis, the PVP-NiB catalyst was significantly more active and slightly more selective than NiB for hydrogenating furfural to furfuryl alcohol and crotonaldehyde to butyraldehyde. A good yield of citronellal, about 90%, could be obtained by reducing citral in cyclohexane at a low reaction temperature of 50 °C over the PVP-NiB catalyst.

Gas separation properties of carbon molecular sieve membranes derived from polyimide/polyvinylpyrrolidone blends: effect of the molecular weight of polyvinylpyrrolidone

Carbon molecular sieve (CMS) membranes were prepared using aromatic polyimide (PI) and polyvinylpyrrolidone (PVP) polymer blends. The characteristics of the carbon structures and the gas permeation properties of the CMS membranes pyrolyzed at 500 and 700 °C were investigated in terms of the molecular weight of PVP (the thermally labile polymer). The PI/PVP blend showed two separate thermal decomposition steps. In an argon atmosphere, PVP underwent complete decomposition first at 350–450 °C, while the thermal degradation of PI occurred at 550–650 °C. The nitrogen adsorption isotherm of the CMS membranes showed that the thermal decomposition of PVP significantly affected the average pore volume of the resultant CMS membranes, and that it depended upon the molecular weight of PVP. CMS membranes with a higher molecular weight of PVP pyrolyzed at 550 °C exhibited an enhanced O 2 gas permeability from 4200.28 × 10 −18 to 6075.405 × 10 −18 m 2 s −1 Pa −1 (560 to 810 barrers) and a reduced O 2/N 2 selectivity of 10–7.

Mechanism of growth of colloidal silver nanoparticles stabilized by polyvinyl pyrrolidone in γ-irradiated silver nitrate solution

Silver nanoparticles were prepared by using polyvinyl pyrrolidone (PVP) as a stabilizer and γ-irradiation. Transmission electron microscopy (TEM) results showed that both the amount and the molecular weight of PVP in the irradiated solution considerably affect the average size of the silver nanoparticles. The average size of the silver nanoparticles decreases with increasing the amount of PVP in the solution, but increases with increasing its molecular weight. Further, TEM showed that the silver nanoparticles become disassembled into smaller nanoparticles after dilution with distilled water and sonication. Since the processes of dilution and sonication are not expected to result in chemical reactions or to split the silver nanoparticles, we conclude that each silver nanoparticle prepared by γ-irradiation consists of several smaller nanoparticles surrounded by PVP. Thus, based on these observations, we propose a three-step mechanism for the growth of the silver nanoparticles under the conditions considered here. In the first step, the silver ions interact with PVP, then in the second step the silver ions that are exposed to γ-irradiation are reduced to silver atoms; nearby silver atoms then aggregate at close range. These aggregates are the primary nanoparticles. Finally, these primary nanoparticles coalesce with other nearby primary nanoparticles or interact with PVP to form larger aggregates which are the secondary (final) nanoparticles.

Nanoscopic behavior of polyvinylpyrrolidone particles on polysulfone/polyvinylpyrrolidone film

We revealed morphology and physicochemical behavior of a widely used powerful hydrophilizing agent, polyvinylpyrrolidone (PVP), present on polysulfone (PS)/PVP films by atomic force microscopy (AFM). This is the first time such clear PS/PVP phase-separated morphology was observed by nanoscopic technique. The film surfaces were observed by the identical observation mode, probe and scanning conditions to reveal the change of PVP morphology and behavior between dry and wet conditions. Morphology was related to biocompatibility by combining AFM data with results of surface element composition, contact angle, adhesion amount of rabbit platelet and relative amount of adsorbed fibrinogen. PVP nano-particles of one or several molecules were formed on the dry PS/PVP film surfaces. Amount of PVP present on the surfaces increased with the molecular weight of PVP. At a mixed amount of 1–5 wt%, PVP K90 formed crowded particles on the dry surface. When wet, they swelled, followed by their union to produce a smooth surface leading to improved biocompatibility. The highest biocompatibility with excellent mechanical strength is achieved by blending the highest molecular weight PVP K90 at 1–5 wt%.

High-throughput analysis of telomerase by capillary electrophoresis.

The enzyme telomerase is expressed in (85-90)% of all human cancers, but not in normal, non-stem cell somatic tissues. Clinical assays for telomerase in easily obtained body fluids would have great utility as noninvasive, cost-effective methods for the early detection of cancer. The most commonly used method for the detection and quantification of telomerase enzyme activity is the polymerase chain reaction (PCR)-based assay known as the telomerase repeat amplification protocol or TRAP assay. Most of the TRAP assay systems use a slab-gel based electrophoresis system to size and quantify the PCR-amplified extension products. We are developing high-throughput capillary electrophoresis (CE) methods for the analysis of TRAP/PCR products. The TRAP assay was conducted on lysates of the human lung cancer cell line A-549 in reactions containing 5-100 cells. TRAP/PCR products were generated using a fluorescent 4,7,2'4'5'7',-hexachloro-6-carboxyfluorescein(HEX)-labeled TS primer and analyzed on the Applied Biosystems Model 310 CE system using POP4 polymer. After analysis with GeneScan and Genotyper software, the total peak areas of the TRAP ladder extension products were computed using Microsoft Excel. Results were compared with unlabeled TRAP/PCR products analyzed on the Bio-Rad BioFocus 3000 CE system using 6% high molecular weight polyvinylpyrrolidone (HMW PVP) polymer and SYBR Green I dye. Both CE systems were able to resolve the TRAP ladder products with high reproducibility and sensitivity (5-15 cells). With the appropriate robotic sample handling system, these CE methods would enable performing the telomerase TRAP assay with increased sensitivity, reproducibility and automation over slab-gel methods.

Effects of molecular weight of polyvinylpyrrolidone on precipitation kinetics during the formation of asymmetric polyacrylonitrile membrane

AbstractThe effects of the molecular weight of polyvinylpyrrolidone (PVP) on the precipitation kinetics during the formation of an asymmetric polyacrylonitrile membrane and the resulting membrane morphology were investigated. The precipitation kinetics of a polyacrylonitrile membrane was explored using the light‐transmission method and optical microscopic observation, with an emphasis on the effective diffusion coefficient of the nonsolvent as a measure of the solvent/nonsolvent exchange rate. The retarded precipitation behaviors were not observed in all dope solutions. Also, the phase‐ separation rate was steeply decreased with the amount of PVP. It was deduced that increase of the viscosity of the polymer solution upon the addition of PVP hindered the intrusion of the nonsolvent, resulting in a decrease of the phase‐separation rate. When the same amount of PVP with a different molecular weight was used, the precipitation rate decreased with increase of the molecular weight of PVP. Therefore, the nonsolvent tolerance, the interaction between PVP and H2O, as well as the viscosity are regarded as important factors influencing the precipitation rate. The effective diffusion coefficient of the nonsolvent is closely related to the nonsolvent tolerance of the polymer solution, resulting from a pseudoternary phase diagram. The use of high molecular weight PVP strongly depressed the formation of macrovoids inside of the membrane and allowed a dense skin layer to form. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 57–68, 2002

Evaluation of Solid Dispersions of Clofazimine

ABSTRACTClofazimine (CLF) was formulated with polyethylene glycol (PEG) and polyvinyl pyrrolidone (PVP) as a solid solid dispersion (SSD) to increase the aqueous solubility and dissolution rate of the drug. Different molecular weights of PEG (1500, 4000, 6000, and 9000 Da) and PVP (14,000 and 44,000 Da) were used in different drug:carrier weight ratios (1:1, 1:5, and 1:9) and their effect on the dissolution performance of the drug was evaluated in USP Type 2 apparatus using 0.1 N HCl medium. The dissolution rate was compared with corresponding physical mixtures, a currently marketed soft gelatin capsule product, and free CLF. The effect of different methods of preparation (solvent/melt) on the dissolution rate of CLF was evaluated for PEG solid dispersions. Saturation solubility and phase solubility studies were carried out to indicate drug:carrier interactions in liquid state. Infrared (IR) spectroscopy and X-ray diffraction (XRD) were used to indicate drug:carrier interactions in solid state. Improvement in the drug dissolution rate was observed in solid dispersion formulations as compared to the physical mixtures. The dissolution rate improved with the decreasing weight fraction of the drug in the formulation. Polyvinyl pyrrolidone solid dispersion systems gave a better drug release profile as compared to the corresponding PEG solid dispersions. The effect of molecular weight of the PEG polymers did not follow a definite trend, while PVP 14,000 gave a better dissolution profile as compared to PVP 44,000. Improvement in saturation solubility of the drug in the solid dispersion systems was noted in all cases. Further, IR spectroscopy indicated drug:carrier interactions in solid state in one case and XRD indicated reduction in the crystallinity of CLF in another. It was concluded that solid-dispersion formulations of Clofazimine can be used to design a solid dosage form of the drug, which would have significant advantages over the currently marketed soft gelatin capsule dosage form.

Synthesis of Polyvinylpyrrolidone under Secondary Inhibition Conditions

A new approach to controlling the molecular weight of polyvinylpyrrolidone in radical polymerization is considered. When the reaction is performed in the presence of a stable nitroxyl radical, 2,2,6,6-tetramethylpiperidyl-1-oxyl, the effect of secondary inhibition is manifested after the end of the induction period. This effect can be used for preparing polymers with prescribed molecular weights.

Effect of Polyvinylpyrrolidone on the States of Water in Water-in-Oil Microemulsions with Betaine Surfactant

A water-in-oil (w/o) microemulsion was prepared with the zwitterionic surfactant dodecyl betaine (C12BE), n-pentanol (C5OH), n-heptane (C7H16) and water. Effects of polyvinylpyrrolidone (PVP) with different molecular weight on the state of water in w/o microemulsions at a given water/C12BE molar ratio were investigated by FT-IR and differential scanning calorimetry (DSC). The experimental results showed that addition of PVP resulted in an increase of the content of the bound water in water pool of a w/o microemulsion, but a decrease of the amount of the bulky water. The higher the molecular weight of PVP, the more bound water; and the less bulk water. The change of the trapped water was not obvious due to the interference of C5OH.

Composite Fibers Based on Chitin

Composite fibers containing chitin and cellulose ethers (methyl, hydroxyethyl, and hydroxypropyl cellulose) and also chitin and polyvinylpyrrolidone were prepared. The effect of the ratio of system components and also the molecular weight of polyvinylpyrrolidone on the deformation-strength characteristics of the composite fibers and their supramolecular organization was studied.