High Molecular Weight Polyvinylpyrrolidone Research Articles

Hierarchical Lotus Leaf-Like Mesoporous Silica Material with Unique Bilayer and Hollow Sandwich-Like Folds: Synthesis, Mechanism, and Applications

A facile and straightforward strategy was developed to synthesize hierarchical lotus leaf-like mesoporous silica material (LLMSM) with unique bilayer and hollow sandwich-like folds using hexadecylamine as a structure-directing agent, high molecular weight polyvinylpyrrolidone as a structure-stabilizing agent, and tetraethyl orthosilicate as a silica precursor in the mixed solvents of water and ethanol. The formation mechanism of LLMSM was proposed based on a series of experimental investigations. This new particulate platform exhibited superior adsorption capacity toward organic dye, effective catalytic reduction of 4-nitrophenol as a Ag catalyst supporter, and a multistage sustained drug release profile. Many other applications can be also envisaged for such a hierarchical structure.

Network structure studies on γ–irradiated collagen–PVP superabsorbent hydrogels

Collagen–polyvinylpyrrolidone (PVP) superabsorbent hydrogels were synthesized by γ– irradiation in the absence of oxygen, using high molecular weight PVP and acidic collagen Type I. Sol–gel analysis and swelling experiments were performed in order to determine the gel fraction, network parameters, the yield of cross–linking, respectively scission, as well as to establish the diffusion characteristics of water. Rheological experiments and characterization of the chemical structure before and after irradiation were conducted in order to evaluate the gel character and its stability upon irradiation. The relationship between these parameters and radiation dose was also established. Gel fraction reached up to 90%, and the p0/q0 ratio (degradation vs. cross–linking ratio) shows a negligible degradation process. The collagen–PVP hydrogels present swelling in the range 1000–2000%, the diffusion exponent (n) was found to be between 0.59 and 0.68. The network parameters as the molecular weights between two successive cross−links (Mc), the cross–linking density (ϑe) and the mesh size (ξ) are ranged between 3.39–8.08×104g·mol–1, 1.24–2.95×10–5mol·cm–3, respectively 75–134nm.

Influence of macromolecular additive on reinforced flat-sheet thin film composite pressure-retarded osmosis membranes

The salinity gradient is a renewable and sustainable energy source that can be utilized by a pressure-retarded osmosis (PRO) process. Development of the PRO technology was impeded by shortage of efficient membranes until recent surge on PRO research. In this work, flat-sheet thin film composite (TFC) PRO membranes with reinforced support layer were developed. The membrane properties were optimized by blending high molecular weight polyvinylpyrrolidone (PVP) into the polysulfone (PSf) casting solution. Influences of PVP addition on the kinetic and thermodynamic properties of the casting solution, resultant membrane properties as well as PRO performance were systematically investigated. It is showed that PVP can effectively improve the membrane morphology and pore structure. By adjusting the PSf/PVP composition in the substrate recipe, the reinforced TFC membrane is able to achieve a power density of 12.9W/m2 at 22bar using 1M NaCl draw solution and pure water feed. Long-term PRO test at the peak power density and multi-pressure cycle tests were performed on the membranes. Consistent power density and low salt flux/water flux ratio were observed in the whole tests. The results demonstrated that the reinforced TFC membrane in this study had excellent mechanical strength and stability. It would be promising for future engineering application.

High-surface area co-electrospun TiO2 nanowires fabricated using shrinkage of polyvinylpyrrolidone for improved photovoltaic performance

Surface-roughened TiO2 nanowires (NWs) were fabricated using co-electrospinning with different molecular weights of polyvinylpyrrolidone (PVP) polymer: low molecular weight PVP (Mw=360,000g/mol) for the core region and high molecular weight PVP (Mw=1,300,000g/mol) for the shell region. Together with the formation mechanism, their surface property, morphology, crystal structure, and photovoltaic performance were studied. The results showed that the surface-roughened TiO2 NWs had an enhanced specific surface area because of the rough NW surface compared to the pure TiO2 NWs. As a result, the short-circuit current density (8.94mA/cm2) of DSSCs fabricated with the surface-roughened TiO2 NWs is higher than that (5.88mA/cm2) of the pure TiO2 NWs. Therefore, the photoconversion efficiency of the surface-roughened TiO2 NWs exhibited a high value of ~3.63% compared to that of the pure TiO2 NWs. This phenomenon can be explained by the enhancement of short-circuit current density by an increased dye adsorption; this is because of the increased specific surface area induced by the NW shrinkage due to the different thermal decomposition behavior of PVP depending on the different molecular weights of PVP.

Sandwich-structured hollow fiber membranes for osmotic power generation

In this work, a novel sandwich-structured hollow fiber membrane has been developed via a specially designed spinneret and optimized spinning conditions. With this specially designed spinneret, the outer layer, which is the most crucial part of the sandwich-structured membrane, is maintained the same as the traditional dual-layer membrane. The inner substrate layer is separated into two layers: (1) an ultra-thin middle layer comprising a high molecular weight polyvinylpyrrolidone (PVP) additive to enhance integration with the outer polybenzimidazole (PBI) selective layer, and (2) an inner-layer to provide strong mechanical strength for the membrane. Experimental results show that a high water permeability and good mechanical strength could be achieved without the expensive post treatment process to remove PVP which was necessary for the dual-layer pressure retarded osmosis (PRO) membranes. By optimizing the composition, the membrane shows a maximum power density of 6.23W/m2 at a hydraulic pressure of 22.0bar when 1M NaCl and 10mM NaCl are used as the draw and feed solutions, respectively. To our best knowledge, this is the best phase inversion hollow fiber membrane with an outer selective PBI layer for osmotic power generation. In addition, this is the first work that shows how to fabricate sandwich-structured hollow fiber membranes for various applications.

Antimicrobial electrospun silver-, copper- and zinc-doped polyvinylpyrrolidone nanofibers

The use of electrospun polyvinylpyrrolidone (PVP) nanofibers containing silver, copper, and zinc nanoparticles was studied to prepare antimicrobial mats using silver and copper nitrates and zinc acetate as precursors. Silver became reduced during electrospinning and formed nanoparticles of several tens of nanometers. Silver nanoparticles and the insoluble forms of copper and zinc were dispersed using low molecular weight PVP as capping agent. High molecular weight PVP formed uniform fibers with a narrow distribution of diameters around 500nm. The fibers were converted into an insoluble network using ultraviolet irradiation crosslinking. The efficiency of metal-loaded mats against the bacteria Escherichia coli and Staphylococcus aureus was tested for different metal loadings by measuring the inhibition of colony forming units and the staining with fluorescent probes for metabolic viability and compromised membranes. The assays included the culture in contact with mats and the direct staining of surface attached microorganisms. The results indicated a strong inhibition for silver-loaded fibers and the absence of significant amounts of viable but non-culturable microorganisms. Copper and zinc-loaded mats also decreased the metabolic activity and cell viability, although in a lesser extent. Metal-loaded fibers allowed the slow release of the soluble forms of the three metals.

Effect of tablet structure on controlled release from supersaturating solid dispersions containing glyceryl behenate.

The objective of this study was to evaluate the use of glyceryl behenate as a plasticizer and release modifier in solid dispersion systems containing itraconazole and carbamazepine. Amorphous solid dispersions of high molecular weight polyvinylpyrrolidone were prepared by hot-melt extrusion, the processing of which was improved by the inclusion of glyceryl behenate. Dispersions were milled and subsequently compressed into tablets. Solid dispersions were also prepared by KinetiSol Dispersing, which allowed for the manufacture of monolithic tablets of the same composition and shape as compressed tablets. Tablets without glyceryl behenate and all compressed tablets were observed to have an incomplete release profile likely due to drug crystallization within the tablet as this occurred at conditions in which dissolution concentrations were below saturation. Monolithic tablets formulated to be more hydrophobic, by including glyceryl behenate, allowed for sustained release below and above saturation conditions.

THE ANTIMICROBIAL BIODEGRADABLE COMPOSITION BASED ON HIGH-MOLECULAR WEIGHT POLYVINYLPYRROLIDONE FOR THE PROPHYLAXIS OF EXPERIMENTAL OSTHEOMYELITIS

The aim of study was to evaluate the efficacy of antimicrobial composition of amikacin with dioxydin and polyvinylpyrrolidone as a biodegradable prolonging agent for the post-surgery infections prophylaxis. The data obtained show the efficacy of the amikacin combination with dioxydin based on high-molecular weight polyvinylpyrrolidone and an opportunity to it's application for the post-surgery infections prophylaxis in traumatology, orthopedics and other surgery areas.

Fabrication of Cross-Linked Polyethyleneimine Microfibers by Reactive Electrospinning with In Situ Photo-Cross-Linking by UV Radiation

The objective of this work is to demonstrate the feasibility of fabrication of cross-linked polyethyleneimine microfibers by a reactive photo-electrospinning technology. Linear polyethyleneimine (L-PEI) has been grafted with cross-linkable methacrylate moiety by reaction with glycidyl methacrylate (GMA), enabling the polymer to cross-link upon UV exposure. The photo-cross-linking reaction was characterized by a photo-rheometer. Neat L-PEI or methacrylated L-PEI tends to aggregate rendering it very difficult to electrospin into microfibers. A high molecular weight polyvinylpyrrolidone (PVP) is an efficient chain entanglement enhancer for both L-PEI and methacrylated L-PEI and helpful to maintain fibrous structure. An optimized composition consisted of 10% methacrylated L-PEI (less than 14.8% methacrylation of total L-PEI) combined with 2% PVP and 1% photoinitiator in ethanol was successfully electrospun into smooth cross-linked microfibers using the reactive electrospinning device. Diameters of cross-linked fibers can be controlled from 419 nm to 2 μm depending on methacrylation degree and UV irradiation intensity. The resultant cross-linked L-PEI microfibers have demonstrated significantly improved solvent resistance, thermal stability, and mechanical properties. The distinguished characteristics of this novel reactive electrospinning technology are the high cross-linking efficiency and minimal toxic chemical residues in the products. The stability of the fibers can be readily modified and controlled by the cross-linking degree, which is of great importance for biomedical applications.

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.

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.

Comparison of relative viscosity measurement of polyvinylpyrrolidone in water by glass capillary viscometer and differential dual‐capillary viscometer

AbstractThe relative viscosity (RV) of polyvinylpyrrolidone (PVP) with different molecular weights was measured with a glass capillary viscometer and with a differential dual‐capillary viscometer in water at different concentrations. For the differential dual‐capillary viscometer, RV increases with a decreasing flow rate, especially for high molecular weight PVP at a 1% concentration. A good agreement in the RV between the two methods can be obtained for PVP with different molecular weights and at various concentrations if an appropriate flow rate is selected for the differential dual‐capillary viscometer. Special precaution is needed when using the differential dual‐capillary viscometer to measure the viscosity of a pure solvent. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1312–1315, 2002

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

Oxidative carbonylation of phenol to diphenyl carbonate catalyzed by bis(benzonitrile)dichloropalladium in the presence of polyvinylpyrrolidone

Pd(PhCN) 2Cl 2 [bis(benzonitrile)dichloropalladium] were investigated in the presence of polyvinylpyrrolidone (PVP) as a polymer support for the direct synthesis of diphenyl carbonate (DPC) by the oxidative carbonylation of phenol using carbon monoxide (CO) and air. Pd(PhCN) 2Cl 2 was found to be more efficient than the conventional PdBr 2 system, and its efficiency was accelerated in the presence of high molecular weight PVP with M w=360,000 and 1,300,000. The best efficiency of Pd(PhCN) 2Cl 2/Mn(TMHD) 3 [tris(2,2,6,6-tetramethyl-3,5-heptanedionato)manganese]/(Ph 3P) 2NBr [bis(triphenylphosphoranylidene)ammonium bromide] system was obtained by using 0.241 mmol of PVP with M w=360,000 where TOF (turnover frequency) reached 11.31 (mol-DPC/mol-Pd h, Pd/Mn/Br/phenol=1/2/20/2667; CO 0.50 MPa; air 0.25 MPa, 100°C, 3 h).

Solid-state tyrosinase stability as affected by water activity and glass transition

The effects of water activity ( a W) and the state of the system as dictated by the glass transition temperature ( T g) on tyrosinase storage stability were evaluated in a model food system. Tyrosinase was incorporated into low and high molecular weight polyvinylpyrrolidone (PVP-LMW and PVP-K30, respectively). Samples were equilibrated and stored in desiccators from a W 0.33 to 0.77 at 20°C. Tyrosinase activity was monitored for a week, and pseudo-first order rate constants for activity loss were calculated. Residual activity after equilibration correlated with T g rather than a W. An apparent rate constant increase slightly above T g was observed and rate constants were the same at constant T g, suggesting that molecular mobility as dictated by T g was influencing tyrosinase storage stability.

Radiation‐initiated inverse emulsion polymerization of vinylpyrrolidone

AbstractThe radiation‐induced inverse emulsion polyerization of vinylpyrrolidone using an isoparaffinic hydrocarbon and nonionic emulsifier blend is described. High molecular weight polyvinylpyrrolidone (PVP) (1 million to 2 million Mv) was readily obtained at rapid polmerization rates (Rp ∼ 10–35 mol 1−1 s−1) to high conversions (90–95%). The polydispersity of the polymer varied from 2.6 to 4.4, suggesting that chain transfer to the polymer had occurred. Adding a polymeric surfactant to the nonionic blend modified the polymerization rate and particle‐size distribution. © 1994 John Wiley & Sons, Inc.

Aluminium-Magnesium Hydroxide Tablets: Effect of Processing and Composition of Granulating Solution on the Granule Properties and In Vitro Antacid Performance

AbstractWet granulation experiments on aluminium-; magnesium hydroxide; mannitol blends were carried out, in order to produce chewable antacid tablets.The influence of binder solvent, of type and concentration of polyvinylpyrrolidone as a binder and of granulating and drying equipment on the granule and tablet characteristics was investigated.Water as a binder solvent offered several advantages over the use of alcohol. The use of high molecular weight polyvinylpyrrolidone reduced the antacid capacity and caused some manufacturing problems.The granulating equipment (high shear granulator or planetary mixer) and the drying technique (oven or fluidized bed) had no major influence on the granule and tablet characteristics.

Polymeric Additives to Angiographic Contrast Medium: Development of an Adhesive Contrast Material

An angiographic contrast medium which would adhere to the endothelium of the cardiovascular system would increase the duration of the radiographic information while smaller doses injected at lower rates could be employed. Agar, gum acacia, polyvinylpyrrolidone (PVP), high and low molecular weight dextran, serum albumi, and gelatin were considered as additives to 60% meglumine diatrizoate. Agar and gum acacia did not yield solutions suitable for testing. The other solutions were tested for adhesiveness, and their electrical conductivity, as a possible toxicologic parameter, was measured in equiviscous solutions of 60-65 cps. Low molecular weight dextran and serum albumin did not adhere. For solutions containing high molecular weight dextran, PVP, and gelatin, the washout times were significantly increased relative to 60% meglumine diatrizoate. Serum albumin lowered the conductivity of 60% meglumine diatrizoate by 30%, low molecular weight dextran by 50%, PVP by 3%, high molecular weight dextran by 19%, and gelatin by 32%. Gelatin was considered the additive of choice since it conferred adhesiveness and it is non-toxic and bio-degradable. A type which was originally developed as a plasma expander was deionized, bleached, and depyrogenized. It was combined with diatrizoic acid in an attempt to form a stable compound. Results of infrared spectrography, Sephadex chromatography, and equilibrium dialysis proved that no compound or complex was formed. It was found that a solution of 6% or 8% gelatin in 60% meglumine diatrizoate provided a stable medium which upon injection into the vessel adhered to its walls for a period of several seconds.

Intestinal excretion of low and high molecular weight polyvinylpyrrolidone (PVP) in patients with proteinuria.

Abstract. Excretion of polyvinylpyrrolidone (PVP) by the gastrointestinal tract has been investigated in a group of patients with proteinuria due to primary renal disease and a group of normal controls. Two types of PVP were used, one with a mean molecular weight of 40,000, labelled with 125I (LMW‐PVP), the other with a mean molecular weight of 160,000, labelled with 131I (HMW‐PVP). The purpose of this study was to obtain more information about the possibility of increased gastrointestinal protein loss in patients with proteinuria and, if present, to acquire data on its mechanism. In six of 30 patients PVP excretion was definitely above normal. Mean faecal PVP excretion was nearly twice as high as compared with the control group. The data obtained in this investigation point to a simultaneous involvement of the capillary wall in the gut in at least some of the patients with the nephrotic syndrome. A preferential excretion of the LMW‐PVP was shown in both groups, which indicates a sieving effect in the excretion of macro‐molecules. Faecal PVP excretion however appears to be less “selective” than urinary PVP excretion. A theory is developed to explain the gradually decreasing ratio