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A convenient approach from a practical point of view is proposed for assessing rheology of aqueous acetic acid rat tail collagen solutions by determining the kinematic viscosity (v), which depends only on the solution outflow time and is directly measured on cheap and affordable capillary viscometers. In this case, it is irrelevant to take into account the solvent outflow time and temperature correction, unlike relative, specific, reduced and intrinsic viscosities. Influence of the temperature as well as duration and periodicity of ultrasonic treatment on v of 0.3 wt.% solution of rat tail collagen in 0.02 M aqueous CH3COOH was studied for the first time. Additionally, the influence of a temperature on v of mixtures of this collagen solutions with CaCl2, poly(NIPAM), poly(N-vinylpyrrolidone), pluronic F-127 as well as with CaCl2+poly(NIPAM), CaCl2+poly(N-vinylpyrrolidone) and with CaCl2+pluronic F-127 in a similar acetic acid aqueous solutions was studied. Linear regression dependences of the influence of a temperature on v of collagen solutions and its above-mentioned mixtures (R2 is closest to 1) up to 40°C have been found, which make it possible to predict the viscosity characteristics of these solutions at the temperature of interest. It was found that shorter initial sonication periods at 20°C followed by relaxation stages minimize the decrease in v of pure collagen solutions. Results of the research can be useful for scientists, doctors and tissue engineers who carry out research in the field of regenerative medicine in predicting and selecting a temperature as well as ultrasonic parameters for bioprinting with collagen bioinks. [ABSTRACT FROM AUTHOR]

Curcumin attracts huge attention because of its biological properties: it is antiproliferative, antioxidant, anti-inflammatory, immunomodulatory and so on. However, its usage has been limited by poor water solubility and low bioavailability. Herein, to solve these problems, we developed curcumin-loaded nanoparticles based on end-capped amphiphilic poly(N-vinylpyrrolidone). Nanoparticles were obtained using the solvent evaporation method and were characterized by dynamic and electrophoretic light scattering, transmission electron (TEM) and atomic force (AFM) microscopy. The average particle size was 200 nm, and the ζ-potential was −4 mV. Curcumin-release studies showed that nanoparticles are stable in aqueous solutions. An in vitro release study showed prolonged action in gastric, intestinal and colonic fluids, consistently, and in PBS. In vitro studies on epidermoid carcinoma and human embryonic kidney cells showed that the cells absorbed more curcumin in nanoparticles compared to free curcumin. Nanoparticles are safe for healthy cells and show high cytotoxicity for glioblastoma cells in cytotoxicity studies in vitro. The median lethal dose was determined in an acute toxicity assay on zebrafish and was 23 μM. Overall, the curcumin-loaded nanoparticles seem promising for cancer treatment. [ABSTRACT FROM AUTHOR]

The progress achieved in recent years in the biomedical field justifies the objective evaluation of new techniques and materials obtained by using silver in different forms as metallic silver, silver salts, and nanoparticles. Thus, the antibacterial, antiviral, antifungal, antioxidant, and anti-inflammatory activity of silver nanoparticles (AgNPs) confers to newly obtained materials characteristics that make them ideal candidates in a wide spectrum of applications. In the present study, the use of hydroxypropyl methyl cellulose (HPMC) in the new formulation, by embedding AgNPs with antibacterial activity, using poly(N-vinylpyrrolidone) (PVP) as a stabilizing agent was investigated. AgNPs were incorporated in HPMC solutions, by thermal reduction of silver ions to silver nanoparticles, using PVP as a stabilizer; a technique that ensures the efficiency and selectivity of the obtained materials. The rheological properties, morphology, in vitro antimicrobial activity, and stability/catching of Ag nanoparticles in resulting HPMC/PVP-AgNPs materials were evaluated. The obtained rheological parameters highlight the multifunctional roles of PVP, focusing on the stabilizing effect of new formulations but also the optimization of some properties of the studied materials. The silver amount was quantified using the spectroscopy techniques (energy-dispersive X-ray fluorescence (XRF), energy-dispersive X-ray spectroscopy (EDX)), while formation of the AgNPs was confirmed using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM), and dynamic light scattering (DLS). Also, the morphological examination (Atomic Force Microscopy (AFM) and Scanning electron microscopy (SEM)) by means of the texture roughness parameters has evidenced favorable characteristics for targeted applications. Antibacterial activity was tested against Escherichia coli and Staphylococcus aureus and was found to be substantially improved was silver was added in the studied systems. [ABSTRACT FROM AUTHOR]

The development of green preparation methods for acidic metal oxide supported gold catalysts is of great importance for the extensive use of gold catalysts as well as for a comprehensive understanding of gold catalysts. In this study, poly(N -vinylpyrrolidone) (PVP) was used as the stabilizer of gold colloids to deposit gold nanoparticles on an acidic metal oxide, Nb 2 O 5. The effects of the PVP ligand on the preparation of Au(-PVP)/Nb 2 O 5 and on the catalytic activities for gas-phase CO oxidation and liquid-phase furfural oxidation were investigated. As removing more ligand PVP of Au(-PVP)/Nb 2 O 5 , the catalytic activities for both CO oxidation and furfural oxidation increased. The optimal calcination temperature for Au(-PVP)/Nb 2 O 5 was determined to be 400 °C, and calcination at that temperature gave gold nanoparticles with an average size of 6.4 ± 2.5 nm and of the support of Nb 2 O 5 remained as the original crystalline structure. The temperature for 50% CO conversion (T 50%) of Au(-PVP)/Nb 2 O 5 (calcined at 400 °C) was 81 °C. In addition, Au(-PVP)/Nb 2 O 5 (calcined at 400 °C) presented 43% furfural conversion with 100% selectivity of furoic acid under a mild conditions (0.5 MPa O 2 , 40 °C) in the batch system. These results suggested that Au(-PVP)/Nb 2 O 5 is a good catalyst for both gas-phase and liquid-phase reactions. [Display omitted] • A green preparation method of Au/Nb 2 O 5 catalyst by using Au-PVP cluster. • The existence of ligand PVP on Nb 2 O 5 is good for obtaining small Au nanoparticles. • The ligand PVP inhibits both CO oxidation and furfural oxidation. • The calcination temperature of 400 °C is optimized for obtaining good Au/Nb 2 O 5. [ABSTRACT FROM AUTHOR]

The present work investigates, for the first time, the synthesis and properties of some nanocomposite (NC) hydrogels obtained by the aqueous solution free radical polymerization of N-vinylpyrrolidone (NVP) in the presence of Laponite XLG (XLG) as a crosslinker, in comparison with the corresponding hydrogels prepared by using two conventional crosslinking divinyl monomers: N,N′-methylenebisacrylamide (MBA) and tri(ethylene glycol) divinyl ether (DVE). The structure and properties of the hydrogels were studied by FTIR, TEM, XRD, SEM, swelling and rheological and compressive mechanical measurements. The results showed that DVE and XLG are much better crosslinking agents for the synthesis of PNVP hydrogels than MBA, leading to larger gel fractions and more homogeneous network hydrogels. The hydrogels crosslinked by either DVE or XLG displayed comparable viscoelastic and compressive mechanical properties under the experimental conditions employed. The properties of the XLG-crosslinked hydrogels steadily improved as the clay content increased. The addition of XLG as a second crosslinker together with a divinyl monomer strongly enhanced the material properties in comparison with the hydrogels crosslinked by only one of the crosslinkers involved. The FTIR analyses suggested that the crosslinking of the NC hydrogels was the result of two different interactions occurring between the clay platelets and the PNVP chains. Laponite XLG displayed a uniform distribution within the NC hydrogels, the clay being mostly exfoliated. However, a small number of platelet agglomerations were still present. The PNVP hydrogels described here may find applications for water purification and in the biomedical field as drug delivery systems or wound dressings. [ABSTRACT FROM AUTHOR]

In this study, an efficient, stable, and reusable hydrogen-releasing Polyvinylpyrrolidone (PVP) modified PtRh nanoparticles were synthesized and used in the dehydrogenation of dimethylamine borane (DMAB), which is a safe and suitable hydrogen transporter for batteries, and fuel at ambient conditions. The PVP modified PtRh nanoparticles showed high catalytic activity in this reaction and its characterization was performed by TEM and XRD techniques. The characterization studies have shown that the PVP modified PtRh nanoparticles have a particle size of 2.491 ± 0.808 nm. The PVP-modified PtRh nanoparticles have been tested in various parameters such as temperature, substrate, and catalyst concentrations. The experiments showed that the catalytic activity of the PVP modified PtRh nanocatalyst in the dehydrogenation of DMAB under ambient conditions is quite high (TOF = 544.821 h−1). In addition, the activation energy for the catalytic dehydrogenation reaction of dimethylamine borane was calculated as Ea = 23.51 kJ.mol−1. Besides, to accurately predict the catalytic activity, the artificial neural networks (ANNs) model was developed. It was obtained the optimum condition predicted by the ANN model, concentration of PVP modified PtRh nanocatalyst = 9.00 mM, DMAB concentration effect of 137.2 mM, and temperature of 32.6 °C which in this case catalytic activity was obtained (TOF = 561.173 h-1). • PVP modified Pt-Rh nanocatalyst was synthesized using PVP as support. • Dehydrogenation of PVP modified Pt-Rh catalyst on DMAB was performed. • The characterization of nanocatalyst was performed by TEM, and XRD techniques. • TOF value was determined as 544.821 h−1 for hydrogen generation. • ANN model well predicted the optimum conditions of catalytic activity. [ABSTRACT FROM AUTHOR]

[Display omitted] A new polymer-analogous transformations of poly(N -vinylpyrrolidone) was used to prepare new complex-forming macromolecular systems containing thiourea and thio-semicarbazone sites. Two variants of modification were realized, namely, the method including the preliminary in situ activation of nucleophilic centres of the polymer amide fragments with dimethyl sulfate followed by introducing nucleophilic agents into the system, and the method including partial hydrolysis of poly(N -vinylpyrrolidone) followed by the amide coupling. The obtained modified polymeric materials react with silver ions in aqueous solution. [ABSTRACT FROM AUTHOR]

N-grafted copolymers of chitosan (460 kDa) with poly(N-vinylpyrrolidone) (2.4 kDa) or poly(vinyl alcohol) (2.0 ​kDa) as side chains were synthesized. Depending on the polymer-to-chitosan mass ratio the degree of amino group substitution with side chains in chitosan backbone was varied in the range of 0.01–0.33. Layer-by-layer films consisted of copolymers and dextran sulfate as polyanion were obtained. Thickness, hydrophilicity, and morphology of the films were investigated using QCM, UV-vis spectrophotometry, AFM, and contact angle measurements. The obtained films show enhanced protein-repellent properties in fetal bovine serum medium. The mass of adsorbed proteins on LbL films based on copolymer with a degree of substitution of 0.2 decreases by 50 ​% compared to unmodified chitosan. Protein-repellent properties of copolymer-based films are common for LbL films of grafted chitosan copolymers and depend on hydrophilic side chain density on the surface.

We report on a simple approach for synthesis of temperature-responsive giant unilamellar vesicles (GUVs) from poly(N-vinylcaprolactam)15-block-poly(dimethylsiloxane)65-block-poly(N-vinylcaprolactam)15 (PVCL15-PDMS65-PVCL15) triblock copolymer and non-temperature responsive small and giant vesicles from novel poly(N-vinylpyrrolidone)-block-poly(dimethylsiloxane)-block-poly(N-vinylpyrrolidone) (PVPON15-PDMS65-PVPON15 and PVPON6-PDMS30-PVPON6) triblock copolymers using microfluidic mixing at 25 °C. We show that temperature-responsive PVCL15-PDMS65-PVCL15 GUVs with the average diameter of 1.4 ± 0.2 µm while being stable at room temperature for at least 14 days, transformed irreversibly into small vesicles of 168 ± 40 nm after incubation of their aqueous solution at 42 °C for 24 h. We hypothesized that this transformation is induced by local compressive stresses of the vesicle membrane due to the collapse of PVCL blocks above the copolymer lower critical solution temperature (LCST) leading to the decrease of the vesicle membrane thickness. Consequently, we found that the temperature-induced size transformation of the PVCL-based GUVs at 42°C can be suppressed by substituting PVCL with its hydrophilic homologue PVPON, or by suppressing the PVCL's LCST behavior through hydrogen-bonding with tannic acid molecules. In the former case, novel PVPONn-PDMSm-PVPONn triblock copolymers (n = 15, m = 65 and n = 6, m = 30) assemble into vesicles stable from 25 °C to 55 °C as confirmed by optical and electron microscopy, dynamic light scattering (DLS) and small-angle neutron scattering (SANS). In the latter, hydrogen bonding interactions of PVCL with the polyphenol tannic acid (TA) at room temperature resulted in stable PVCL-based GUVs at 42°C as confirmed by optical, electron, and atomic force microscopies. We also found that physical crosslinking of the PVCL corona through hydrogen bonding with TA in PVCL15-PDMS65-PVCL15 GUVs will delay their low pH-induced degradation at 37°C by 48 h compared to non-modified GUVs. Our findings open opportunities for the development of temperature-regulated stable micro-vehicles that would change their structural characteristics in the physiologically relevant temperature range from 25 to 42°C and can be utilized for cell mimicking studies. The developed GUVs also have potential in theranostic drug delivery as substitutes for polymer microcapsules and lipid microbubbles as well as for stimuli-triggered sensing, protection, and rapid response in an aqueous environment.

The study concerns the preparation of Rh nanoparticles (NPs) by room-temperature, methyl viologen (MV2+) mediated electrochemical reduction of RhCl3 in the presence of poly(N-vinylpyrrolidone) (PVP, 40000 Da) and nanocellulose (NC, d = 57±36 nm) at a controlled potential of generation of MV·+ radical cations in aqueous medium. When a theoretical amount of electricity is passed, the mediator is not consumed, while Rh(III) is quantitatively reduced to Rh(0). The reduction results in the Rh@PVP (141–191 nm in size) and Rh@PVP/NC nanocomposites dispersed in the solution bulk. The Rh@PVP/NC nanocomposite represents PVP globules (42±13 nm in size) with encapsulated ultrasmall spherical Rh NPs (1.3±0.4 nm in size) bound to the surface of NC fibers. The Rh nanocomposites exhibited high catalytic activity in the model reaction, viz., reduction of p-nitrophenol with sodium borohydride in aqueous medium. The catalytic activity increased in the presence of cetyltrimethylammonium chloride (CTAC). [ABSTRACT FROM AUTHOR]

In this study, several experimental techniques were applied to probe thermal properties, molecular dynamics, crystallization kinetics and intermolecular interactions in binary mixtures (BMs) composed of flutamide (FL) and various poly(N-vinylpyrrolidone) (PVP) polymers, including a commercial product and, importantly, samples obtained from high-pressure syntheses, which differ in microstructure (defined by the tacticity of the macromolecule) from the commercial PVP. Differential Scanning Calorimetry (DSC) studies revealed a particularly large difference between the glass transition temperature (Tg) of FL+PVPsynth. mixtures with 10 and 30 wt% of the excipient. In the case of the FL+PVPcomm. system, this effect was significantly lower. Such unexpected findings for the former mixtures were strictly connected to the variation of the microstructure of the polymer. Moreover, combined DSC and dielectric measurements showed that the onset of FL crystallization is significantly suppressed in the BM composed of the synthesized polymers. Further non-isothermal DSC investigations carried out on various FL+10 wt% PVP mixtures revealed a slowing down of FL crystallization in all FL-based systems (the best inhibitor of this process was PVP Mn = 190 kg/mol). Our research indicated a significant contribution of the microstructure of the polymer on the physical stability of the pharmaceutical—an issue completely overlooked in the literature.

The preparation of Ag, Au, and Pd nanoparticles (NPs) by methylviologen (MV2+) was investigated—mediated electrochemical reduction of 1.5 mM Ag(I), Au(I), and Pd(II), respectively, in the presence of poly(N-vinylpyrrolidone) (PVP) and nanocellulose (NC) at the controlled potential of MV·+ radical cation generation in aqueous medium at room temperature. Au(I) and Pd(II) ions were added to the solutions as chloride salts and Ag(I) by in situ dissolving of the Ag-anode during electrolysis. Metal ions are reduced quantitatively to M0 when the theoretical amount of electricity was passed. Dispersion of the Ag anode along with dissolution results in a current yield of Ag0 166%. The result of the synthesis is the nanocomposites of spherical Ag (28 ± 8 nm), Au (10 ± 3 nm), and Pd (5 ± 1 nm) NPs encapsulated in the PVP shell, which are bound on the NC surface and dispersed in the solution volume. The dimensions of the Ag, Au, and Pd crystallites are in the range of values 7.14 ÷ 14.4, 5.7 ÷ 9.0, and 4.5 ÷ 6.2 nm, respectively. The Pd nanocomposite shows a high catalytic activity increasing in time; the Ag and Au nanocomposites are significantly less active in the test reaction of p-nitrophenol reduction with sodium borohydride in an aqueous medium. When cetyltrimethylammonium chloride (CTAC) is added to the nanocomposites, the catalytic reaction rate increases by 57, 2.5, and 1.2 times for Ag, Pd, and Au nanocomposites, respectively. [ABSTRACT FROM AUTHOR]

In this contribution, we reported the synthesis of 2,6-bis(1-butyl-1H-1,2,3- triazol-1-yl)pyridine-capped poly(N-vinylpyrrolidone)s (denoted BTP-PVPy). First, a 2,6-bis-(1-butyl-1H-[1,2,3]triazol-4-yl)-pyridin-4-yl]-methanol (BTP-CH2OH) was synthesized. The as-obtained BTP-CH2OH was then employed to react with 4-cyano-4-isopropoxythiocarbonylsulfanyl-4-methyl-butyric acid to obtain a BTP-functionalized xanthate. The latter was used to mediate the radical polymerization of N-vinylpyrrolidone (NVP). It was found that the radical polymerization of NVP was in living/controlled manner in the presence of BTP-functionalized xanthate. By controlling the molar ratios of NVP to the BTP-functionalized xanthate, the BTP-capped PVPy samples were obtained with various lengths of PVPy chains. The BTP-capped PVPy samples displayed the self-assembly behavior in aqueous media. Notably, the self-assembly behavior was significantly influenced with the complexation of BTP end groups with the metal ions [Pt(II), Zn(II), and Eu(III)]. The sizes and morphologies of the self-organized nanoobjects were quite dependent on the coordination behavior of the tridentate ligand (viz. BTP) with the metal ions. In addition, the self-assembled nanoobjects in aqueous suspension displayed different photoluminescent behavior, depending on the types of metal ions. [ABSTRACT FROM AUTHOR]

This paper reports for the first time the use of poly(N‐vinylpyrrolidone) (PVP) as an effective additive for controlling the melt crystallization behavior of poly(p‐phenylene sulfide) (PPS). The PPS/PVP blends form two‐phases, whose melt crystallization temperature decreases drastically upon the addition of PVP accompanied by a delayed onset of crystallization and a decreased crystallization rate. Monitoring spherulite growth during isothermal annealing revealed that in blends with less than 5 wt% of PVP the diminution of the crystallization rate of PPS is due to a decrease in both the nucleation rate and the spherulite growth rate, whereas in blends with higher PVP content the falloff in rate is mainly caused by slow nucleation. A change was observed in the glass transition temperature and melting temperature of PPS upon blending, suggesting that the blends are partially miscible. The delay in crystallization is likely due to the partial miscibility disturbing exclusion of PVP from the crystalline growth front. [ABSTRACT FROM AUTHOR]

Chitosan takes second place of the most abundant polysaccharides naturally produced by living organisms. Due to its abundance and unique properties, such as its polycationic nature, ability to form strong elastic porous films, and antibacterial potential, it is widely used in the food industry and biomedicine. However, its low solubility in both water and organic solvents makes its application difficult. We have developed an environmentally friendly method for producing water-soluble graft copolymers of chitosan and poly ( N -vinylpyrrolidone) with high grafting efficiency and a low yield of by-products. By using AFM, SEM, TGA, DSC, and XRD, it has been demonstrated that the products obtained have changed properties compared to the initial chitosan. They possess a smoother surface and lower thermal stability but are sufficient for practical use. The resulting copolymers have a higher viscosity than the original chitosan, making them a promising thickener and stabilizer for food gels. Moreover, the copolymers exhibit an antibacterial effect, suggesting their potential use as a component in smart food packaging.

Proteasome inhibitor bortezomib is an anticancer agent approved for treatment of multiple myeloma and mantle cell lymphoma. However, its application in other types of cancer, primarily in solid tumors, is limited due to poor pharmacokinetics, inefficient tissue penetration, low stability and frequent adverse effects. In the present study, a novel micellar nano-scaled delivery system was manufactured, composed of amphiphilic poly(N-vinylpyrrolidone) nanoparticles loaded with bortezomib. Similar nanoparticles loaded with prothionamide, a drug without anticancer effect, were used as control. The size and zeta potential of the obtained polymeric micelles were measured by dynamic light scattering. Bortezomib-loaded micelles exhibited significant cytotoxic activity in vitro in monolayer tumor cell cultures (IC50 ~6.5 µg/ml) and in 3D multicellular tumor spheroids (IC50 ~8.5 µg/ml) of human glioblastoma cell lines U87 and T98G. Additionally, the toxic effects in vivo were studied in zebrafish Danio rerio embryos, with an estimated 50% lethal concentration of 0.1 mg/ml. Considering that bortezomib and other molecules from the class of proteasome inhibitors are potent antitumor agents, nanodelivery approach can help reduce adverse effects and expand the range of its applications for treatment of various oncological diseases. [ABSTRACT FROM AUTHOR]

Nanoparticles based on the biocompatible amphiphilic poly(N-vinylpyrrolidone) (Amph-PVP) derivatives are promising for drug delivery. Amph-PVPs self-aggregate in aqueous solutions with the formation of micellar nanoscaled structures. Amph-PVP nanoparticles are able to immobilize therapeutic molecules under mild conditions. As is well known, many efforts have been made to exploit the DR5-dependent apoptosis induction for cancer treatment. The aim of the study was to fabricate Amph-PVP-based nanoparticles covalently conjugated with antitumor DR5-specific TRAIL (Tumor necrosis factor-related apoptosis-inducing ligand) variant DR5-B and to evaluate their in vitro cytotoxicity in 3D tumor spheroids. The Amph-PVP nanoparticles were obtained from a 1:1 mixture of unmodified and maleimide-modified polymeric chains, while DR5-B protein was modified by cysteine residue at the N-end for covalent conjugation with Amph-PVP. The nanoparticles were found to enhance cytotoxicity effects compared to those of free DR5-B in both 2D (monolayer culture) and 3D (tumor spheroids) in vitro models. The cytotoxicity of the nanoparticles was investigated in human cell lines, namely breast adenocarcinoma MCF-7 and colorectal carcinomas HCT116 and HT29. Notably, DR5-B conjugation with Amph-PVP nanoparticles sensitized resistant multicellular tumor spheroids from MCF-7 and HT29 cells. Taking into account the nanoparticles loading ability with a wide range of low-molecular-weight antitumor chemotherapeutics into hydrophobic core and feasibility of conjugation with hydrophilic therapeutic molecules by click chemistry, we suggest further development to obtain a versatile system for targeted drug delivery into tumor cells.

The viscosity behaviour and physical properties of blends containing hyaluronic acid (HA) and poly(N-vinylpyrrolidone) (PVP) were studied by the viscometric technique, steady shear tests, tensile tests and infrared spectroscopy. Viscometric and rheological measurements were carried out using blends of HA/PVP with different HA weight fractions (0, 0.2, 0.5, 0.8 and 1). The polymer films and HA/PVP blend films were prepared using the solution casting method. The study of HA blends by viscometry showed that HA/PVP was miscible with the exception of the blend with high HA content. HA and its blends showed a shear-thinning flow behaviour. The non-Newtonian indices (n) of HA/PVP blends were calculated by the Ostwald–de Waele equation, indicating a shear-thinning effect in which pseudoplasticity increased with increasing HA contents. Mechanical properties, such as tensile strength and elongation at the break, were higher for HA/PVP films with wHA = 0.5 compared to those with higher HA contents. The elongation at the break of HA/PVP blend films displayed a pronounced increase compared to HA films. Moreover, infrared analysis confirmed the existence of interactions between HA and PVP. The blending of HA with PVP generated films with elasticity and better properties than homopolymer films.

• Uniform and smooth Cu(0)-loaded polymeric fibers were prepared by one-step electrospinning. • Microwave Ar plasma treatments allowed to generate Cu/Cu 2 O nanostructures on fibers. • Various morphologies of Cu/Cu 2 O nanostructures were modulated by plasma treatments. • The plasma treated fibers displayed the highest photocatalytic activity toward methyl orange and 4-NP under visible light. Self-standing photocatalytic materials based on transition-metal decorated electrospun fiber mat have attracted considerable attention for photodegradation of toxic refractory organic pollutants in the environment. In this study, poly(N-vinylpyrrolidone)/copper(II) nitrate fibers (Cu/PVP-F) were prepared by electrospinning of PVP/Cu(NO 3) 2 solution followed by crosslinking using microwave-induced argon plasma (MAP) to produce Cu/Cu 2 O composites on the surface of fibers. The optimization for the electrospinning fibers was conducted such that the optimized electrospun composite fibers exhibited excellent visible light photocatalytic activity, corresponding to the narrowest band gap energy based on photoluminescence analyses. Moreover, the experimental results showed that the electro-spinning Cu/PVP-F fibers treated with MAP revealed the highest rate of photodegradation efficacy toward methyl orange (MO) and 4-nitrophenol (4- NP), that could be employed in the subsequent photocatalysis cycles with good recovery. [ABSTRACT FROM AUTHOR]

• Sorption in IPNs occur by inclusion within CD cavities and specific interactions. • Synergistic sorption of naphthalenes and additive for tannic acid are found. • Cetirizine and pseudoephedrine, drugs used in combined therapies, can be loaded. Interpenetrating polymer network (IPN) hydrogels were synthesised using β-cyclodextrin (β-CD) and N-vynil-2-pyrrolidone (NVP) crosslinked with epichlorohydrin and divinylbenzene, respectively, and prepared by four different procedures: simultaneous, sequential, hybrid and a novel one named hybrid-sequential. The IPNs prepared have been characterised by infrared spectroscopy and thermal analysis. The equilibrium swelling in water and the sorption of model substances into the IPNs have also been studied. The model sorbates (1-naphthol, 2-acetylnaphthalene and tannic acid) were selected according to the affinities towards each one of the two constituent polymers. Our studies reveal that these IPNs can be applied for the sorption of substances that can interact with the network by two mechanisms, i.e. inclusion within cyclodextrin cavities and/or via specific interactions with the functional groups present. Besides, due to the complementary character of their constituent polymers, these networks could also serve to retain two substances of different nature such as cetirizine and pseudoephedrine. [ABSTRACT FROM AUTHOR]

In this contribution, we reported the synthesis of polyhedral oligomeric silsesquioxane (POSS)-capped poly(N-vinyl pyrrolidone) (PVPy) via reversible addition-fragmentation chain transfer/macromolecular design via interchange of xanthate (RAFT/MADIX) polymerization. First, a POSS macromer bearing xanthate moiety was synthesized and was then used as the chain transfer agent to mediate the radical polymerization of N-vinylpyrrolidone (NVP). By controlling the mass ratios of the POSS-CTA to NVP, a series of the POSS-capped PVPy amphiphiles were successfully synthesized with various molecular weights. It was found that in bulks, the POSS-capped PVPy was microphase-separated and the POSS end groups were self-organized into the spherical microdomains with the size of 10~100 nm in diameter. In the solvent selective for PVPy (e.g., water), the POSS-capped PVPy was capable of self-assembling into the spherical micelles with an average diameter of 20~50 nm as evidenced by dynamic laser scattering (DLS) and transmission electron microscopy (TEM). Owing to the amphiphilicity, POSS-capped PVPy also displayed the self-assembly behavior in poly(vinylidene fluoride) (PVDF), in which the POSS cages were aggregated into 10~30 nm microdomains. In the nanocomposites of PVDF with POSS-capped PVPy, the spherical POSS microdomains were readily etched by using hydrofluoric acid, leaving the nanopores in the materials.ᅟ [ABSTRACT FROM AUTHOR]

Abstract: Carbon sorbents modified with poly(N-vinylpyrrolidone), betulin, and poly(N-vinylpyrrolidone) together with betulin have been synthesized. The synthesized samples have been studied by a complex of physicochemical methods (low-temperature nitrogen adsorption, thermal analysis, elemental analysis). Under model conditions, the antioxidant properties of the modified sorbents with respect to their ability to deactivate hydrogen peroxide have been studied. The effect of the carbon sorbents on the hydrogen peroxide decomposition rate has been determined by the gasometric method; the reaction rate constants have been calculated. Dependences of the hydrogen peroxide concentration on the time of contact with the test sorbents have been studied by the optical method using an LIR-2 interferometer. [ABSTRACT FROM AUTHOR]

Poly(N-vinylpyrrolidone)/poly(N-isopropylacrylamide) (PVP/PNIPAM) microgels were successfully synthesized by soap-free emulsion polymerization of N-isopropylacrylamide monomer in the presence of PVP, using an anionic radical initiator and a chemical crosslinker. The dried microgels exhibited nonspherical morphology and submicron size with good monodispersity. In aqueous phase, the microgels shrank when elevating temperature, displaying a negatively thermoresponsive nature with volume phase transition temperature (VPTT) of ca. 33.1 °C. The microgel dispersions remained colloidally stable even being heated far above their VPTT but gelled with the addition of electrolyte. Such thermo-induced in situ gelation behavior was studied in detail by small-deformation oscillatory rheological measurements within the linear viscoelastic region. The dynamic temperature ramp sweeps showed that the gelation temperature decreased independently as the polymer content or electrolyte concentration was increased. The isothermal time sweeps were performed to study the gelation kinetics. It was found that the microgel dispersions formed gel more quickly at larger polymer content, larger electrolyte concentration and higher temperature. [ABSTRACT FROM AUTHOR]

We demonstrated in this study the removal of copper ions from aqueous solutions by a new and cost efficiency adsorbent based on poly(N-vinylpyrrolidone) modified sodium bentonite. The X-ray diffraction analysis confirmed that the poly(N-vinylpyrrolidone) is well intercalated in the clay inter-sheets. Adsorption of copper was analyzed by the atomic absorption spectroscopy technical. Quantitative removal of copper in aqueous solution and the optimum conditions in batch experimental set-up were attained by following searching effects such as contact time, initial metal concentration, pH and temperature. The elimination of this pollutant by this a new composite reached 3.27 mg.g−1, which is more important than the amount of copper adsorbed by the non-modified clay (1.5 mg.g−1). The experimental results showed that the equilibrium and shaking time was attained within 05 min. The better retention capacity of copper was obtained at pH between 4 and 5.8. Equilibrium data were well fitted with the Langmuir, Freundlich and Elovich models. Also, the pseudo first order and pseudo-second-order were also applied. The experimental data follow well the pseudo-second-order kinetics. The thermodynamic of this new adsorbent of copper shows spontaneous and exothermic process with a negative value of ΔS. [ABSTRACT FROM AUTHOR]

The production of polymer mixtures is a widely used method to improve polymer performance, as such mixtures can combine advantageous properties from each component. In this study, mixtures based on carboxymethyl chitosan (CMCh) and poly(N-vinylpyrrolidone) (PVP) were characterized using steady shear measurements, viscometry, infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, and atomic force microscopy. Viscometry and steady shear studies were performed on solutions of the native polymers and their mixtures with various weight proportions (80/20, 50/50, and 20/80% w /w). The rheological tests revealed that the apparent viscosity of solutions of CMCh/PVP mixtures was higher than that of the native polymer solutions. The rheological data showed that CMCh solutions and their mixtures were typical pseudoplastic liquids, which could be accurately described by the Cross and power law models. Viscometric parameters were determined using the method proposed by Garcia et al., which indicated good miscibility between CMCh and PVP in aqueous solution. Furthermore, the morphology, structure, and thermal properties of CMCh films changed when PVP was added. The obtained analytical data showed the formation of stable mixtures of CMCh and PVP, with a high miscibility ratio between these polymers, through intermolecular interactions between the polymer chains. [ABSTRACT FROM AUTHOR]

We propose a method for the synthesis of a colloidal ZnO solution with poly(N-vinylpyrrolidone) (PVP) as stabilizer. Stable colloidal solutions with good luminescence properties are obtained by using PVP as stabilizer in the synthesis of ZnO nanoparticles by a sol–gel method assisted by ultrasound. Nanoparticles with sizes of 30–40 nm in a PVP matrix are produced as a solid product. The colloidal ZnO/PVP/methanol solution, apart from the most intense PL band at 356 nm coming from the PVP, exhibits a strong PL band at 376 nm (3.30 eV) which corresponds to the emission of the free exciton recombination in ZnO nanoparticles.

A mini-library of star-shaped thermoresponsive polymers having six arms was prepared using a hexafunctional xanthate by reversible addition-fragmentation chain transfer (RAFT) polymerization. Star polymers with homopolymeric arms of poly(N-vinylcaprolactam) (PNVCL), copolymeric arms of poly(N-vinylcaprolactam-co-N-vinylpyrrolidone) (PNVCL-co-PNVP) and also arms of block copolymers of PNVCL-b-PVAc, (PNVCL-co-PNVP)-b-PVAc, and combinations of them changing the order of the block was achieved exploiting the R-RAFT synthetic methodology (or R-group approach), wherein the thiocarbonyl group is transferred to the polymeric chain end. Taking advantage of the RAFT benefits, the molecular weight of the star polymers was controlled (Mn = 11,880-153,400 g/mol) to yield star polymers of different sizes and lower critical solution temperature (LCST) values. Removing the xanthate group of the star polymers allowed for the introduction of specific functional groups at the ends of the star arms and resulted in an increase of the LCST values. Star PNVCL-b-PVAc diblock copolymers with PVAc contents of 5-26 mol % were prepared; the hydrophobic segment (PVAc) is located at the end of the star arms. Interestingly, when the PVAc content was 5-7 mol %, the hydrodynamic diameter (Dh) value of the aggregates formed in water was almost the same sa the Dh of the corresponding PNVCL star homopolymers. It is proposed that these star block copolymers self-assemble into single flowerlike micelles, showing great stability in aqueous solution. Star block copolymers with the PVAc hydrophobic block in the core of the star, such as PVAc-b-(PNVCL-co-PNVP), form micellar aggregates in aqueous solution with Dh values in the range from ~115 to 245 nm while maintaining a thermoresponsive behavior. Micellar aggregates of selected star polymers were used to encapsulate methotrexate (MTX) showing their potential in the temperature controlled release of this antineoplasic drug. The importance of the order in which each block constituent is introduced in the arms of the star polymers for their solution/aggregation behavior is demonstrated. [ABSTRACT FROM AUTHOR]

Through the reversible addition–fragmentation chain transfer (RAFT) copolymerization of 3-ethyl-1-vinyl-2-pyrrolidone (C2NVP) and N-vinylpyrrolidone (NVP), a series of well-defined P(C2NVP-co-NVP) copolymers were synthesized (Mn = ca. 8000 to 16,000 and Mw/Mn <1.5) by using a difunctional chain transfer agent, S-(1-methyl-4-hydroxyethyl acetate) O-ethyl xanthate (MHEX). Copolymerizing kinetics and different monomer ratio in feeds were conducted to study the apparent monomer reaction rate and reactivity ratios of NVP and C2NVP, which indicated similar reaction rates and predominantly ideal random copolymers for the two monomers. The Tgs of the obtaining P(C2NVP-co-NVP) copolymers significantly corresponded to not only molecular weights MWs but also copolymer compositions. These copolymers presented characteristic lower critical solution temperatures (LCST) behavior. We then studied the cloud points (CPs) of the copolymers with varying MWs and compositions. With different MWs, the CPs were linearly decreased from ca. 51 to 45 °C. With different compositions, the CPs of the copolymers decreased from ca. 48 to 29 °C with C2NVP content (i.e., from 60.8 to 89.9 mol %). Fitting the CPs by the theoretical equation, the result illustrated that the introduction of more hydrophobic units of C2NVP suppressed the hydrophilic interaction between the polymer chain and water. We then successfully proceeded the chain extension through the ring-opening polymerization (ROP) of ε-caprolactone (CL) to the synthesis of a novel P(C2NVP-co-NVP)-b-PCL amphiphilic block copolymer (Mn,NMR = 14,730 and Mw/Mn = 1.59). The critical micelle concentration (CMC) of the block copolymer had a value of ca. 1.46 × 10−4 g/L. The block copolymer micelle was traced by dynamic light scattering (DLS), obtaining thermosensitive behaviors with a particle size of ca. 240 nm at 25 °C and ca. 140 nm at 55 °C, respectively. [ABSTRACT FROM AUTHOR]

Fe3O4:PVP/Au nanocomposite synthesized via a two-step procedure was tested as a quasi-homogenous alcohol oxidation catalyst. It was found that the nanocomposite was able to carry out aerobic oxidation of alcohols in water at room temperature. Studies show rapid magnetic recoverability and reusability characteristics.

Hydrogels based on copolymers of N-vinylpyrrolidone and ethylidene-bis-3-( N-vinyl-2-pyrrolidone) (EBVP) were prepared as polymer matrices for controlled release of high loads of hydrophilic compounds into the gastrointestinal tract. EBVP was synthesized and used as a crosslinking agent for the N-vinylpyrrolidone monomer. The polymerization mixtures, containing 65-80 wt.% of the model pharmacologically active compound, were polymerized to create cylindrical formulations. The release experiments were carried out under conditions corresponding to the digestive tract. Various compositions of hydrogel matrices were tested to reveal the influence of the active compound content and the crosslinking ratio on the release kinetics. Processes such as hydrogel swelling, dissolution and formulation disintegration were evaluated. The results obtained show that the system offers many possibilities to control the drug release to meet various medicinal requirements. [ABSTRACT FROM AUTHOR]

A commercial polyamide reverse osmosis (RO) membrane was surface modified in a sequential two-step dip coating process for improvement of the hydrophilicity and fouling resistance. In the first step, an ultrathin metal-polyphenol precursor layer was deposited onto the membrane surface via the self-assembly of tannic acid (TA) and Fe(III) ions, and polyethylenimine (PEI) was added as a covalent cross-linker. In the second step, poly(N-vinylpyrrolidone) (PVP), a common hydrophilic polymer, was immobilized onto the metal-polyphenol precursor layer through the strong hydrogen bonding interactions between the lactam groups in PVP and the phenolic hydroxyl groups in the precursor layer. X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), transmission electron microscopy (TEM) and zeta potential measurements confirmed the successful immobilization of the precursor layer and PVP. Atomic force microscopy (AFM) test indicated a smoother surface of the modified membrane. Furthermore, the water flux of the modified membrane was only slightly decreased and the salt rejection was almost unchanged. More importantly, static contact angle measurement showed that the membrane surface hydrophilicity was significantly improved after the PVP immobilization (contact angle from 59.0±1.2° to 14.5±2.4°). Membrane fouling experiments were performed over three “filtration–rinsing” cycles using two proteins (lysozyme and bovine serum albumin) and one polysaccharide (sodium alginate) as model foulants. The results of the fouling experiments revealed that the fouling resistance of the reverse osmosis membrane was obviously improved by the surface immobilization of PVP. Besides, cross-flow filtration test under high hydrodynamic shear condition for 15 days indicated the excellent stability of the immobilized PVP. This work provided a new potential strategy for improving the fouling resistance of RO membranes. [ABSTRACT FROM AUTHOR]

Discovering fluorescence of existing compounds, which are generally regarded as non-fluorescent, is of important academic and technical significance. This article reports the fluorescence of common compounds containing pyrrolidone ring(s) and their oxidized hydrolyzates. Poly( N-vinylpyrrolidone) (PVP), polymerized from a very weak fluorescent monomer N-vinyl-2-pyrrolidone (NVP), exhibits strong intrinsic fluorescence. Moreover, the fluorescence of its 'hydrolyzate' is dramatically enhanced by about 1000 times. The 'hydrolyzate' of N-methyl-pyrrolidone (NMP) also exhibits significantly enhanced fluorescence. By studying the chemical structures and fluorescence of the hydrolyzates, the enhanced fluorescence is attributed to the formation of secondary amine oxide. The much stronger fluorescence of the polymers compared to the corresponding small molecular compounds is ascribed to the 'aggregation-induced emission' (AIE) effect of the luminophores. PVP and its oxidized hydrolyzate also show some phenomena different to the common AIE effect. The fluorescence of PVP and its oxidized hydrolyzate shows stimuli response to metal ions and pH values. This study introduces novel fluorescent materials for various potential applications. [ABSTRACT FROM AUTHOR]

In this contribution, we reported the synthesis of poly(N-isopropylacrylamide)- block -poly(N-vinylpyrrolidone)- block -poly(N-isopropylacrylamide) (PNIPAM- b -PVP- b -PNIPAM) triblock copolymers through sequential reversible addition–fragmentation chain transfer/macromolecular design via the interchange of xanthate (RAFT/MADIX) process. The triblock copolymers have been characterized by means of 1 H nuclear magnetic resonance (NMR) spectroscopy, gel permeation chromatography (GPC) and differential scanning calorimetry (DSC). This ABA triblock copolymer displayed a typical thermoresponsive gelation behavior. In this work, the thermoresponsive gelation behavior was investigated by means of rheological measurements, micro-differential scanning calorimetry (Micro-DSC) and small angle X-ray scattering (SAXS). The thermoresponsive gelation behavior could endow the triblock copolymers with the potential application as injectable hydrogels. [ABSTRACT FROM AUTHOR]

The effect of poly (N-vinylpyrrolidone) (PVP) molecular weight (MW) on the flash light sintering of copper nanopaste was investigated. The copper nanopaste was coated on polyimide substrates using doctor blade method. PVP was used as reducing agent to functionalize the copper nanoparticles during flash light sintering process. To find the optimum sintering conditions of copper nanoparticles, the various MWs of PVP (10 000, 40 000 and 55 000) were used and the flash light irradiation energy was varied from 7.5 J/cm 2 to 17.5 J/cm 2 . Meanwhile, other flash light irradiation conditions (pulse numbers, on-time and off-time durations) and amounts of PVP were fixed to clarify the effect of the PVP MW. As the results, it was found that flash light sintered copper nanofilms have the resistivity of 54 μΩcm without any damages to the polymer substrate. To characterize the microstructures and transformation crystal phase of the sintered copper nanofilms, scanning electron microscopy and X-ray diffraction were conducted. In order to understand the interaction between oxidized copper and PVP, X-ray photoelectron spectroscopy was analyzed. To observe the electrical conductivity of flash light sintered copper nanofilms, the sheet resistance of the sintered copper nanofilms was measured using a four-point probe method and the sheet resistance changes during the flash light irradiation process were monitored using in-situ monitoring system. [ABSTRACT FROM AUTHOR]

The main objective of this study was carry out synthesis of silver nanoparticles (AgNPs) stable at room temperature with controlled morphology and size. To achieve our aim, chemical reduction method was used. In the experimental design, it studied effect of concentration of silver nitrate, hydrazine and Poly(N-vinylpyrrolidone)(PVP), as well as reaction temperature on the synthesis of AgNPs. Prepared AgNPs were characterized by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and UV-VIS spectroscopy. AgNPs size was evaluated using DinamicLigth Scattering (DLS) and its stability with Zeta Potential analysis using ZetasizerNano ZS. The results obtained in this study shown the preparation of AgNPs with spherical morphology and 10 nm size, stable at room temperature for further applications. The optimal reaction was in aqueous medium at low temperature, 25 mM AgNO3 and 100-125 mg of PVP. [ABSTRACT FROM AUTHOR]

• Curcumin loaded EGCG/PVP nanoparticles was successfully fabricated via self-assembly driven by hydrogen bonding. • CEP-NPs had better stability and antioxidant capacity than curcumin. • EGCG in CEP-NPs not only regulated the release of curcumin in different pH but also inhibited its glucuronidation. • CEP-NPs showed higher cellular uptake, Caco-2 monolayer permeation and oral bioavailability than curcumin. The biological activity and absorption of curcumin (Cur) is limited in application due to its low water solubility, poor stability and rapid metabolism. In this work, Cur loaded (-)-epigallocatechin-3-gallate (EGCG)/poly(N -vinylpyrrolidone) (PVP) nanoparticles (CEP-NPs) was successfully fabricated via self-assembly driven by hydrogen bonding, providing with desirable Cur-loading efficiency, high stability, strong antioxidant capacity, and pH-triggered intestinal targeted release properties. Molecular dynamics simulations further indicated the Cur was coated with EGCG and PVP in CEP-NPs and high acid prolonged release property was attribute to low ionization degree of EGCG. Besides, the enhanced intestinal absorption of Cur was related to inhibition of Cur metabolism by EGCG, enhancement of cellular uptake and higher Caco-2 monolayer permeation. Pharmacokinetic study showed that the oral bioavailability presented nearly 12-fold increment. Therefore, this study provides a new horizon for improving the Cur utilization in food and pharmaceutical fields. [ABSTRACT FROM AUTHOR]

Abstract: Poly(N-vinylpyrrolidone)-grafted-acrylic acid biocompatible nanogels (NGs) were prepared using an exiting industrial-type electron accelerator and setups, starting from semi-dilute aqueous solutions of a commercial PVP and the acrylic acid monomer. As a result, NGs with tunable size and structure can be obtained quantitatively. Sterility was also imparted at the integrated dose absorbed. The chemical structure of the NGs produced was confirmed through Fourier Transformer Infrared Spectroscopy (FT-IR). The molecular and physico-chemical properties of NGs, such as the hydrodynamic dimensions and surface charge densities, for various polymer and monomer concentrations in the irradiated solutions, are discussed here. [Copyright &y& Elsevier]

Highlights: [•] Aminated polyethersulfone (PES-NH2) was synthesized by a simple method. [•] PVP-grafted PES membrane showed excellent hydrophilic property. [•] PVP-grafted PES membrane showed improved blood compatibility. [Copyright &y& Elsevier]

Abstract: Study of macromolecular structure and dynamics of networks formed by pulsed electron-beam irradiation of poly(N-vinyl pyrrolidone) (PVP) aqueous solutions, at relatively low energy per pulse and across different concentration regimes, provides the basis for the understanding of a new generation of functional nanostructures. Networks are the result of the follow–up reactions initiated by a continuous series of electron pulse-generated hydroxyl radicals, which may have a different fate at the variance of polymer concentration. Different spectroscopic techniques, FT-IR, 13C {1H} CP-MAS NMR and Raman, applied to characterize the formed networks, describe a profound modification of the chemical structure when network size is approaching the nanoscale. Static light scattering measurements provide further information on the average weight molecular weight modification of PVP when forming nanogel particles. From the simultaneous control of network size and modification of chemical functionality stems also an intrinsic fluorescence of these nanogels never observed before. Altogether the obtained radiation-sculptured nanogels exhibit interesting multifunctionality that, coupled with the already proven biocompatibility, can be exploited in the biomedical field. [Copyright &y& Elsevier]