Different Concentrations Of Polyvinylpyrrolidone Research Articles

Bioprospecting a Film-Forming System Loaded with Eugenia uniflora L. and Tropaeolum majus L. Leaf Extracts for Topical Application in Treating Skin Lesions.

Natural products can be used as complements or as alternatives to synthetic drugs. Eugenia uniflora and Tropaeolum majus are natives of Brazil and have antimicrobial, anti-inflammatory, and antioxidant activities. This study aimed to develop a film-forming system (FFS) loaded with plant extracts with the potential for treating microbial infections. E. uniflora and T. majus leaf extracts were prepared and characterized, and the individual and combined antioxidant and antimicrobial activities were evaluated. The FFS was developed with different concentrations of polyvinylpyrrolidone (PVP) and polyvinyl alcohol (PVA) and analyzed for physicochemical characteristics. The combination of extracts showed a superior antioxidant effect compared to the individual extracts, justifying the use of the blend. FFS prepared with 4.5% PVA, 4.5% PVP, 7.81% E. uniflora extract, and 3.90% T. majus extract was adhesive, lacked scale formation, presented good malleability, and had a suitable pH for topical application. In addition, the viscosity at rest was satisfactory for maintaining stability; water solubility was adequate; skin permeation was low; and the antimicrobial effect was superior to that of the individual extracts. Therefore, the developed FFS is promising for the differentiated treatment of skin lesions through topical application.

Facile synthesis of PtMn@Pt core-shell nanowires for oxygen reduction reaction

Platinum-based alloy nanowires are often employed in oxygen reduction reaction (ORR) due to their exceptional performances. However, most platinum-based alloy nanowires suffer from poor stability in strong acidic electrolytes, as well as their complex preparation methods. Herein, PtMn@Pt core-shell nanowires were successfully prepared by one-step hydrothermal with different concentrations of polyvinylpyrrolidone (PVP) and replacement reaction. The results show that the microstructure of nanowires gradually change with the increase of PVP concentration. Meanwhile, the outer layer of the PtMn nanowires contains a Pt-skin of about 1–2 nm. Moreover, the mass activity of the prepared PtMn@Pt core-shell nanowires with 50 mg PVP is 0.409 A mg−1 (@0.9 V), which is 3.86 times higher than that of commercial Pt/C. The as-prepared nanowires display excellent stability mainly due to the existence of Pt-skin. This paper provides a relatively simple method to synthesize Platinum-based core-shell nanowires with outstanding ORR performance.

Biodegradable, Stretchable and Transparent Plastic Films from Modified Waterborne Polyurethane Dispersions.

Waterborne polyurethane dispersions can be designed to generate highly functional and environmentally friendly polymer systems. The use of water as the main dispersion medium is very advantageous for the environment and the introduction of linear and aliphatic polyols such as polyether and polyesters in the formulations can make them highly biocompatible and susceptible to biodegradation. In this study, we fabricated biodegradable, flexible and transparent plastic films by hybridizing a waterborne aliphatic polyester polyurethane (PU) suspension with polyvinylpyrrolidone (PVP) using mechanical homogenization in water. Films were cast containing different concentrations of PVP. The hybrids containing 50 wt.% PVP (PU/PVP_50/50) were hydrophobic, stretchable, highly transparent and ductile beyond 100% strain compared to highly brittle PVP. The mechanical properties of the PU/PVP_50/50 film remained stable after repeated immersion wet–dry cycles, each lasting 2 days, and the dried films recovered their mechanical properties after each cycle. Based on a 28-day biochemical oxygen demand (BOD) test, the hybrid PU/PVP_50/50 film underwent extensive biodegradation. This simple but effective process can be very suitable in producing biodegradable ductile films with very good transparency that can serve a number of applications such as agricultural mulches, food and pharmaceutical packaging and biomedical field.

FORMULATION OF EFFERVESCENT GRANULES FROM RED GINGER (ZINGIBERIS OFFICINALE ROSCOE VAR. RUBRUM) EXTRACT AND ITS ANTIOXIDANT ACTIVITY

Objective: Ginger is one of the Indonesian plants that has been used as traditional medicine. The flavonoids and phenols compounds contained high antioxidant activity. This study aimed to formulate effervescent granules (EG) from red ginger (RG) extract and evaluate its antioxidant activity. Methods: The formulation of EG from RG extract was prepared by the wet granulation method using different concentrations of polyvinylpyrrolidone (PVP). Furthermore, the flowability of granules was evaluated, including flow rate, angle of repose, bulk density, tapped density, Carr's index, Hausner ratio, and effervescent time. The physical stability of granules such as organoleptic evaluation, effervescent time, and pH measurement was also evaluated after 28 d of storage, and the antioxidant activity of EG from RG extract was determined using 1,1-diphenyl-2-picrylhydrazyl (DPPH). Results: The result showed that the EG of RG extract was successfully prepared by wet granulation with a concentration of 15%. In addition, the flowability study showed that all formulas of EG from RG extract have good flow properties, and the granules showed excellent flow properties based on Carr′s index results. The effervescent time of granules remained within the acceptable range according to USP, and the physical stability did not change even after 28 d of storage. The IC50 of EG from RG extract was 283.28±3.6 ppm and has moderate in free radicals scavenging activity. Conclusion: EG from RG extract can be used as food supplements to protect the human body from free radicals and inhibit oxidases.

Water-based graphene/AgNPs hybrid conductive inks for flexible electronic applications

Currently, inkjet printing of the hybrid conductive inks plays a critical role in the technological advancement to fabricate flexible electronics. In this study, flexible electronics based on water-based graphene, silver nanoparticles (AgNPs), and graphene/AgNPs hybrid printed on polyethylene terephthalate substrate (PET) substrate were developed. The properties of the conductive inks were evaluated based on different concentrations of polyvinylpyrrolidone (PVP) surfactants (0.1, 0.3, 0.5, and 0.7 wt%). Among the conductive ink formulations, G/AgNPs hybrid inks fabricated with 0.5 wt% PVP surfactant exhibited better stability, wettability, and electrical conductivity. Moreover, the electrical conductivity of G/AgNPs hybrid conductive traces performed more than 100 times higher than G and AgNPs conductive traces. In addition, it was observed that under 50% tensile and 100 bending times, the printed hybrid conductive traces exhibited only 4% and 3% drop in conductivity, respectively. Therefore, conductive inks prepared from water-based G/AgNPs hybrid ink are thought to be appropriate for usage in printed flexible electronic applications.

Antioxidante e giberelina no cultivo in vitro de Eugenia involucrata DC.

Eugenia involucrata presents recalcitrant seeds and is endowed with a high economic and environmental potential, which justifies the realization of studies related to the production of seedlings via tissue culture. The present work aimed to evaluate the effects of distinct concentrations of polyvinylpyrrolidone (PVP) and GA3 in the in vitro culture. Different concentrations of PVP were tested: 0; 0,5; 1 or 1,5 g L-1 and, in a second experiment, of GA3: 0; 1; 2 or 4 μM, in two in vitro culture periods (30 or 60 days). There was no significant effect of PVP, with high survival rates (83,10%) and establishment (73%), but low for phenolic oxidation (16,55%). Significant effect of the cultivation period was observed only for survival rate, whereas average height and number of shoots were affected only GA3 had an effect. The greatest survival occurred at 30 days (88,10%), decreasing at 60 days (61,45%). For shoot height, the highest mean (0,52 cm) was at 4 μM of GA3, and in the absence, the lowest mean (0,12 cm) occurred. For the number of shoots, a higher mean was obtained (4,5) in its absence, whereas, at 4 μM, the lowest number occurred (0,15). PVP is dispensable; GA3 has an effect on in vitro elongation but reduces the number of shoots in E. involucrata.

Zinc sulfide quantum dots coated with PVP: applications on commercial solar cells

In this study, we report the synthesis and characterization of zinc sulfide quantum dots (ZnS QDs) coated with different concentrations of polyvinylpyrrolidone (PVP), as well as their deployment as luminescent films on the window side of previously characterized commercial silicon solar cells to quantify their influence on the power conversion efficiency (PCE). The synthesis of the semiconductor nanoparticles was carried out by the reaction of zinc nitrate with sodium sulfide in an aqueous solution at room temperature. XRD measurements indicated a cubic sphalerite phase of the QDs crystal structure, which was not modified by the addition of PVP in the synthesis process. However, the PVP concentration was a key parameter to modulate the size distribution and the luminescent intensity of the QDs, suggesting that an increase in the PVP concentration produced a slight decrease in the QDs size and improved their luminescent properties desired for the photovoltaic applications. The obtained nanoparticles presented great absorption of photons with energies above 3.72 eV and a broad intense blue photoluminescent emission centered at around 450 nm, under excitation of ultraviolet light of 325 nm. The implementation of the synthesized ZnS QDs as spectral response enhancer produced improvements on the performance of solar cells, leading to increases of 0.7%, 1.9%, and 6.1% on the efficiencies of commercial polycrystalline solar cells after the deposition of ZnS QDs synthesized without PVP, with 0.05 mM PVP and with 0.10 mM PVP, respectively.

The Effect of PVP Concentration on Particle Size, Morphological and Optical Properties of Cassiterite Nanoparticles

Different concentrations of polyvinylpyrrolidone (PVP) have been successfully employed to prepare high purity tetragonal cassiterite nanoparticles, and control the growth of particle size. The effect of PVP on the structural, morphological, size, composition, and optical properties of the prepared cassiterite nanoparticles has been investigated. It has been found that various characteristics of tetragonal cassiterite nanoparticles could be optimized by simply changing the values of PVP. The pure tetragonal cassiterite nanoparticles have been produced at the optimum calcination temperature. The XRD and SEM results indicated the structural and morphological properties of the tetragonal cassiterite nanoparticles, respectively. The particles' size and their distribution have been displayed by TEM images. The composition phase and the surface composition of the prepared samples have been evaluated via FTIR and XPS, respectively. The optical properties of the prepared tetragonal cassiterite nanoparticles have been studied using UV-vis and PL spectroscopy. Outcomes cassiterite nanoparticles are useful for antibacterial activity and application of solar energy.

Effect of PVP concentration on prepared PEI membranes for potential use on water treatment: effect of additive on membranes prepared for water treatment

Abstract In this work, a series of polyetherimide (PEI) flat sheet membranes were produced with different concentrations of polyvinylpyrrolidone (PVP) addition via the phase inversion method. The effects of additions on membrane morphology and performance were investigated. Synthesized membrane had the properties of ultrafiltration membrane. Although PEI is not widely used for water treatment, in this study, the ferrous iron removal rate was investigated and good results were obtained. Through the membrane production experiments, the PEI content was 22 wt%. PVP was added as a pore-forming agent with concentrations of 2, 4 and 8 wt%. N-methyl-2-pyrrolidone (NMP) was used as solvent. Distilled water was used for the coagulation bath. After production, all membranes were characterized by using contact angle, permeability, porosity, and scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT/IR) analyses. With the increasing doses of PVP addition, the permeability of the PEI membranes produced in this study increased, while porosity results were changeable. The permeability was 23 L/m2h bar for the membrane with 2 wt% PVP content, while the permeability for the membrane with 8 wt% PVP content was 32 L/m2h bar. Contact angles increased with PVP addition to PEI membranes. With the increasing PVP concentration, the finger-like pores and the pores located in the sub-layer expanded.

Characterization of Zinc Ferrite Nanoparticles Capped with Different PVP Concentrations

The effects of polyvinyl pyrrolidone (PVP) as a capping agent on the structure, morphology, magnetic hysteresis (M–H) loop, optical and dielectric properties of ZnFe2O4 nanoparticles synthesized by a co-precipitation method were investigated. The precursors used during preparation were FeCl3·6H2O, ZnCl2, and 4 M NaOH with different concentrations of PVP: 0 (pure sample), 0.35 × 10−3 M, 0.69 × 10−3 M, 1.03 × 10−3 M, and 1.38 × 10−3 M. The prepared samples were characterized and investigated using x-ray powder diffraction (XRD), transmission electron microscope (TEM), UV–visible optical spectroscopy, Fourier transform infrared (FTIR), magnetic hysteresis (M–H), and dielectric measurements. XRD patterns reveal a face-centered cubic structure for ZnFe2O4 and confirm that the lattice parameter decreases as the PVP concentration increases. TEM results reveal some aggregation of nanoparticles and a decrease in crystallite size with increasing PVP addition. The energy gap (Eg) increases with an increase of PVP concentration, confirming the decrease of crystallite size as the PVP concentration increases. The FTIR results indicate that PVP addition induces a blue shift with slight variations in the wavelengths of the metal oxide bands. M–H results show that the uncapped PVP sample exhibits ferromagnetic behavior that changes to superparamagnetic with PVP addition up to 1.03 × 10−3 M, along with an increase in the saturation magnetization Ms. The coercivity Hc increases up to a PVP concentration of 0.35 × 10−3 M, and then decreases up to a PVP concentration of 1.03 × 10−3 M. The dielectric constant and dielectric loss measured at room temperature decrease when increasing the frequency, but increase when increasing the temperature or PVP concentration. These results indicate that there is a critical amount of PVP that must be added in order to control the properties of ZnFe2O4 nanoparticles to use them for dielectric and magnetic applications.

Investigation on the coating modification effect of nano-SiO2 particles on nano-TiO2 particles

TiO2 has received significant scientific attention as a highly operative, stable, and low-cost photocatalyst. However, the decomposition of organic matrices due to its photocatalytic action is considered to be one of the main drawbacks of TiO2 nanoparticles in its applications in inks. To overcome this problem, this study aims to coat the surface of the nano-TiO2 particles with a layer of nano-SiO2 particles through a sol-gel method. The nano-TiO2 powder was dispersed by polyvinylpyrrolidone (PVP) and 4-vinylpyridine (4VP). The effects of different concentrations of PVP and 4VP, molar ratios of silicon to titanium, and ammonia water dosage on the properties of the composite particles were investigated. Scanning electron microscopy (SEM) analysis showed that the coating effect is best when the PVP had a mass of 2 g, the 4VP had a volume of 2 ml, the ratio of titanium to silicon was 1:2, and the amount of ammonia was 5 ml. The transmission electron microscopy (TEM) images show that titania particles were successfully coated on the surface of nano-TiO2. The x-ray diffraction (XRD) patterns showed no change in the crystal structure of nano-TiO2 before and after coating with nano-SiO2. Comparing the Fourier-transform infrared (FT-IR) and x-ray photoelectron (XPS) spectra, it was found that the Ti–O–Si bond is present in the nano-TiO2/SiO2 composite particles, and the Si element is present in the TiO2 crystal in the form of Ti–O–Si. These results indicate that the nano-SiO2 was coated on the surface of the nano-TiO2 successfully, and the ultraviolet (UV) resistance of pure nano-TiO2 is effectively improved.

Preparation of arrayed helical micro/nanofibers by near-field electrospinning

The helical micro/nanofiber arrays of polyvinylpyrrolidone (PVP) were successfully prepared by Near-field electrospinning(NFES) with different concentrations of PVP and different voltages by a gradient of per 0.5 kV from 1 kV to 2.2 kV. It is found that the morphology of the arrayed fibers evolved with regularity with the increase of the working voltage, and the uniformity of the fiber arrays also increased. The formation mechanism of the arrayed helical micro/nanofibers was analyzed. This may be a cost-effective method for the large-scale production of morphologically controllable spiral fibers, which opens up an effective way for the precise and controlled deposition of electrospun helical fibers and the integration of single or array spiral fibers with functional devices.

Synthesis of poly(N-vinyl-2-pyrrolidone) adsorbed-AuPt/C bimetallic nanoparticles and their unusual electrocatalytic activity towards methanol tolerant oxygen reduction reaction

It has been suggested that the presence of adsorbed impurities, such as capping agent or organic reaction products adsorbed on the metallic nanoparticles, severely affects the electrocatalytic activity of surface sensitive reactions. At least in some cases, these adsorbed impurities may alter the electronic nature of nanoparticles and thus alter the electrocatalytic activity. In this work, we report the synthesis of AuPt/C bimetallic nanoparticles (BNPs) supported on Vulcan carbon using the polyol method in the presence of different concentrations of polyvinylpyrrolidone (0.01, 0.1, and 1 %) as a capping agent and electrocatalytic activity of the synthesized AuPt/C BNPs. We found that the PVP adsorbs on the AuPt BNPs through C = O functional group, but not through the N-atom. The oxygen reduction reaction (ORR) activity and the methanol tolerance were evaluated on those PVP adsorbed AuPt/C BNPs catalysts. Remarkably, AuPt/C BNPs catalyst with 0.1 % PVP showed a balance of ORR electrocatalysis and methanol tolerance when compared to the PVP free AuPt BNPs. The adsorbed PVP on AuPt BNPs alters the electronic properties of the Pt through electronic interaction with Pt and also controls the surface geometry suitable to ORR, but not the methanol adsorption.

Solvation consequences of polymer PVP with biological buffers MES, MOPS, and MOPSO in aqueous solutions

Densities and viscosities were measured for the aqueous buffer (MES, MOPS, or MOPSO) solutions containing different concentrations of polyvinylpyrrolidone (PVP) (5, 10, 15, 20 and 30)mass% at temperatures from (298.15 to 318.15)K under atmospheric pressure. The DFT calculations were also performed and the binding energies of the possible (PVP+buffer) complexes were obtained. The experimental and computational results reveal the interactions of the PVP with the constituent compounds in the aqueous buffer solutions. Additionally we have explored the solvation behavior of the buffers by measuring the densities and the viscosities data of the aqueous buffer solutions from (0.0 to 1.0)mol·kg−1 at temperatures from (298.15 to 318.15)K. The viscosity results were correlated with the Jones–Dole equation. The correlated results confirmed that all the investigated buffers behave as Kosmotropes (structure makers).

Single step thermal treatment synthesis and characterization of lithium tetraborate nanophosphor

This study includes the synthesis of nano-sized lithium tetraborate by an innovative single step thermal treatment method and characterization of the products. The heating temperature for the synthesis was varied between 200 and 850°C with the retention time of 2h. Polyvinyl pyrrolidone (PVP) with different concentrations was used as surfactant. Characterization of the samples was achieved by thermogravimetric analysis (TGA), derivative thermogravimetry analysis (DTG), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM) techniques and UV–vis spectroscopy. Thermal analysis of initial solution allowed the optimization of the heat treatment program and showed that the thermal stability of samples is started at 460°C. FT-IR, XRD and TEM results proved the formation of pure nano-crystalline lithium tetraborate at temperature between 460 and 750°C. Furthermore, the band gap investigation was performed using UV–vis spectra in the presence of different concentrations of PVP and in variety of calcination temperatures. The estimated optical bandgap was found to be between 5.2 and 6.2eV.

Enhanced separation performance of PVDF/PAN blend membrane based on PVP tuning

Ultrafiltration (UF) membranes were prepared from blends of poly(vinylidene fluoride) (PVDF)/polyacrylonitrile (PAN) via phase inversion method induced by immersion precipitation. Polyvinylpyrrolidone (PVP) was used as pore former and hydrophilic polymeric additive. N,N-dimethylacetamide (DMAc) and water were used as solvent and coagulant (non-solvent), respectively. The effect of different concentrations of PVP on the morphology and performance of the prepared membranes was investigated. Performance of the membranes was evaluated based on pure water flux and filtration of buffered bovine serum albumin (BSA) solution. The contact angle measurements indicated that the hydrophilicity of PVDF/PAN membranes improved by increasing the PVP concentration in the casting solution. However, such improvement was limited to PVP concentration of the casting solution up to 4 (wt.%) and then decreased by further addition of PVP. According to the obtained results, the rejection of BSA decreased with increase in the PVP concentration in the casting solution. The morphology of the prepared membranes was studied by scanning electron microscopy.

Effect of carbon coating on the electrochemical properties of Bi2WO6 nanoparticles by PVP-assisted sonochemical method

Polyvinylpyrrolidone (PVP)-assisted Bi2WO6 nanoparticles were successfully synthesized by sonochemical method. Three different concentrations of PVP (0.05, 0.1, and 0.2 g) were used, and their effects over the structural, morphological, compositional, and electrochemical analysis were studied. The structural investigation revealed the formation of 100 % pure Bi2WO6 phase. The presence of carbon in the PVP-assisted materials was evidenced from differential scanning calorimetry, Fourier transform infra red (FT-IR) spectroscopy and Raman analysis. There was a reduction in the particle size of Bi2WO6 (30–35 nm) upon using PVP. The highly crystalline nature and the presence of carbon coating over Bi2WO6 were evidenced from the high-resolution transmission electron microscopic image. Besides, the calculated d-spacing of 0.19 nm attributed to (2 0 6) lattice plane of Bi2WO6 nanoparticles. Subsequently, a shift in binding energy toward larger values while using PVP was identified through X-ray photoelectron spectroscopic analysis. The electrochemical analysis showed a subsequent enhancement in specific capacitance of PVP-assisted Bi2WO6 (462 F g−1) compared with pristine Bi2WO6 (304 F g−1) at 3 mA cm−2.

Polyvinylpyrrolidone Quantification in Paracetamol Using Phase-Resolved Photoacoustic Method

In this study, photoacoustic spectroscopy was used to quantify polyvinylpyrrolidone in paracetamol samples with different proportions of polyvinylpyrrolidone. Samples with 10%, 20%, and 30% of polyvinylpyrrolidone added to pure paracetamol were used. The results showed an increase in the intensity of the characteristic bands of polyvinylpyrrolidone centered at 1450 nm and 1170 nm; the intensity of these bands increased in relation to the concentration of polyvinylpyrrolidone. The phase-resolved photoacoustic method was applied in Photoacoustic spectra to provide further information. The results show that phase-resolved photoacoustic method can provide an alternative analytical method to detect different concentrations of polyvinylpyrrolidone in paracetamol samples.

Influence of polyvinyl pyrrolidone on the dispersion of multi-walled carbon nanotubes in aqueous solution

The sonication-driven suspensions of multi-walled carbon nanotubes (MWNTs) were prepared using the polyvinyl pyrrolidone as a dispersant. UV-visible absorbency, surface tension, zeta potential, adsorption isotherm and transmission electron microscopy, were used to characterize the homogeneity and stability of MWNTs suspensions with different concentrations of polyvinyl pyrrolidone. All results show that the optimum concentration of polyvinyl pyrrolidone in suspension is 0.5 g/L.

One-pot eco-friendly synthesis of gold nanoparticles by glycerol in alkaline medium: Role of synthesis parameters on the nanoparticles characteristics

In this work we studied the role of experimental variables in an ecologically-correct synthesis of gold nanoparticles carried out by glycerol in alkaline medium at ordinary temperatures (25°C and 0°C). Variation of pH allowed the production of spherical and anisotropic nanoparticles. Different concentrations of polyvinylpyrrolidone (PVP) directly impacted the size and stability of the nanoparticles. In contrast, glycerol concentration had little influence on the synthetic process. The empirical rate law was determined for the process with respect to glycerol and gold ions. From the kinetic study it was possible to establish that the rate of nanoparticle formation is only slightly more dependent on gold ions than on glycerol. Thus, to increase the rate of nanoparticles formation, it is economically and environmentally more advantageous to increase the glycerol concentration than the Au3+ concentration.