Polyvinylpyrrolidone

The influence of biological membranes on in vitro bioadhesion property of Carbopol 934P (CP), Polyvinylpyrrolidone (PVP K90) and sodium
carboxymethylcellulose (Cekol 10,000) was studied using a texture analyzer equipment. Polymer/biological membrane interaction was significantly
influenced by the contact time used during the study. An increase in contact time also increased bioadhesion strength. An intermediate
contact time of 180s was deemed to be the most suitable contact time. In addition, different polymers produced different values of bioadhesion
strength. Moreover, polymer molecular weight is directly correlated with bioadhesion strength. Biological membrane, such as rabbit gastric
mucosa, cow intestine, pig intestine or chicken pouch, is a less significant determinant in affecting the bioadhesion strength as compared to
the type of polymer used. Chicken pouch, an easily available and uniform tissue, offers an attractive alternative to be employed as a model
biological membrane in bioadhesion study.

Context: The use of quercetin as a potential active pharmaceutical ingredient is limited by low aqueous solubility leading to low bioavailability. A spray-dried solid dispersion technique is used to increase the solubility and dissolution profiles of quercetin.

Aims: To prepare and characterize quercetin solid dispersion using polyvinylpyrrolidone (PVP) K-30.

Methods: Solid dispersions (SDs) were prepared by spray drying technique at quercetin/PVP K-30 ratios of 10/90, 20/80, 30/70, 40/60 and 50/50. A physical mixture of quercetin/PVP K-30 (50/50) and pure quercetin were used as comparisons. The SDs were characterized by powder X-Ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-transform IR (FTIR) spectroscopy, solubility and dissolution studies. The effect of the drug/polymer ratio on the solubility of quercetin was also studied.

Results: Quercetin SDs appeared as amorphous form as confirmed by XRD. Quercetin was better dispersed as the drug/polymer ratio decreased. SD with ratio 10/90 showed regular spherical particles in the size range of 0-35 µm. The solubility of quercetin increased with decreasing drug/polymer ratio. Preparation of SDs influence the solubility significantly (p<0.01). The increase in solubility is probably due to a hydrogen bond between quercetin and PVP K30 as confirmed by FTIR spectra. SD with ratio 10/90 showed a high dissolution rate (95.12 ± 1.83%) within 120 min in comparison to pure quercetin (19.37 ± 0.58%) or physical mixture (37.85 ± 0.85%).

Conclusions: Preparation of quercetin SDs with PVP K30 by spray drying technique results in amorphous spherical particles. There was an increase in solubility and percent dissolved with a decrease in drug/polymer ratio.

Due to its properties such as biocompatibility, water solubility and stability, polyvinylpyrrolidone (PVP) becomes more and more attractive for biomedical applications. This polymeric material is used in various applications such as pharmaceutical aid, complexing agent or solubilizer. PVP nanofibers are often produced using PVP solutions in solvents with high toxicity such as dimethylformamide (DMF). The aim of this study is to investigate the effect of process parameters on the electrospinning behavior of polyvinylpyrrolidone in solvents with lower toxicity such as dimethylsulfoxide (DMSO) or ethanol. Therefore, solutions of PVP in ethanol, PVP in DMSO or PVP in binary solvent systems such as DMSO/ethanol or DMSO/acetone were prepared and electrospun. The effect of process parameters such as voltage, flow rate, tip-to-collector distance were examined. A solution parameter, the polymer concentration was also considered. The morphology and diameter of the electrospun nanofibers were characterized by scanning electron microscopy (SEM). The effect of the solution viscosity was also questioned. Nanofibers with a homogeneous cylindrical morphology were obtained in the case of PVP in ethanol solutions for a polymer concentration of 7 wt.%. The process parameters were: a voltage of 15kV, tip-tocollector distance of 15 cm and a flow rate of 1.25 mL/h. PVP in DMSO solutions didn't allow the obtention of solid nanofibers on the collector where a wetness zone appears. This shows that the solvent could not evaporate quickly. A wetness was also observed with PVP solutions prepared using binary solvent systems where a more volatile solvent such as ethanol or acetone was used.

Electrospraying technique has been successfully used to synthesize composite submicron particles of polyvinylpyrrolidone (PVP) and green tea extract (GTE). The precursor solutions were PVP in ethanol (15 wt%) and GTE in ethanol (10 wt%), which were then mixed at varying ratio. The mixed solution then underwent electrospraying process at an applied voltage of 15 kV, a distance of collector to the nozzle at 15 cm, and a flow rate of 3 µL/min. The composite submicron particles of PVP-GTE showed smooth and fine spherical morphology without fibers or beaded fibers. To a certain degree, the increase of GTE content in the PVP-GTE mixed solution decreased the average diameter of PVP-GTE composite particles. Moreover, the analysis of the FTIR spectra confirmed the existing molecular interaction between PVP and GTE in the composite submicron particles as shown by the shift of PVP wavenumber towards GTE, which has typically smaller wavenumber.

The most significant characteristics of high voltage power transformers are capability to withstand breakdown voltage through faults in insulation system. Dielectric breakdown cause degradation of insulation system and study of its performance can give useful data regarding the condition of insulation. In this paper, the experimental investigations on Breakdown voltage were carried out at various temperatures on different thickness of laminated precompressed pressboards prepared by an insulating polymers polyvinyl alcohol (PVA) and polyvinylpyrrolidone (PVP). A test were conducted on a transformer model insulation comprising of precompressed pressboards impregnated with transformer oil kept between electric field electrodes arrangement for its behavior for high voltage applications. A variable high voltage AC were applied to test samples until breakdown occurs in the form of puncture and the readings were recorded. Investigations were done for different thickness samples at various temperatures and the results obtained shows superiority of PVP over PVA precompressed pressboards in regards to withstanding the breakdown voltage.

The aim of this work was to elaborate the 3D printed polylactide (PLA) polymeric scaffolds and, subsequently, study the possibility of coating thereof with a biomedical polyvinylpyrrolidone (PVP) hydrogel through the previously patented protocol. Such materials have a potential to be applied in biomedical engineering, e.g. for tissue regeneration. PVP layer according to the present paper could constitute a useful biocompatible supporting layer for drug delivering implant surfaces of any shape. Polylactide (PLA) both in forms of flat foils and 3D-printed scaffolds was used to be coated with PVP layer with the Fenton-type reaction that enables the polymeric scaffold grafting with hydrogel in two easy steps. The study revealed that PVP was successfully grafted to PLA substrates. Most optimal parameters for PVP grafting process were selected. The PLA-PVP materials were found to be hydrophilic and non-toxic which is promising considering their biomedical application. The method comprising well-tested PLA scaffolds printing and then grafting them with PVP layer has a promising potential to be brought in to the industrial production due to its simplicity.

Green Tea Extract (GTE) as an active substance has successfully loaded to PVP nanostructures using electrohydrodynamic spraying technique. The precursor solution was the mixture of ethanolic polyvinylpyrrolidone (PVP) with a molecular weight of 1,300 kg/mol and ethanolic GTE solutions at a weight concentration of 4 wt.% and 2 wt.%, respectively, and it was estimated that the entanglement number was 2. The electrospraying was conducted at the voltage of 15 kV, the flow rate of 10 µL/min., and the distance between the collector and the tip of the nozzle of 10 cm. The SEM images showed that the PVP/GTE nanostructures had a combination of agglomerated beads (less spherical particles) and nanofibers. This occurred because if the PVP concentration is low, the PVP/GTE composite has weak core structures that cause the shell to be easily agglomerated each other. The intermolecular interaction between PVP and GTE in the PVP/GTE nanostructures occurred as confirmed by the peak at 3396 cm-1 , which is the carboxyl group, proving that the PVP/GTE nanostructures contained water, alcohols, and phenols. The peak at 1040 cm-1 , which is the stretching of CO group in amino acid, gave another proof to the intermolecular interaction.