Low Molecular Weight Polyvinylpyrrolidone Research Articles

Miscibility of Amorphous Solid Dispersions: A Rheological and Solid-State NMR Spectroscopy Study

Miscibility is critical in the prediction of stability against crystallization of amorphous solid dispersions (ASDs) in the solid state. However, currently available approaches for its determination are limited by both theoretical and practical considerations. Recently, a rheological approach guided by the polymer overlap concentration (c*) has been proposed for miscibility quantification of ASDs [J. Pharm. Sci., 112 (2023) 204−212] and shown to be useful in predicting both accelerated and long term physical stability in the absence of moisture. However, this approach can only be performed at high temperatures (slightly above the melting temperature, Tm, of drugs), and little is known about the difference in miscibility between high and low temperatures (e.g., below the glass transition temperature, Tg). Here we compare the miscibility of nifedipine (NIF)/polyvinylpyrrolidone (PVP) ASDs as determined by the rheological approach at 175°C (∼3°C above Tm of NIF) and solid state NMR (ssNMR) 1H T1 and T1ρ relaxation times at -20°C (∼66°C below Tg of NIF). Our results indicate agreement between the two methods. For low molecular weight (Mw) PVP, T1ρ measurements are more consistent with the rheological approach, while T1 measurements are closer for relatively high Mw PVP. Our findings support the use of the c* based rheological approach for inferring miscibility of deeply cooled ASDs.

Recovery therapy after photodynamic therapy of background and precancerous diseases of the vulva

A comprehensive approach that includes the treatment of background and precancerous diseases of the vulva by photodynamic therapy and plasma therapy as rehabilitation therapy was developed. The method’s effectiveness was evaluated. The study is also aimed at evaluating the effectiveness of plasma therapy after treatment of background and precancerous diseases of the vulva by photodynamic therapy. The work is based on the study results of 60 patients aged 32 to 70 years old, mean age was (53.3+3.6) years, with a morphologically verified diagnosis of vulvar intraepithelial neoplasia, mixed vulvar dystrophy (Lichen sclerosus et atrophicus, squamous cell hyperplasia), which were divided into two groups. Patients of both groups underwent photodynamic therapy using an intravenous photosensitizer «Fotolon®» (RUE «Belmedpreparaty», Republic of Belarus), which is a complex of chlorine ебс trisodium salt with low molecular weight polyvinylpyrrolidone. The session of photodynamic therapy was performed 3^1 hours after the end of the FS infusion using a universal laser coagulator «Likar-Hirurg (Surgeon)» («Photonica Plus», Ukraine, A-660 nm). Plasma therapy was performed for patients of group 2 after photodynamic therapy. It has been established that the use of photodynamic therapy and plasma therapy increases the effect of treatment of background and precancerous diseases of the vulva, accelerates the period of damaged tissues regeneration and rehabilitation of patients twice and prolongs the recurrence-free period of the disease. Keywords: photodynamic therapy, plasma therapy, precancerous diseases of the vulva.

Formulation, characterization and evaluation of mRNA-loaded dissolvable polymeric microneedles (RNApatch)

In this paper, we report a proof of concept study on the fabrication, characterization and therapeutic evaluation of in vitro transcribed messenger RNA (mRNA) loaded in a dissolving microneedle patch (RNApatch). We show that low molecular weight polyvinylpyrrolidone (PVP) can directly be used without further purification for RNApatch fabrication with no detectable mRNA degradation. Physical and functional integrity of mRNA stored within the RNApatch are completely preserved for at least 2 weeks under ambient conditions. While the loading of mRNA into RNApatch is limited by the solubility of mRNA in concentrated PVP solution, mechanical strength of RNApatch is not compromised by the presence of mRNA. RNApatch can mediate in vivo transgene expression of mRNA encoding luciferase for up to 72 hours and transfection efficiency and kinetics mediated by RNApatch compares favorably to subcutaneous injection. Interestingly, mRNA transfection efficiency does not correlate with contact surface area but instead increases with deeper delivery depths. In an E.G7-OVA immunotherapy model, RNApatch induces slightly higher cellular and humoral immune responses compared to subcutaneous injection. In conclusion, RNApatch is a viable delivery platform for mRNA and represents an attractive option with significant translation potential for the delivery of mRNA therapeutics.

Novel and simple method to synthesize donut-like TiO2 with photocatalytic activity

This paper presents a novel and simple method to fabricate donut-like TiO2 with efficient photocatalytic activity. Donut-like TiO2 was successfully prepared via electrospraying technique using a low molecular weight polyvinyl pyrrolidone (PVP) polymer. X-ray diffraction measurements show that donut-like TiO2 maintains a pure anatase structure. A transmission electron microscopy image reveals hollow donut-like TiO2. The effects of applied voltage parameter on energy gap, atomic force microscopy micrographs, field emission scanning electron microscopy pictures, and photoluminescence spectra are examined. The photocatalytic properties of donut-like TiO2 were evaluated with photocatalytic degradation of methylene blue (MB) in water under UV light irradiation. Donut-like TiO2 exhibits an efficient photocatalytic activity that reaches 67% after the degradation of MB in aqueous solution for 200min.

Structural-thermochromic relationship of polydiacetylene (PDA)/polyvinylpyrrolidone (PVP) nanocomposites: Effects of PDA side chain length and PVP molecular weight

Abstract Reversible thermochromic polydiacetylene (PDA)/polyvinylpyrrolidone (PVP) nanocomposites are prepared by using 6 diacetylene (DA) monomers. The use of relatively low molecular weight (MW) PVP provides the nanocomposites with reversible thermochromism. The shortening of PDA alkyl tail causes the decrease of color-transition temperature, ranging from 75 to 85 °C. The shortening of alkyl segment adjacent to PDA carboxylic head group, however, does not provide the same trend. The nanocomposites constituting PDAs with 8, 6 and 4 methylene units exhibits color-transition at about the same temperature. The increase of PVP MW reduces the color-transition temperature and also affects thermochromic reversibilty of the PDA/PVP nanocomposites.

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.

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.

Role of mexidol (2-ethyl-6-methyl-3-hydroxypyridine succinate) in the obtaining of stabilized magnetite nanoparticles for biomedical application

Magnetite nanoparticles (NPs) are studied as agents for magnetic resonance imaging, hyperthermia of malignant tumors, targeted drug delivery as well as anti-anemic action. One of the main problems of such NPs is their aggregation that requires creation of methods for magnetite NPs stabilization during preparation of liquid medicinal forms on their basis. The present work is devoted to the possibility of mexidol (2-ethyl-6-methyl-3-hydroxypyridine succinate) use for solubilization of magnetite NPs in hydrophilic medium. For this purpose, the condensate produced by electron-beam evaporation and condensation, with magnetite particles of size 5-8 nm deposited into the crystals of sodium chloride were used in conjunction with substance of mexidol (2-ethyl-6-methyl-3-hydroxypyridine succinate), and low molecular weight polyvinylpyrrolidone (PVP). The NP condensate was dispersed in distilled water or PVP or mexidol solutions. NPs size distribution in the liquid phase of the systems was determined by photon correlation spectroscopy, iron (Fe) concentration was evaluated by atomic emission spectrometry. It is shown that in the dispersion prepared in distilled water, the major amount of NPs was of 13-120 nm in size, in mexidol solution - 270-1700 nm, in PVP solution - 30-900 nm. In the fluid containing magnetite NPs together with mexidol and PVP, the main fraction (99.9%) was characterized by the NPs size of 14-75 nm with maximum of 25 nm. This system had the highest iron concentration: it was similar to that in the sample with mexidol solution and 6.6-7.3 times higher than the concentration in the samples with distilled water or PVP. Thus, in the preparation of aqueous dispersions based on magnetite NPs condensate, mexidol provides a transition of Fe to the liquid phase in amount necessary to achieve its biological activity, and PVP stabilizes such modified NPs.

Transfer of Silver Nanoparticles through the Placenta and Breast Milk during in vivo Experiments on Rats

Silver nanoparticles (NPs), widely used in the manufacture of various types of consumer products and for medical applications, belong to novel types of materials that pose potential risks to human health. The potential negative effects of the influence of these NPs on reproduction are insufficiently researched. A quantitative assessment of the transfer of metallic silver nanoparticles through the placenta and breast milk was carried out during an in vivo experiment. We used 34.9 ± 14.8 nm in size silver NPs that were stabilized by low-molecularweight polyvinylpyrrolidone and labeled with the (110m)Ag radioactive isotope using thermal neutron irradiation in a nuclear reactor. [(110m)Ag]-labeled NPs preparations were administered intragastrically via a gavage needle to pregnant (20(th) day of gestation) or lactating (14-16th day of lactation) female rats at a dose of 1.69-2.21 mg/kg of body weight upon conversion into silver. The accumulation of NPs in rat fetuses and infant rats consuming their mother's breast milk was evaluated using a low-background semiconductor gamma-ray spectrometer 24 and 48 hours following labeling, respectively. In all cases, we observed a penetration of the [(110m)Ag]-labeled NPs through the placenta and ther entry into the mother's milk in amounts exceeding by 100-1,000 times the sensitivity of the utilized analytical method. The average level of accumulation of NPs in fetuses was 0.085-0.147% of the administered dose, which was comparable to the accumulation of the label in the liver, blood, and muscle carcass of adult animals and exceeded the penetration of NPs across the hematoencephalic barrier into the brain of females by a factor of 10-100. In lactating females, the total accumulation of [(110m)Ag]-labeled NPs into the milk exceeded 1.94 ± 0.29% of the administered dose over a 48 h period of lactation; not less than 25% of this amount was absorbed into the gastrointestinal tract of infant rats. Thus, this was the first time experimental evidence of the transfer of NPs from mother to offspring through the placenta and breast milk was obtained.

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

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

Preparation and characterization of polyvinylidene fluoride (PVDF) hollow fiber membranes

Polyvinylidene fluoride (PVDF) hollow fiber membranes were prepared by dry/wet and wet phase inversion methods. In spinning these PVDF hollow fibers, dimethylacetamide (DMAc) and polyvinyl pyrrolidone (PVP) were used as a solvent and an additive, respectively. Water was used as the external coagulant. Water or ethanol was used as the internal coagulants. The membranes were characterized in terms of water flux, molecular weight cut-off for the wet membranes. Gas permeation fluxes and effective surface porosity were determined by a gas permeation method for the dried membranes. The cross-sectional structures were examined by scanning electron microscopy. The effects of polymer concentration, air-gap, PVP molecular weight, PVP content in the polymer dope, and the internal coagulant on the permeation properties and membrane structures were examined. Highly permeable PVDF hollow fiber membranes could be prepared from a polymer dope containing low molecular weight PVP and using ethanol as the internal coagulant.

Bioplastique at 6 years: clinical outcome studies.

Bioplastique is a biphasic polymer for the permanent augmentation of some soft tissues. It was developed in 1987, and clinical studies at this institution were begun in 1990. The combination of low molecular weight polyvinylpyrrolidone and solid polymer particles allows the implantation of permanent polymer spheres through a small needle under local anesthesia. In this study 127 cases are reviewed of consecutive patients who have received Bioplastique for scar revision, wrinkles, and augmentation for soft-tissue defects at 6 years after application. All patients who had not been in for follow-up recently were contacted by mail and questioned on the permanence of augmentation and migration of particles. About 30 percent of the patients were unreachable and had their charts reviewed for permanence and migration of particles. In eight of these cases, Bioplastique was removed because of overcorrection, two of them may have had infection. Bioplastique has gained wide use throughout the world and although some complications have been reported, in general, it functions quite well when used in selected cases.

The Misti Gold bio-oncotic gel filled breast prosthesis: an acceptable alternative to silicone?

Concern about the use of silicone gel as a filler for breast prostheses has stimulated interest in other materials. We have evaluated the Misti Gold prosthesis which contains a “bio-oncotic” gel of low molecular weight Polyvinylpyrrolidone (PLASDONE 24AUK). Our experience of its use in breast augmentation is that the aesthetic results obtained with retromammary placement are inferior to those obtained from a silicone gel filled prosthesis. Nonetheless there are theoretical advantages for its use which will need to be considered in the light of recent regulatory decisions.

Cryopreservation of bone marrow with low molecular weight polyvinylpyrrolidone

The cryoprotective effectiveness of low molecular weight polyvinylpyrrolidone (PVP), K-15 and K-17, in the preservation of rat and mouse bone marrow has been evaluated on the basis of tissue culture followed by phase contrast microscopy, by incorporation of glycine-C 14 , and by the 30-day survival of lethally irradiated mice. Optimal concentration for PVP K-15 and K-17 was found to be 20%. Low molecular weight PVP proved very effective in the preservation of bone marrow, and comparable in this respect to dimethyl sulfoxide. Because of the high protection it offers and its rapid renal excretion, low molecular weight PVP should be further tested for its effectiveness in the cryopreservation of human bone marrow.