Resistance mechanisms of Saccharomyces cerevisiae against silver nanoparticles with different sizes and coatings

To investigate the underlying resistance mechanisms of Saccharomyces cerevisiae against Ag-NPs with different particle sizes and coatings, transcriptome sequencing (RNA-seq) technology was used to characterize the transcriptomes from S. cerevisiae exposed to 20-PVP-Ag, 100-PVP-Ag, 20-CIT-Ag and 100-CIT-Ag, respectively. The steroid biosynthesis was found as a general pathway for Ag-NPs stress responding, in which ERG6 and ERG3 were inhibited and ERG11, ERG25 and ERG5 were significantly up-regulated to resist the stress by supporting the later mutation and resistance and modulate drug efflux indirectly. The resistance mechanism of S. cerevisiae to 20-PVP-Ag seems different from that of 100-PVP-Ag, 20-CIT-Ag and 100-CIT-Ag. Under the 20-PVP-Ag, transmembrane transporter activity, transition metal ion homeostasis and oxidative phosphorylation pathway were main resistance pathways to enhance cell transport processes. While 100-PVP-Ag, 20-CIT-Ag and 100-CIT-Ag mainly impacted RNA binding, structural constituent of ribosome and ribosome pathway which can provide more energy to maintain the number and function of protein in cells. This study reveals the differences in resistance mechanisms of S. cerevisiae to Ag-NPs with different particle sizes and coatings, and explains several main regulatory mechanisms used to respond to silver stress. It will provide theoretical basis for the study of chemical risk assessment.

In praise of povidone-iodine application in ophthalmology

Polyvinyl pyrrolidone or povidone-iodine (PVP-I) is a water-soluble complex formed by the combination of iodine and a water-soluble polymer, polyvinyl pyrrolidone. This complex exerts bactericidal, fungicidal, and virucidal action by gradually releasing free iodine at the site of application to react with pathogens. In ophthalmology, PVP-I is used as a disinfectant and antiseptic agent for preoperative preparation of the skin and mucous membranes and for treating contaminated wounds. PVP-I has been shown to reduce effectively the risk of endophthalmitis in various ocular procedures, including cataract surgery and intravitreal injections; however, it has also been used in the treatment of conjunctivitis, keratitis, and endophthalmitis, with promising results especially in low-resource situations. PVP-I has been associated with complications such as postoperative eye pain, persistent corneal epithelial defects, ocular inflammation, and an attendant risk of keratitis. In cases of poor PVP-I tolerance, applying PVP-I at lower concentrations or using alternative antiseptics such as chlorhexidine should be considered. We provide an update on the efficacy of PVP-I in the prophylaxis and treatment of conjunctivitis, keratitis, and endophthalmitis and a comprehensive analysis of the current literature regarding the use of PVP-I in the management of these ocular conditions. Also, PVP-I-related adverse effects and toxicities and its alternatives are discussed. The goal is to present a thorough evaluation of the available evidence and to offer practical recommendations for clinicians regarding the therapeutic usage of PVP-I in ophthalmology.

Ternary cyclodextrin systems of terbinafine hydrochloride inclusion complexes: Solventless preparation, solid-state, and in vitro characterization

Cyclodextrins (CD) are used extensively in the pharmaceutical industry to improve the water solubility and bioavailability of drugs. Preparing ternary systems by applying a third component can enhance these beneficial effects. The complexation methods of these ternary systems are the same as those of two-component complexes. These methods are solvent (co-evaporation, co-precipitation, etc.) or solventless "green" techniques (co-grinding, microwave irradiation, etc.). Using solvent-free methods is considered to be an economically and environmentally desirable technology. This study aimed to prepare ternary systems by the co-grinding method and evaluate the effect of a third component by comparing it to products obtained by solvent methods, binary systems, and marketed products. For that, we used terbinafine hydrochloride as a model drug, sulfobutyl-ether-beta-cyclodextrin as a complexation agent and 5 or 15 w/w% of polyvinylpyrrolidone K-90 (PVP) or hydroxypropyl methylcellulose (HPMC) as auxiliary components. Physicochemical evaluation (X-Ray Diffractometry, Differential Scanning Calorimetry, Thermogravimetry) showed that new solid phases were formed, while Scanning Electron Microscopy was performed to study morphological aspects of the products. Fourier transform infrared spectroscopic measurements suggested different intermolecular interactions depending on the type of polymer. In vitro dissolution studies showed beneficial effects of CD and further improvement with the applied polymers. Products showed less cell toxicity with one exception. Both polymers enhanced the physicochemical and in vitro properties, suggesting a greater bioavailability of the model drug. However, the percentage of polymers applied did not appear to be an influencing factor for these properties.

Robust microfluidic construction of polyvinyl pyrrolidone microfibers incorporated with W/O emulsions stabilized by amphiphilic konjac glucomannan

In this work, we prepared polyvinyl pyrrolidone (PVP) microfibers incorporated water-in-oil (W/O) emulsions. The W/O emulsions were fabricated by hexadecyl konjac glucomannan (HKGM, emulsifier), corn oil (oil phase) and purple corn anthocyanins (PCAs, water phase). The structures and functions of emulsions and microfibers were characterized by confocal laser scanning (CLSM) and scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), Raman and nuclear magnetic resonance (NMR) spectroscopy. The results showed that W/O emulsions exhibited good storage stability for 30 d. Microfibers presented ordered and uniform arrays. Compared with pure PVP microfiber films, the addition of W/O emulsions with PCAs improved the water resistance (WVP from 1.28 to 0.76 g mm/m² day kPa), mechanical strength (Elongation at break from 18.35 % to 49.83 %), antioxidation (free radical scavenging rate from 2.58 % to 16.37 %), and antibacterial activity (inhibition zone against E. coli: 27.33 mm and inhibition zone against S. aureus: 28.33 mm) of microfiber films. Results showed that microfiber film exhibited controlled release of PCAs in W/O emulsions, and about 32 % of the PCAs were released from the microfiber film after 340 min. The as-prepared microfiber films exhibited potential applications for food packaging.

Engineering of tetanus toxoid-loaded polymeric microneedle patches

This study is aimed to fabricate tetanus toxoid laden microneedle patches by using a polymeric blend comprising of polyvinyl pyrrolidone and sodium carboxymethyl cellulose as base materials and sorbitol as a plasticizer. The tetanus toxoid was mixed with polymeric blend and patches were prepared by using vacuum micromolding technique. Microneedle patches were evaluated for physical attributes such as uniformity of thickness, folding endurance, and swelling profile. Morphological features were assessed by optical and scanning electron microscopy. In vitro performance of fabricated patches was studied by using bicinchoninic acid assay (BCA). Insertion ability of microstructures was studied in vitro on model skin parafilm and in vivo in albino rat. In vivo immunogenic activity of the formulation was assessed by recording immunoglobulin G (IgG) levels, interferon gamma (IFN-γ) levels, and T-cell (CD4⁺ and CD8⁺) count following the application of dosage forms. Prepared patches, displaying sharp-tipped and smooth-surfaced microstructures, remained intact after 350 ± 36 foldings. Optimized microneedle patch formulation showed ~ 74% swelling and ~ 85.6% vaccine release within an hour. The microneedles successfully pierced parafilm. Histological examination of microneedle-treated rat skin confirmed disruption of epidermis without damaging the underneath vasculature. A significant increase in IgG levels (~ 21%), IFN-γ levels (~ 30%), CD4⁺ (~ 41.5%), and CD8⁺ (~ 48.5%) cell count was observed in tetanus vaccine-loaded microneedle patches treated albino rats with respect to control (untreated) group at 42nd day of immunization. In conclusion, tetanus toxoid-loaded microneedle patches can be considered as an efficient choice for transdermal delivery of vaccine without inducing pain commonly experienced with hypodermic needles.

Task-specific polymeric membranes to achieve high gas-liquid mass transfer

In the current study, Polyimide (P84)-based polymeric membranes were fabricated and used as spargers in the bubble column reactor (BCR) to get a high gas-liquid mass transfer (GL-MT) rate of oxygen in water. Different polymeric membranes were fabricated by incorporating polyvinyl pyrrolidone (PVP) as a porogen and a Zeolitic Imidazolate Framework (ZIF-8) to induce high porosity and hydrophobicity in the membranes. The GL-MT efficiency of membranes was evaluated by measuring the overall volumetric mass transfer coefficient (k_La) of oxygen in air. The k_La of O₂ (in air) was measured by supplying the gas through a fixed membrane surface area of 11.94 cm² at a fixed gas flow rate of 3L/min under atmospheric pressure. The results revealed that adding porogen and ZIF-8 increased the porosity of the membranes compared to the pure polymeric membranes. In comparison, the ZIF-8 (3 wt%) based membrane showed the highest porosity (80%), hydrophobicity (95° contact angle) and k_La of oxygen in air (241.2 h^-1) with 78% saturation in only 60 s. ZIF-8 based membranes showed the potential to increase the amount of dissolved oxygen in BCR by reducing the bubble size, increasing the number of bubbles, and improving the hydrophobicity. The study showed that ZIF-8 based membrane diffusers are expected to produce high GL-MT in microbial syngas fermentation. To the best of our knowledge, this is the first study on the fabrication and application of polymeric membranes for GL-MT applications. Further research should be conducted under real fermentation conditions to assess the practicality of the system to support substrate utilization, microbial growth, and product formation.

Addition of polyvinyl pyrrolidone during density separation with sodium iodide solution improves recovery rate of small microplastics (20-150 μm) from soils and sediments

The purpose of this study was to identify a method to accurately separate small microplastics (<100 μm) from soil and sediment. We initially conducted spike-and-recovery tests using polyethylene microbeads and density separation and found that the recovery rate of microplastic particles smaller than 100 μm was less than 60%. This result suggested that previous reports have underestimated the concentrations of microplastics smaller than 100 μm in soil. When polyvinyl pyrrolidone was added and dispersed in a heavy liquid, the recovery rate exceeded 90%, regardless of the microplastic particle size. This improved recovery rate was independent of the type of polymer (polyethylene, polypropylene, polystyrene, polyethylene terephthalate, or nylon 6) and the physicochemical properties of the soil (Andisols, Entisols, or Ultisols), and the method was also effective for marine and lake sediments. Using this method, we measured microplastic concentrations in paddy soil. The results showed that the most common particle size, 20-100 μm, accounted for 64% of all microplastics. Accurate separation from the soil of fractions smaller than 100 μm, which account for the majority of microplastics in soil, will enable an accurate assessment of the impact of microplastics on the soil ecosystem. The method identified in this study can serve as the basic technique for achieving that goal.

One-step synthesis of blue emission copper nanoclusters for the detection of furaltadone and temperature

Polyvinyl pyrrolidone (PVP), playing roles as a templating agent, can be applied to prepare blue-emitting copper nanoclusters (Cu NCs@PVP) on the basis of a rapid chemical reduction synthesis method. The Cu NCs@PVP displayed a blue emission wavelength at 430 nm and the corresponding quantum yield (QY) could reach 10.4%. Subsequently, the as-synthesized Cu NCs@PVP were used for the trace analysis of furaltadone based on the inner filter effect (IFE) between Cu NCs@PVP and furaltadone, which caused the fluorescence to be effectively quenched. Additionally, this proposed determination platform based on the Cu NCs@PVP for furaltadone sensing possessed an excellent linear range from 0.5 to 100 μM with a lower detection limit of 0.045 μM (S/N = 3). Meanwhile, the Cu NCs@PVP also could be applied for the sensing of temperature. Furthermore, the practicability of the sensing platform has been successfully verified by measuring furaltadone in real samples, affirming its potential to increase fields for the determination of furaltadone.

Performance study of fouling resistant novel ultrafiltration membranes based on the blends of poly (ether ether sulfone)/poly (vinyl pyrrolidone)/nano-titania for the separation of humic acid, dyes and biological macromolecular proteins from aqueous solutions

This study explains the use of a ultrafiltration membrane made of polyvinyl pyrrolidone (PVP) and poly(ether ether sulfone) (PEES)/Nano-titania (n-TiO₂) for the separation of organic compounds. The results of the tests for porosity, water content, surface chemistry, membrane morphology, and contact angle demonstrated that the developed membranes have more hydrophilicity than PEES membranes due to the redundant hydrophilic nature of PVP and n-TiO₂. The membrane pure water flux, which contains 5 wt% PVP and 1.5 wt% n-TiO_2, was 312.76 Lm^-2h^-1, about three-fold higher than that of pristine membrane (95.71 Lm^-2h^-1). Employing bovine serum albumin as a model foulant, the fouling resistance of the PEES/PVP/n-TiO₂ membrane was examined. According to the analysis of flux recovery ratio and irreversible resistance, modified membranes were less likely to foul, and the PEES/n-TiO₂ membrane with 5% PVP addition was recommended as optimal. The fabricated membranes effectively removed more than 95% of various organic compounds such as humic acid, safranin O, egg albumin, pepsin, and trypsin from aqueous solution. Permeability of safranin O and humic acid of PEES/PVP/n-TiO₂ membranes was about 118 Lm^-2h^-1 and 138 Lm^-2h^-1, respectively.

Facile synthesis of the crescent-like SnS nanocrystals capped by polyvinyl pyrrolidone and its performance of adsorbing dyes

With using Sn²⁺ as tin source, l-cysteine as sulphur source and polyvinyl pyrrolidone (PVP, M_w = 1300000) as surfactant, a novel three-dimensional and crescent-like SnS nanocrystal (NCs) was successfully synthesized in a one-pot hydrothermal method. The as-prepared SnS NCs displayed uniform crescent-like morphological structure, and demonstrated excellent efficiency for the adsorption of cationic dyes such as rhodamine B (RhB) and methylene blue (MB). Kinetic analysis indicated that the adsorption process followed the pseudo second-order model, and the maximum capacity of the SnS NCs to adsorb MB was determined by Langmuir equation to be 252 mg⋅g^-1 at 298 K. The pH dependence of SnS NCs on the adsorption of cationic dyes and the characterization of zeta potential jointly suggested the existence of electrostatic attraction in the process. Overall, this study showed that electrostatic field of functional groups and the capping of PVP could significantly enhance the adsorption performance of the SnS NCs, and also provides a novel insight into the development of highly efficient inorganic adsorbents for cationic dyes.

Wound dressing of chitosan-based-crosslinked gelatin/ polyvinyl pyrrolidone embedded silver nanoparticles, for targeting multidrug resistance microbes

Wound dressing composed of chitosan, based crosslinked gelatin/ polyvinyl pyrrolidone, embedded silver nanoparticles were fabricated using solution casting method. The membrane was characterized by FTIR, SEM and TGA. Glutaraldehyde (0.5 %) was used for the crosslinking of membrane components and associated with 7-folds boosted mechanical performance, 28 % more hydrolytic stability, 3-folds thickness reduction and morphological roughness. Silver nanoparticles were characterized by UV-vis, XRD and TEM for an average size of 9.9 nm. The membrane with higher concentration of silver nanoparticles showed maximum antibacterial activity against human pathogenic bacteria; and the measured inhibition zones ranged from 1.5 to 3 cm. The activity of the particles ranged from severe to complete reduction in Penicillin, Erythromycin and Macrolide family's resistance genes expression such as β-Lactamase, mecA and erm. This developed membrane can serve as promising and cost-effective system against severe diabetic and burn wound infections.

Strawberry-like SiO2/Ag nanocomposites immersed filter paper as SERS substrate for acrylamide detection

In this work, based on the strawberry-like SiO₂/Ag nanocomposites (SANC) immersed filter paper, a newly surface-enhanced Raman scattering (SERS) substrate was constructed for the detection of acrylamide (AAm) in food products. To construct filter paper-based SANC (F-SANC) SERS substrates, SiO₂ nanoparticles (SNP) were firstly synthesized and acted as carriers. After that, the in-situ preparation of silver nanoparticles (Ag NP) on SNP surface was carried out to form the strawberry-like three-dimensional (3D) structure of SANC. Finally, SANC were entangled into the filter paper to produce nanoarchitecture, thus providing enhanced plasmon resonance between SANC with strong SERS signal. Under the optimized conditions, the method exhibited good performance toward AAm with a vast linear response from 0.1 nM to 50 μM (R = 0.9935), limit of detection (LOD) of 0.02 nM (S/N = 3), and the recoveries of 80.5%~105.6% for practical samples. This strategy showed good robustness in the rapid and sensitive detection of AAm, which could be a promising strategy in food analysis and verification.

One-pot synthesis of polypyrrole nanoparticles with tunable photothermal conversion and drug loading capacity

With an excellent near-infrared (NIR) light-responsive property, polypyrrole (PPy) nanoparticle has emerged as a promising NIR photothermal transducing agent for tumor photothermal therapy (PTT). Herein, we reported the PVP mediated one-pot synthesis of colloidal stable and biocompatible PPy nanoparticles (PPy-PVP NPs) for combined tumor photothermal-chemotherapy. The influence of molecular weight and PVP concentration on the spectroscopic characteristic, photothermal feature, drug loading performance, and antitumor efficiency of the resultant PPy-PVP NPs was systematically studied. By choosing PVP with a molecular weight of 360 kDa (concentration of 5 mg/mL) as the template and surface modifier during the synthesis, PPy-PVP NPs with optimal spectroscopic characteristic, photothermal feature, drug loading performance, and antitumor efficiency were synthesized. Findings in this study are anticipated to provide an in-depth understanding of the important character of surface engineering in the rational design and biomedical applications of PPy NPs.

Formulation and Optimization of Oral Mucoadhesive Patches of Myrtus Communis by Box Behnken Design

Purpose: Recurrent aphthous stomatitis (RAS) is the most common painful ulcerative disease of oral mucosa happening in ~20% of people. Aimed to develop Myrtus communis L. (Myrtle) containing oral patches, we applied box-behnken design to evaluate the effect of polymers such as Polyvinyl pyrrolidone (PVP), Gelatin, Methylcellulose (MC) and Pectin. Methods: The patches properties such as tensile strength, folding endurance, swelling index, thickness, mucoadhesive strength and the pattern of myrtle release were evaluated as dependent variables. Then, the model was adjusted according to the best fitted equation with box behnken design. Results: The results indicated that preparation of myrtle patch with hydrophilic polymers showed the disintegration time up to 24h and more. Using of polyvinyl pyrrolidone as a water soluble polymer and a pore-former polymer led to faster release of soluble materials from the patch to 29 (min-1). Also it decreases swelling index by increasing the patch disintegration. Gelatin and Pectin, with rigid matrix and water interaction properties, decreased the swelling ratio. Pectin increased the tensile strength, but gelatin produced an opposite effect. Thinner Myrtle patch (about 28µm) was obtained by formulation of methyl cellulose with equal ratio with polyvinyl pyrrolidone or gelatin. Conclusion: Altogether, the analysis showed that the optimal formulation was achieved with of 35.04 mg of Gelatin, 7.22 mg of Pectin, 7.20 mg of polyvinyl pyrrolidone, 50.52 mg of methyl cellulose and 20 mg of Myrtle extract.

Fabrication of electrospun nanofibres of BCS II drug for enhanced dissolution and permeation across skin

The present work reports preparation of irbesartan (IBS) loaded nanofibre mats using electrospinning technique. The prepared nanofibres were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, X-ray diffraction analysis, in vitro diffusion and ex vivo skin permeation studies. FTIR studies revealed chemical compatibility of IBS and polyvinyl pyrrolidine (PVP K-30). SEM images confirmed formation of nanofibres wherein IBS existed in amorphous form as revealed by DSC and XRD analyses. The prepared nanofibre mats of IBS were found to be superior to IBS loaded as cast films when analysed for in vitro IBS release and ex vivo skin permeation studies since the flux of IBS loaded nanofibres was 17 times greater than as cast film. The improvement in drug delivery kinetics of IBS loaded nanofibres could be attributed to amorphization with reduction in particle size of IBS, dispersion of IBS at molecular level in PVP matrix and enormous increase in the surface area for IBS release due to nanonization. Thus transdermal patch of IBS loaded nanofibres can be considered as an alternative dosage form in order to improve its biopharmaceutical properties and enhance therapeutic efficacy in hypertension.

Nanocomposite scaffold with enhanced stability by hydrogen bonds between collagen, polyvinyl pyrrolidone and titanium dioxide

In this study, three-dimensional (3D) nanocomposite scaffolds, as potential substrates for skin tissue engineering, were fabricated by freeze drying the mixture of type I collagen extracted from porcine skin and polyvinyl pyrrolidone (PVP)-coated titanium dioxide (TiO2) nanoparticles. This procedure was performed without any cross-linker or toxic reagents to generate porosity in the scaffold. Both morphology and thermal stability of the nanocomposite scaffold were examined. The swelling behavior, mechanical properties and hydrolytic degradation of the composite scaffolds were carefully investigated. Our results revealed that collagen, PVP and TiO2 are bonded together by four main hydrogen bonds, which is an essential action for the formation of nanocomposite scaffold. Using Coasts-Redfern model, we were able to calculate the thermal degradation apparent activation energy and demonstrated that the thermal stability of nanocomposites is dependent on amount of PVP incorporated. Furthermore, SEM images showed that the collagen fibers are wrapped and stabilized on scaffolds by PVP molecules, which improve the ultimate tensile strength (UTS). The UTS of PVP-contained scaffold is four times higher than that of scaffold without PVP, whereas ultimate percentage of elongation (UPE) is decreased, and PVP can enhance the degradation resistance.

Development of an effective and efficient DNA isolation method for Cinnamomum species

Different species of Cinnamomum are rich in polysaccharide's and secondary metabolites, which hinder the process of DNA extraction. High quality DNA is the pre-requisite for any molecular biology study. In this paper we report a modified method for high quality and quantity of DNA extraction from both lyophilized and non-lyophilized leaf samples. Protocol reported differs from the CTAB procedure by addition of higher concentration of salt and activated charcoal to remove the polysaccharides and polyphenols. Wide utility of the modified protocol was proved by DNA extraction from different woody species and 4 Cinnamomum species. Therefore, this protocol has also been validated in different species of plants containing high levels of polyphenols and polysaccharides. The extracted DNA showed perfect amplification when subjected to RAPD, restriction digestion and amplification with DNA barcoding primers. The DNA extraction protocol is reproducible and can be applied for any plant molecular biology study.

One-pot synthesis of fluorescent DHLA-stabilized Cu nanoclusters for the determination of H2O2

A facile one-pot approach has been developed to prepare orange-emitting Cu nanoclusters (NCs) using tetrakis(hydroxymethyl)phosphonium chloride as a reducing agent and lipoic acid as a capping agent under an alkaline medium at room temperature. The as-prepared Cu NCs exhibited excellent water solubility, large Stokes shift, long lifetime and good dispersion. After the addition of polyvinyl pyrrolidone, the fluorescence intensity of dihydrolipoic acid-stabilized Cu NCs (DHLA-Cu NCs) was greatly enhanced, and their fluorescence signal remained stable for 5 weeks storage in the dark at room temperature. Based on H2O2-induced fluorescence quenching, DHLA-Cu NCs showed high sensitivity and selectivity for the detection of H2O2 in aqueous solution with a detection limit of 0.3μM, and were applied successfully to the detection of H2O2 in human urine samples.

Preparation and in-vitro evaluation of indomethacin nanoparticles

BACKGROUND AND THE PURPOSE OF THE STUDY

During the last two decades one of the most important problems in drug formulations has been low aqueous solubility of new molecules. However, numerous techniques, such as milling, co-solvent solubilization and solid dispersion have been used conventionally for aqueous solubility enhancement and the rate of solubility. Recently, nanoparticle engineering processes have been developed and reported for pharmaceutical applications to increase the dissolution rate of low-soluble drugs which in turn may leads to substantial increases in bioavailability. In this study, a controlled precipitation method was used to produce indomethacin nano-solid suspension in a polymeric matrix (as a model), in order to increase the solubility and rate of the dissolution of poorly soluble model drug.

METHODS

Nano-solid suspension of indomethacin in polyvinyl pyrrolidine (PVP) was prepared by controlled precipitation technique, characterized by differential scanning calorimetry (DSC), X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and evaluated for in vitro solubility and dissolution rate.

RESULTS AND MAJOR CONCLUSION

Absence of thermal and diffractional peaks in DSC and XRD studies indicated that indomethacin interacts with PVP in solid phase. The solubility of indomethacin in nano-solid suspension compared to crystalline form was increased to about four-fold. It was found that particle size distribution depend to the polymer MW and drug: polymer ratios. Spectroscopy methods and Transmission Electron Microscopy (TEM) images showed that indomethacin dispersed as amorphous nanosize particles in freeze dried powder. Enhanced solubility and dissolution rate of indomethacin compared to physical mixtures and crystalline form of indomethacin (polymorph I), demonstrated that it interacts with PVP via hydrogen bond and probably forming eutectic mixture.