Poly N-vinylpyrrolidone Research Articles

The effect of PVP and PVA on hydrate formation kinetics of ethane and propane mixture in the presence of kaolin nanoparticles

AbstractThe blockage of gas transmission pipelines due to gas hydrates poses a significant challenge for the gas industry. Low‐dosage hydrate inhibitors (LDHI) are utilized to influence the kinetics of hydrate formation, including nucleation, growth, and/or agglomeration. In the current study, a series of batch, isochoric, and isothermal tests were carried out to investigate the impacts of two LDHIs, poly N‐vinylpyrrolidone (PVP) and polyvinyl alcohols (PVA). This study examined the influence of these inhibitors on nucleation and growth of ethane+propane mixture in the presence of kaolin nanoparticles. In laboratory studies and using pure constituents, the rate of hydrate formation is low to investigate the inhibitors effect. To enhance the rate of hydrate formation, kaolin nanoparticles were utilized as they serve as a suitable representative for solid minerals commonly found in pipelines. The gas phase's compositional change were measured using a gas chromatograph. The results revealed that the growth stage of mixed‐gas exhibited two distinct steps, attributed to the formation of two different structures known as structure II and structure I. During the first step, structure II was formed, and the cavities were occupied by both gas components. In the second stage, structure I was formed by ethane. The effect of temperature on the induction time (nucleation rate) and the growth rate during the second stage was lower than that at the first stage. The increase in PVA concentration resulted in an increase in the induction time and a decrease in the rate of growth during the first stage. The performance of PVA was found to be affected by temperature. Lower temperatures resulted in the formation of less foam, providing improved performance for PVA at −0.5°C. PVP had a stronger impact on induction time and both growth steps compared to PVA, indicating stronger inhibitory impact of PVP on nucleation of hydrates initiated by propane and the growth of both propane and ethane hydrates.

Chitosan and Poly(N-vinyl-pyrrolidone) Interaction Properties. Pharmaceutical and Biomedical Applications

The naturally occurring polymers, chitosan (CH) and poly(N-vinyl-pyrrolidone (PVP), have attracted the interest of researchers in a variety of biomedical and pharmaceutical applications areas, such as drug delivery, cosmetics, and tissue engineering. However, PVP and CH have certain limitations for use in controlled aqueous CH/PVP mixed solutions. In this study aqueous solutions of PVP and CH with the same concentration of 10 g/l and pH 6 were mixed under atmospheric conditions. The effects of temperature and molar volume fraction, X1, of CH on the decreased dynamic viscosity of the CH/PVP mixed solutions were studied at various temperatures ranging from 15 °C to 80 °C. We highlighted that different regions can be distinguished in the aqueous CH/PVP complexes, depending on the composition and electrostatic interactions of the solutions, which are associated with significantly different phase behaviors.

Antimicrobial properties of chlorophyll and hemin incorporated into the polymeric matrix of poly-N-vinylpyrrolidone

The increase in the number of antibiotic-resistant strains of microorganisms is becoming more widespread. Metalloporphyrins are promising and modern antimicrobial agents. The most well-known representatives of metalloporphyrins are chlorophyll (Chl) and hemin. This paper presents the results of studies on the effectiveness of Chl and hemin complexes with poly-N -vinylpyrrolidone (PVP) as an antimicrobial agent against Staphylococcus aureus and Escherichia coli. The method for preparing polymeric forms of Chl and hemin is presented. The binding constants of these substances to the polymer were calculated, which were 0.5×105 L/mol for Chl and 3.3×104 L/mol for hemin. Experimental data on the release of substances from the polymeric matrix were obtained. It was found that the complete release of Chl from PVP was observed after 13 h, and hemin – after 10 h. The data on the comparative antimicrobial effect of substances in free and polymeric form were obtained in a microbiological test. Further these results can be used in the development of medicines against microbial infections.

L-DOPA BIOSYNTHESIS WITH Agaricus bisporus TYROSINASES ASSISTANCE

L-DOPA (3,4-dihydroxyphenyl-L-alanine) is a drug of choice in Parkinson's disease treatment. However the chemical method of its synthesis has a number of drawbacks, so biotechnological approaches are being explored as an alternative. Aim. The goal is to develop a new affordable and effective method of biosynthesis of L-DOPA using mushroom tyrosinase, immobilized using an economical carrier, which ensures stability and enzyme multiple uses. Methods. Agaricus bisporus isolated tyrosinase was used in the work. L-DOPA biosynthesis was carried out in aqueous and organic medium. The obtained product was analyzed using mass spectrometry, specific rotation and melting point. The enzyme immobilization was carried out in poly-N-vinylpyrrolidone (PVP), the interaction with the carrier, pH-optimum and the application frequency were determined. Results. A partially purified preparation of tyrosinase was isolated from Agaricus bisporus. In aqueous solution in enzyme presence, only 5.1% of L-DOPA was obtained due to the subsequent formation of complex polycyclic compounds. The biosynthesis of L-DOPA derivative in methylene chloride with the addition of a buffer solution made it possible to obtain a product with a yield of 55%. Tyrosinase immobilized in PVP showed activity 30% higher than free in CH2Cl2 medium and carried out biocatalysis for 7 cycles. Conclusions. A method of L-DOPA synthesizing using an available biocatalyst based on immobilized tyrosinase was developed, which enabled to obtain L-DOPA during 7 cycles of use in a methylene chloride medium.

Green Synthesis and Analytical Characterization of Core-Shell Copper Sub-Microparticles.

This study demonstrates a simple and reproducible approach to synthesize green core-shell copper sub-microparticles stabilized by poly(n-vinyl)pyrrolidone (PVP). Cu@PVP colloids were here prepared using copper sulfate pentahydrate as precursor and glucose as reducing agent. The presence of PVP in the synthetic medium eliminates the need for an inert atmosphere during the process, thus simplifying the whole method. Both the morphology and the spectroscopic properties of Cu@PVP colloids were investigated by transmission electron microscopy, and infrared, UV-Vis and X-ray photoelectron spectroscopies. Size distributions and average shell thickness were obtained by statistical analysis on TEM micrographs, and spectroscopies demonstrated the formation of a PVP layer around the copper core. The produced colloids were employed in composite thin films for potential antimicrobial application, in association with a highly-recyclable polymer: polycarbonate (4,4'-(1-methylethylidene)bis(phenol)).

ПЕРСПЕКТИВЫ ИСПОЛЬЗОВАНИЯ ДЕЗИНФИЦИРУЮЩЕГО СРЕДСТВА НА ОСНОВЕ ПОРФИРИНОВОГО МАКРОЦИКЛА

The paper presents the incorporating method of FeIIICl-tetraphenylporphyrin (FeClTPP) into the poly-N-vinylpyrrolidone (PVP) polymeric matrix. The resulting FeClTPP-PVP complex was diluted to final concentrations of 10, 20, 40, 60, 80 and 100 mmol and deposited on the inner surfaces of glass vessels. These vessels were used to simulate the surfaces of objects of veterinary and sanitary control that require periodic disinfection. The antibacterial activity of indicated concentrations of FeClTPP-PVP against antibiotic-resistant gram-negative and gram-positive microorganisms – Escherichia coli (strain 1257) and Staphylococcus aureus (strain 209-P) was demonstrated. As these microorganisms are also representatives of the most frequently encountered contaminants, we have studied the prepared bacterial suspensions from daily cultures of E. coli and S. aureus in dilutions from 108 to 104 CFU/mL. After that, the artificial contamination of the inner surfaces of the test objects was carried out. Antibacterial activity was determined by the degree of inhibition and was recorded visually and spectrophotometrically (OD600 nm ). The inhibitory effect on the growth of E. coli and S. aureus was directly proportional to the concentration of FeClTPP-PVP and inversely proportional to the degree of microorganism’s dilution. The greatest effect (about 87% reduction in bacterial growth) was achieved by the influence of FeClTPP-PVP maximum concentration.

Detection of the Freshness of Kiwifruit With a TD-GC-MS and a Gas-Sensing Array Based on the Surface-Acoustic-Wave Technique.

An electronic nose is an arrayed gas sensor mimicking the human olfactory system that can analyze and identify a flavour on collecting an odour from an environment. In our experiments, an electronic-nose system based on a surface acoustic wave (SAW) was used to measure the freshness of kiwifruit. 128° YX-LiNbO3 acted as a piezoelectric material; Au was deposited as an electrode and sensing area. With a polymer coating of various types on the sensing area and a connection to an oscillator circuit, a 113-114 MHz SAW was obtained. Depending on the properties of varied polymers, the frequency shift varied due to absorbed volatile organic compounds (VOC). In this way, with four surface-acoustic-wave sensors coated with varied polymers we built a kiwi-flavour database according to results from a TD-GC-MS system. When the concentration of esters increased, the kiwifruit began to ripen, accompanied by increased concentrations and types of VOC. As a result, polystyrene (PS) and fluoropolymer (CYTOP) polymers, which played the role of sensing materials, served as major materials to determine the ester aroma profile. Polyvinyl alcohol (PVA), polyvinyl butyral (PVB) and poly-N-vinylpyrrolidone (PNVP) were used to trap the alcohols and acids during a kiwifruit ripening period. This research proved that discrimination of differences is feasible from an unripe stage to a ripe stage and from a ripe stage to an over-ripe stage.

Developing polysulfone-based mixed matrix membrane containing hydrazone-linked covalent organic frameworks towards dye wastewater purification

The shortage of water resources and the increased demand for clean water warrant focused investigations on wastewater treatment. In this regard, mixed matrix membranes (MMMs) have been introduced as economic and efficient tools for removing contaminants from wastewater. The current study deals with the synthesis of a hydrazone-linked covalent organic framework (Hz-TFPTZ-COF) and its incorporation into polysulfone (PSf)/ poly N-vinylpyrrolidone (PVP) matrix to obtain Hz-TFPTZ@PSf/PVP MMM containing different concentrations of Hz-TFPTZ-COF (0–1 wt%). The synthesized Hz-TFPTZ-COF and the prepared MMMs were fully characterized using various analytical techniques. The negative surface charge of Hz-TFPTZ-COF made it a good candidate for removing cationic dyes. Moreover, the effect of Hz-TFPTZ-COF loading on the mechanical properties, porosity, pure water permeability (PWP), and dye rejection of the prepared MMMs was investigated. Hz-TFPTZ-COF concentration as low as 1.0 wt% in the MMM formulation yielded a PWP as high as 94.69 L. m−2. h−1. bar−1 and dye rejection of 92% and 88% for Basic Blue 41 and Methyl Violet, respectively. In addition, the tensile strength of the prepared MMMs was increased from 2.26 to 3.43 MPa. Overall, incorporating the Hz-TFPTZ-COF into PSf/PVP polymeric matrix affords a MMM with superior performance in the purification of cationic dye wastewater.

Синтез, структура и механические свойства композиционных гидрогелей медицинского назначения

The mechanism of formation of slightly crosslinked composite hydrogels based on natural agar-agar polysaccharide, synthetic polymers for medical purposes – poly-N-vinylpyrrolidone (PVP) and low-molecular plasticizers (polyethylene glycol PEG-400 and glycerin) synthesized by electron irradiation was considered from the point of view of analyzing their mechanical characteristics under various types of applied efforts. It is established that the synthesis conditions and the component composition of the initial mixture determine the formed structure of the hydrogel compositions and their mechanical properties. A new interpretation of the formation of the structure of composite hydrogels in the presence of various plasticizers is given. A detailed analysis of the deformation curves of composite hydrogels is presented taking into account the elastic-elastic, highly elastic and forced-elastic states.

Kinetics of methane + hydrogen sulfide clathrate hydrate formation in the presence/absence of poly N-vinyl pyrrolidone (PVP) and L-tyrosine: Experimental study and modeling of the induction time

Gas hydrates, or clathrate hydrates, formation can dramatically damage the transmission lines and operational equipment of the natural gas dominated system, which in turn to ruptured pipeline or destruction equipment. To prevent these problems, hydrate inhibitor injection is one of the most practical approaches. Subsequently, in several experimental studies, the induction time appraisement is employed as an expression for the inhibition accomplishment of kinetic hydrate inhibitor (KHI). Therefore, predicting/estimating the gas hydrate induction time is a crucial and essential subject in this field. To tackle this substantial issue, in the current investigation, the kinetics of methane + hydrogen sulfide hydrate formation (induction time) was investigated. The effects of using two types of KHI including Poly N-vinyl pyrrolidone (PVP) and L-Tyrosine with different concentrations (less than 2 wt%) on the induction time of the aforesaid system were revealed. The experiments were performed in a 100 cm3 stirred autoclave at temperatures ranging from 274.15 to 280.15 K over the primary pressure of 10 MPa. The experimental results indicate that KHIs at low concentrations (less than 2 wt%) approximately have no observational effects on thermodynamic equilibrium conditions but have a significant impact on increasing the induction time and abating the gas consumption during crystalline solid formation. This study also aimed at utilizing the Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT) based model of induction time for hydrate phase appearance of the binary gaseous comprising of 0.995 mole fraction (MF) CH4 + 0.005 mole fraction (MF) H2S at different subcooling in the presence and absence of PVP and L-Tyrosine applying the Freundlich adsorption isotherm. Model results show a satisfactory agreement with experimental data. The model can be used for reliable calculation of hydrate formation induction time for the methane + hydrogen sulfide + water system in the presence/absence of the aforementioned KHIs.

Influence of acetic acid on the photocatalytic activity of photosensitiser–amphiphilic polymer complexes in the oxidation reaction of tryptophan

The effect of acetic acid on the photosensitizing activity of dimegin (DMG), chlorin e6 (Ce6), and their complexes with amphiphilic polymers-Pluronic F-127 and poly-N-vinylpyrrolidone (PVP)-in the model reaction of tryptophan photo-oxidation has been established. It was shown that the photocatalytic activity of photosensitizers (PS), which is characterized by the effective constant of the tryptophan photo-oxidation rate (keff), increases by 1.4 times for DMG, while for Ce6, it decreases by 1.2 times in a weak acidic medium (pH ∼ 4). The influence of acetic acid on the effective constant keff of the tryptophan photo-oxidation rate in the presence of PS-amphiphilic polymer complexes is determined by the nature of the polymer. Thus, the photocatalytic activity of the PS-F127 system decreases at pH ∼ 4.0, and the photocatalytic activity of PS-PVP complexes is insensitive to the presence of acetic acid in the medium. It has been suggested that the observed effects in the PS-F127 system in a weak acidic medium (pH ∼ 4) are associated with the influence of acetic acid on the supramolecular structure of Pluronic F127.

Free radical synthesis of cross-linking gelatin base poly NVP/acrylic acid hydrogel and nanoclay hydrogel as cephalexin drug deliver

In this research, we presented the synthesis of cross-linking poly N-vinyl pyrrolidone /acrylic acid hydrogel and nanoclay hydrogel based on gelatin which named gelatin-g-NVP-AA, gelatin-g-NVP-AA/MMT and used them as cephalexin drug delivery. These hydrogels were fully characterized by FTIR, SEM, TEM, XRD, TGA, DSC, Also, the effect of difference saline solution, temperature, the percentage of nanoclay and time were investigated. In addition, because of pH sensitivity of hydrogels, the swelling, drug loading and drug releasing were studied in different pHs, distilled water and buffers to determine the best condition for each situation which resulted illustrated the universal buffer in pH 8 was the least interaction with hydrogels and had maximum drug loading and releasing in this condition. Antibacterial activities of hydrogels were examined against the S. aureus and the E. coli and showed an interesting result for the loaded drug on gelatin-g-NVP-AA/MMT.

Role of the Surface Composition and Structure of Titanium(IV) Oxide in the Manifestation of Antimicrobial Properties in Poly-N-vinylamide/Titanium(IV) Oxide Hybrid Materials

Hydrolysis of TiOSO4 · xH2SO4 · yH2O and TiOSO4 · xH2O, performed in the presence of poly-N-vinylcaprolactam (PVCL) or poly-N-vinylpyrrolidone (PVP) and in an aqueous medium, has provided for the first time samples containing nanophases of, respectively, η-modification of TiO2 – x · nH2O ( intercalates TiO2 – x · (nH2O, PVCL) or TiO2 – x · (nH2O, PVP)) and with anatase structure (TiO2). The samples have been characterized by X-ray diffraction and X-ray photoelectron spectroscopy. They are found to have different antimicrobial activities. A relationship is established between the antimicrobial activity and the structural features of titanium(IV) oxide; concentration of hydrated titanium dioxide in the samples; and the content of free water and hydroxyl and $${\text{SO}}_{4}^{{2 - }}$$ groups on the surface of anatase and η-phase nanoparticles, respectively. The choice of polymer does not affect the antimicrobial activity.

Инсулиномиметически активные макромолекулярные металлокомплексы ванадия на основе поли-N-винилпирролидона. Часть 2. Оценка гипогликемической активности макромолекулярного металлокомплекса ванадия

In a previous work, a method for the synthesis of a new metal-polymer complex of oxovanadium (IV) based on poly-N-vinylpyrrolidone was described, its structure was studied by spectral methods, and its composition was determined. Based on the data of electronic and vibrational spectroscopy, it was shown that the complex is formed due to the interaction of the metal with nitrogen and oxygen atoms of the polymer lactam ring, it should be noted that this type of interaction can occur both by intramolecular or intermolecular coordination. Using the Prozorovsky’s express method for estimation of acute oral toxicity the median value of LD50 of the synthesized complex was determined and it amounted to 1350 ± 160 mg/kg. The obtained LD50 value allow to attribute this metal-polymer complex to the class of low-toxic substances, which opens up some prospects for its further research on insulinomimetic activity. The aim of this work is to investigate the hypoglycemic activity of new polymer derivatives of vanadyl (VO2+) based on poly-N-vinylpyrrolidone (PVP) and to explore the possibility of using these compounds or compositions based on them for the prevention and treatment of type 2 diabetes. The work describes a method for creating an experimental model of type 2 diabetes mellitus in animals, combining the use of a high-fat diet and streptozotocin as a diabetogenic agent. The results of evaluating the effect of the studied metal-polymer complexes on such indicators of carbohydrate metabolism of laboratory animals as changes in blood glucose and urine, change daily diuresis of animals during treatment. The results of evaluating the effect of the metal-polymer complexes on such indicators of carbohydrate metabolism in laboratory animals as a change in blood and urine glucose, a change in the daily diuresis of animals during and after treatment are presented. The investigation of the effect of the obtained vanadium compounds on carbohydrate indices was carried out using metformin as a comparison drug. It was found that the new metal-polymer complexes of vanadium have hypoglycemic activity, normalizing the blood glucose level of laboratory animals with high-fat diet/ streptozotocin induced diabetes.

Инсулиномиметически активные макромолекулярные металлокомплексы ванадия на основе поли-N-винилпирролидона. Часть 1. Синтез макромолекулярного металлокомплекса ванадия и оценка его острой пероральной токсичности

Diabetes mellitus (DM) is a severe chronic disease affecting virtually all kinds of metabolic processes in the human body. As incidence and prevalence of DM are increasing worldwide, WHO estimates the number of people living with diabetes to be as high as half a billion and still rising. Long-term health complications of DM, such as diabetic nephropathy, retinopathy, neuropathy, and cardiovascular pathology, although preven-table in most cases, are known to be severe, potentially life-threatening and often irreversible, which makes the search for new effective antidiabetic drugs a research priority and one of the most pressing issues in health care today. To date, the insulin-mimetic properties of vanadium compounds have been the subject of quite a significant number of studies. In vivo experiments have shown that vanadium, acting in an insulin-like fashion, takes part in the regulation of glucose and lipid metabolism. In particular, vanadium stimulates glucose uptake and metabolism in insulin target tissues, increases the intensity of glycogen and lipid biosynthesis, and inhibits that of gluconeogenesis, glycogenolysis, and lipolysis. Organic vanadium complexes are known to be less toxic than its inorganic salts, which are characterized by a number of potentially serious adverse effects, mainly but not exclusively on the central nervous system and the kidneys; in addition to lower toxicity, organic vanadium compounds have been found to have higher bioavailability when to compared to those of inorganic nature. Such observations clearly hold promise for the development of an entirely novel therapeutic class of antidiabetic drugs. The aims of this study are to obtain new polymeric vanadyl(VO2+) derivatives based on poly-N-vinylpyrrolidone (PVP) that would exert hypoglycemic effect in vivo, and to explore the possibilities of using such compounds or formulations derived thereof for type 2 DM prophylaxis and/or treatment. This work gives a method of obtaining and isolation of an oxovanadium(IV)-polymer metallocomplex, and describes the structural features of said compound, confirmed experimentally. The results of the acute oral toxicity study revealed that the newly synthesized compound is of low toxicity, having a median lethal dose (LD50) that is at a level well above those typical of inorganic vanadium salts.

Thermodynamic and kinetic effect of biodegradable polymers on carbondioxide hydrates

In this work, the effect of biodegradable polymers, i.e. pectin (PC), sodium-carboxymethyl cellulose (Na-CMC), tapioca starch (TS) and dextran (DX) on thermodynamics and kinetics of CO2 hydrates are evaluated on sapphire hydrate reactor. The CO2 hydrate liquid vapour equilibrium (HLwVE) data is evaluated in the presence of biopolymers (1.5wt%) using isochoric T-cycle method at temperature and pressure ranging from 278.7 to 283.0K and 2.3 to 4.3MPa respectively. The effect of biopolymers on HLwVE curve is reported by measuring average increment temperature (ΔŦ). The constant cooling method is used to evaluate the kinetics of CO2 hydrates at 4.3MPa in the presence of biopolymers (0.12–1.5wt%) at 274.15K and 277.15K. The inhibition effect of biopolymers on the kinetics of CO2 hydrate is reported by measuring induction time, hydrate formation rate and amount of gas consumed. The kinetic inhibition strength of biopolymers is compared with poly-N-vinylpyrrolidone (PVP) and with two non-commercial inhibitors, i.e. glycine and tetra-methyl ammonium chloride (TMACl) through relative inhibition strength (RIS). Results reveal that DX shows maximum increment temperature of 0.36K. While PC and Na-CMC delayed CO2 hydrate nucleation for 423 and 181min respectively. Additionally, biodegradation study on biopolymers indicates that, compared to PVP, biopolymers are easily biodegradable and show potential for gas hydrate offshore applications.

UV Luminescence and Light Scattering in Photoditazine Systems with Sodium Alginate, Poly-N-Vinylpyrrolidone, and Tryptophan

Fluorescence and Rayleigh light scattering in polymer systems based on the chlorine photosensitizer photoditazine (PD) for photodynamic therapy are studied upon excitation at wavelengths λex = 260, 280, 400, and 450 nm. Nontoxic water-soluble poly-N-vinylpyrrolidone (PVP) and a plant polysaccharide (sodium alginate (SA)) were used as polymers. The PD–SA double system is characterized by dependence of its characteristics on the synthesis conditions, while the PD–SA–PVP triple complex exhibits a positive combined effect of SA and PVP polymers on the PD molecule due to the formation of a local microenvironment of the active PD center with a higher polarity. It is shown that the introduction of tryptophan, which is used as a substrate in model photooxidation processes for testing the efficiency of photosensitizers in singlet-oxygen generation, does not considerably change the fluorescence parameters of the PD–SA–PVP complex.

Single-Layer Assembly of Multifunctional Carboxymethylcellulose on Graphene Oxide Nanoparticles for Improving in Vivo Curcumin Delivery into Tumor Cells.

Nanodrug delivery systems are considered as promising therapeutic platforms to convey drugs to tumor cells. In this study, a single layer of carboxymethylcellulose (CMC) and poly N-vinylpyrrolidone (PVP) was cross-linked through disulfide bond and deposited on graphene oxide nanoparticles (GO NPs) using layer-by-layer technique. Overexpression of folate receptors on tumor cells is a great hallmark for drug delivery systems; though the NPs were functionalized by monoclonal folic acid antibody (FA) using polyethylene glycol (PEG) as linker. The mean diameter of synthesized nanoparticles was 60 nm. Curcumin was encapsulated within CMC layer with high encapsulation capacity of 94%. In vitro investigation showed 87% curcumin release at simulated tumor environment. Curcumin loaded FA modified CMC/PVP GO NPs showed high inhibition of 76 and 81% against Saos2 and MCF7 cell lines in vitro. In vivo investigations on 4T1 bearing breast cancer mice model exhibited 76% antitumor efficiency via active targeting mechanism of folate mediated transport without any significant side effect. Immunohistochemistry and immunofluorescence analyses showed enhanced antiangiogenesis, apoptosis and tumor growth inhibition.

Ультрафиолетовая люминесценция и светорассеяние систем фотодитазина с альгинатом натрия, поли-N-винилпирролидоном и триптофаном-=SUP=-*-=/SUP=-

As part of the study of polymer systems based on a chlorine photosensitizer, photodithazine (PD), photodynamic therapy was used to study the fluorescence and Rayleigh scattering spectra upon excitation at wavelengths lambdaex = 260, 280, 400, and 450 nm. Non-toxic water-soluble poly-N-vinylpyrrolidone (PVP) and vegetable polysaccharide were used as the polymer. sodium alginate (SA). The data of the PD-SA dual system is characterized by variability of characteristics depending on the preparation conditions, while in the PD-SA-PVP ternary complex, there is a favorable mutual influence of two SA and PVP polymers on the PD molecule, due to the creation of a local microenvironment of the active center PD with increased polarity . It was shown that the introduction of tryptophan (Trp), used as a substrate in model photo-oxidation processes, when testing the effectiveness of photosensitizers in the generation of singlet oxygen, does not significantly change the fluorescence parameters of the PD-SA-PVP complex.

Silver polymer nanocomposites by photoreduction of AgNO3 and simultaneous photocrosslinking of the acrylic matrix: effect of PVP on Ag particle formation

Abstract We studied the effect of poly-N-vinylpyrrolidone (PVP) and its concentrations on the photoinduced formation of silver nanoparticles (Ag NPs) as well as Ag-polymer nanocomposites. First, the effect of PVP concentration on the photoinduced reduction of Ag nitrate (AgNO3) in solution was studied by UV-Vis absorption spectroscopy monitoring the plasmon band of Ag. Dynamic light scattering (DLS) results showed that Ag NPs formed in the presence of stabilizer up to 4 wt% were narrower; the size distribution was also narrower. The PVP also had a significant influence on the formation of polymer nanocomposites by simultaneous photoinduced synthesis of NPs and polymerization of the acrylic matrix; NPs embedded in the crosslinked polymer were well dispersed, as detected by field-emission scanning electron microscopy (FESEM), and showed an average diameter of 20 nm.