Effective multifunctional coatings with polyvinylpyrrolidone-enhanced ZIF-67 and zinc iron layered double hydroxide on microarc oxidation treated AZ31 magnesium alloy

Modulating metal-organic framework’s(MOF)crystallinity and size using a polymer,in conjunction with a high surface area of layered double hydroxide,yields an effective strategy for concurrently enhancing the electrochemical and photocatalytic performance.In this study,we present the development of an optimized nanocomposite,denoted as 0.5PVP/ZIF-67,developed on AZ31 magnesium alloy,serving as an efficient and durable multifunctional coating.This novel strategy aims to enhance the overall performance of the porous coating through the integration of microarc oxidation(MAO),ZnFe LDH backbone,and ZIF-67 formation facilitated by the addition of polyvinylpyrrolidone(PVP),resulting in a three-dimensional,highly efficient,and multifunctional material.The incorporation of 0.5 g of PVP proved to be effective in the size modulation of ZIF-67,which formed a corrosion-resistant top layer,improving the total polarization resistance(R_(p)=8.20×10^(8)).The dual functionality exhibited by this hybrid architecture positions it as a promising candidate for mitigating environmental pollution,degrading 97.93%of Rhodamine B dye in 45 min.Moreover,the sample displayed exceptional degradation efficiency(96.17%)after 5 cycles.This study illuminates the potential of nanocomposites as electrochemically stable and photocatalytically active materials,laying the foundation for the advancements of next-generation multifunctional frameworks.

Preparation,physicochemical characterization and cyctotoxicity of solid dispersion of paclitaxel and polyvinylpyrrolidone

The objective of this study was to prepare and characterize paclitaxel-polyvinylpyrrolidone （PTX-PVP） solid dispersions with the intention of improving its solubility and dissolution properties. The PTX-PVP solid dispersion systems were prepared by solvent method. The release rate ofpaclitaxel was determined from dissolution studies and the physicochemical properties of solid dispersion were investigated by differential scanning calorimetry （DSC）, powder X-ray diffraction （PXRD） and scanning electron microscopy （SEM）. The cytotoxicities ofpaclitaxel in solid dispersion to the SKOV-3 cells were assayed by a SRB staining method. The results showed that the solubility and dissolution rate of paclitaxel were significantly improved in solid dispersion system compared with that of the pure drug and physical mixture. The results of DSC and PXRD showed that the paclitaxel in solid dispersion was amorphous form. No paclitaxel crystals in the solid dispersions was found during SEM analysis. Cytotoxicity study suggested that the inhibitory rates of PTX-PVP solid dispersion to SKOV-3 cells were higher than that of pure paclitaxel. The solubility and dissolution of paclitaxel were improved by solid dispersion technique. In vitro cytotoxicity of paclitaxel in solid dispersion was higher than that of pure drug.

Preparation and physicochemical characterization of solid dispersion of quercetin and polyvinylpyrrolidone

Aim The objective of this study was to prepare and characterize quercetin-polyvinylpyrrolidone （Qurc-PVP） solid dispersion with the intention of improving its dissolution properties, Methods Qurc-PVP sclid dispersion was prepared by solvent method. The release rate of quercetin was determined from dissolution studies and the physicochemical properties of solid dispersion were investigated by differential scanning calorimetry （DSC）, infrared spectroscopy （IR）, powder X-ray diffraction （PXRD） and scanning electron microscopy （SEM）. Results The results showed that the dissolution rate of quercetin was significantly improved by solid dispersion compared to that of the pure drug and physical mixture, Solubility studies revealed a markedly increase in the solubility of quercetin. The results of DSC and PXRD showed that the quercetin in solid dispersion was amorphous form. From SEM analysis, there was no quercetin crystal observed in the solid dispersions. Conclusion The solubility and dissolution of quercetin were improved by solid dispersion technique.

Polyvinylpyrrolidone-based bioink:influence of bioink properties on printing performance and cell proliferation during inkjet-based bioprinting

Among the different bioprinting techniques,the drop-on-demand(DOD)jetting-based bioprinting approach facilitates contactless deposition of pico/nanoliter droplets ofmaterials and cells for optimal cell–matrix and cell–cell interactions.Although bioinks play a critical role in the bioprinting process,there is a poor understanding of the influence of bioink properties on printing performance(such as filament elongation,formation of satellite droplets,and droplet splashing)and cell health(cell viability and proliferation)during the DOD jetting-based bioprinting process.An inert polyvinylpyrrolidone(PVP360,molecular weight=360 kDa)polymerwas used in this study to manipulate the physical properties of the bioinks and investigate the influence of bioink properties on printing performance and cell health.Our experimental results showed that a higher bioink viscoelasticity helps to stabilize droplet filaments before rupturing from the nozzle orifice.The highly stretched droplet filament resulted in the formation of highly aligned“satellite droplets,”which minimized the displacement of the satellite droplets away from the predefined positions.Next,a significant increase in the bioink viscosity facilitated droplet deposition on the wetted substrate surface in the absence of splashing and significantly improved the accuracy of the deposited main droplet.Further analysis showed that cell-laden bioinks with higher viscosity exhibited higher measured average cell viability(%),as the presence of polymer within the printed droplets provides an additional cushioning effect(higher energy dissipation)for the encapsulated cells during droplet impact on the substrate surface,improves the measured average cell viability even at higher droplet impact velocity and retains the proliferation capability of the printed cells.Understanding the influence of bioink properties(e.g.,bioink viscoelasticity and viscosity)on printing performance and cell proliferation is important for the formulation of new bioinks,and we have demonstrated precise DOD deposition of living cells and fabrication of tunable cell spheroids(nL–μL range)using multiple types of cells in a facile manner.

Synthesis and Characterization of Terbium-Trimesic Acid Luminescent Complex in Polyvinylpyrrolidone Matrix

Tb（Ⅲ ）-trimesic acid （TMA） luminescent complexes were synthesized in the polyvinylpyrrolidone （PVP） matrix. The elemental analysis, inductively coupled plasma-atomic emission spectroscopy （ICP-AES） and fourier-transform infrared spectroscopy （FT-IR） indicated that its chemical constitution is PVP/Tb（MTA）· 4H2O. The XRD patterns showed that the complex is a new kind of crystal. The TEM image indicates that the complex is rod shaped. The rod diameter is about 200 nm, and the length ranges from hundred of nanometer to a few micrometers. In addition, the dispersity is better. TG-DTA curves indicate that the complex is thermally stable before 463℃. Photoluminescence analysis indicates that the complex emits Tb^3＋ characteristic luminescence under ultraviolet excitation.

VISCOMETRIC INVESTIGATIONS OF POLYVINYLPYRROLIDONE IN MIXED SOLVENTS AND WITH VARYING TEMPERATURE

The viscosity behavior of polyvinylpyrrolidone(PVP)has been determined at 25℃ in mixed solvents comprising water/dimethylformamide(DMF)and water/methanol(MeOH).Analysis of the data has considered the PVP as being both host and guest polymer in solution.The intrinsic viscosity of PVP in DMF is higher than in water and in MeOH,but also increases in a mixed solvent with high water content because of the effect of polymer-solvent interactions.It was also found that the intrinsic viscosity of PVP at finite concentration,[η_(pvp)]_c decreases with an increase in the concentration of PVP in solution.The viscosity behavior of PVP in a mixed solvent is affected by the concentration-dependent intermolecular excluded volume effect,which can be quantitatively expressed by the parameter,b_Y,which reflects the shrinkage of PVP chain coils,resulting in a decrease of[η_(pvp)]_c.The effect of temperature on the viscosity behavior of PVP in MeOH shows that the interaction parameter increases up to a maximum value,and then decreases after a certain temperature.

Analysis about the Behavior and Modeling of pH-Sensitive Hydrogels with Different Ratios of Chitosan and Polyvinylpyrrolidone

Smart material can be defined as a material that can dock or convert energy between physical domains or as a material that can generate a response, in their characteristics, properties or geometries, when submitted to an external stimulus, for example, to heat, water presence, light, etc. In this paper, the second definition will be approached. Hydrogels are crosslinked materials that can absorb a big amount of water. They generally can be considered as smart materials once they exhibit sensibility to external stimuli like to pH variation, as will be approached in this paper. Thus, chitosan/polyvinylpyrrolidone hydrogels of three different ratios between these two polymers (1:1, 7:3 and 3:7) were synthesized and putted in aqueous solution with different pHs. The pH was adjusted adding drops of NaOH and HCl, slowly. After the collection of results and in order to understand the phenomena in a visual way, models of the molecules were also elaborated using the Avogadro software. Therefore, it was possible to realize that the greater the ratio of chitosan in the hydrogel, the greater its sensitivity to pH. Such characteristic is associated with the amino (-NH2) groups in it structure, which are capable of protonating and deprotonating (depending of the pH), generating charges under the chemical structure of the material, which will expand its volume in order to minimize the repulsion between charges. In addition, it was also noted that the hydrogel expansion is inversely proportional to the pH increase. By practical tests, it was possible to conclude that chitosan/PVP hydrogel with ratio 7:3 is the most interesting once it presented a greater quantity of chitosan in its composition, what implied in more rigidity than the others and greater ease of handling, resulting in more reliable results. This hydrogel also showed higher sensitivity to pH.

INTERACTION OF POLYVINYLPYRROLIDONE WITH METAL CHLORIDE AQUEOUS SOLUTIONS

Interactions of polyvinylpyrrolidone (PVP) with metal chlorides (MgCl 2 , CaCl 2 , KCl and BaCl 2 ) have been investigated by viscometric and spectrophotometric techniques in aqueous solutions. Intrinsic viscosity [η] of (PVP) has shown a discontinuity with varying concentration of metal chlorides. The decreasing order of effectiveness of cation is K 1+ > Ca 2+ > Mg 2+ > Ba 2+ for poly(vinylpyrrolidone) solution. Changes in the absorption spectra of the cosolutes were observed in the presence of PVP in the lower limit of the UV-visible region i.e. 200-210 nm. These changes were attributed to interaction of PVP molecules with the cosolute molecules. As the concentration of the cosolute increased, a red shift in the peaks was observed, indicating an increase in interaction between PVP and cosolutes.

Well-dispersed ultrafine nitrogen-doped TiO_2 with polyvinylpyrrolidone(PVP) acted as N-source and stabilizer for water splitting

In this paper, ultrafine nitrogen-doped TiO2 photocatalyst with enhanced photocatalytic water-splitting properties was successfully fabricated via a solvothermal method. Herein, polyvinylpyrrolidone（PVP） was used as both nitrogen source and stabilizer. The enhancement in water-splitting process can be attributed to the doping of element nitrogen, which could supply an intermediate energy level and promote the separation of photo-excited holes and electrons. Moreover, this paper provides a new application of high-molecular polymer to synthesize solar-driven water-splitting photocatalysts.

THE PREPARATION OF DOXORUBICIN-POLYVINYLPYRROLIDONE-NANOPARTICLES BY INVERSE EMULSION POLYMERIZATION

Doxorubicin-loaded nanoparticles, using doxorubicin （ADM） as model drug and vinylpyrrolidone as matrix, were prepared by inverse emulsion polymerization in the paper. The nanoparticles were characterized by telescope electron microscopy （TEM）, laser light scattering technique （LLS） and infrared spectrum （IR）. LLS test showed that the optimal prepared ADM-loaded nanoparticles had an average size 18.8nm and a narrow size distribution between 15nm and 32nm, which was consistent with the result obtained by TEM. And 1R results indicated that the nanoparticles consisted of ADM and polyvinylpyrrolidone （PVP）.

Tough Semi-interpenetrating Polyvinylpyrrolidone/Polyacrylamide Hydrogels Enabled by Bioinspired Hydrogen-bonding Induced Phase Separation

Semi-interpenetrating(semi-IPN)hydrogels formed by the continuous interpenetration of cross-linked polymer network and linear non-crosslinked polymer with multifunctionality are widely used in biomedical and other fields.However,the negative impact of linear polymer on the homogeneity of the cross-linked network often leads to a decrease in the mechanical properties of semi-IPN hydrogels and severely limits their applications.Herein,a bioinspired hydrogen-bonding induced phase separation strategy is presented to construct the tough semi-IPN polyvinylpyrrolidone/polyacrylamide hydrogels(named PVP/PAM hydrogels),including the linear polymer polyvinylpyrrolidone(PVP)and cross-linked polyacrylamide(PAM)network.The resultant PVPx/PAM hydrogels exhibit unique phase separation induced by the hydrogen bonding between PVP and PAM and affected by the amount of substance of PVP.Meanwhile,the phase separation of PVPx/PAM hydrogels results in excellent mechanical properties with a strain of 2590%,tensile strength of 0.28 MPa and toughness of 2.17 MJ/m^(3).More importantly,the hydrogen bonding between PVP and PAM firstly disrupts to dissipate energy under external forces,so the PVPx/PAM hydrogels exhibit good self-recovery properties and outperform chemically cross-linked PAM hydrogels in impact resistance and damping applications.It is believed that the PVPx/PAM hydrogels with hydrogen-bonding induced phase separation possess more potential application prospects.

Selective removal of Cr(Ⅵ)using polyvinylpyrrolidone and polyacrylamide co-modified MoS_(2) ccomposites by adsorption combined with reduction

Cr(Ⅵ),one of the most hazardous metal pollutants,poses significant threats to the environment and human health.Herein,a novel MoS_(2) composite(MoS_(2)/PVP/PAM)modified by polyvinylpyrrolidone(PVP)and polyacrylamide(PAM)was synthesized to enhance the removal of Cr(Ⅵ).Characterization analysis including SEM,XRD,FTIR,and XPS indicated that PVP and PAM could increase the interlayer spacing and the dispersibility of MoS_(2),and introduce pyrrolic N and amino functional groups.The batch experiments showed that MoS_(2)/PVP/PAM represented excellent Cr(Ⅵ)removal performance over a wide p H range,and exhibited a significantly higher maximum Cr(Ⅵ)adsorption capacity(274.73 mg/g,at p H 3.0,and 298 K)than pure MoS_(2).The adsorption of Cr(Ⅵ)followed Langmuir and pseudo-second-order kinetic model,which was a homogeneous monolayer chemisorption process.MoS_(2)/PVP/PAM showed stable removal of Cr(Ⅵ)in the presence of humic acid(HA),interfering cations and anions at different concentrations.Moreover,it had excellent selectivity for Cr(Ⅵ)(K_(d) value of 1.69×10^(7)m L/g)when coexisting with a variety of competing ions.Multiple characterization revealed that Cr(Ⅵ)was reduced to low toxicity Cr(Ⅲ)by Mo^(4+)and S^(2-),and then chelated on the surface of the adsorbent by pyrrolic N.This research expanded the design concept for MoS_(2) composites by demonstrating the potential of MoS_(2)/PVP/PAM as a promising material for selective elimination of Cr(Ⅵ)in water.

Study on Antibacterial and Biocompatibility of Thermally Crosslinked Polyvinylpyrrolidone Nanofiber Iodine Complexes

Polyvinylpyrrolidone-iodine (PVP-I) complexes are widely used in the medical and health field due to its strong antimicrobial properties and good biocompatibility,but their water solubility negates the possibility to be used as a wound dressing.In this work,the problem of PVP dissolving in water was solved by the method of thermally crosslinking,and it was found that the thermally crosslinked PVP nanofiber heated at 170 ℃ for 6 h had good liquid absorption capacity,stability and good fiber morphology.In addition,the thermally crosslinked PVP nanofiber is complexed with I2 to endow it with excellent antibacterial properties.It has been demonstrated to have good biocompatibility through cytotoxicity and hemolysis experiments,which provides the possibility for it to be a dressing for the treatment of infectious wounds.

Preparation and Visible-light Photochromism of Phosphomolybdic Acid/Polyvinylpyrrolidone Hybrid Film

The visible-light photochromic hybrid film was constructed by entrapping phosphomolybdic acid（PMoA） into polyvinylpyrrolidone（PVPd） networks. The microstructure, photochromic properties and mechanism were inves- tigated with transmission electron microscopy（TEM）, atomic force microscopy（AFM）, Fourier transform infrared （FTIR） spectroscopy, ultraviolet-visible（UV-Vis） spectra and X-ray photoelectron spectroscopy（XPS）. The results in- dicate that the Keggin geometry of PMoA and the basic structure of PVPd are not destroyed during the composite process. Irradiated with visible light, the transparent PMoA/PVPd film changes color from colorless to blue and ex- hibits reversible photochromism in the presence of oxygen. According to the XPS analysis, the charge-transfer bridge of N-H-O has been built between PMoA and PVPd matrix via non-covalent bonding, and the appearance of Mo5＋ species indicates that the photo-reduction process is in accordance with the proton transfer mechanism.

Light Electrospun Polyvinylpyrrolidone Blanket for Low Frequencies Sound Absorption

Light polymeric soundproofing materials （density = 63 kg/m3） of interest for the transportation industry were fabricated through electrospinning. Blankets of electrospun polyvinylpyrrolidone （average fiber diameter = （1.6 ± 0.5） or （2.8 ± 0.5） μm） were obtained by stacking disks of electrospun mats. The sound absorption coefficients were measured using the impedance tube instrument based on ASTM E1050 and ISO 10534-2. For a given set of disks （from a minimum of 6） the sound absorption coefficient changed with the frequency （in the range 200-1600 Hz） following a bell shape curve with a maximum （where the coefficient is greater than 0.9） that shifts to lower frequencies at higher piled disks number and greater fiber diameter. This work showed that electrospinning produced sound absorbers with reduced thickness （2-3 cm） and excellent sound-absorption properties in the low and medium frequency range.

Polyvinylpyrrolidone/graphene oxide thin films coated on quartz crystal microbalance electrode for NH_3 detection at room temperature

In this paper, composite film based on polyvinylpyrrolidone(PVP)/graphene oxide(GO) was fabricated by spray method on AT-cut 9.986 MHz quartz crystal microbalance(QCM) for NH_3 sensing. The thin films were characterized by scanning electron microscope(SEM), Fourier transform infrared spectroscopy(FTIR) and ultraviolet-visible spectroscopy(UV-VIS) to investigate the morphologies and the composition contents, respectively. The experimental results reveal that PVP/GO based sensor holds higher sensitivity, larger responsiveness and smaller baseline drift than those based on pure PVP at room temperature. Besides, the prepared sensor exhibits greater response to NH_3 than other gases such as CO, CO_2 and NO_2 at the same concentration. The good linearity, reproducibility and stability demonstrate the practicability of PVP/GO hybrid film in detecting NH_3.

Formation and aggregation number of sodium dodecyl sulphonate-polyvinylpyrrolidone aggregates

THE interaction of surfactants with water-soluble polymers has been an active subject for manyyears. Early investigations were mainly concerned with the effect of synthetic detergents onnatural proteins, such as gel. These studies were motivated by observations of biologicalphenomena involving surfactants and proteins such as the inactivation of bacterial

Further Study on Separation of DNA Fragments by Capillary Electrophoresis by Quasi-interpenetrating Network of Polyacryamide and Polyvinylpyrrolidone with UV Detection

Quasi-interpenetrating network of polyacrylamide （PAA） and polyvinylpyrrolidone （PVP） had been successfully used for single-base resolution of double-stranded DNA （0.76 for 123 bp/124 bp） and single-stranded DNA fragments （0.97 for 123 b/124 b） with UV detection. This quasi-IPN （interpenetrating network） sieving matrix showed low viscosity （23.5 mPa·s at 25 ℃） and decreased with increasing temperature. This polymer also exhibited dynamically coating capacity and could be used in the uncoated capillary. The effects of temperature and electric field strength on the DNA separation of quasi-IPN matrix were also investigated and found that the temperature and electric field strength could markedly affected the mobility behavior of DNA fragments. This polymer matrix has also applied to separate the bigger DNA fragments by capillary electrophoresis with UV detection. Under the denaturing conditions, this matrix separated the samples with last fragment of 1353 base in 40 rain, in which the doublet of 309/310 base was partial separated and the resolution was 0.88.

Behavior of MC3T3-E1 Osteoblast Cultured on Chitosan Modified with Polyvinylpyrrolidone

The physical and chemical properties of four kinds of modified chitosan materials made by blending chitosan with polyvinylpyrrolidone （PVP） were investigated. All four of these modified chitosan materials were hydrophilic with water contact angles ranging from 59°to 69°. Fourier transform-infrared spectra of the modified materials showed a new band at 1288 cm^-1, implying formation of a surface physical interpenetrating network structure. Enzyme linked immunosorbent assay results indicated that much less fibronectin was adsorbed on the modified materials than on only chitosan. The viability of MC3T3-E1 osteoblasts cultured on the materials was assessed by 3-（4,5-dimethyl-2-thiazolyl）-2,5-diphenyl- 2H-tetrazolium bromide assay. The results show that adding PVP10000 into the chitosan promotes adhesion of MC3T3-E1 osteoblasts on the modified materials, but has no effect on cell growth and proliferation; while adding PVP40000 reduces cell adhesion, growth, and proliferation. The results suggest that the increased hydrophilicity of the material surface does not always improve its biocompatibility, which will influence the selection and design of biomaterials.

Polyvinylpyrrolidone as an Efficient Stabilizer for Silver Nanoparticles

Aggregation of nanoparticles is a serious problem in their applications.In this article,stability of biosynthesized silver nanoparticles(AgNPs)was initially studied with different concentrations of sodium chloride(NaCl).Surfactant screening showed that polyvinylpyrrolidone(PVP)was an ideal stabilizer,which not only was effective at a low concentration(0.1%,V/V),but also could protect silver colloids from aggregation for a long period at 1 mol•L^(−1) NaCl,and 6 h even at 3 mol•L^(−1) NaCl.However,some other surfactants,such as sodium dodecyl(SDS),Triton X-100,Tween-20,and Tween-80,could not prevent AgNPs from aggregation even at a high concentration up to 0.5%(V/V).This AgNPs stabilizer is simple and convenient for a variety of applications compared with others.