Molecular Weight Poly Vinyl Alcohol Research Articles

Comparative Analysis of Crosslinking Methods and Their Impact on the Physicochemical Properties of SA/PVA Hydrogels.

Hydrogels, versatile materials used in various applications such as medicine, possess properties crucial for their specific applications, significantly influenced by their preparation methods. This study synthesized 18 different types of hydrogels using sodium alginate (SA) and two molecular weights of polyvinyl alcohol (PVA). Crosslinking agents such as aqueous solutions of calcium (Ca2+) and copper (Cu2+) ions and solutions of these ions in boric acid were utilized. The hydrogels were subjected to compression strength tests and drying kinetics analysis. Additionally, six hydrogel variants containing larger PVA particles underwent Fourier-transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) post-drying. Some samples were lyophilized, and their surface morphology was examined using scanning electron microscopy (SEM). The results indicate that the choice of crosslinking method significantly impacts the physicochemical properties of the hydrogels. Crosslinking in solutions with higher concentrations of crosslinking ions enhanced mechanical properties and thermal stability. Conversely, using copper ions instead of calcium resulted in slower drying kinetics and reduced thermal stability. Notably, employing boric acid as a crosslinking agent for hydrogels containing heavier PVA molecules led to considerable improvements in mechanical properties and thermal stability.

Encapsulation of Neem oil from Azadirachta indica into Poly (lactic-co-glycolic acid) as a novel sprayable miticide system with long-term storage stability and controlled release kinetic

In this study, Neem oil (NO) was extracted from the seeds of Azadirachta indica as a natural miticide agent. To prolong the insecticidal activity and control the sustainable release, various concentrations of NO were encapsulated in poly(D, L-lactic-co-glycolic) acid (PLGA) copolymers and high and low molecular weight (Mw) polyvinyl alcohol (PVAH and PVAL) microparticles (MPs) using the single and double emulsion solvent evaporation method. The effects of different parameters, such as the molecular weight of the stabilizing agent (PVA), stirring time, and polymer concentrations, on the size, stability, morphology, encapsulation efficiency, and release kinetics of the MPs were investigated. The presence of NO in PLGA/PVA MPs was confirmed by a shift in the glass transition temperature (Tg) to lower temperatures in the DSC thermograph, the appearance of peaks at 2854 cm−1 in the FTIR spectrum, a peak at 205 nm in the UV–vis spectrum and a rough surface in SEM. Moreover, the release kinetics of the MPs demonstrated sustained release of NO over 48 h. In terms of MPs storage, temperature affected short-term stability, while long-term stability after one year in a dark environment at room temperature was confirmed by the particles' strength. The miticide assay on dust mites Dermatophagoides pteronyssinus revealed that MPs with the highest NO concentration (PLGA/PVAL/NO 65%) exhibited the most effective miticidal activity, achieving a 100% kill rate after 24 h. Finally, the colloidal dispersion and stability of the MPs over time were assessed using rheology, and the results confirmed the particles' spray ability for miticide application.

Ex Vivo Transdermal Delivery of Nicotinamide Mononucleotide Using Polyvinyl Alcohol Microneedles.

Nicotinamide mononucleotide (NMN), which has recently been spotlighted as an anti-aging agent, is a precursor of the coenzyme nicotinamide adenine dinucleotide that plays an important role in intracellular redox reactions. NMN capsules for oral administration currently on the market have a problem in that they are almost fully metabolized in the stomach and liver and excreted as nicotinamide. Therefore, there is a need to develop a patient-friendly delivery method that can improve the bioavailability of NMN. For this purpose, various polyvinyl alcohol (PVA)-based microneedle patches were fabricated to develop a transdermal delivery system for NMN. First, the molecular weight effect of PVA on the shape and microstructure of microneedles was studied. After selecting the optimal molecular weight PVA, the swelling of the microneedles and the ex vivo release of NMN were studied. The effect of carboxymethyl cellulose (CMC) and dimethyl sulfoxide on NMN release was also investigated. The highest NMN release of 91.94% in 18 h was obtained using a 9.5 kDa molecular weight PVA microneedle containing NMN and CMC.

Bionic artificial penile Tunica albuginea

Bionic artificial penile Tunica albuginea

In situ electrospun aloe-nanofiber membrane for chronic wound healing

Alleviating excessive inflammation while accelerating chronic wound healing to prevent wound infection has remained challenging, especially during the coronavirus disease 2019 (COVID-19) pandemic caused by SARS-CoV-2 when patients experienced difficulties with receive appropriate healthcare. We addressed this issue by developing handheld electrospun aloe-nanofiber membranes (ANFMs) with convenient, environmentally friendly properties and a therapeutic capacity for wound closure. Our results showed that ANFMs fabricated with high molecular weight polyvinyl alcohol (PVA) to form fibers during electrospinning had uniform fibrous architecture and a porous structure. Given the value of aloe gel in accelerating wound healing, liquid extracts from ANFMs significantly downregulated the expression of the pro-inflammatory genes, interleukin-6 (IL-6) and inducible nitric oxide synthase (iNOS), and markedly suppress the generation of reactive oxygen species (ROS) induced by lipopolysaccharide in RAW264.7 macrophages. These results indicated the excellent antioxidant and anti-inflammatory effects of ANFMs. After implantation into a mouse diabetic wound model for 12 days in situ, ANFMs notably expedited chronic wound healing via promoting angiogenesis and enhancing cell viability. Our ANFMs generated by handheld electrospinning in situ healed chronic wounds offer a convenient and promising alternative for patients to heal their own wounds under variable conditions.

The mechanism of influence of polyvinyl alcohol (9 kDa) on the formation of ice crystals in aqueous solutions

Preventing crystallization of the liquid phase during freeze-thawing of cells is one of the main problems that need to be solved for the successful preservation of biomaterial at low temperatures. One highly effective recrystallization inhibitor is polyvinyl alcohol (PVA). However, the mechanisms of its cryoprotective effect have not been finally elucidated. In particular, it is not clear which structural features contribute to the realization of the antirecrystallization properties of PVA in the region of its cryoprotective concentrations. The influence of PVA on solvent crystallization and structural rearrangements of associations of PVA molecules in phosphate-buffered saline (PBS) was experimentally investigated. Solutions of PVA (molecular weight 9 kDa) in PBS were studied by cryomicroscopy and fluorescence spectroscopy methods. It was shown that molecular associations of PVA in PBS undergo a rearrangement of about 0.5−1 wt%, which is accompanied by a change in their size and hydrophilic-hydrophobic properties. PVA also changes the morphological structure of ice upon cooling and prevents crystallization upon heating. It is suggested that the mechanism of the antirecrystallization activity of PVA may be due to the formation of its complexes with the surface of ice crystals.

РЕОЛОГИЯ ВОДНОГО РАСТВОРА НИЗКОМОЛЕКУЛЯРНОГО ПОЛИВИНИЛОВОГО СПИРТА

The rheology of aqueous solutions of polyvinyl alcohol (PVA) was studied by the method viscometry. The values of the verification coefficients were estimated depending on both the concentration of PVA, and on the average molecular weight of the PVA itself. It is shown that in water a solution of low molecular weight PVA (70-140 kDa) with a concentration of up to 0.035% dominant is the interaction of polymer chains with water (the first belief coefficient), and above 0.035% PVA, the interaction of polymer chains between itself (the second confidence factor).

Optimizing the surface properties of nanofiltration membrane by tailoring the diffusion coefficient of amine monomer

High-performance hollow fiber NF membranes with network structure were successfully prepared by introducing macromolecular polyvinyl alcohol (PVA) into aqueous phase to change the diffusion coefficient of amine monomer (piperazine, PIP) in organic phase. Based on Wilke-Change equation, a theoretical model (DAO) dealing with viscosity of aqueous phase, molecular weight of PVA, and diffusion coefficient of amine monomer in organic phase was proposed. The applicability of the DAO model was verified by ultraviolet spectrophotometry (UV) monitoring and one-dimensional diffusion model. Subsequently, the structure of NF membranes was analyzed by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The results suggested that the diffusion coefficient of amine monomer was negatively correlated with aqueous phase's viscosity and polymer's molecular weight. With PVA205 (Molecular weight is 205000 Da) used to change the viscosity of aqueous phase, the diffusion coefficient of PIP (in n-hexane) was close to 2.70 × 10−6 cm2/s, and the resultant NF membrane (NF-PVA205-1) showed excellent performance; specifically, NF-PVA205-1 achieved a flux as 107 L/m2·h (4 bar), which is 3.5-times higher than that of pure polyamide NF membrane, and the rejection rate for sodium sulfate can reach 97.9%. Such a facile fabrication method proposed in this study can balance the "trade-off" effect of traditional NF membrane.

Shape memory polymer hydrogels with cell-responsive degradation mechanisms for Crohn's fistula closure.

Crohn's disease, a form of inflammatory bowel disease, commonly results in fistulas, tunneling wounds between portions of the urinary, reproductive, and/or digestive systems. These tunneling wounds cause pain, infection, and abscess formation. Of Crohn's patients with fistula formation, 83% undergo surgical intervention to either drain or bypass the fistula openings, and ~23% of these patients ultimately require bowel resections. Current treatment options, such as setons, fibrin glues, and bioprosthetic plugs, are prone to infection, dislodging, and/or require a secondary removal surgery. Thus, there is a need for fistula filling material that can be easily and stably implanted and then degraded during fistula healing to eliminate the need for removal. Here, the development of a shape memory polymer hydrogel foam containing polyvinyl alcohol (PVA) and cornstarch (CS) with a disulfide polyurethane crosslinker is presented. These materials undergo controlled degradation by amylase, which is present in the digestive tract, and by reducing thiol species such as glutathione/dithiothreitol. Increasing CS content and using lower molecular weight PVA can be used to increase the degradation rate of the materials while maintaining shape memory properties that could be utilized for easy implantation. This material platform is based on low-cost and easily accessible components and provides a biomaterial scaffold with cell-responsive degradation mechanisms for future potential use in Crohn's fistula treatment.

Aqueous polyvinyl alcohol solution foaming at different molecular masses

Objectives. Investigation of aqueous polyvinyl alcohol (PVA) foaming process and the influence of its water solution structure, when possessed of different molecular weights and concentrations, on foaming multiplicity.Methods. Solution foaming analysis was performed on the data of dynamic light scattering obtained on the Zetasizer Nano particle analyzer.Results. In this work, the foaming ability and foaming multiplicity of aqueous PVA solutions (as a main component for obtaining special-purpose foams) have been studied. It is shown that PVA solutions in water are colloidal dispersed systems consisting of different-sized associates (from 4.8 to 68.1 nm), depending on the molecular weight of PVA. Dependencies of aqueous PVA solution foaming multiplicities on the concentration, molecular weight, and solution temperature were given. Optimal values of concentration and molecular PVA weight, as well as optimal foaming process conditions from aqueous PVA solutions, were established.Conclusions. Increasing PVA concentrations in aqueous solutions cause foaming multiplicity to decrease for all molecular weights by 1.5 times, and increasing molecular weight increases foaming multiplicity by 2 times. The foaming ratio of aqueous PVA solutions with different concentrations and molecular weights (depending on a solution temperature characterized by a maximum of 30 °C) is associated with decreased viscosity and surface tension.

Oriented ZnO nanoflowers obtained after calcination of electrospinning poly(vinyl alcohol)/zinc oxide/zinc acetate composite mats

Recently, nanofibers have attracted attention from researchers worldwide because they can be applied in various fields. The obtaining of oriented ZnO nanoflowers from polyvinyl alcohol (PVA) at a concentration of 10 wt% loaded with ZnO nanoparticles and zinc acetate (Zn(OAc)2) at various concentrations by electrospinning was investigated. The molecular weight of PVA was determined to be approximately 63,547 g/mol. The effects of the Zn(OAc)2 concentration on the electrical conductivity of the polymer suspension and the morphological properties of the composite nanofibers were also determined. The electrical conductivity increased with increasing Zn(OAc)2 concentration as a consequence of greater availability of charge. Also, this is likely because the accumulation of particles might increase the charge, which would result in an increase in the average fiber diameter of the obtained electrospun product. Finally, FT-IR spectra indicated that ZnO and Zn(OAc)2 were merely suspended in the aqueous PVA solution without any chemical bonding of ZnO and Zn(OAc)2 with the PVA chains. They also indicated that PVA could be composed entirely of nanofibers and, simultaneously, Zn(OAc)2 could be converted to ZnO after calcination at 600 °C.

Controllable release of pirfenidone by polyvinyl alcohol film embedded soft contact lenses in vitro and in vivo

To increase the amount of pirfenidone (PFD) loaded in polyvinyl alcohol (PVA) film embedded soft contact lens (SCL), and evaluate its function of sustaining delivery of drug in vitro and in vivo. Drug loading efficiency within PVA film and SCLs, drug release from SCLs in vitro, and the effects of parameters of SCLs and external environment on drug release in vitro were evaluated by ultraviolet–visible spectrophotometer at 312 nm. Safety of SCLs was evaluated in vitro by transformed human corneal epithelial cell. Safety in vivo was determined by optical coherence tomography and histology of anterior segment of rabbits. Drug release study in tear fluid and aqueous humor were measured by ultra-performance liquid chromatography. SCLs had smooth surface and were fit for experimental rabbits. Amount of PFD in PVA film and SCLs were 153.515 μg ± 12.508 and 127.438 μg ± 19.674, respectively, PFD in PVA film was significantly higher than SCLs (p=.006) and closed to 150 μg (targeting amount of PFD to be loaded). Thickness of SCLs, molecular weight of PVA, and amount of PVA used in SCLs affected drug release in vitro significantly. Thickness of PVA film and amount of drug in SCLs had no effect on drug release rate in vitro. SCLs were safe in vitro and in vivo, PFD released from SCLs could be detected around 12 hours in tears and aqueous humor, and the concentration of drug was higher than eye drop at all detected time points while amount of PFD in SCLs was lower than eye drop. Drug loaded PVA film embedded SCLs may be a promising ocular drug delivery system.

Synthesis and Characterization of Poly (vinyl alcohol) / Fullerene C60 Membrane via Chemical and Radiation Crosslinking

Abstract Fullerene C60 (FULL-C60) was used as a nano-filler in the preparation of the chemical-crosslinking polyvinyl alcohol (PVA) by glutaraldehyde (Glut) which, copolymerized with acrylate oligomers, 2-carboxyethyl acrylate (CEA) followed by gamma irradiation. The effect of the FULL-C60 content on the gel content and swelling behavior of Glut-(PVA/CEA)-FULL-C60 copolymer hydrogel was investigated. The results revealed an increase in the gel content and a significant reduction in swelling of the nanocomposite material. There are influences for the PVA molecular weight, fullerene content, and absorbed dose on the gel content of the prepared nanocomposite. The irradiation of chemical crosslinked nanocomposites demonstrated approximately a 90% gelation over a range of 50-300 kGy irradiation doses. A scanning electron microscopy (SEM) analysis showed a homogeneous distribution of nanocomposites in the composite matrix. Improvement in the thermal stability of radiation Glut-(PVA/CEA) and Glut-(PVA-CEA)-FULL-C60 was evaluated using thermogravimetric analysis (TGA). The mechanical properties were examined via dynamic mechanical analysis (DMA) which showed significant variation because of the addition of nanocomposites and irradiation doses.

Development and evaluation of polyvinyl alcohol stabilized polylactide-co-caprolactone-based nanoparticles for brain delivery

The biodegradable polymer poly-ε-(D, l-lactide-co-caprolactone) (PLCL) can be used to produce nanoparticles with tailored release pattern. In this study; the anti-epileptic drug, lamotrigine, was loaded in PLCL nanoparticles stabilized using various molecular weights and concentrations of polyvinyl alcohol (PVA). The nanoparticles were prepared by emulsification solvent evaporation technique. Nanoparticles were characterized for their morphology, particle size (PS), Zeta potential (ZP), entrapment efficiency (EE), drug loading capacity (DLC), yield percentage (YP)-values and drug release pattern. Drug concentration in Albino rats’ blood and brain after intravenous injection of selected nanoparticles was also analyzed. Results indicated that PS, EE, DLC, YP and ZP-values for the PLCL nanoparticles decreased with increasing PVA concentration. Formulated nanoparticles using LPVA were stable under various storage conditions. Lamotrigine release from nanoparticles was sustained for nearly a week. The selected formulation showed significantly high drug concentration in the brain compared to that for oral conventional tablet. In conclusion; varying PVA concentration and molecular weight used to stabilized PLCL nanoparticles helped in providing versatile properties for designing nanoparticles with wide range of properties.

Anti-Platelet Effect Induced by Iron Oxide Nanoparticles: Correlation with Conformational Change in Fibrinogen.

Iron oxide nanoparticles are developed for various biomedical applications, however, there is limited understanding regarding their effects and toxicity on blood components. The particles traveling in circulation inevitably interact with blood cells and plasma proteins and may interfere with hemostasis. Specifically, this study focuses on the influence of superparamagnetic iron oxide nanoparticles (SPIONs) coated with a biocompatible polymer, polyvinyl alcohol (PVA), on platelet function. Here, engineered SPIONs that are functionalized with various PVA coatings to provide these particles with different surface charges and polymer packing are described. These formulations are assessed for any interference with human platelet functions and coagulation, ex vivo. Positively charged SPIONs induce a significant change in platelet GPIIb-IIIa conformation, indicative of platelet activation at the dose of 500µg mL-1 . Remarkably, engineered PVA(polyvinyl alcohol)-SPIONs all display a robust dose-dependent anti-platelet effect on platelet aggregation, regardless of the PVA charge and molecular weight. After assessing hypotheses involving SPION-induced steric hindrance in platelet-platelet bridging, as well as protein corona involvement in the antiplatelet effect, the study concludes that the presence of PVA-SPIONs induces fibrinogen conformational change, which correlates with the observed dose-dependent anti-platelet effect.

Nanocomposite polyaniline for environmental and energy applications

Abstract In situ polymerization techniques had been used for the development of nanoTiO2 based conducting polymer Polyaniline nanocomposite materials. The film was developed with aqueous soluble high molecular weight polyvinyl alcohol (PVA) and nano TiO2 for increasing thermal stability and mechanical properties of nanocomposite material. The different weight compositions of nanocomposite (30%-40%) had been used for the fabrication of film with PVA. The film was characterized by dc conductivity between 20 V and 500 V and it was observed that dc conductivity of the film can be regulated between these voltages.

Influence of PVA Molecular Weight and Concentration on Electrospinnability of Birch Bark Extract-Loaded Nanofibrous Scaffolds Intended for Enhanced Wound Healing.

Triterpenes from the outer bark of birch (TE) are known for various pharmacological effects including enhanced wound healing. Apart from an already authorized oleogel, electrospun nanofiber mats containing these triterpenes in a polyvinyl alcohol (PVA) matrix appear to be an advantageous application form. The effects of PVA molecular weight and concentration on the fiber morphology have been investigated. Three different molecular weights of PVA ranging from 67 to 186 kDa were used. The concentration of PVA was varied from 5 to 20 wt%. Polymer solutions were blended with colloidal dispersions of birch bark extract at a weight ratio of 60:40 (wt.%). The estimated viscosity of polymer solutions was directly linked to their concentration and molecular weight. In addition, both pure and blended solutions showed viscoelastic properties with a dominant viscous response in the bulk. Fiber morphology was confirmed using scanning electron microscopy (SEM). Both polymer concentration and molecular weight were found to be significant factors affecting the diameter of the fibers. Fiber diameter increased with a higher molecular weight and polymer concentration as more uniform fibers were obtained using PVA of higher molecular weight (146–186 kDa). In vitro drug release and ex vivo permeation studies indicated a faster drug release of betulin from electrospun scaffolds with lower PVA molecular weight. Our research suggests that the fabricated TE-loaded PVA electrospun dressings represent potential delivery systems of TE for wound care applications.

A nanocomposite interpenetrating hydrogel with high toughness: effects of the posttreatment and molecular weight

Previously, we prepared a tough nanocomposite interpenetrating hydrogel by chemical crosslinking of acrylamide (AM) with vinyl-modified silica nanoparticles (VSNPs), combined with physical crosslinking of polyvinyl alcohol (PVA). It is well-known that posttreatment method and molecular weight play important roles in the mechanical properties of the tough hydrogels. In this paper, different post-treatment methods, i.e., freeze-thaw and annealing-swelling and varying PVA degree of polymerization (500 and 1700) were used to prepare the nanocomposite interpenetrating hydrogels. The effects of posttreatment and PVA molecular weight on the mechanical and swelling properties were investigated in detail. Tensile tests showed that annealing-swelling process exerted a more pronounced influence on elevating the tensile strength of nanocomposite interpenetrating hydrogels, which arose from the increased crystallization degree of PVA and the denser network. Hydrogels with lower PVA molecular weight have higher tensile strength after freeze-thaw cycle than that with higher PVA molecular weight. Cyclic loading–unloading tests revealed that the gels with lower molecular weight of PVA can dissipate higher energy at 100% strain. The swelling kinetic study revealed that the swelling behaviors of nanocomposite interpenetrating hydrogels followed the pseudo-second-order dynamic equation.

Preparation of Microcapsules Coating and the Study of Their Bionic Anti-Fouling Performance.

With the increasing demands to better the marine environment, environmentally friendly anti-fouling coatings have attracted attention from society. Adding hydrolyzable microcapsules without toxin to paints is a very useful and safe method to get bionic anti-fouling coatings with a micro-nano surface structure. Based on this trend, a form of environment-friendly microcapsules were prepared through mini-emulsion polymerization. The target microcapsules had a poly(urea-formaldehyde) (PUF) shell and a mixed core of silicone oil and capsaicin. Additionally, the microcapsules were introduced into zinc acrylate resin to obtain bionic anti-fouling coatings with micro-nano morphology. The effects of polyvinyl alcohol (PVA) molecular weight, stirring rate, and temperature on the morphology of the microcapsules were studied by optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It was found that spherical nanoparticles with smooth surfaces were obtained, and the mean diameter was approximately 1.38 μm when the molecular weight of PVA was 77 K, the stirring rate was 600 rpm and the temperature was 55 °C. Fourier-transform infrared spectra (FTIR) results showed that the silicone oil and capsaicin were successfully encapsulated, the core materials of the microcapsules reached 72.37% and the yield of microcapsules was 68.91% by the Soxhlet method. Furthermore, the hydrophobicity, corrosion resistance and anti-fouling performance of the coatings were evaluated by the water contact angle, electrochemical and real-sea tests. The results indicated that the anti-fouling coatings had excellent hydrophobicity and anti-fouling performance due to the micro-nano convex structure and the release of core materials. Encouragingly, the anti-fouling coatings show excellent and long-term anti-fouling performance, which is expected to be widely applied in marine anti-fouling coatings.

A novel method for detection of lipid oxidation in edible oil

Lipid oxidation is a major food safety issue for edible oils. The objective of this study was to develop a simple method for detecting lipid oxidation through the color change of a composite film. Schiff's reagent which can form color compound with lipid oxidation products—aldehydes was incorporated into polyvinyl alcohol (PVA) to form the composite film. The effects of PVA molecular weight (Mw), Schiff's reagent/PVA ratio and glycerol content on the response of the composite film to aldehyde were investigated. Sunflower seed oil with various extent of oxidation was used to evaluate the effectiveness of the composite film for lipid oxidation detection. The results showed that the composite film formed with lower PVA Mw turned from colorless to purple upon aldehyde exposure. Higher Schiff's reagent/PVA ratio and glycerol content led to shorter response time and larger color change after aldehyde exposure. The color change of the composite film was linearly (R2 = 0.96) related to aldehyde concentration. The oxidation status of four sunflower seed oil samples out of five were correctly identified by the composite film. Although the accuracy of this method was 80% in this study, it still shows great potential for lipid oxidation detection application.