Low Molecular Weight Polyvinyl Alcohol Research Articles

Investigating Cellulose Nanocrystal and Polyvinyl Alcohol Composite Film in Moisture Sensing Application

This study focused on utilizing cellulose nanocrystal (CNC)–polyvinyl alcohol (PVA) composite in optical sensor applications to detect high humidity conditions and determine water concentration in ethanol. We focused on the composite’s effectiveness in moisture absorption to demonstrate visual color change. We demonstrated that the different molecular weights of PVA significantly affect CNC’s chiral nematic structure and moisture absorption capability. PVA with molecular weight 88 k–97 k exhibited the disintegration of its chiral nematic structure at 30 wt%, whereas low molecular weight PVA (n~1750) showed no structural disintegration even at 100 wt% concentration when analyzed through UV-Vis spectroscopy. Further, the thermal crosslinking of the CNC-PVA composite showed no significant loss of moisture sensitivity for all molecular weights of the PVA. We observed that the addition of PVA to the sulfated CNC obtained from sulfuric acid hydrolysis did not facilitate moisture absorption significantly. A CNC-PVA sensor was developed which can detect high humidity with 2 h. of exposure time. 2,2,6,6-tetramethylpiperidin-1-piperidinyloxy oxidized CNC (TEMPO-CNC) having carboxylic functionality was also used to prepare the CNC-PVA composite films for comparing the effect of functional groups on moisture sensitivity. Finally, we demonstrated a facile method for utilizing the composite as an optical sensor to detect water concentration in ethanol efficiently; thus, it can be used in polar organic solvent dehydration applications.

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).

Modified low molecular weight poly-vinyl alcohol as viscosity enhancer

Dry Eye Disease (DED) is a multifactorial disease that provokes a reduced vision quality and eye fatigue. It is often treated with artificial tears that must have enhanced viscosity in comparison with human tears. Phosphorylated low molecular weight PVA was synthesized to obtain a viscosity enhancer for the production of artificial tears. Three different concentrations were analyzed, verifying that, thanks to the combined action of low molecular weight and presence of anionic groups inserted along the chains, formulations can be sterilized by filtration without losing their viscosity properties, stability and transparency (light trasmittance >85%). Formulations were characterized by Infrared and UV spectroscopy, thermal analyses and rheology. The developed viscosity enhancer shows adequate viscosity values for the foreseen application. Indeed, its viscosity is higher than natural tears (1.5 mPa.s) but lower than 30 mPa.s (sticky sensation) at the shear stress values the eye is subjected. It shows a mean viscosity value of 20 mPa.s at shear rate 1 s−1 (interblinking phase: open eye), and 10.5 mPa.s at 10,000 s-1 (blinking phase).

Statistically optimized fast dissolving microneedle transdermal patch of meloxicam: A patient friendly approach to manage arthritis

IntroductionThe long term administration of Meloxicam for the management of arthritis, a chronic disorder, results in gastrointestinal disturbances leading to poor patient compliance. Considering the favorable molecular weight, therapeutic dose, biological half-life and log P value of meloxicam for transdermal delivery, its fast dissolving microneedle patch, with an ability to breach the stratum corneum and efficiently deliver the cargo to deeper skin layers, were developed. MethodsMicroneedle patch of low molecular weight polyvinyl alcohol and polyvinylpyrrolidone was prepared using Polydimethylsiloxane micromolds. The ratio of polyvinyl alcohol to polyvinyl pyrrolidone and solid content of matrix solution was optimized to achieve maximum needle strength. The optimized batch was extensively evaluated for in vitro dissolution, drug release, stability, ex vivo skin permeation/deposition, histopathology and in vivo pharmacodynamic study. ResultsThe patch containing 9:1 polyvinyl alcohol to polyvinylpyrrolidone ratio with 50% solid content had shown maximum axial needle fracture force (0.9N) suitable for penetrating the skin. The optimized batch was found to be fast dissolving and released almost 100% drug in 60min following dissolution controlled kinetics. The formulation showed a significant drug deposition within skin (63.37%) and an improved transdermal flux (1.60μg/cm2/h) with a 2.58 fold enhancement in permeation as compared to plain drug solution. The formulation showed a comparable anti-inflammatory activity in rats when compared to its existing approved marketed oral tablet. Histopathology and stability evaluations demonstrated acceptable safety and shelf-life of the developed formulation. ConclusionThe successful verification of safety, efficacy and stability of microneedle patch advocated the suitability of the formulation for transdermal use.

Nanoparticles as tool for enhanced ophthalmic delivery of vancomycin: a multidistrict-based microbiological study, solid lipid nanoparticles formulation and evaluation

Context: A microbiological multidistrict-based survey from different Egyptian governorates was conducted to determine the most prevalent causative agents of ocular infections in the Egyptian population. Antibiotic sensitivity testing was then performed to identify the most potent antimicrobial agent. Vancomycin (VCM) proved the highest activity against gram-positive Staphylococcus bacteria, which are the most commonly isolated causative agents of ocular infection. However, topically applied VCM suffers from poor ocular bioavailability because of its high molecular weight and hydrophilicity. Objective: The aim of the present study was to develop VCM-loaded solid lipid nanoparticles (SLNs) using water-in-oil-in-water (W/O/W) double emulsion, solvent evaporation technique to enhance ocular penetration and prolong ophthalmic residence of VCM. Method: Two consecutive full factorial designs (24 followed by 32) were adopted to study the effect of different formulation and process parameters on SLN formulation. The lipid type and structure, polyvinyl alcohol (PVA) molecular weight and concentration, sonication time, as well as lipid:drug ratio were studied as independent variables. The formulated SLN formulae were evaluated for encapsulation efficiency (EE%), particle size (PS), and zeta potential as dependent variables. Results: The statistically-optimized SLN formula (1:1 ratio of glyceryltripalmitate:VCM with 1% low molecular weight PVA and 1 min sonication time) had average PS of 277.25 nm, zeta potential of −20.45, and 19.99% drug encapsulation. Scanning and transmission electron micrographs showed well-defined, spherical, homogenously distributed particles. Conclusion: The present study suggests that VCM incorporation into SLNs is successfully achievable; however, further studies with different nanoencapsulation materials and techniques would be valuable for improving VCM encapsulation.

Preparation and catalytic application of sulfonated PVA-Zr-pillared clay nanocomposite materials towards one pot synthesis of hexahydropyrimidines

A series of sulfonated polyvinyl alcohol-Zr-pillared clay nanocomposites were synthesized. A low molecular weight polyvinyl alcohol (PVA) was sulfonated using chlorosulfonic acid. The sulfonated PVA was intercalated inside the parent clay and Zr-pillared clay (Zr-P) matrix. In an alternative approach, the polyvinyl alcohol was initially intercalated into the clay and Zr-P structure followed by in-situ sulfonation inside the clay matrix. The composite materials were characterized using XRD, FTIR, Raman, UV–vis and FE-SEM analytical techniques. Expansion in clay interlayer due to insertion of the polymeric species and the Zr-pillars was observed from XRD study. FTIR and UV–vis study revealed presence of hydrated sulfonic acid clusters in the composite materials. The clay sheets were largely present in an exfoliated state in the clay-polymer composite materials. Insertion of the Zr-pillar imparts structural rigidity and consequent changes in the morphological features. The catalytic activity of the Zr-pillared clay-sulfonated polyvinyl alcohol composite materials has been investigated for synthesis of hexahydropyrimidines by multicomponent condensation of substituted aniline, formaldehyde and β-dicarbonyl compounds. The composite materials were found to be highly active for synthesis of structurally diverse hexahydropyrimidines in high yield and purity.

Electrospinning and Characterization of Novel Opuntia ficus-indica Mucilage Biomembrane

ABSTRACTOpuntia ficus-indica (Ofi) cactus non-gelling (NE) mucilage nanofibers were electrospun with acetic acid solution and polyvinyl alcohol (PVA) as a polymer. The best fiber coverage was achieved with an aqueous 50% acetic acid solution and 9% low molecular weight PVA at a 70:30 PVA:Mucilage volume ratio. Other volume ratios (30:70 and 50:50) produced beads and other deformities. Fibers were formed with an average diameter of 180nm as measured by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Favorable electrospinning conditions were used to fabricate a 1 cm x 1 cm Ofi nanofiber biomembrane. Heat flow (W/g) versus temperature peaks ranged from 214 – 222°C, which is comparable to endothermic peak ranges observed for crystalline PVA. This could possibly further indicate some form of crystallinity within the Ofi nanofiber membrane. The electrospun process used precursors that were biodegradable, non-toxic, and sustainable to optimize the mucilage nanofiber formation, which will help enhance the potential performance of the Ofi nanofiber biomembrane in filtration and sensory systems.

Highly sensitive and spatially resolved polyvinyl alcohol/acrylamide photopolymer for real-time holographic applications

By employing low molecular-weight polyvinyl alcohol (PVA) as binder, the spatial resolution of a red-sensitive PVA/acrylamide based photopolymer are improved from 1000 lines/mm to 3000 lines/mm. By increasing the ambient temperature during the holographic recording, the photosensitivity of photopolymer is also increased about 5 times. The optimized photopolymer system has high capacity such as high photosensitivity (8 mJ/cm(2)), high spatial resolution (over 3000 lines/mm) and high diffraction efficiency (over 94%). To our knowledge, its holographic recording performance is the best of ever reported PVA/acrylamide based photopolymer systems. It has good application prospects in real-time holographic interferometry, holographic storage and holographic display.

In vitromicrobiological evaluation of polyvinyl alcohol-based ocular inserts of Ciprofloxacin hydrochloride

Soluble inserts of ciprofloxacin hydrochloride using high and low molecular weight polyvinyl alcohol alone and in various combinations were fabricated by a casting technique. The in vitro drug release from the prepared inserts was studied using a continuous flow-through model, developed in our laboratory. The antimicrobial efficacies of the prepared inserts against common ocular pathogens, viz., Staphylococcus aureus ATCC 25923 and Pseudomonas aeruginosa ATCC 27853, were evaluated using a modified in vitro microbiological model. Ciprofloxacin hydrochloride release from the inserts followed matrix diffusion kinetics showing an anomalous release mechanism (erosion-controlled) based on the calculated release exponent (n) values. Drug release increased with an increase in the proportion of high molecular weight polyvinyl alcohol in the inserts. The in vitro microbiological model demonstrated the effectiveness of the inserts against the two microorganisms. Further, the results of the in vitro release studies correlated well with that of the antimicrobial studies.

Poly-vinyl-alcohol (PVA) coating of cochlear implant electrode arrays: an in-vivo biosafety study

Objective The tissue response and biosafety of poly-vinyl-alcohol (PVA) has been investigated to explore its potential use as an agent to straighten pre-curved cochlear implant electrode arrays for surgical insertion. Methods Test arrays were implanted either subcutaneously or into the cochlea of guinea pigs for 3 months. The arrays were uncoated (Treatment 1) or coated with low molecular weight (MW) PVA (Treatment 2), high MW PVA (Treatment 3) or a 50:50 mixture of low and high MW PVA (Treatment 4). After explantation the tissues were examined histologically. Results In both study groups, Treatment 2 dissolved completely and induced the least tissue reaction, while Treatments 3 and 4 not only dissolved incompletely, but also induced more fibrous tissue growth. Treatment 4 coated arrays induced severe insertion trauma in all the cochleas, most likely due to the thickness of the coat and the resulting rigidity of the array. Spiral ganglion cell density (SGCD) in the basal turn of the scala tympani was reduced for both Treatments 2 and 4. While the reduction in SGCD in the Treatment 4 group is likely to be a result of the insertion trauma caused and the subsequent loss of peripheral dendrites, it is unknown what caused the reduction of SGCD in the Treatment 2 group. Conclusion Prior to the specific use of PVA as electrode array coating material, the ideal composition and its biosafety needs to be reassessed.

Poly-vinyl-alcohol (PVA) coating of cochlear implant electrode arrays: an in-vivo biosafety study

Objective The tissue response and biosafety of poly-vinyl-alcohol (PVA) has been investigated to explore its potential use as an agent to straighten pre-curved cochlear implant electrode arrays for surgical insertion.Methods Test arrays were implanted either subcutaneously or into the cochlea of guinea pigs for 3 months. The arrays were uncoated (Treatment 1) or coated with low molecular weight (MW) PVA (Treatment 2), high MW PVA (Treatment 3) or a 50:50 mixture of low and high MW PVA (Treatment 4). After explantation the tissues were examined histologically.Results In both study groups, Treatment 2 dissolved completely and induced the least tissue reaction, while Treatments 3 and 4 not only dissolved incompletely, but also induced more fibrous tissue growth. Treatment 4 coated arrays induced severe insertion trauma in all the cochleas, most likely due to the thickness of the coat and the resulting rigidity of the array. Spiral ganglion cell density (SGCD) in the basal turn of the scala tympani was reduced for both Treatments 2 and 4. While the reduction in SGCD in the Treatment 4 group is likely to be a result of the insertion trauma caused and the subsequent loss of peripheral dendrites, it is unknown what caused the reduction of SGCD in the Treatment 2 group.Conclusion Prior to the specific use of PVA as electrode array coating material, the ideal composition and its biosafety needs to be reassessed.

Characterization of Low-molecular-weight Polyvinyl Alcohol for Restoration Purposes

Low molecular weight polyvinyl alcohol, used in the paper industry as a pigment coating adhesive, was tested as a re-sizing agent used in paper restoration to strengthen decayed papers. All of the tests (pH, degree of polymerisation, folding endurance, tensile strength, opacity, blue reflectance and reversibility) done after accelerated aging in different ambient conditions and for various lenghts of time resulted in very good results for the tested type of polyvinyl alcohol for the intended purpose

Vaginal Absorption of Polyvinyl Alcohol in Fischer 344 Rats

Polyvinyl alcohol (PVA) is a polymer with a wide range of molecular weights and uses. Recently, low molecular weight formulations of PVA have been used as components of contraceptive products designed for intravaginal administration in human females. Previous studies in animals have determined that little or no absorption of PVA occurs from the gastrointestinal (GI) tract. However, there is some concern that PVA of lower molecular weights might be absorbed across membranes of the reproductive tract. Consequently, this work has investigated the absorption of low molecular weight PVA across biological membranes of the reproductive and GI tracts of Fischer 344 rats. Oral administration of ten consecutive daily doses of 14C PVA resulted in little apparent absorption of the dose from the GI tract. In contrast, intravaginal administration of 14C PVA resulted in increasing concentrations of PVA-derived radioactivity in major tissues following one, three or ten daily doses of the estimated human dose of 3 mg/kg. PVA-derived radioactivity was concentrated mainly in the liver, reaching a peak greater than 1750 ng equivalents/g tissue 24 hours following ten daily doses. Over 300 ng equivalents/g tissue were still present in the liver 30 days following the last dose.

Peculiar effects of temperature and polyvinylalcohol on the activity of bovine serum amine oxidase

An inflexion point of enzyme activity at 38 - 42 degrees C of the bovine serum amineoxidase was found. This result, associated with non-strict Arrhenius curves and slightly different activation energies in various temperature intervals, suggests some conformational transitions at the mentioned temperatures. The high molecular weight polyvinylalcohol (100,000 Da) generated an activatory effect and a sigmoidal (non-Michaelis) curve of the dependence of the activity on the substrate concentrations, while the low molecular weight polyvinylalcohol (20,000 Da) does not produce this effect. The different ratio of the two types of polyvinylalcohol/enzyme monomer sizes is considered to be responsible for these different effects on the enzyme kinetics.

ON THE ANTI-REDEPOSITION EFFECT OF CMC AND PVA

The anti-redeposition action of sodium carboxy-methyl cellulose (CMC) and polyvinyl alcohol (PVA) in washing process was investigated. CMC having various degree of polymerization (70_??_1, 000) or PVA (_??_=500_??_1, 800) with various degrees of substitution of acethyl group prepared by hydrolysis of polyvinyl acetate (78.5_??_99.4mol%) was added as a builder to the model soiling bath in which carbon black was dispersed in sodium dodecyl sulfate aqueous solution. The degrees of anti-redeposition effect of cotton and nylon fabrics and nylon film were measured by optical reflctance method after the treatment in the soiling bath.The addition of CMC to the soiling bath prevents soil deposition on cotton fabric at the concentrations more than 1×10-3%, while it shows no obvious effect on nylon fabric.When PVA is used, soil deposition on cotton and nylon fabrics and nylon film is prevented. By the addition of any PVA more than 1×10-4%, the cotton fabric is slightly soiled. In the case of nylon fabric, the soil prevention effect becomes more remarkable with the increased degree of hydrolysis of PVA. In the degrees of hydrolysis from 78.5% to 81.5%, low molecular weight PVA is more effective for the prevention of soil deposition on nylon fabric than high molecular weight PVA.It is concluded from above results that PVA is effective as an anti-redeposition agent for cotton and nylon, and that.PVA highly hydrolyzed has a remarkable effect for soil prevention.