Enhanced stability of PVA electrospun fibers in water by adding cellulose nanocrystals

Holzforschung ◽  
2015 ◽  
Vol 69 (6) ◽  
pp. 737-743 ◽  
Author(s):  
Anna Sutka ◽  
Andris Sutka ◽  
Sergej Gaidukov ◽  
Martin Timusk ◽  
Janis Gravitis ◽  
...  
Keyword(s):  
Aqueous Medium ◽  
Steam Explosion ◽  
Thermal Studies ◽  
Poly Vinyl Alcohol ◽  
Electrospun Fibers ◽  
Alkaline Extraction ◽  
Experimental Findings ◽  
Nanofiber Mats ◽  
First Time ◽  
Enhanced Stability

Abstract The solubility of electrospun poly(vinyl alcohol) nanofiber mats (PVAES-NFM) is strongly influenced by loading with nanocellulose (NC). The NC was derived from hemp shives obtained by steam explosion autohydrolysis followed by water and alkaline extraction, ball milling, and ultrasonication treatments. It was demonstrated for the first time that PVAES-NFM does not disintegrate in aqueous medium after simple adding of NC without any additional chemical or physical modification (PVAES-NFMNC). The structural and thermal studies on PVAES-NFMNC indicated that enhanced stability in aqueous medium can be explained by interactions between surface groups of NC and PVA macromolecules as well as by reinforcing the effect of NCs. The experimental findings could be important for filtration applications in environments with high relative humidity.

scholarly journals First thermal studies on visible-light-switchable negative T-type photochromes of a nitrile-rich series

RSC Advances ◽  
2021 ◽  
Vol 11 (34) ◽  
pp. 21097-21103
Author(s):  
Mikhail Yu. Belikov ◽  
Mikhail Yu. Ievlev
Keyword(s):  
Thermal Stability ◽  
Visible Light ◽  
Temperature Effect ◽  
Thermal Studies ◽  
First Time ◽  
Thermal Stability Of

The temperature effect on the thermal stability of both the initial and photoinduced forms of nitrile-rich T-type photochromes was studied for the first time.

Ciprofloxacin-loaded alginate/poly (vinyl alcohol)/gelatin electrospun nanofiber mats as antibacterial wound dressings

2021 ◽  
pp. 152808372199746
Author(s):  
Tittaya Thairin ◽  
Patcharaporn Wutticharoenmongkol
Keyword(s):  
Weight Loss ◽  
Vinyl Alcohol ◽  
Diffusion Method ◽  
Poly Vinyl Alcohol ◽  
Burst Release ◽  
Electrospun Nanofiber ◽  
Total Immersion ◽  
Water Swelling ◽  
Nanofiber Mats ◽  
And Diffusion

Herein, ciprofloxacin (CIP)-loaded alginate/poly (vinyl alcohol)/gelatin (SPG) (CIP–SPG) nanofiber mats were successfully fabricated by electrospinning. The average fiber diameters of the mats before and after crosslinking were in the range of 190–260 and 385–484 nm, respectively. The chemical integrity of CIP remained intact after encapsulation into the mats. The degree of weight loss and water swelling decreased with an increase in the gelatin content of the electrospun nanofiber mats. A release study was carried out by total immersion and diffusion methods using phosphate buffer as a release medium. Burst release of CIP was observed in case of the total immersion method, while a more sustained release was observed in case of the diffusion method. The maximum amounts of CIP released during total immersion and diffusion were in the range of 70–90% and 72–85%, respectively. For both the total immersion and diffusion methods, the released amounts of CIP decreased and the release slowed down with an increase in the gelatin content; this result is consistent with the weight loss and water swelling values. The Young’s modulus increased, while the tensile strength and strain at break decreased with an increase in the gelatin content. The CIP–SPG nanofiber mats were slightly toxic to L929 mouse fibroblasts as evaluated by indirect cytotoxicity assay. The electrospun CIP–SPG nanofiber mats exhibited excellent antimicrobial activity against Staphylococcus aureus and Escherichia coli. These results reveal that the electrospun CIP–SPG nanofiber mats are potentially promising materials for wound healing applications.

scholarly journals Fabrication and Characterization of Lignin/Dendrimer Electrospun Blended Fiber Mats

Molecules ◽  
2021 ◽  
Vol 26 (3) ◽  
pp. 518
Author(s):  
Somaye Akbari ◽  
Addie Bahi ◽  
Ali Farahani ◽  
Abbas S. Milani ◽  
Frank Ko
Keyword(s):  
Thermal Characteristics ◽  
Dendritic Polymers ◽  
Amino Groups ◽  
Fiber Mats ◽  
Potential Applications ◽  
Solution Electrospinning ◽  
Nanofiber Mats ◽  
Softwood Kraft Lignin ◽  
First Time

Blending lignin as the second most abundant polymer in Nature with nanostructured compounds such as dendritic polymers can not only add value to lignin, but also increase its application in various fields. In this study, softwood Kraft lignin/polyamidoamine dendritic polymer (PAMAM) blends were fabricated by the solution electrospinning to produce bead-free nanofiber mats for the first time. The mats were characterized through scanning electron microscopy, Fourier transform infrared (FTIR) spectroscopy, zeta potential, and thermogravimetry analyses. The chemical intermolecular interactions between the lignin functional groups and abundant amino groups in the PAMAM were verified by FTIR and viscosity measurements. These interactions proved to enhance the mechanical and thermal characteristics of the lignin/PAMAM mats, suggesting their potential applications e.g. in membranes, filtration, controlled release drug delivery, among others.

scholarly journals Nanofibre Electrospinning Poly(vinyl alcohol) and Cellulose Composite Mats Obtained by Use of a Cylindrical Electrode

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Anna Sutka ◽  
Silvija Kukle ◽  
Janis Gravitis ◽  
Rimvydas Milašius ◽  
Jolanta Malašauskienė
Keyword(s):  
Vinyl Alcohol ◽  
Steam Explosion ◽  
Combined Treatment ◽  
Poly Vinyl Alcohol ◽  
Cylindrical Electrode ◽  
Cellulose Nanofibres ◽  
Hemp Fibres ◽  
Pva Solutions ◽  
Atr Spectroscopy ◽  
Cellulose Composite

A study of nanofibre composites obtained by electrospinning from poly(vinyl alcohol) (PVA) solutions of steam exploded hemp fibres and shives is reported. A combined treatment of steam explosion (SE), ball milling, and high-intensity ultrasound (HIUS) is applied to prepare cellulose nanofibres (CNF) from hemp fibres (CNF-F) and shives (CNF-S). The reflectance Fourier transform infrared (FTIR ATR) spectroscopy is used to analyze the obtained PVA/CNF composite mats. Morphology of the PVA/CNF composites was studied by scanning electron microscopy (SEM).

scholarly journals Electrospun fibers for vaginal administration of tenofovir disoproxil fumarate and emtricitabine in the context of topical pre-exposure prophylaxis

2021 ◽  
Author(s):  
Rute Nunes ◽  
Sarah Bogas ◽  
Maria João Faria ◽  
Hugo Gonçalves ◽  
Marlene Lúcio ◽  
...  
Keyword(s):  
Tenofovir Disoproxil Fumarate ◽  
Drug Exposure ◽  
Female Genital Tract ◽  
Poly Vinyl Alcohol ◽  
Electrospun Fibers ◽  
Strict Adherence ◽  
Vaginal Administration ◽  
Drug Concentrations ◽  
Exposure Prophylaxis

AbstractWomen are particularly vulnerable to sexual HIV-1 transmission. Oral pre-exposure prophylaxis (PrEP) with tenofovir disoproxil fumarate and emtricitabine (TDF/FTC) is highly effective in avoiding new infections in men, but protection has only been shown moderate in women. Such differences have been associated, at least partially, to poor drug penetration of the lower female genital tract and the need for strict adherence to continuous daily oral intake of TDF/FTC. On-demand topical microbicide products could help circumventing these limitations. We developed electrospun fibers based on polycaprolactone (PCL fibers) or liposomes associated to poly(vinyl alcohol) (liposomes-in-PVA fibers) for the vaginal co-delivery of TDF and FTC, and assessed their pharmacokinetics in mice. PCL fibers and liposomes-in-PVA fibers were tested for morphological and physicochemical properties using scanning electron microscopy, differential scanning calorimetry and X-ray diffractometry. Fibers featured organoleptic and mechanical properties compatible with their suitable handling and vaginal administration. Fluorescent quenching of mucin in vitro – used as a proxy for mucoadhesion – was intense for PCL fibers, but mild for liposomes-in-PVA fibers. Both fibers were shown safe in vitro and able to rapidly release drug content (15-30 min) under sink conditions. Liposomes-in-PVA fibers allowed increasing genital drug concentrations after a single intravaginal administration when compared to continuous daily treatment with 25-times higher oral doses. For instance, the levels of tenofovir and FTC in vaginal lavage were around 4- and 29-fold higher, respectively. PCL fibers were also superior to oral treatment, although to a minor extent (approximately 2-fold higher drug concentrations in lavage). Vaginal tissue drug levels were generally low for all treatments, while systemic drug exposure was negligible in the case of fibers. These data suggest that proposed fibers may provide an interesting alternative or an ancillary option to oral PrEP in women.

scholarly journals Fabrication and Properties of High-Content Keratin/Poly (Ethylene Oxide) Blend Nanofibers Using Two-Step Cross-Linking Process

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Yong Liu ◽  
Xia Yu ◽  
Jia Li ◽  
Jie Fan ◽  
Meng Wang ◽  
...  
Keyword(s):  
Ethylene Oxide ◽  
Average Diameter ◽  
Diglycidyl Ether ◽  
Cross Linking ◽  
Electrospun Fibers ◽  
Hydrophobic Property ◽  
Poly Ethylene Oxide ◽  
Cross Linker ◽  
Poly Ethylene ◽  
Nanofiber Mats

High-content keratin/poly (ethylene oxide) (PEO) (90/10) blend nanofibers were prepared by electrospinning combined with a two-step cross-linking process. The keratin/PEO aqueous solution was firstly mixed with ethylene glycol diglycidyl ether (EGDE) as cross-linker and then electrospun into nanofibers. The resulting nanofibrous mats were cross-linked with EGDE vapor to decrease the solubility of nanofibers in water. The morphologies and properties of electrospun fibers were investigated by SEM, FTIR, TG, XRD, and contact angle testing, respectively. The results showed that the morphologies of nanofibers were uniform at the fiber average diameter of 300 nm with negligible bead defects by adding EGDE to keratin/PEO solutions. The cross-linking results showed that EGDE vapor could improve the hydrophobic property of blended nanofibers. The crystallinity of the keratin/PEO blend nanofiber mat increased from 13.14% for the uncross-linked sample to 21.54% and 35.15% for the first cross-linked and second cross-linked samples, respectively. Free defect nanofiber mats with high keratin content producing from this two-step cross-linking process are particularly promising for tissue engineering and cell-seeded scaffold.

Dual-Charge Nanofiber Mats Made of Chitosan(CS)/Poly(Vinyl Alcohol) (PVA) and Poly-(Acrylic Acid-Co-Maleic Acid) (PAMA)/PVA

2019 ◽  
Vol 819 ◽  
pp. 145-150
Author(s):  
Thapakorn Chareonying ◽  
Junnasir M. Sakilan ◽  
Theerasak Rojanarata ◽  
Prasopchai Patrojanasophon ◽  
Prasert Akkaramongkolporn ◽  
...  
Keyword(s):  
Acrylic Acid ◽  
Maleic Acid ◽  
Vinyl Alcohol ◽  
Electrospinning Process ◽  
Poly Vinyl Alcohol ◽  
Water Capacity ◽  
Ft Ir ◽  
Nanofiber Mats ◽  
Positively Charged ◽  
Poly Acrylic Acid

Nanofibers have been widely used for tissue engineering. Using charged polymers for the preparation of nanofibers can be useful for the loading of substances or macromolecules. Dual charge nanofiber mats are expected to be able to immobilize both positively charged and negatively charged substances in one versatile nanofiber mat. The purpose of this study was to prepare and characterize dual-charge nanofibers generated from poly (vinyl alcohol) (PVA)/poly-(acrylic acid-co-maleic acid) (PAMA) and chitosan (CS)/PVA. The polymer solutions of PAMA/PVA (1:1.63 w/w) and CS/PVA (1:2.33 w/w) were electrospun to form the nanofibers using dual-jet electrospinning process. The obtained dual-charge nanofibers were thermally crosslinked by leaving the nanofibers in the oven at 110-130 °C for 0.5, 1, 3, 5 h. The appearance of the nanofiber mat was characterized by a scanning electron microscope (SEM), and the diameter of nanofibers were determined by an image analysis software (J-micro vision®). The percentage water insolubilization and FT-IR spectra were also determined. The dual-size nanofiber mats with smooth and bead-free fibers were obtained. The diameter of the PAMA/PVA and CS/PVA fibers was 574.54 ± 142.98 nm and 225.69 ± 41.92 nm, respectively. The desirable temperature and time for the crosslink of the dual-charge nanofiber mats was 130 °C for 1 h which could provide a high insolubilization with water capacity of 93.22 ± 2.23%.

Patterns of Locomotor Drive to Motoneurons and Last-Order Interneurons: Clues to the Structure of the CPG

2001 ◽  
Vol 86 (1) ◽  
pp. 447-462 ◽  
Author(s):  
R. E. Burke ◽  
A. M. Degtyarenko ◽  
E. S. Simon
Keyword(s):  
Fictive Locomotion ◽  
Cutaneous Reflex ◽  
Reflex Pathways ◽  
Locomotor Control ◽  
Low Threshold ◽  
Experimental Findings ◽  
Differential Control ◽  
Flexor Digitorum ◽  
First Time ◽  
Shed Light

We have examined the linkage between patterns of activity in several hindlimb motor pools and the modulation of oligosynaptic cutaneous reflex pathways during fictive locomotion in decerebrate unanesthetized cats to assess the notion that such linkages can shed light on the structure of the central pattern generator (CPG) for locomotion. We have concentrated attention on the cutaneous reflex pathways that project to the flexor digitorum longus (FDL) motor pool because of that muscle's unique variable behavior during normal and fictive locomotion in the cat. Differential locomotor control of last-order excitatory interneurons in pathways from low-threshold cutaneous afferents in the superficial peroneal and medial plantar afferents to FDL motoneurons is fully documented for the first time. The qualitative patterns of differential control are shown to remain the same whether the FDL muscle is active in early flexion, as usually found, or during the extension phase of fictive locomotion, which is less common during fictive stepping. The patterns of motor pool activity and of reflex pathway modulation indicate that the flexion phase of fictive locomotion has distinct early versus late components. Observations during “normal” and unusual patterns of fictive stepping suggest that some aspects of locomotor pattern formation can be separated from rhythm generation, implying that these two CPG functions may be embodied, at least in part, in distinct neural organizations. The results are discussed in relation to a provisional circuit diagram that could explain the experimental findings.

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