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This study proposes the braided bone scaffolds. First, biologically degradable polylactic acid (PLA) filaments and polyvinyl alcohol (PVA) filaments are plied into composite yarns using a doubling and twisting machine. The composite yarns are tested to determine the optimal mechanical properties and a stabilized morphology. The PLA/PVA composite yarns are then braided into bone scaffolds, during which the optimal braiding process parameters and yarn ratio are determined. Based on the surface observation and tensile strength, a gear ratio of 45:45 provides the tubular braids with an optimal morphology and porosity that meet the biological requirements. When the PLA/PVA ratio is 3:1, the braids exhibit the maximum tensile properties and the most stable space structure. Furthermore, to make the braids a bioactive material with surface active sites, the braids are coated with hydroxyapatite (HA) by electrodeposition. The resulting HA-electrodeposited bone scaffolds are tested by in vitro biological experiments using a scanning electronic microscope (SEM), energy dispersive x-ray analysis(EDAX), X-ray Diffraction(XRD), and Fourier transform infrared spectroscopy(FT-IR), thereby examining their characteristics and microstructure. Results suggest that HA is electrodeposited over the bone scaffolds successfully. The immersion in simulated body fluid (SBF) is proven to contribute a good in vitro bioactivity to bone scaffolds. As a result, bone scaffolds are a good candidate for the application in the cancellous bone repairing field., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

This study proposes structural models of biodegradable vascular stents. One, two, or three plies of biodegradable polyvinyl alcohol (PVA) yarns are combined and twisted with twist factors of 2, 3, 4, 5, and 6 to form one-, two-, and three-ply PVA twisted yarns. The braided, warp-knitted, and weft-knitted PVA vascular stents are composed of PVA twisted yarns by using a braider, a warp knitting machine, and a weft knitting machine. The formation and mechanical properties of PVA vascular stents are evaluated, and the biological properties are examined in terms of biocompatibility through in vitro assay and subcutaneous embedding using in vivo assay. Test results indicate that the compression strength of PVA vascular stents is improved when using PVA twisted yarns containing a high number of plies and twist factor. Specifically, weft-knitted PVA vascular stents exhibit the optimal compression strength. PVA vascular stents treated with chemical cross-linking show weight loss lower than 3% after immersion in PBS solution for 30 days. Moreover, the antibacterial test and cell culture results suggest that PVA vascular stents are nontoxic and biocompatible. Subcutaneous embedding results show that PVA vascular stents retain intact formation when subcutaneously embedded in vivo for 28 days, indicating their good biological property. PVA vascular stents are suitable candidates for tissue engineering applications., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Antibacterial materials are one of the important materials in our daily lives, especially in the medicine where antibacterial efficacy is indispensable. Moreover, the precise electronic instrument also requires highly electromagnetic interference shielding effectiveness (EMI SE) and as such to prevent mutual interference. Therefore, the acquisition of antibacterial property and EMI SE is essential. In this study, carbon nanotube (CNT) and triclosan (TCS) are used as conductive and antibacterial substances separately during the production of polypropylene (PP)-based antibacterial and conductive composite planks. The planks are tested for a series of physical property tests, EMI SE measurement, and antibacterial efficacy as related to the CNT content and the TCS content. The test results indicate regardless of whether it is CNT or TCS that is added, the planks exhibit good crystallinity. Furthermore, the presence of TCS contributes good antibacterial efficacy against staphylococcus aureus (S. Aureus), and the antibacterial efficacy effectuated by 0.1 wt% TCS also meets the related EU standard. In addition, the incorporation of both CNT and TCS adversely affects the EMI SE of the planks, but the resulting EMI SE remains to be between −15 dB and −20 dB. [ABSTRACT FROM AUTHOR]

Sulfur dioxide (SO2) pollution often poses a threat to the environment and human health, and there is an urgent need to develop flexible and convenient SO2 detection materials. MOF-5 treated with amino groups was added to polyvinyl alcohol, and then MOF-5-NH2/Polyvinyl alcohol (PVA) nanocomposite films were made by electrostatic spinning technology, and the MOF-5-NH2/PVA composite films such as mechanical and thermal stability and sensing of SO2 were systematically investigated. The results show that the MOF-5-NH2/PVA nanocomposite film has a certain tensile strength of 1.42 MPa, and the thermal stability of the MOF-5-NH2/PVA nanocomposite film is getting better as the ratio of MOF-5-NH2/PVA increases and the diameter of the fiber becomes smaller. Moreover, the produced composite film has fluorescence turn-on effect only for SO2, but not for other gases, showing a good specificity. Therefore, this study provides a new strategy for the preparation of highly sensitive and specific SO2 sensors. [ABSTRACT FROM AUTHOR]

Janus nanofibrous membranes with thin fiber diameter, small pore size, and easy-tailored wettability/thickness gradient have attracted considerable attention in the directional water transport field. However, designing textiles that ensure continuous directional water transport and outstanding moisture permeable, breathable performances has remained a great challenge. In this study, a novel polyacrylonitrile/polyvinyl alcohol–thermoplastic polyurethane (TPU) sandwich nanofibrous membrane with robust moisture permeable, breathable, and directional water transport performance is successfully fabricated with an innovation strategy combining electrospinning with structure-induced method. A good water vapor transmission rate of 9760 g/m2 d and robust breathability of 103 mm/s are obtained by turning the mass ratio of polyacrylonitrile and polyvinyl alcohol and the opening porous structure of TPU; these values are approximately five times those of commercial membranes. The sandwich fibrous membranes are suggested as promising candidates for various applications, especially in moisture-wicking clothing. [ABSTRACT FROM AUTHOR]

Bioelectric signals are an important factor that maintain cell functions and affect cell behavior. Conductive polymers (CPs) can facilitate cell activity and reinforce the signal transmission among cells, so CPs have triggered attention to the tissue regeneration. In this study, layer-by-layer strategy is employed and polyvinyl alcohol (PVA)/polylactic acid (PLA) braids are polymerized in polypyrrole (PPy) by ice template method. The stents that are deposited with PPy are then immersed in dopamine solution, which during polydopamine (PDA) is coated over the stents naturally. Finally, PDA is used as a template to form hydroxyapatite (HA) coating layer with the aim of electrochemical deposition. The test results indicate that PPy forms an even conductive network over the surface of braids while the electrochemically deposited HA made with PDA is adsorbed over the scaffolds in a needle pattern. According to the cyclic voltammetry measurement, the CV curves of HA/PDA/PPy scaffolds basically retain specified and thus the scaffolds possess stabilized electrochemical activity. At last, HA/PDA/PPy scaffolds are immersed in a simulated body fluid (SBF) for ten days and the surface is completely wrapped in HA, indicating an excellent biomineralization capability. MTT assay results suggest that the cell viability of composite scaffolds is improved by 188 %. This study provides a new perspective, a layer-by-layer structured bone scaffolds, broadening the application range of textile structure in the bone tissue engineering field. • This study broadens the application scope of textile structure in bone tissue engineering. [ABSTRACT FROM AUTHOR]

ABSTRACT This study uses the solution mixing method to combine plasticized polyvinyl alcohol (PVA) as a matrix, and multiwalled carbon nanotubes (MWCNTs) as reinforcement to form PVA/MWCNTs films. The films are then laminated and hot pressed to create PVA/MWCNTs composites. The control group of PVA/MWCNTs composites is made by incorporating the melt compounding method. Diverse properties of PVA/MWCNTs composites are then evaluated. For the experimental group, the incorporation of MWCNTs improves the glass transition temperature ( Tg), crystallization temperature, Tc), and thermal stability of the composites. In addition, the test results indicate that composites containing 1.5 wt % of MWCNTs have the maximum tensile strength of 51.1 MPa, whereas composites containing 2 wt % MWCNTs have the optimal electrical conductivity of 2.4 S/cm, and electromagnetic shielding effectiveness (EMI SE) of −31.41 dB. This study proves that the solution mixing method outperforms the melt compounding method in terms of mechanical properties, dispersion, melting and crystallization behaviors, thermal stability, and EMI SE. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43474. [ABSTRACT FROM AUTHOR]

This study proposes braid coronary stents with a form of reticular tube by using a braiding technique. Stainless steel fibers with a diameter of 0.08 mm and nitinol fibers are braided with various tooth numbers on the take-up gear and a specified tooth number on the braid gear with a hollow braiding technique in order to have different braiding angles. The resulting braids are then immersed in a polyvinyl alcohol solution in a custom-made mold to form braid coronary stents. A stereomicroscope is used to observe the cut section, a scanning electron microscope is used to examine the treatment for sharp points of the fibers, and Image Pro Plus software is used to analyze braiding angles and metal cover rate. The experiment results show that braiding angle influences the braiding structure; in addition, the larger the braiding angle, the less easily the fiber interaction points move. The immersion in polyvinyl alcohol solution can effectively bond the fiber interaction points, resulting in a better braiding structure. Metal cover rates are all below 20.9%. This study successfully creates novel braid coronary stents. [ABSTRACT FROM AUTHOR]

In this study, polyvinyl alcohol (PVA)/graphene nano-sheets (GNs) composites are produced via solution mixing and melt compounding methods, where multi-walled carbon nanotubes (MWCNTs) are added during process. After that, the test results show that PVA/GNs composites composed of 0.25 wt% GNs possess the optimal tensile strength, while the others composed of 2 wt% GNs have a higher thermal stability, electrical conductivity, and electromagnetic interference shielding effectiveness (EMI SE). The addition of MWCNTs provides the PVA/GNs composites with better synergy that can enhance the tensile properties, thermal stability, electrical conductivity, and EMI SE of composites. In comparison to the melt compounding method, the solution mixing method can yield improved properties. [ABSTRACT FROM AUTHOR]

The recovery of impaired peripheral nerves is often not as expected, which makes the development of nerve conduits trendy nowadays. To enable the neural messages effectively being delivered as well as to prevent the secondary damage during the removal of nerve conduits, the conductivity and biodegradability are two essential requirements for ideal nerve conduits. In this study, electrospinning is used to produce polyvinyl alcohol (PVA)/carbon nanotubes (CNT) electrospun films, after which the morphology analysis, electrical property, water contact angle, and biological characteristics of the membranes are investigated, thereby determining the optimal nerve conduits based on the employment of electrospinning, PVA, and CNT. The test results indicate that with 0.25 wt% of PVA, the electrospun films exhibit comparatively lower resistance of 25.3 ohm, good fibrous morphology with a diameter being 1 μm. In addition, the electrospun films are cytotoxicity-free and facilitate the growth of cells. It is observed in the MMT assay that after co-cultured with cells for three days, PVA/CNT electrospinning fibrous membranes exhibit a cellular viability that is 18.5 times greater than that of the control group on Day 1. According to all property evaluations, PVA/CNT electrospinning fibrous membranes are a qualified candidate for the use of nervous conduits. [ABSTRACT FROM AUTHOR]

Electrospinning is an efficient method of producing nanofibers out of polymers that shows a great potential for the filtration territory. Featuring water-soluble chitosan (WS-CS), a low-pollution process and a self-made needleless machine, PVA/WS-CS nanofibrous membranes were prepared and evaluated for nanofiber diameter, bacteriostatic property, filtration efficiency, pressure drop, and quality factor. Test results indicate that the minimal fiber diameter was 216.58 ± 58.15 nm. Regardless of the WS-CS concentration, all of the PVA/WS-CS nanofibrous membranes attained a high porosity and a high water vapor transmission rate (WVTR), with a pore size of 12.06–22.48 nm. Moreover, the membranes also exhibit bacteriostatic efficacy against Staphylococcus aureus, an optimal quality factor of 0.0825 Pa−1, and a filtration efficiency as high as 97.0%, that is 72.5% higher than that of common masks. [ABSTRACT FROM AUTHOR]

Particulate matter 2.5 (PM2.5) has become a public hazard to people's lives and health. Traditional melt-blown membranes cannot filter dangerous particles due to their limited diameter, and ultra-fine electrospinning fibers are vulnerable to external forces. Therefore, creating highly efficient air filters by using an innovative technique and structure has become necessary. In this study, a combination of polypropylene (PP) melt-blown and polyvinyl alcohol (PVA)/zeolite imidazole frameworks-8 (ZIF-8) electrospinning technique is employed to construct a PP/PVA/ZIF-8 membrane with a hierarchical fibrous structure. The synergistic effect of hierarchical fibrous structure and ZIF-8 effectively captures PM2.5. The PP/PVA composite membrane loaded with 2.5% loading ZIF-8 has an average filtration efficacy reaching as high as 96.5% for PM2.5 and quality factor (Qf) of 0.099 Pa−1. The resultant membrane resists 33.34 N tensile strength and has a low pressure drop, excellent filtration efficiency, and mechanical strength. This work presents a facile preparation method that is suitable for mass production and the application of membranes to be used as air filters for highly efficient filtration of PM2.5. [ABSTRACT FROM AUTHOR]

This study aims to develop nanofibrous membranes where Eucalyptus globules oil (EGO) is wrapped in polyvinyl alcohol (PVA). The EGO-based nanofibrous membranes are then evaluated for the protection against Forcipomyia taiwana (F. taiwana). In the first stage, the PVA solutions are formulated with different concentrations and are measured for viscosity and electrical conductivity. In the next stage, PVA solution and EGO are blended at different ratios and electrospun into PVA/EGO nanofibrous membranes (i.e., EGO-based repellent). In this study, a PVA concentration of 14 wt% has a positive influence on fiber formation. Furthermore, the finest nanofibers of 291 nm are presented when the voltage is 15 kV. The repellent efficacy can reach 80% in a 60-min release when the repellent is composed of a PVA/oil ratio of 90/10. To sum up, the nanofibrous membranes of essential oil exhibit good repellent efficacy against F. taiwana and significant slow-release effect, instead of adversely affecting the cell viability. [ABSTRACT FROM AUTHOR]

In this study, a self-made continuous needleless dynamic linear electrospinning technique is employed to fabricate large-scale graphene (Gr)/carbon nanotubes (CNT)/polyvinyl alcohol (PVA)/sodium alginate (SA) nanofibrous membranes. The synergistic effect of Gr and CNT fillers in the PVA/SA membrane is explored in depth by changing the volume ratio (v/v) of Gr and CNT as 10:0, 8:2, 6:4, 4:6, 2:8, and 0:10. Microstructure, functional group, conductivity, and hydrophilicity of PVA/SA/Gr/CNT membranes was characterized. Results show that the linear electrode needleless electrospinning technique can be spun into 200-nm diameter fibers. The PVA/SA/Gr/CNT fibrous membrane has good hydrophilicity and thermal stability. A Gr/CN ratio of 6:4 possessed the optimal synergistic effect, which showed the lowest surface resistivity of 2.53 × 103 Ω/m2. This study will provide a reference for the large-scale preparation of nanofibrous membrane used as a artificial nerve conduit in the future. [ABSTRACT FROM AUTHOR]

Hydroxyapatite (HA) coating is successfully prepared by electrodeposition on the surface of polyvinyl alcohol (PVA)/polylactic acid (PLA) braid which serves as a potential biodegradable bone scaffold. The surface morphology, element composition, crystallinity and chemical bonds of HA coatings at various deposition times (60, 75, 90, 105 and 120 min) are characterized by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR), respectively. Average Surface roughness (Ra) of HA coating is observed by confocal microscopy. The results reveal that the typical characteristic peaks of the FTIR spectrum confirm that HA coating is successfully prepared on the rugged surface of the PVA/PLA braid. The XRD results indicate that the crystallinity of HA can be improved by increasing deposition time. In the 90 min-deposition, hydroxyapatite has a dense and uniform coating morphology, Ca/P ratio of 1.7, roughness of 0.725 μm, which shows the best electrodeposition performance. The formation mechanism of granular and plate-like hydroxyapatite crystals is explained by the structural characteristics of a hydroxyapatite unit cell. This study provides a foundation for a bone scaffold braided by biodegradable fibers. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the feasibility of large-scale preparation of porous polyvinyl alcohol/sodium alginate/graphene (Gr) (Gr-AP) nanofiber membranes using a copper wire needleless dynamic linear electrode electrospinning machine. Furthermore, the effects of Gr concentrations (0, 0.0375, 0.075, 0.25, 0.5, and 0.75 wt.%) on the morphology, electrical, hydrophilicity and thermal properties were evaluated. Results indicate that the dynamic linear electrospun Gr-AP membranes have a high yield of 1.25 g/h and are composed of porous finer nanofibers with a diameter of 141 ± 31 nm. Gr improved the morphology, homogeneity, hydrophobicity and thermal stability of Gr-AP nanofiber membranes. The critical conductive threshold is 0.075 wt.% for Gr, which provides the nanofiber membranes with an even distribution of diameter, an optimal conductivity, good hydrophilicity, appropriate specific surface area and optimal thermal stability. Therefore, needleless dynamic linear electrospinning is beneficial to produce high quality Gr-AP porous nanofiber membranes, and the optimal parameters can be used in artificial nerve conduits and serve as a valuable reference for mass production of nanofiber membranes. [ABSTRACT FROM AUTHOR]

With the aim of achieving controllable mass production of electrospun nanofiber films, this study proposes and investigates the feasibility of using a custom-made linear electrode- electrospun device to produce conductive graphene (GR)-filled polyvinyl alcohol (PVA) nanofibers. The film morphology and diameter of nanofibers are observed and measured to examine the effects of viscosity and conductivity of the PVA/GR mixtures. Likewise, the influence of the content of graphene on the hydrophilicity, electrical conductivity, electromagnetic interference shielding effectiveness (EMSE), and thermal stability of the PVA/GR nanofiber films is investigated. The test results show that the PVA/GR mixture has greater viscosity and electric conductivity than pure PVA solution and can be electrospun into PVA/GR nanofiber films that have good morphology and diameter distribution. The diameter of the nanofibers is 100 nm and the yield is 2.24 g/h, suggesting that the process qualifies for use in large-scale production. Increasing the content of graphene yields finer nanofibers, a smaller surface contact angle, and higher hydrophilicity of the nanofiber films. The presence of graphene is proven to improve the thermal stability and strengthens the EMSE by 20 dB at 150–1500 MHz. Mass production is proven to be feasible by the test results showing that PVA/GR nanofiber films can be used in the medical hygiene field. [ABSTRACT FROM AUTHOR]

This study aims to develop coronary artery stents using a spray-coating method. Chitosan is coated onto the polyvinyl alcohol (PVA) fibers in order to form PVA/CS coronary artery stents. The formation of chitosan is evaluated, examining the influences on the PVA/CS stents. The stents are evaluated using surface observation, scanning electron microscope (SEM) observation, thickness measurement, mesh size measurement, braid angle measurement, strut coverage rate measurement, compression strength test, and Fourier transforms infrared spectrometry (FTIR). The test results show that the spray-coating method successfully coats chitosan layer over the PVA/CS stents without sealing the mesh. Moreover, a longer spray coating span improves the compression resistance and maintains the perfect biocompatibility of the PVA/CS stents. This study successfully prepares PVA/CS coronary artery stents that are in a reticular, tubular manner, and coated with a well-formed chitosan layer. [ABSTRACT FROM AUTHOR]

This study aims to examine the properties of the small-diameter vascular grafts that are made by incorporating polyester (PET) yarns and spandex fibers. PET and spandex fibers are warp-knitted or weft-knitted into tubular knits. These two tubular knits are combined with polyvinyl alcohol (PVA) by applying a freezing-thawing method in order to create vascular grafts. The physical properties of vascular grafts are tested by performing tensile tests and a compliance test. The test results indicate that the incorporation of spandex fibers increases the deformation level along the axial direction of the warp-knitted tubular knits. In addition, the vascular grafts that are made of spandex fibers have a greater compliance than that of the commercially available vascular grafts (i.e., ePTFE) and natural blood vessels. [ABSTRACT FROM AUTHOR]

Interfacial solar steam generation (ISSG) is a solution to alleviate the energy crisis by obtaining clean water at low cost. In order to maintain high evaporation rates in high salinity brines, it is necessary to develop a new ISSG device with controlled heat loss and good salt resistance. In this paper, polyvinyl alcohol (PVA) was used as the backbone to construct ion-selective hydrogel, and hydrogel network with multiple hydrophilic groups was formed using Fe 3 O 4 as a broadband light absorber. Specifically, the evaporator is suspended on the water surface with evaporation rate of 3.04 kg·m−2·h−1 under one sun irradiation. The bilayer hydrogels can permeate Cl− and Na+ selectively. The improved salt resistance is due to the exclusion mechanism of the Donnan effect, with the formed potential difference of 157.4 mV at a brine concentration of 3.5 wt%. Even if it is suspended on the water surface in a high concentration of brine, there will be no salt crystals generated. The developed Janus ion-selective hydrogel-based evaporator shows great prospect for desalination and other advanced solar thermal applications. [Display omitted] • Forming a built-in electric field to inhibit salt crystallization. • Double-sided co-evaporation design speeds up the evaporation rate. • Evaporator avoids contact with bulk water to ensure the minimum heat loss. • JIPF evaporator achieves the high evaporation rate of 3.04 kg m−2 h−1. [ABSTRACT FROM AUTHOR]

This study prepares biodegradable bone scaffolds helping the recovery of damaged tibias of rats. Polyvinyl alcohol (PVA) plied yarns are fabricated into hollow braids. The braids are combined with hydroxyapatite (HA)/gelatin/PVA mixtures and processed using freeze-thawing and freeze-drying processes in order to form bone scaffolds. These bone scaffolds are observed by scanning electron scope (SEM) and tested for compression strength. Afterwards, recovery of damaged bone, the morphology of the bone, and the histological observation are evaluated. Results indicate a small amount of HA helps in enhancing the compressive strength of bone scaffolds. Results of in vivo assay indicate the damaged tibias of rats recover and function well eight weeks after the implantation, and exhibit a normal morphology. Histological observation confirms the bone scaffolds gradually decompose, allowing tissue infiltration and facilitating ossification. This study successfully produces bone scaffolds with satisfactory mechanical properties helping in the recovery of damaged tibias of rats. [ABSTRACT FROM AUTHOR]

This study aims at developing biodegradable vascular grafts by combining PVA knits and porous polyvinyl alcohol PVA hydrogels. The proposed tubular PVA composites are compared to the commercially available vascular grafts in terms of compliance that best matches the compliance of natural vessels. The warp knits and weft knits are first evaluated for their circumferential properties, while the hydrogels are examined for their porous structure. The tubular PVA composites containing knits and hydrogels are then tested for variations in their diameter and compliance. The results indicate that the weft knits exhibit greater circumferential deformation. Moreover, vascular grafts composed of weft knits also have a higher porous connectivity and compliance that matches native vessels. [ABSTRACT FROM AUTHOR]