Trilayer composite scaffold for urethral reconstruction:in vitroevaluation of mechanical, biological, and angiogenic properties.

Regeneration of damaged urethral tissue remains a major challenge in the field of lower urinary tract reconstruction. To address this issue, various synthetic and natural biodegradable biomaterials are currently being explored for the fabrication of scaffolds that promote urethral regeneration and healing. In this study, we present an approach to fabricate a trilayer hybrid scaffold comprising a central layer of poly(lactic acid) (PLA) between two layers of chitosan. The chitosan/PLA/chitosan (CPC) scaffolds were fabricated by a sequential electrospinning process and their properties were evaluated for their suitability for urethral tissue engineering. The physical and biological properties of the CPC scaffolds were evaluated in comparison to electrospun PLA scaffolds and acellular dermis (Alloderm) as controls for a synthetic and a natural scaffold, respectively. Compared to the controls, the CPC scaffolds exhibited higher elastic modulus and ultimate tensile strength, while maintaining extensibility and suture retention strength appropriate for clinical use. The CPC scaffolds displayed significant hydrophilicity, which was associated with a higher water absorption capacity of the chitosan nanofibres. The degradation products of the CPC scaffolds did not exhibit cytotoxicity and promoted wound closure by fibroblastsin vitro. In addition, CPC scaffolds showed increased growth of smooth muscle cells, an essential component for functional regeneration of urethral tissue. Furthermore, in a chicken embryo-based assay, CPC scaffolds demonstrated significantly higher angiogenic potential, indicating their ability to promote vascularisation, a crucial aspect for successful urethral reconstruction. Overall, these results suggest that CPC hybrid scaffolds containing both natural and synthetic components offer significant advantages over conventional acellular or synthetic materials alone. CPC scaffolds show promise as potential candidates for further research into the reconstruction of the urethrain vivo.

Current trends and prospects in catalytic upgrading of lignocellulosic biomass feedstock into ultrapure biofuels.

Eco-friendly renewable energy sources have recommended as fossil fuel alternatives in recent years to reduce environmental pollution and meet future energy demands in various sectors. As the largest source of renewable energy in the world, lignocellulosic biomass has received considerable interest from the scientific community to advance the fabrication of biofuels and ultrafine value-added chemicals. For example, biomass obtained from agricultural wastes could catalytically convert into furan derivatives. Among furan derivatives, 5-hydroxymethylfurfural (HMF) and 2, 5-dimethylfuran (DMF) are considered the most useful molecules that can be transformed into desirable products such as fuels and fine chemicals. Because of its exceptional properties, e.g., water insolubility and high boiling point, DMF has studied as the ideal fuel in recent decades. Interestingly, HMF, a feedstock upgraded from biomass sources can easily hydrogenate to produce DMF. In the present review, the current state of the art and studies on the transformation of HMF into DMF using noble metals, non-noble metals, bimetallic catalysts, and their composites have discussed elaborately. In addition, comprehensive insights into the operating reaction conditions and the influence of employed support over the hydrogenation process have demonstrated.

Comparative Study on Gas-Sensing Properties of 2D (MoS2, WS2)/PANI Nanocomposites-Based Sensor.

NH3 is a highly harmful gas; when inhaled at levels that are too high for comfort, it is very dangerous to human health. One of the challenging tasks in research is developing ammonia sensors that operate at room temperature. In this study, we proposed a new design of an NH3 gas sensor that was comprised of two-dimensional (TMDs, mainly WS2 and MoS2) and PANI. The 2D-TMDs metal was successfully incorporated into the PANI lattice based on the results of XRD and SEM. The elemental EDX analysis results indicated that C, N, O, W, S and Mo were found in the composite samples. The bandgap of the materials decreased due to the addition of MoS2 and WS2. We also analyzed its structural, optical and morphological properties. When compared to MoS2 and PANI, the proposed NH3 sensor with the WS2 composite was found to have high sensitivity. The composite films also exhibited response and recovery times of 10/16 and 14/16 s. Therefore, the composite PANI/2D-TMDs is a suitable material for NH3 gas detection applications.

Humidity sensor based on poly(lactic acid)/PANI-ZnO composite electrospun fibers.

The electrospinning technique has been successfully used to prepared micro-fibers of the poly(lactic acid)/polyaniline-zinc oxide (PLA/PANI-ZnO) composite. The polyaniline-zinc oxide (PANI-ZnO) nanocomposites are synthesized by hydrothermal and in situ polymerization methods. X-ray diffraction techniques are used to study the structural properties of the PLA/PANI-ZnO composite fibers and the PANI-ZnO nanocomposite. The average crystallite size of the PANI-ZnO nanocomposite is found to be 36 nm. The morphology and diameter of the composite fibers are analyzed by scanning electron microscopy (SEM). The average fiber diameter of the pure poly(lactic acid) (PLA) fiber is around 2.5 µm and that of the PLA/PANI-ZnO composite fiber is around 1.4 µm. Differential scanning calorimetry (DSC) provides the thermal properties of the PLA/PANI-ZnO composite fibers. The melting temperature (T m) for the pure PLA is observed at 149.3 °C, and it is shifted to 153.0 °C for the PLA/PANI-ZnO composite fibers. The enhanced thermal properties of the composite fibers are due to the interaction between the polymer and the nanoparticles. The water contact angle measurements probe the surface hydrophilicity of the PLA/PANI-ZnO composite fibers. The role of the PANI-ZnO nanocomposite on the sensing behavior of PLA fibers has also been investigated. The humidity sensing properties of the composite fiber based sensor are studied in the relative humidity (RH) range of 20-90% RH. The experimental results show that the composite fiber exhibited good response (85 s) and recovery (120 s) times. These results indicate that the one-dimensional (1D) fiber structure enhances the humidity sensing properties.

Capacitive type humidity sensor based on PANI decorated Cu-ZnS porous microspheres.

Porous microstructure materials are considered good candidates for the development of highly sensitive and fast humidity sensors. In this regard, we prepared polyaniline (PANI) decorated Cu-ZnS porous microsphere structures (PMSs) for the fabrication of humidity sensors. PANI coated Cu-ZnS PMSs were synthesized by a hydrothermal method and in situ polymerization process. The synthesized PMSs were characterized by different techniques to study the structural, morphological and surface absorption properties. Several compositions for the PANI/Cu-ZnS PMS were investigated, which were then compared with pure PANI. The experimental observations demonstrate that a PANI/1%Cu-ZnS PMS has better sensitivity, fast response and good stability compared to pure PANI and other PANI/CuZnS compositions. Finally, a PANI/1% Cu-ZnS PMS was found to be optimized for humidity sensors due to its well distributed roughness, porosity and hydrophilicity. The average response and recovery times for PANI/1% Cu-ZnS were found to be 42 s and 24 s, respectively, which outperform recent results.

La3+/Sr2+ Dual-Substituted Hydroxyapatite Nanoparticles as Bone Substitutes: Synthesis, Characterization, In Vitro Bioactivity and Cytocompatibility.

The present study aims to synthesize biocompatible and bioactive lanthanum (La3+)/strontium (Sr2+) dual ion doped hydroxyapatite (HA) nanomaterials by sol-gel method. The discrete substitution of La3+ and Sr2+ in pure HA enhances the osteoconductivity. The co-substitution of various La3+ concentrations (0.03, 0.06 and 0.1 M) regulates the physical and In Vitro properties. The study also investigates the effect of La3+/Sr2+ substituents on the crystalline property, microstructure, photoluminescence and In Vitro bioactivity of HA samples. La3+/Sr2+ co-substitution decreases the crystallite size of HA without any significant distortion of the crystal structure. In addition, the dual ions doping influences nanoparticles morphology by reducing the particle size from 75 to 20 nm. The In Vitro bioactivity tests for the La3+/Sr2+ co-substituted HA confirm the osteoconductive boneapatite generating capacity. Bactericidal tests against Staphylococcus aureus and Pseudomonas aeruginosa stains show better resistivity of La3+/Sr2+-HA samples. To authenticate the biocompatibility and antimicrobial activity of the synthesized La3+/Sr2+ dual doped HA nanoparticles for bone implant applications, different tests like cell viability and toxicity were conducted using human lung A549 cells.

Investigation of the structural, optical and gas sensing properties of PANI coated Cu-ZnS microsphere composite.

Polyaniline (PANI)/Cu-ZnS composites with porous microspheres are prepared by a hydrothermal and in situ polymerization method. The structural, optical, and morphological properties are characterized by X-ray powder diffraction, FTIR, UV-vis, scanning electron microscope, transmission electron microscope. The XRD results confirmed that the PANI/Cu-ZnS composite is formed. The morphological analyses exhibited that the PANI/Cu-ZnS composite comprises the porous microspherical structures. The emission peaks obtained in photoluminescence spectra confirm the presence of surface defects in the prepared composite. The UV-DRS study shows that the bandgap of the samples is found to decrease for the PANI/Cu-ZnS composite compared to the pure Cu-ZnS sample. The calculated band gap (E g) value of PANI/Cu-ZnS composite is 2.47 eV. Furthermore, the fabricated gas sensor based on PANI/Cu-ZnS can perform at room temperature and exhibits good gas sensing performance toward CO2 gas. In particular, PANI/Cu-ZnS sensor shows good response (31 s) and recovery time (23 s) upon exposure to CO2 gas. The p/n heterojunction, surface defects, and porous nature of the PANI/Cu-ZnS composite microsphere enhanced sensor performance.

Author Correction: Stretchable Electrospun PVDF-HFP/Co-ZnO Nanofibers as Piezoelectric Nanogenerators.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

White Graphene-Cobalt Oxide Hybrid Filler Reinforced Polystyrene Nanofibers for Selective Oil Absorption.

In this work, stable hydrophobic nanocomposites are made from electrospun fibers of polystyrene (PS) containing a hybrid filler combination of (i) hexagonal boron nitride (hBN) and (ii) cobalt oxide (Co3O4) nanomaterials. Good synergistic interaction is observed between the nanomaterials, since the growth of Co3O4 was carried out in presence of white graphene nanosheets. Filler synergy modifies the PS surfaces, by enhancing the filler-polymer interfacial interactions and provides good tensile strength. The hydrophobic films are gamma irradiated to improve crosslinking within the polymer nanocomposites. Since gamma irradiation enhances the surface roughness, its hydrophobicity/oleophilicity increases much and the final nanofibers show good oil-water separation efficiency. The nanofibers act as sponge clothing to skim the oil from a mixture of oil and water. Durability of the fibers in hot water and in presence of ultrasonic waves is also tested and good response is achieved. Contact angle studies are performed to investigate the surface properties and to check the influence of gamma irradiation on the surface wettability. The gamma-irradiated PS nanocomposite fiber shows a contact angle of 152° ± 2° compared to the 140° ± 1° of the neat PS fiber, evidencing the superhydrophobicity. Both the effects of crosslink density enhancement and hybrid filler distribution make the composite fibers stronger in oil absorption application even at higher operation temperatures. The fibers are reported to be robust and durable, in addition.

Toward High Power Generating Piezoelectric Nanofibers: Influence of Particle Size and Surface Electrostatic Interaction of Ce-Fe2O3 and Ce-Co3O4 on PVDF.

Development of flexible piezoelectric nanogenerator (PENG) is a real challenge for the next-generation energy-harvesting applications. In this paper, we report highly flexible PENGs based on poly(vinylidene fluoride) (PVDF)/2 wt % Ce-Fe2O3 and PVDF/2 wt % Ce-Co3O4 nanocomposite fibers. The incorporation of magnetic Ce-Fe2O3 and Ce-Co3O4 greatly affects the structural properties of PVDF nanofibers, especially the polymeric ß and γ phases. In addition, the new composites enhanced the interfacial compatibility through electrostatic filler-polymer interactions. Both PVDF/Ce-Fe2O3 and PVDF/Ce-Co3O4 nanofibers-based PENGs, respectively, produce peak-to-peak output voltages of 20 and 15 V, respectively, with the corresponding output currents of 0.010 and 0.005 µA/cm2 under the force of 2.5 N. Enhanced output performance of the flexible nanogenerator is correlated with the electroactive polar phases generated within the PVDF, in the presence of the nanomaterials. The designed nanogenerators respond to human wrist movements with the highest output voltage of 0.15 V, for the PVDF/Ce-Fe2O3 when subjected to hand movements. The overall piezoelectric power generation is correlated with the nanoparticle size and the existing filler-polymer and ion-dipole interactions.

Designing Carbon Nanotube-Based Oil Absorbing Membranes from Gamma Irradiated and Electrospun Polystyrene Nanocomposites.

Carbon-based materials are outstanding candidates for oil spill clean-ups due to their superhydrophobicity, high surface area, chemical inertness, low density, recyclability, and selectivity. The current work deals with the fabrication of membrane oil absorbents based on carbon nanotube (CNT) reinforced polystyrene (PS) nanocomposites by electrospinning technique. The spun membranes are also irradiated with the gamma radiation to induce enough crosslinks and thus good polymer-filler interactions. The structural, morphological, and surface properties in addition to the oil/water separation efficiency were investigated by varying the concentration of CNT and the dose of γ-irradiation. Fabricated nanofiber membranes show superior hydrophobicity and selective oil absorption at 0.5 wt.% of CNT concentration. The best mechanical properties are also obtained at this particular concentration and at 15 KGy optimum γ-irradiation dosage. The gamma irradiated PS/0.5 wt.% CNT membrane also exhibits good antibacterial effects against the bacteria, Escherichia coli, in the form of bacterial inhibition rings around the membranes. The present study thus shows the environmental applicability of the fabricated PS/CNT membranes in treating oil-contaminated water.

Investigation on the effect of γ-irradiation on the dielectric and piezoelectric properties of stretchable PVDF/Fe-ZnO nanocomposites for self-powering devices.

Stretchable films of PVDF nanocomposites containing iron doped ZnO (Fe-ZnO) nanoflowers are fabricated following simple solution mixing and γ-irradiation treatment. An increase in ß-phase crystallinity is noticed for the PVDF/Fe-ZnO nanocomposite when compared to PVDF/ZnO at the same filler concentration. Specifically, at 1 wt%, the relative crystallinity of the composite containing Fe-ZnO calculated from FTIR is 48.1%, while for ZnO, it is 40.9%. A dielectric constant of 96 is reached for PVDF/Fe-ZnO at 2 wt%, in addition to a peak to peak output piezoelectric voltage of 2.4 V. This is several times higher than that observed for PVDF/ZnO nanocomposites and those fabricated without γ-irradiation (1.1 V). Piezoelectric voltage generation is also observed during the stretching, bending and rolling vibrational movements of the sample, indicating its possible use in flexible electronic devices. The observed superior performance of the PVDF/Fe-ZnO system is attributed to the influence of the star like morphology and dispersion of Fe-ZnO, and the enhanced filler-polymer interaction and crosslink formation by the γ-irradiation process. It is demonstrated that such a system can be applicable in manufacturing piezoelectric nanogenerators for various industrial applications including robotic parts, biomedical devices etc.

Stretchable Electrospun PVDF-HFP/Co-ZnO Nanofibers as Piezoelectric Nanogenerators.

Herein, we investigate the morphology, structure and piezoelectric performances of neat polyvinylidene fluoride hexafluoropropylene (PVDF-HFP) and PVDF-HFP/Co-ZnO nanofibers, fabricated by electrospinning. An increase in the amount of crystalline ß-phase of PVDF-HFP has been observed with the increase in Co-doped ZnO nanofiller concentration in the PVDF-HFP matrix. The dielectric constants of the neat PVDF-HFP and PVDF-HFP/2 wt.% Co-ZnO nanofibers are derived as 8 and 38 respectively. The flexible nanogenerator manipulated from the polymer nanocomposite (PVDF-HFP/Co-ZnO) exhibits an output voltage as high as 2.8 V compared with the neat PVDF-HFP sample (~120 mV). These results indicate that the investigated nanocomposite is appropriate for fabricating various flexible and wearable self-powered electrical devices and systems.

Nanoflower-like Yttrium-doped ZnO Photocatalyst for the Degradation of Methylene Blue Dye.

Pure ZnO and Yttrium-doped (Y-doped) ZnO at various mol% with flower-like nanostructures are synthesized by a microwave-assisted sol-gel method, followed by investigating the morphologies, crystal structures, optical properties and photocatalytic performances. While the phase formations are detected by X-ray diffraction technique, both scanning and transmission electron microscopy images clearly depict the flower-like morphology of ZnO and Y-doped ZnO samples. Formation of flower petals is from the nanoparticles that grew and connected by orientation attachment process. The flower-like architecture is addressed in terms of an Ostwald ripening mechanism. The UV-Vis absorption studies show enhanced absorption for the Y-doped ZnO, whereas the photoluminescence spectra confirm the significance of sample defects in the photocatalytic degradation of organic pollutants. Effects of various experimental parameters such as the amount of photocatalysts, dye concentration and dopant concentration on the dye degradation are also optimized.

In-vitro biocompatibility, bioactivity and photoluminescence properties of Eu3+ /Sr2+ dual-doped nano-hydroxyapatite for biomedical applications.

In the present investigation, we have successfully synthesized luminescent Eu3+ -doped and Eu3+ /Sr2+ codoped hydroxyapatite (HA) nanoparticles through sol-gel assisted precipitation method with the aim of developing novel biomaterials containing osteoblast mineral (Sr2+ ) and luminescence activator (Eu3+ ). The structure, morphology, thermal stability, and luminescence properties of the resultant spherical nanoparticles (50-100 nm diameters) were studied. Moreover, the in-vitro bioactivity of Eu0.1 Sr0.1 HA nanoparticles was investigated by immersing in the simulated body fluid for many weeks. The antimicrobial activity results against gram positive and gram negative bacterial stains, showed better resistivity for the Eu0.1 Sr0.1 HA among the other compositions. The MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay of live/dead cells cultured with Eu3+ /Sr2+ -doped HA nanoparticles retained its normal morphology and did not show a significant impact on cell proliferation at various incubation days, which evidence for the material's superior biocompatible nature even at a higher concentration of 375 µg/mL. Thus, the incorporation of dual ions in HA nanoparticles with strong luminescence properties develops potential biomaterial for live cell imaging and in nanomedicine. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2191-2201, 2018.