Abdalla Abdal-hay

Fabrication of novel high performance ductile poly(lactic acid) nanofiber scaffold coated with poly(vinyl alcohol) for tissue engineering applications

Poly(lactic acid) (PLA) nanofiber scaffold has received increasing interest as a promising material for potential application in the field of regenerative medicine. However, the low hydrophilicity and poor ductility restrict its practical application. Integration of hydrophilic elastic polymer onto the surface of the nanofiber scaffold may help to overcome the drawbacks of PLA material. Herein, we successfully optimized the parameters for in situ deposition of poly(vinyl alcohol), (PVA) onto post-electrospun PLA nanofibers using a simple hydrothermal approach. Our results showed that the average fiber diameter of coated nanofiber mat is about 1265±222 nm, which is remarkably higher than its pristine counterpart (650±180 nm). The hydrophilicity of PLA nanofiber scaffold coated with a PVA thin layer improved dramatically (36.11±1.5°) compared to that of pristine PLA (119.7±1.5°) scaffold. The mechanical testing showed that the PLA nanofiber scaffold could be converted from rigid to ductile with enhanced tensile strength, due to maximizing the hydrogen bond interaction during the heat treatment and in the presence of PVA. Cytocompatibility performance of the pristine and coated PLA fibers with PVA was observed through an in vitro experiment based on cell attachment and the MTT assay by EA.hy926 human endothelial cells. The cytocompatibility results showed that human cells induced more favorable attachment and proliferation behavior on hydrophilic PLA composite scaffold than that of pristine PLA. Hence, PVA coating resulted in an increase in initial human cell attachment and proliferation. We believe that the novel PVA-coated PLA nanofiber scaffold developed in this study, could be a promising high performance biomaterial in regeneration medicine.

Novel, Facile, Single-Step Technique of Polymer/TiO2 Nanofiber Composites Membrane for Photodegradation of Methylene Blue

Novel photocatalyst membrane materials were successfully fabricated by an air jet spinning (AJS) technique from polyvinyl acetate (PVAc) solutions containing nanoparticles (NPs) of titanium dioxide (TiO2). Our innovative strategy for the production of composite nanofibers is based on stretching a solution of polymer with a high-speed compressed air jet. This enabled us to rapidly cover different substrates with TiO2/PVAc interconnected nanofibers. Surprisingly, the diameters of the as-spun fibers were found to decrease with increasing amount of NPs. Our results showed that AJS PVAc-based fibrous membranes with average fiber diameters of 505-901 nm have an apparent porosity of about 79-93% and a mean pore size of 1.58-5.12 μm. Embedding NPs onto the as-spun fibers resulted in increasing the tensile strength of the obtained composite fiber mats. The photodegradation property of TiO2 membrane mats proved a high efficiency in the decomposition of methylene blue dye. The novel fiber spinning technique discussed in this paper can provide the capacity to lace together a variety of types of polymers, fibers and particles to produce interconnected fibers layer. Our approach, therefore, opens the door for the innovation in nanocomposite mat that has great potential as efficient and economic water filter media and as reusable photocatalyst.

Titanium Dioxide Nanofibers and Microparticles Containing Nickel Nanoparticles

The present study reports on the introduction of various nanocatalysts containing nickel (Ni) nanoparticles (NPs) embedded within TiO2 nanofibers and TiO2 microparticles. Typically, a sol-gel consisting of titanium isopropoxide and Ni NPs was prepared to produce TiO2 nanofibers by the electrospinning process. Similarly, TiO2 microparticles containing Ni were prepared using a sol-gel syntheses process. The resultant structures were studied by SEM analyses, which confirmed well-obtained nanofibers and microparticles. Further, the XRD results demonstrated the crystalline feature of both TiO2 and Ni in the obtained composites. Internal morphology of prepared nanofibers and microparticles containing Ni NPs was characterized by TEM, which demonstrated characteristic structures with good dispersion of Ni NPs. In addition, the prepared structures were studied as a model for hydrogen production applications. The catalytic activity of the prepared materials was studied by in situ hydrolysis of NaBH4, which indicated that the nanofibers containing Ni NPs can lead to produce higher amounts of hydrogen when compared to other microparticles, also reported in this paper. Overall, these results confirm the potential use of these materials in hydrogen production systems.

A novel simple one-step air jet spinning approach for deposition of poly(vinyl acetate)/hydroxyapatite composite nanofibers on Ti implants

A biocompatible coating consists of a poly(vinyl acetate)/hydroxyapatite (PVAc/HA) composite nanofiber mat was applied to NaOH-treated titanium metal by means of a novel, facile and efficient air jet spinning (AJS) approach. Results showed that HA nanoparticles (NPs) strongly embedded onto the AJS single fiber surface resulting in a strong chemical interfacial bonding between the two phases due to the difference in kinetic energies. It was proven that AJS membrane coatings can provide significant improvement in the corrosion resistance of titanium substrate. Interestingly, the biocompatibility using MC3T3-E1 osteoblast to the PVAc/HA fiber composite layer coated on Ti was significantly higher than pure titanium-substrates.

In vitro bioactivity of titanium implants coated with bicomponent hybrid biodegradable polymers

In order to improve the bioactivity and biocompatibility of titanium (Ti) implants, we designed a novel biodegradable hybrid (polycaprolactone/polylactic acid, PCL/PLA) membrane to coat Ti surfaces. The bicomponent PCL/PLA membrane was applied to a Ti substrate starting with the coating of Ti samples with a porous PLA film layer using a dip-coating technique. This was followed by deposition of electrospun PCL nanofibers onto the Ti substrate, resulting in a PCL/PLA bicomponent hybrid coating layer. The cytocompatibility, bioactivity and corrosion performance of PCL/PLA-coated Ti samples was compared to PLA-coated Ti samples and untreated Ti samples. When placed in Hanks’ solution, apatite formed on the treated Ti samples but not on untreated Ti samples. When assessing Ti cytocompatibility and MC3T3-E1 osteoblast adherence, proliferation, and survival, our results showed superior performance by polymer-treated Ti samples compared to untreated Ti samples, and maximal osteoblast cell viability was achieved with the bicomponent PCL/PLA hybrid coating layer. Furthermore, during the potentiodynamic polarization test in simulated body fluid, the polymer-coated Ti samples showed corrosion resistance. Therefore, the approach described herein may serve as a basis for the development of polymer-coated Ti surfaces that can be used in dental or orthopedic implants.

Biocorrosion behavior of biodegradable nanocomposite fibers coated layer-by-layer on AM50 magnesium implant.

This article demonstrates the use of hybrid nanofibers to improve the biodegradation rate and biocompatibility of AM50 magnesium alloy. Biodegradable hybrid membrane fiber layers containing nano-hydroxyapatite (nHA) particles and poly(lactide)(PLA) nanofibers were coated layer-by-layer (LbL) on AM50 coupons using a facile single-step air jet spinning (AJS) approach. The corrosion performance of coated and uncoated coupon samples was investigated by means of electrochemical measurements. The results showed that the AJS 3D membrane fiber layers, particularly the hybrid membrane layers containing a small amount of nHA (3 wt.%), induce a higher biocorrosion resistance and effectively decrease the initial degradation rate compared with the neat AM50 coupon samples. The adhesion strength improved highly due to the presence of nHA particles in the AJS layer. Furthermore, the long biodegradation rates of AM50 alloy in Hanks balanced salt solution (HBSS) were significantly controlled by the AJS-coatings. The results showed a higher cytocompatibility for AJS-coatings compared to that for neat Mg alloys. The nanostructured nHA embedded hybrid PLA nanofiber coating can therefore be a suitable coating material for Mg alloy as a potential material for biodegradable metallic orthopedic implants.

A Novel Approach for Facile Synthesis of Biocompatible PVA-Coated PLA Nanofibers as Composite Membrane Scaffolds for Enhanced Osteoblast Proliferation

This chapter discusses a novel approach for facile synthesis of biocompatible poly(vinyl alcohol) PVA-coated polylactide (PLA) as composite membrane scaffolds for enhanced osteoblast proliferation. The composite scaffolds combined from PLA nanofiber-based materials coated with PVA thin layer were fabricated using hydrothermal treatment. The effects of deposition of the hydrophilic PVA on the MC3T3-E1 osteoblast cell attachment and proliferation were investigated by in vitro cell compatibility tests. The morphology, structure, chemical interfacial bonding, and thermal and mechanical properties of the scaffolds were studied. Results showed that PVA thin layer was successfully deposited onto the electrospun PLA fiber surfaces during hydrothermal treatment. The hydrothermal process induced crystalline conformation due to enhanced chain mobility of PLA. The mechanical tests showed that PLA could be turned from rigid to ductile with enhanced tensile strength, due to maximizing the hydrogen bond interaction during the heat treatment and the presence of PVA. The adhesion and proliferation properties of MC3T3-E1 cells on composite scaffolds were significantly higher than on the pristine fibers. The treatment process on PLA and producing composite samples from substrates could contribute to decelerating the rapid acidic phase release from the PLA molecules in the surrounding physiological environment. Based on the experimental results, PVA-coated PLA mats could be of particular interest in bone tissue engineering for tissue regeneration.

Fabrication and characterization of silver nanostructures conformal coating layer onto electrospun N6 nanofibers with improved physical properties

AbstractIn this communication, colloidal silver (Ag) nanostructures were synthesized and deposited directly onto electrospun nylon 6 (N6) fibers without using surface modifier in the form of an ultrathin conformal coating layer via a hydrothermal treatment. The morphological, structural, and thermal properties of the Ag/N6 nanocomposite membranes were analyzed by field-emission scanning electron microscopy (FESEM), X-ray diffraction, X-ray photoelectron spectroscopy, and differential scanning calorimetry (DSC). FESEM imaging showed that the Ag coating on individual N6 nanofibers was continuous, uniform, and compact. A DSC study of the nanocomposites illustrated a strong interfacial adhesion of the Ag layer with N6 nanofiber surfaces via strong hydrogen bonds. A possible mechanism for hydrogen bond formation during the hydrothermal process was proposed. Further, it was found that the transition of the meta-stable γ-form into the thermodynamically more stable α-form of N6 structure was achieved; therefore, the hydrothermal process did not cause chain degradation.

Fabrication of a thick three-dimensional scaffold with an open cellular-like structure using airbrushing and thermal cross-linking of molded short nanofibers

Nanoscale fibers mimicking the extracellular matrix of natural tissue can be produced by conventional electrospinning, but this approach results in two-dimensional thin dense fibrous mats which can hinder effective cell infiltration. The aim of the present study was to design a thick, three-dimensional (3D) cylindrical scaffold with an open pore structure assembled from short polycaprolactone (PCL) fibers using a facile airbrushing approach. In addition, magnesium particles were incorporated into the PCL solution to both enhance the mechanical properties of the scaffold and stimulate cellular activity following cell seeding. Separated short composite airbrushed fibers were assembled into a 3D cylindrical structure by cold-press molding and thermal cross-linking. The microstructure, chemical composition, porosity and thermal properties were subsequently investigated, along with changes in mechanical performance following immersion in PBS for 60 d. The results showed that the assembled 3D fibrous 10 mm thick cylindrical matrix had an interconnected fibrous network structure with 31.5%-60% porosity. Encapsulation of the Mg particles into the 3D assembled fibrous scaffold enhanced the mechanical properties of the plain PCL scaffolds. The results also demonstrated controlled release of Mg ions into the PBS media for up to 60 d, as evaluated by changes in Mg ion concentration and pH of the media. In addition, the 3D fibrous assembled matrix was shown to support human osteoblast-like cell adhesion, proliferation and penetration. The results suggest that this novel fabrication method of biodegradable thick 3D scaffolds with an open pore structure is promising for the production of a new generation of 3D scaffolds for tissue regeneration applications.

Study on Water Absorption and Impact Properties of Vegetal Composites Material: Composite Structures

The delamination and fibers pull out have been the main factors failure application of natural fibers in various engineering fields. To address these problems, particles reinforced composites are the promising candidate. The present paper investigates on vegetal particles (date palm seed particles/DPSp) and applies it as composites material reinforced unsaturated polyester (USP). The influence of alkali treatment on the surface morphology and structure of DPSp was investigated. They investigated by SEM and Energy Dispersive Spectroscopy (EDS) mapping. The water absorption results showed directly proportion with the particles loading as the relative increases were 0.645% and 7.345% for 10 wt% and 40 wt% of DPSp content, respectively. In addition, the water absorption ability of the composites showed low value comparing with many natural fibers. In addition, the fracture toughness of the composites was studied. Overall, addition of the proposed DPSp particles may be opens a new avenue to exploit the utilized natural cheap material to produce a green composite.