Hany El-Hamshary

Superabsorbent 3D Scaffold Based on Electrospun Nanofibers for Cartilage Tissue Engineering

Electrospun nanofibers have been used for various biomedical applications. However, electrospinning commonly produces two-dimensional (2D) membranes, which limits the application of nanofibers for the 3D tissue engineering scaffold. In the present study, a porous 3D scaffold (3DS-1) based on electrospun gelatin/PLA nanofibers has been prepared for cartilage tissue regeneration. To further improve the repairing effect of cartilage, a modified scaffold (3DS-2) cross-linked with hyaluronic acid (HA) was also successfully fabricated. The nanofibrous structure, water absorption, and compressive mechanical properties of 3D scaffold were studied. Chondrocytes were cultured on 3D scaffold, and their viability and morphology were examined. 3D scaffolds were also subjected to an in vivo cartilage regeneration study on rabbits using an articular cartilage injury model. The results indicated that 3DS-1 and 3DS-2 exhibited superabsorbent property and excellent cytocompatibility. Both these scaffolds present elastic property in the wet state. An in vivo study showed that 3DS-2 could enhance the repair of cartilage. The present 3D nanofibrous scaffold (3DS-2) would be promising for cartilage tissue engineering application.

Removal of heavy metal using poly (N-vinylimidazole)-grafted-carboxymethylated starch

Carboxymethyl starch (CMS) grafted with N-vinyl imidazole was investigated for heavy metal removal from aqueous solutions. Poly (N-vinyl imidazole)-grafted carboxymethyl starch (PVI-g-CMS) was prepared in aqueous solution using potassium persulfate (KPS) as initiator. The produced grafted copolymer was characterized by FTIR, TGA, surface area and elemental analysis. The grafted material was used for the sorption of Mn(II), Zn(II) and Cd(II). Uptake parameters such as affinity of metal ions, effect of metal ion concentration, adsorbent amount and agitation time were investigated. The polymers were more sensitive to Cd(II) and Zn(II) and the order of metal ion binding was Cd(II)>Zn(II)>Mn(II). The adsorption data was fitted very well in a Freundlich isotherm equation and the kinetics of adsorption was found to follow the pseudo-first order kinetic model.

Polypyrrole-coated poly(L-lactic acid-co-ε-caprolactone)/silk fibroin nanofibrous membranes promoting neural cell proliferation and differentiation with electrical stimulation

Polypyrrole (Ppy), as a conductive polymer, is commonly used for nerve tissue engineering because of its good conductivity and non-cytotoxicity. To avoid the inconvenience of Ppy processing, it was coated on electrospun poly(l-lactic acid-co-ε-caprolactone)/silk fibroin (PLCL/SF) nanofibers via the in situ oxidative polymerization of pyrrole monomers in this study. Ppy-coated PLCL/SF membranes were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and thermogravimetric (TG) analysis. The results confirmed the disposition of Ppy on the PLCL/SF nanofibers, and the nanofibers kept their nanofibrous morphology and thermal stability, in comparison to the untreated ones. The conductivities and water contact angles were evaluated as well, and indicated that the conductivity and hydrophilicity of Ppy-coated nanofibers were increased. Furthermore, this study showed that electrical stimulation (ES) promoted PC12 cell differentiation and axonal extension on Ppy-coated nanofibers. The MTT assay suggested that both Ppy and ES could promote Schwann cell (SC) proliferation. Immunofluorescence staining and real time-qPCR (RT-qPCR) testing demonstrated that ES could induce PC12 cell differentiation even without nerve growth factor (NGF) treatment, and moreover, Ppy coating increased the inducing effects on PC12 cell differentiation. The overall results indicated the promising potential of Ppy-coated PLCL/SF nanofibrous membranes for peripheral nerve repair and regeneration.

Synthesis and antibacterial of carboxymethyl starch-grafted poly(vinyl imidazole) against some plant pathogens

Poly(N-vinyl imidazole) (PVI) has been grafted onto carboxymethyl starch (CMS) in aqueous solution using potassium persulfate (KPS) as initiator. Reaction parameters that affect grafting efficiency and percentage grafting such as monomer and initiator concentration, the reaction temperature and time were investigated. The grafted products were characterized by FTIR, thermal analysis, SEM photograph and elemental analysis. The antibacterial effects of the carboxymethyl starch-grafted-poly(N-vinylimidazole) (CMS-g-PVI) was examined against two plant pathogens Gram negative bacteria: Xanthomonas perforanss and Xanthomonas oryzae. Generally, upon application of the CMS-g-PVI to the bacterial cells; the mortality rate increased from 45.71 to 59.37% for Xanthomonas perforans and X. oryzae, respectively. While the MIC for most of both bacterial strains were recorded at concentration of 60 μg/mL. The results indicate that CMS-g-PVI has bactericidal properties and can be used for seed treatment to control xanthomonads associated with bacterial leaf spot (BLS).

Oxidation of Phenol by Hydrogen Peroxide Catalyzed by Metal-Containing Poly(amidoxime) Grafted Starch

Polyamidoxime chelating resin was obtained from polyacrylonitrile (PAN) grafted starch. The nitrile groups of the starch-grafted polyacrylonitrile (St-g-PAN) were converted into amidoximes by reaction with hydroxylamine under basic conditions. The synthesized graft copolymer and polyamidoxime were characterized by FTIR, TGA and elemental microanalysis. Metal chelation of the polyamidoxime resin with iron, copper and zinc has been studied. The produced metal-polyamidoxime polymer complexes were used as catalysts for the oxidation of phenol using H2O2 as oxidizing agent. The oxidation of phenol depends on the central metal ion present in the polyamidoxime complex. Reuse of M-polyamidoxime catalyst/H2O2 system showed a slight decrease in catalytic activities for all M-polyamidoxime catalysts.

Preparation of biocompatible system based on electrospun CMC/PVA nanofibers as controlled release carrier of diclofenac sodium

ABSTRACT Nanofibers of naturally modified polymer such as carboxymethyl cellulose (CMC) blended with poly(vinyl alcohol) (PVA) at different ratios was obtained by electrospinning technique. The blended solutions of CMC and PVA loaded with and without diclofenac sodium (DS) were electrospun using environmentally benign electrospinning technique in the absence of organic solvents. Scanning electron microscopy (SEM), Fourier transform infrared (FTIR), thermogravimetric analysis (TGA) were used to investigate the surface morphology functional groups, as well as the thermal stability of DS loaded CMC/PVA nanofibers mat. The mechanical properties of the as prepared electrospun nanofibers was also evaluated. The entrapment efficiency and the in vitro release of DS loaded CMC/PVA nanofibers were characterized using UV-Vis spectroscopy. The obtained results displayed that the blended nanofibers have shown a smooth morphology, no beads formation when the concentration of CMC was equal or below 5% and beads formation above 5%. FTIR data demonstrated that there were good interactions between CMC and PVA possibly via the formation of hydrogen bonds. The electrospun blended CMC/PVA nanofibers exhibit good mechanical properties. From the in vitro release data, it was found that with the presence of CMC, the release of DS from the nanofibers mats became sustained controlled. Due to the biocompatibility and low cost of the two blended polymers (CMC and PVA), the blended nanofibers system can be considered as one of the promising materials for the preparation of excellent drug carrier.

Modified alginate and gelatin cross-linked hydrogels for soft tissue adhesive

Abstract Soft tissue adhesives made from natural hydrogel are attractive in clinical applications due to their excellent properties, such as high water content, good biocompatibility, low immune, good biodegradability. Hydrogels derived from natural polysaccharides and proteins are ideal components for soft tissue adhesive since they resemble the extracellular matrices of the tissue composed of various sugar and amino acids-based macromolecules. In this paper, a series of novel tissue adhesives mixed by aldehyde sodium alginate (ASA) with amino gelatin (AG) were developed and characterized. The effect of aldehyde content in ASA and amino group content in AG on the properties of ASA/AG cross-linked hydrogel was measured. The results showed the gelling time, swelling behavior and the bonding strength of the hydrogel can be tuned by varying the content of aldehyde groups in ASA and the content of amino groups in AG. The gelation time could be controlled within 4–18 min. When the aldehyde content of ASA is 75.24% and the amino content of AG is 0.61 mmol/g, the hydrogel almost has the adhesive strength equal to the commercially available adhesive fibrin glue. So, this tunable ASA/AG hydrogels in this study could be a promising candidate as soft tissue adhesive and have a wide range of biomedical applications.

Green Electrospining of Hydroxypropyl Cellulose Nanofibres for Drug Delivery Applications

Electrospun nanofibers mats are green synthesized using hydroxypropyl cellulose (HPC) individually or in conjugation with either poly(vinyl alcohol) (PVA) or Polyvinylpyrrolidone (PVP) to enhance the mechanical properties of the nanofibers mats. Desirable attributes of the as-obtained nanofibers mats are manifested via using SEM, FT-IR, TGA and conventional tools for mechanical and physical properties. The obtained data from SEM images demonstrated that the diclofenac sodium (DS) loaded nanofibers mats did not provide significant change of the morphological structure to the mats. In addition the thermal stability and the visual and mechanical properties of PVA or PVP was dramatically enhanced with the addition of HPC. The in vitro sustained release of DS drug was controlled when loaded into electrospun nanofibers of HPC with either PVA or PVP.

Development of poly (L-lactide-co-caprolactone) multichannel nerve conduit with aligned electrospun nanofibers for Schwann cell proliferation

ABSTRACT Biomaterials are playing a significant role in understanding and promoting the plasticity and repair of the nervous system. Biomimetic nanofibrous scaffolds mimicking important features of the native extracellular matrix provide a promising strategy to restore functions or achieve favorable responses for tissue regeneration and autograft nerve conduit is one of the most promising nerve regeneration strategies. The present study is based on novel fabrication method by using a special collector for 3D multichannel nerve conduit, longitudinally oriented with aligned electrospun nanofibers. The conduit contained a high number of channels (varying from 7 to 19) and each channel showed a separate morphology. Nerve channels were fabricated with the varying length ranging from 4 to 9 cm and total diameter ranging from 2200 ± 40 µm to 3951 ± 196 µm, while the channel diameter ranging from 350 ± 86 µm to 780 ± 20 µm. It has been clearly shown that the average porosity of nerve conduits has reached almost 89%. In this study, we optimized the parameters to control the structural stability, including the size and the number of channels in the nerve conduit. We also checked in vitro cell biocompatibility of multichannel nerve conduit and demonstrated that Schwann cells have the tendency to grow along the direction of nanofibers and high cell growth was observed in high number of channels compared to low number of channels. These results elaborated the potential use of this biocompatible multichannel nerve conduit for further in vivo testing. GRAPHICAL ABSTRACT

Application of a bilayer tubular scaffold based on electrospun poly(L-lactide-co-caprolactone)/collagen fibers and yarns for tracheal tissue engineering

A bilayer tubular scaffold (BLTS) consisting of poly(l-lactide-co-caprolactone) (P(LLA-CL))/collagen submicron sized fibers and micron sized yarns, was prepared via electrospinning. Then, autologous tracheal epithelial cells and chondrocytes were separately seeded onto the two layers of the BLTS. After culturing for 7 days, the cell-seeded BLTS (CS-BLTS) was implanted and wrapped in rat tracheal fascia for pre-vascularization. The pre-vascularized BLTS (PV-BLTS) was subjected to an in situ trachea regeneration study using a rat trachea injury model, along with CS-BLTS and bare BLTS for comparison. The results presented the bilayer structure of the BLTS, and the two layers were arranged conterminously. The porosity of the outer layer (collagen/P(LLA-CL) yarns) was found to be significantly higher (P < 0.05) than that of the inner layer (collagen/P(LLA-CL) fibers). In vitro biological analysis demonstrated that the collagen/P(LLA-CL) showed good biocompatibility, which promoted tracheal epithelial cell initial adhesion and proliferation with a highly significant difference (P < 0.001) or significant difference (P < 0.05) compared to those of pure P(LLA-CL) materials respectively. Chondrocyte activity and proliferation were also enhanced on collagen/P(LLA-CL) yarns with a significant difference (P < 0.05) compared to those of pure P(LLA-CL). Chondrocyte penetration was promoted as well, due to the loose and porous structure of the electrospun collagen/P(LLA-CL) yarns. The in vivo evaluation results of immune response analysis and histological investigation demonstrated that the PV-BLTS performed better in new capillary regeneration, reducing immunogenicity and improving tracheal tissue regeneration compared to the CS-BLTS and bare BLTS, indicating its promising potential as a new tissue engineered alternative for trachea repair and regeneration.