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A unique composite nanodiamond-based porous material with a hierarchically-organized submicron-nano-structure was constructed for potential bone tissue engineering. This material consisted of submicron fibers prepared by electrospinning of silicon oxide (SiOx), which were oxygen-terminated (O-SiOx) and were hermetically coated with nanocrystalline diamond (NCD) films. The NCD films were then terminated with hydrogen (H-NCD) or oxygen (O-NCD). The materials were tested as substrates for the adhesion, growth and osteogenic differentiation of human osteoblast-like Saos-2 cells. The number and the spreading area of the initially adhered cells, their growth rate during 7 days after seeding and the activity of alkaline phosphatase (ALP) were significantly higher on the NCD-coated samples than on the uncoated O-SiOx samples. In addition, the concentration of type I collagen was significantly higher in the cells on the O-NCD-coated samples than on the bare O-SiOx samples. The observed differences could be attributed to the tunable wettability of NCD and to the more appropriate surface morphology of the NCD-coated samples in contrast to the less stable, rapidly eroding bare SiOx surface. The H-NCD coatings and the O-NCD coatings both promoted similar initial adhesion of Saos-2 cells, but the subsequent cell proliferation activity was higher on the O-NCD-coated samples. The concentration of beta-actin, vinculin, type I collagen and alkaline phosphatase (ALP), the ALP activity, and also the calcium deposition tended to be higher in the cells on the O-NCD-coated samples than on the H-NCD-coated samples, although these differences did not reach statistical significance. The improved cell performance on the O-NCD-coated samples could be attributed to higher wettability of these samples (water drop contact angle less than 10°), while the H-NCD-coated samples were hydrophobic (contact angle >70°). NCD-coated porous SiOx meshes can therefore be considered as appropriate scaffolds for bone tissue engineering, particularly those with an O-terminated NCD coating.

NanospiderTMmethod allows preparation of nanofiber sheets with desired specific mass and fiber diameter between 100-600 nm. The fiber diameter can be modified by solvent system, concentration of polymer solution, and external conditions of the electrospinning process, in particular by air humidity and temperature. We have long experience with continual electrospinning from free surface of the polymer solution and in this case we focus on polymer blend polyamide 6/chitosan nanofiber form. Chitosan is an excellent material providing biocompatibility and numerous primary amine groups. On the other hand, polyamide 6 is well known and easy-to-prepare stable polymer guaranteeing sufficient mechanical properties. Blend nanofibers containing synthetic and natural polymers are usually difficult to continuously prepare. Natural polymer bring certain inhomogeneity due to varying chemical and physical properties of each brew. We compared chitosan from four different suppliers and finally fabricated homogenous and long-term stable layers. Successfully prepared nanofiber sheets were used as a support for enzyme immobilization. We showed that our layers can be used as a carrier for numerous biomolecules.

In this study, silk nanofibre sheets were prepared by a needleless electrospinning from silk fibroin in a mixture of formic acid and calcium chloride. The influences of the concentration of calcium chloride on the properties of spinning solution, morphology of the silk electrospun fibres and the spinning performance of the spinning process were examined. The results show that calcium chloride can improve the solubility of silk fibroin in formic acid. The morphology of electrospun fibres was characterized by a scanning electron microscope (SEM), which indicates that the morphology of obtained fibres was influenced by the weight ratio of silk fibre to calcium chloride in the spinning solution. It was observed that the concentration of calcium chloride in the spinning solution influenced the diameter of the silk electrospun fibres, with an increase in the concentration of calcium chloride increasing the diameters of the electrospun fibres. The silk nanofibres had diameters ranging from 440 to 1900 nm. However, increasing the concentration of calcium chloride in the spinning solution had a less influence on the spinning performance of electrospinning process.

In this study, nanofibres consisting of silk fibroin (SF) and gelatin (GP) with different composition ratio were fabricated by needleless electrospinning method. The influences of SF/GP blending ratio on the properties of spinning solution and the morphology of electrospun fibres were investigated. A variety of compositions of the silk fibroin/gelatin blend solutions were successfully electrospun into nanofibres sheet. The morphology of electrospun fibre was characterized by a scanning electron microscope (SEM) which indicates that the morphology of obtained fibres was influenced by the weight ratio of gelatin to silk fibroin in the spinning solution. It was observed that the blending ratio of gelatin to silk fibroin in spinning solution played an important role in spinning performance of the process and the diameter of obtained fibres. An increasing in gelatin content in blended solution resulted in bigger diameter of the obtained electrospun fibres. The silk fibroin/gelatin electrospun fibres had diameters ranging from 200 to 660 nm.

A quantitative measurement of degree of deacetylation of Sterculia urens gum and its effect on the thermal properties changes is presented in this study. Sterculia urens gum was deacetylated at varying deacety- lation reaction temperature and time. The acetyl group is replaced by hydroxyl which leads to better solubility of the sterculia gum in water. Thermal properties were charac- terized using differential scanning calorimetry and ther- mogravimetric analysis. DSC analysis reveals that after the deacetylation, the glass transition temperature appears at around 60 C of the S. urens gum. After deacetylation, the TG degradation clearly shows three different peaks. Deacetylation reaction temperature plays the major role in the thermal stability and structure of the S. urens gum.

In this work, we presented plasma modification of low-density polyethylene (PE) powder using unconventional chemicals. This work focused on the thermal behavior of modified PE. Plasma modification of PE was carried out using unconventional chemical vapor i.e., acetone, toluene, ethanol, methanol, isopropanol, and chloroform, respectively. For all the process, the modification time was kept constant for 2 min. Chamber pressure of 100 Pa was used for the study. The thermal behavior of the plasma-modified and unmodified PE was carried out by differential scanning calorimetry and thermogravimetric analysis. We have found that there is a maximum improvement of crystallinity and thermal stability of PE when ethanol is used for plasma modification. Results obtained from DSC showed that plasma modification of PE in ethanol vapors increases the crystallinity of the PE without damaging the surface properties. Thermal stability of PE plasma modified in ethanol gives maximum thermal improvement to almost 25 °C at 5 mass% mass loss compared to unmodified PE.

This study was focused on the preparation of electrospunnanofibres from silk fibroin (SF)/gelatin (GP) blends solution using a roller electro spinning method. The effects of mixing ratio in SF/GP blend solution on properties of spinning solution (e.g., viscosity, conductivity and surface tension) and morphology of electrospunfibres were studied. The SF/GP blends solution containing up to the gelatin content of 30% could be electro spun into the continuous fibrous structure. Average diameter of SF/GP electrospunfibres were increased by increasing the amount of gelatin in spinning solution. The SF/GP electrospunfibres showed bigger diameter and broader diameter distribution than pure silk fibroin electrospunfibres. The SF/GP nanofibres had diameters ranging from 400 to 1300 nm.

The paper is focused on the preparation of nanofiber layers of polyesteramides with various ratios of e-caprolactam/e-caprolactone structural units. We have studied the effect of the system parameters, i.e., the composition of the copolymer, its molar mass and the concentration of the solution on morphology of fiber layers being formed during the electrostatic wet spinning. The process parameters were constant during the processing. Morphology of the fiber layers is given by the composition of the copolymer, i.e., by its polarity, the content of the crystalline phase and thus its separation in the process of evaporating the solvent. Fibers with diameters ranging from 100 to 160 nm were obtained for polyesteramides containing 20 or 40 mol% lactone units during optimizing the system parameters, i.e., the concentration of the solution and molar mass of polyesteramide.

We demonstrate here the structural, thermal, and wettability characteristics of low density polyethylene powder before and after plasma treatments. The plasma treatment was carried out using different working gas i.e. air, oxygen and a mixture of hydrogen and oxygen at an atmospheric pressure of 100 Pa. The plasma treatment time was kept constant at 2 min for all the specimens. Fourier transform infrared (FTIR), dynamic capillary rising using Washburn method, differential scanning calorimetry (DSC), and thermogravimetric analysis has been carried out for both pristine and plasma treated polyethylene specimens. Our study shows that there is 88% increase in the wettability after plasma treatments. Plasma treatment in air atmosphere gives the maximum wettability. Thermogravimetric analysis (TGA) investigation shows plasma treatment in the H 2 + O 2 mixture atmosphere gives maximum thermal stability whereas the DSC results reveal the lowest crystallinity for plasma treatment in air atmosphere. The lowest latent heat of fusion (154 J/g) calculated from the melting curve of DSC is observed for LDPE treated in air atmosphere. The FTIR spectroscopy of the plasma-treated LDPE powder reveals that plasma treatment introduces polar group on the LDPE surface leading to the increased surface free energy and surface active sites. The CH 2 concentration increases after plasma treatments.

The formation of novel high aspect ratio nanofibers from polyesteramides based on ε-caprolactam and ε-caprolactone is reported. Nanofibers were prepared by the electrospinning method from polymer solution. Scanning electron microscopy images of nanofiber layers revealed that the diameter of fibers depended on the nature of the solvent or the mixture of solvents used and especially on the composition of polyesteramides.

The new electrospinning technology NanospiderTM offering a realistic potential for industrial production was used for creation of nanofiber sheets from aqueous solutions of partially neutralized poly(acrylic) acid with crosslinking agent. Produced nanofiber sheet was crosslinked by heat treatment. Absorption capacity and rate of absorption were tested and compared with superabsorbent particles and commercial superabsorbent fibers. The morphology of electrospun fibers was observed using a scanning electron microscope (SEM). Possibilities of fiber diameter influence were studied.

The history of electrospinning is briefly introduced at the beginning of the article. The fundaments of the process are then analysed physically to be translated into a successful technology. Self-organisation of fluid in electrospinning is perceived as a consequence of various instabilities, based on electrohydrodynamics and, thus, highlighted as a key factor, theorising the subject successfully to elevate it to a highly productive technology to manufacture nano-scale materials. The main physical principle of the self-organisation is appearance of unstable tiny capillary waves on liquid surfaces, either on a free liquid surface or on that confined in a capillary, which is influenced by external fields. The jet path is described, as well as its possible control, by special collectors and spinning electrodes. Two electrospinning variants, i.e. melt and core–shell electrospinning, are discussed in detail. Two scarcely referred exceptional features of electrospinning, electric wind and accompanying irradiati...

The new electrospinning technology NanospiderTM, offering a real potential for industrial production of nanofibers, is used for the preparation of nanofiber sheets from aqueous solutions of polymer blends. The nanofiber sheets are prepared from a mixture of chitosan and polyethylenoxide (PEO) and using the novel continual electrospinning process (Jirsak et al., 2005, www.nanospider.cz) affords a network with typical fiber diameters that are less than 500 nm. Effects of solvents, molecular weight of both polymers, monovalent salt, surfactant and composition of chitosan blend on electrospinning are also studied. The optimal conditions for electrospinning by the NanospiderTM technology, including applied high voltage, distance between both electrodes, air temperature and air humidity, are also found. The crosslinking of the nanofiber sheet is achieved by heat treatment. The morphology of electrospun fibers is observed by using a scanning electron microscope (SEM). Chitosan in the nanofiber sheets format has a great potential to be widely used in various applications derived from its biocompatibility and biodegradability.

The goal was to electrospin 2-hydroxyethyl methacrylate — based biocompatible polymers and prepare submicron fibres (nanofibers) for biomedicinal applications. Syntheses of poly(2-hydroxyethyl methacrylate) (HEMA) and its copolymer with 2-ethoxyethyl methacrylate (EOEMA), and their characterization by viscometry and molecular weight are described. Their relation to electrospinning is discussed. Electrospinning of HEMA homopolymer from water-ethanol is successful for molecular weights 6.31 × 105 and 1.80 × 106 g/mol. Electrospinning of HEMA/EOEMA copolymers is feasible from ethanol.

In recent years, there has been an increase in efforts to improve wastewater treatment as the concentration of dangerous pollutants, such as endocrine disrupting chemicals, in wastewater increases. These compounds, which mimic the effect of hormones, have a negative impact on human health and are not easily removed from water. One way to effectively eliminate these pollutants is to use enzymatically activated materials. In this study, we report on the use of laccase from the white rot fungus Trametes versicolor immobilized onto polyamide 6/chitosan (PA6/CHIT) nanofibers modified using two different spacers (bovine serum albumin and hexamethylenediamine). We then tested the ability of the PA6/CHIT-laccase biocatalysts to eliminate a mixture containing 50μM of two endocrine disrupting chemicals: bisphenol A and 17α-ethinylestradiol. The PA6/CHIT nanofiber matrix used in this study not only proved to be a suitable carrier for immobilized and modified laccase but was also efficient in the removal of a mixture of endocrine disrupting chemicals in three treatment cycles.

Sterculia urens (Gum Karaya) based polyvinyl alcohol (PVA) composite nanofibres have been successfully electrospun after chemical modification of S. urens to increase its solubility. The effect of deacetylated S. urens (DGK) on the morphology, structure, crystallization behaviour and thermal stability was studied for spuned fibres before and after spinning post treatment. An apparent increase in the PVA crystallinity were observed in the PVA-DGK composite nanofibres indicating S. urens induced crystallization of PVA. The pure PVA nanofibre and the nanofibres of PVA-DGK composites were introduced to post electrospinning heat treatment at 150°C for 15 min. The presence of sterculia gum reduced the fibre diameter and distribution of the nanofibres due to the increased stretching of the fibres during spinning. Switching of the thermal behaviour occurs due to post spinning heat treatments.

In this study, silk nanofibres were prepared by electrospinning from silk fibroin in a mixture of formic acid and calcium chloride. A needle and a rotating cylinder were used as fibre generators in the spinning process. The influences of the spinning electrode and spinning parameters (silk concentration and applied voltage) on the spinning process, morphology of the obtained fibres, and the production rate of the spinning process were examined. The concentration of the spinning solution influenced the diameter of the silk electrospun fibres, with an increase in the concentration increasing the diameters of the fibres in both spinning systems. The diameters of the electrospun fibres produced by roller electrospinning were greater than those produced by needle electrospinning. Moreover, increasing the concentration of the silk solution and the applied voltage in the spinning process improved the production rate in roller electrospinning but had less influence on the production rate in needle electrospinning.

The aim of the study was to evaluate the effect of a cell-free hyaluronate/type I collagen/fibrin composite scaffold containing polyvinyl alcohol (PVA) nanofibers enriched with liposomes, basic fibroblast growth factor (bFGF) and insulin on the regeneration of osteochondral defects. A novel drug delivery system was developed on the basis of the intake effect of liposomes encapsulated in PVA nanofibers. Time-controlled release of insulin and bFGF improved MSC viability in vitro. Nanofibers functionalized with liposomes also improved the mechanical characteristics of the composite gel scaffold. In addition, time-controlled release of insulin and bFGF stimulated MSC recruitment from bone marrow in vivo. Cell-free composite scaffolds containing PVA nanofibers enriched with liposomes, bFGF, and insulin were implanted into seven osteochondral defects of miniature pigs. Control defects were left untreated. After 12 weeks, the composite scaffold had enhanced osteochondral regeneration towards hyaline cartilage and/or fibrocartilage compared with untreated defects that were filled predominantly with fibrous tissue. The cell-free composite scaffold containing PVA nanofibers, liposomes and growth factors enhanced migration of the cells into the defect, and their differentiation into chondrocytes; the scaffold was able to enhance the regeneration of osteochondral defects in minipigs.

Polymer blends can be very effective for the processing of nanofibers, especially for the novel electrospinning process of Nanospider™ (Jirsak et al., 2005, www.nanospider.cz), offering the realistic potential for industrial production of nanofiber sheets. Polymer blending is designed to generate materials with optimized chemical, structural, mechanical, morphological and biological properties.

The structural properties of microfiber meshes made from poly(2-hydroxyethyl methacrylate) (PHEMA) were found to significantly depend on the chemical composition and subsequent cross-linking and nebulization processes. PHEMA microfibres showed promise as scaffolds for chondrocyte seeding and proliferation. Moreover, the peak liposome adhesion to PHEMA microfiber scaffolds observed in our study resulted in the development of a simple drug anchoring system. Attached foetal bovine serum-loaded liposomes significantly improved both chondrocyte adhesion and proliferation. In conclusion, fibrous scaffolds from PHEMA are promising materials for tissue engineering and, in combination with liposomes, can serve as a simple drug delivery tool.

A simple and effective method for the fabrication of porous nanofibers based on the solvent evaporation methods in one-step electrospinning process from the commercial polyvinyl butyral (PVB) is presented. The obtained nanofibers are prevalently amorphous with diameters ranging from 150 to 4350 nm and specific surface area of approximately 2–20 m2/g. Pore size with irregular shape of the porous PVB fibers ranged approximately from 50 to 200 nm. The effects of polymer solution concentration, composition of the solvents mixture, and applied voltage on fiber diameter and morphology were investigated. The theoretical approach for the choice of poor and good solvents for PVB was explained by the application Hansen solubility parameter (HSP) and two-dimensional graph. Three basic conditions for the production of porous PVB nanofibers were defined: (i) application of good/poor solvent mixture for spinning solution, (ii) differences of the evaporation rate between good/poor solvent, and (iii) correct ratios of good/poor solvent (v/v). The diameter of prepared porous PVB fibers decreased as the polymer concentration was lowered and with higher applied voltage. These nanofiber sheets with porous PVB fibers could be a good candidate for high-efficiency filter materials in comparison to smooth fibers without pores.

Five methods of preparation of macroporous hydrogels are described and compared: precipitation polymerization, polymerization in presence of salt, polymerization in presence of gas-releasing compound, lyophilization and electrospinning. Crosslinked copolymers based on 2-hydroxyethyl methacrylate were selected as model hydrogels. Hydrogels were characterized by SEM microscopy, porosity, communicating/non-communicating pore ratio, pore sizes and their distributions. The advantages and drawbacks of the methods of preparation, modification of hydrogel properties, reproducibility and issues related to their preparation are discussed. The most convenient method was preparation in presence of salts. One type of porous hydrogel was based on a hydrogel matrix composed of nanofibers prepared by electrospinning method. The nanofibers have shown unique properties due to their large specific surface. The least suitable method seems to be the preparation of porous hydrogels by polymerization using gas (nitrogen) releasing initiator, 2,2´-azobisisobutyronitrile. The use of prepared porous hydrogels is intended especially for scaffolds in tissue engineering.

Recent advances in the preparation of nanofibre layers, especially using the Nanospider™ technology, allow prepare a sufficiently large area of nanofibrous layer of reproducible thickness and structure. Subsequently, it is possible to employ these layers as cell carriers and evaluate their efficiency in laboratory bioreactors. The construction of the functional hepatal bioreactor is particularly given by the positive response of hepatocyte cells to the used carrier layer as well as by the cell morphology, their viability and biological activity in certain period of time. We compared cell growth on collagen with nanofibres electrospun from selected copolymers of methacrylic esters (HEMA/EOEMA) and from differently prepared polycaprolactone (PCL) layers. The morphology was evaluated using Phaloidin/DAPI staining. On the nanofibres based on methacrylates, the cells survived and showed a common morphology comparing with cells grown on collagen (controls). On the PCL nanofibres, the cells attached well and showed a better growth than cells grown on collagen (controls). The results obtained in laboratory bioreactor proved the biochemical functionality of the studied system.