Sadok Roudesli

Chemical, biological and microbiological evaluation of cyclodextrin finished polyamide inguinal meshes ☆

This study describes the use of cyclodextrins (CDs) as a finishing agent of polyamide (PA) fibers used in order to obtain inguinal meshes with improved antibiotic delivery properties. The finishing process involved polymerization between citric acid and CDs, which yielded a cross-linked polymer that physically adhered to the surface of PA fibers. This permanent functionalization was characterized by evaluating the damping property with a polar liquid (glycerol) via the drop contact angle method for various rates of modification of the fabrics. The biological and microbiological effects of the PA, which were functionalized with hydroxypropylated derivate of gamma-CD (HP-gamma-CDs) and charged with ciprofloxacin (CFX), were evaluated by cell culture assays. We observed a good adhesion and proliferation of fibroblastic cells (NIH3T3) after 3 and 6 days and no detectable toxicity of the modified substrate. The in vitro antibacterial activity of the HP-gamma-CD grafted PA fabrics charged with CFX against the bacteria Staphylococcus aureus, Staphylococcus epidermidis and Escherichia coli was greatly superior to that of the virgin sample within a 24h batch experiment in human blood plasma medium. In conclusion, these results from our study offer an insight into the efficient performance of CDs as drug delivery systems for multiple applications in the fields of biomaterials and medical textiles.

Desalination of brackish water from Tunisian Sahel using composite polymethylhydrosiloxane-cellulose acetate membranes

Abstract Composite cellulose acetate (CA) based membranes having a hydrophobic top layer made of polymethylhydrosiloxane (PMHS) were prepared with the aim of desalination of brackish waters from the Sahel region of Tunisia having a total dissolved salt content (TDS) of about 4100 g.m-t-3. The porous substructure made of CA was obtained by a phase separation process from acetone/formamide ( 2 1 wt wt ) casting solutions. Two polymer concentrations (20 and 22 wt. %) were used with a heat post-treatment temperature going from 60 to 90°C in order to produce membranes with pore sizes responding to nanofiltration needs. Overcoating the CA substructure with a PMHS thin layer gave rise to the composite membranes. Scanning electron microscopy analysis showed the asymmetric and composite feature of the CA-PMHS membrane morphology. Contact angle measurements clearly pointed out a marked hydrophobic character of the composite membranes due to the PMHS surface modification. When compared to the corresponding unmodified CA membranes, the salt rejection determined by conductivity in the range of 78–93% was strongly enhanced whereas the pure water permeability of the composite membranes was reduced by a factor of 15–50% depending on the starting pore size. It results in the same salt retention — an improvement factor of 50–100% for the permeation rate when using the composite membranes. The ion rejection in decreasing order was SO42− > Cl− > NO32− and Mg2+ ≥ Ca2+ > Na+ for anions and cations, respectively.

Transport properties of PVA/PEI/PEG composite membranes: sorption and permeation characterizations

Poly(vinylalcohol)/poly(ethyleneglycol)/poly(ethyleneimine) blend membranes were prepared by solution casting followed by solvent evaporation. The chemical structure of the prepared membranes was analyzed by FTIR and DSC. The sorption behavior as well as the permeabilities of the membranes for pure CO2 and N2 were investigated. The results show that the PVA/PEI/PEG membranes possess a higher permeability of CO2 and a lower permeability of N2. The membrane displays a CO2 permeability of 27 Barrer, and a N2 permeability of 3 Barrer at 25°C and 1 bar. CO2 sorption behavior of the composite membrane, which can be classified as a dual-mode sorption model, and N2 sorption behavior of the copolymeric membrane is in agreement with the Fickian diffusion model.

Use of the [Copper(II)/MAA-nylon] Complex for the Adsorption of Residual Acid Dyes

Nylon fibres were converted into a strong ion-exchange polymer by grafting with methacrylic acid (MAA). The modified nylon fibres were monitored for their ability to remove copper(II) ions and dyes from aqueous solutions. Evidence for the grafting of MAA onto nylon was provided by weight uptake experiments and atomic force microscopy (AFM). The exchange capacity of MAA–nylon was evaluated by potentiometric titration of the grafted acidic groups. Due to complexation, the acidic grafted groups immobilize Cu(II) ions from Clark–Lubs buffered solution at a pH value of 8. The formation of a 1:1 complex was demonstrated by the values of the adsorption limits. The binary [Cu(II)/MAA–nylon] system was then tested for the adsorption of two Acid dyes, i.e. Acid Blue 25 (AB 25) and Calmagite (Calma), as ligands in the metal-coordinating process. The adsorption of Cu(II) onto MAA–nylon and of the dyes onto Cu(II)/MAA–nylon was followed spectrometrically. The observed stoichiometries of the ternary [dye/Cu(II)/MAA–nylon] complex formed were [] for AB 25 and [] for Calma at 20°C. Theoretical modelling of the adsorption process was performed employing the Langmuir, Freundlich and Jossen equations. Thermodynamic parameters such as the free energy change (ΔG0), the enthalpy change (ΔH0) and the entropy change (ΔS0) for adsorption were also investigated. The adsorption process is exothermic, which leads to a reduction in the extent of dye adsorption with increasing temperature.

Bacteriological effects of functionalized cotton dressings

This study aims to achieve effects of improved hydrophilicity and microorganism inhibition, which are rarely simultaneously present in wound dressings. Cotton gauzes were modified using the grafting of a polymer-based β-cyclodextrin. After optimizing the grafting conditions, the untreated and modified cellulosic samples were principally characterized using FT-IR spectroscopy, TGA/DTA analysis, in vitro drug release, and wettability measurements. In light of desired characteristics of wound dressings, the effectiveness of procedures was evaluated. It was found that contact angles for cotton gauzes decreased after functionalization, which means that hydrophilicity was proven to become excellent. A successful Methylene Blue complexation was confirmed through measure of the dyebath exhaustion using UV-spectrophotometry. Then, during Methylen Blue release test, we reported an initial burst release of active ingredient over 7 h, followed by zero-order release. The treatment effect on antimicrobial activity was investigated by growth inhibition, which was proven against Staphylococcus aureus and Escherichia coli.

The effect of hot water setting treatment on the dyeing properties of grafted polyamide 6.6 microfibres

Polymeric fibres are semicrystalline structures in which macromolecules are rarely oriented in their equilibrium state. Further instabilities are imparted when the fibres are converted into yarns and the yarns into fabrics. Heat setting is an important industrial process, as it reduces the fibre strain to an acceptable limit. Although this process provides dimensional stability to polyamide 6.6, yet it affects its dyeability. This paper investigates the effects of hot water setting treatment on the dyeing properties of grafted polyamide 6.6 microfibres dyed with a cationic dye. It reveals that the dye uptake of the hot water-set samples is inferior to those unset. A kinetic study showed a change in the build-up rate. In addition, an increase in the percentage of grafting improved the quantity of the dye fixed on both unset and hot water-set samples. Comparing the wash fastness of the unset samples, the hot water ones are found to be lower. The modelling of the adsorption isotherms using Langmuir, Freundlich and Jossen relations allows the determination of isotherm constants. The results obtained have been modelled using standard adsorption isotherms.

Separation of ultimate and technical esparto grass fibres: comparison between extraction methods

Esparto grass fibres are used as cordage or paper pulp. Ultimate and technical fibres used in pulp or cords have specific characteristics. Technical fibres have higher mechanical properties. However, ultimate fibres have a higher cellulosic rate, hence higher absorbency and retention capacity. To produce ultimate fibres, we must look for an appropriate method of extraction. In this paper, a method of extraction that gives cellulosic fibres without any damage is investigated and a comparison with other methods is also made. The structure of esparto grass technical fibres is discontinuous, where cellulosic fibres are found in matrix which contains pectin, lignin and hemicelluloses. The ultimate fibres from esparto grass have a length between 0, 2 and 3 mm and a diameter between 6 and 22 µm. This shows that ultimate fibres are very short; however, they have very interesting features. The chosen extraction method has many specifications: protecting properties using a combined method which is accomplished in a short time and which takes the ecological impact into consideration. In this work different stages are followed to obtain cellulosic fibres. These fibres are then characterised through several analyses such as scanning electron microscopy, X‐ray diffraction, diameter and rate of lignin elimination.

Extraction and characterization of polysaccharides from Mesembryanthemum crystallinum

Abstract Water-soluble polysaccharides were isolated from Mesembryanthemumcrystallinum. Two methods were applied, based (i) on the extraction in hot water (for fresh and dry plants, FP and DP) and (ii) on freeze-thawing of fresh plants (FT). Each fraction was purified by precipitation in ethanol followed by ultrafiltration of recovered solids dissolved in water through a membrane with a molecular weight cut off of 100 000. Elemental analysis demonstrated that the extracted products were polysaccharides exempt from proteins. The yield relative to the corresponding dry matter varied from 1.6 to 3% depending on the starting sample and the extraction process. Obtained products were characterised by their structural (sugar composition, degree of methylation (DM) and acetylation, molar mass of acid equivalent unit) and macromolecular characteristics (molar mass and intrinsic viscosity). A galacturonic-acid content larger than 65% and a DM value of c. 40% showed that the isolated polysaccharides belong to the fairly methylated pectin class. FP and FT structures consisted of the two blocks homogalacturonan (HG) and rhamnogalacturonan-I (RG-I) with relative proportions of 62 - 68% and 29 - 34%, respectively. They showed very similar physicochemical behaviour. On the other hand, DP exhibited significant differences in the chemical structure (50% HG and 46% RG-I blocks) and physical properties, indicating that partial degradation of HG moieties occurred during plant drying.

Drop Impact on Textile Material: Effect of Fabric Properties

Abstract This paper presents an experimental study of impact of water drop on a surface in a spreading regime with no splashing. Three surfaces were studied: virgin glass, coating film and woven cotton fabric at different construction parameters. All experiments were carried out using water drop with the same free fall high. Digidrop with high-resolution camera is used to measure the different parameters characterising this phenomenon. Results show an important effect of the height of the free fall on the drop profile and the spreading behaviour. An important drop deformation at the surface impact was observed. Then, fabric construction as the weft count deeply affects the drop impact. For plain weave, an increase of weft count causes a decrease in penetration and increase in the spreading rate. The same result was obtained for coated fabric. Therefore, the impact energy was modified and the drop shape was affected, which directly influenced the spreading rate.

Drying Morphologies and Emport Rate Effect on Wetting and Spreading Behaviours

The main idea of this work is to study the different phenomena of spreading, evaporation, and diffusion that bound to the ink-jet printing. The coating film is studied as well as its drying morphologies and its wetting behavior. Then the drop water spreading on coated fabric is investigated. At that time spreading kinetic is characterized by the digidrop 3S which permits to measure precisely the various parameters such as contact angle, diameter, height, volume and drop profile in contact with the support during wetting phenomenon. This survey shows, on the one hand, that the coating film structure is deeply affected by drying morphologies. On the other hand, drying conditions influence different parameters of kinetic drop spreading on virgin glass and cotton material. Then the increasing of coating film thickness encourages the drop spreading.