Preparation of Bioactive Polyamide Fibres Modified with Acetanilide and Copper Sulphate.

This paper presents a simple method of obtaining polyamide 6 fibres modified with acetanilide and copper ions. During the spinning of the fibres with the additives applied, a partial reduction of CuSO4 to Cu2+ and Cu+ ions occurs, which is observed as a change in the blue colour of the prepared polyamide granulate to the grey-brown colour of the formed fibres. CuMPs obtained as a result of the salt reduction should give the obtained fibres bioactive properties. Three types of microorganisms were selected to assess the microbiological activity of the obtained fibres, i.e., Gram-positive Staphylococcus aureus and Gram-negative Pseudomonas aeruginosa and Escherichia coli. The fibres have antibacterial activity against Gram-positive and Gram-negative bacteria. The largest inhibition zones were obtained for the Gram-positive bacteria Staphylococcus aureus, ranging from 1.5 to 4.5 mm, depending on the concentration of CuMPs. The morphology of the fibres' surfaces was examined by means of scanning electron microscopy (SEM) and optical microscopy (OM). The changes in the polymer structure chemistry are studied by Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray structure studies (WAXS and SAXS) and an energy-dispersive spectroscopy (EDS) analysis. The newly obtained bioactive polyamide fibres can be used in many areas, including medicine, clothing and environmental protection for the production of filters.

Graphene Oxide as a Collagen Modifier of Amniotic Membrane and Burnt Skin.

INTRODUCTION: The aim of this interdisciplinary study was to answer the question of whether active antioxidants as graphene oxide (GO), sodium ascorbate, and L-ascorbic acid modify at a molecular and supramolecular level the tissue of pathological amnion and the necrotic eschar degraded in thermal burn. We propose new solutions of modifiers based on GO that will become innovative ingredients to be used in transplants (amnion) and enhance regeneration of epidermis degraded in thermal burn. METHODS: A Nicolet 6700 spectrophotometer with Omnic software and the EasiDiff diffusion accessory were used in FTIR spectroscopic analysis. A Nicolet Magna-IR 860 spectrometer with an FT Raman accessory was used to record the Raman spectra of the samples. The surface of the samples was examined using a Phenom ProX scanning electron microscope with an energy-dispersive X-ray spectroscopy detector to diagnose and illustrate morphological effects on skin and amnion samples. SAXS measurements were carried out with a compact Kratky camera equipped with the SWAXS optical system. RESULTS: Characterisation of amide I-III regions, important for molecular structure, on both FTIR and FTR spectra revealed distinct shifts, testifying to organization of protein structure after GO modification. A wide lipid band associated with ester-group vibrations in phospholipids of cell membranes and vibrations of the carbonyl group of GO in the 1,790-1,720 cm-1 band were observed in the spectra of thermally degraded and GO-modified epidermis and pathological amnion. SAXS studies revealed that GO caused a significant change in the structure of the burnt skin, but its influence on the structure of the amnion was weak. CONCLUSION: Modification of burn-damaged epidermis and pathological amnion by means of GO results in stabilization and regeneration of tissue at the level of molecular (FTIR, FTR) and supramolecular (SAXS) interactions.

Chemical and Electronic Structure Characterization of Electrochemically Deposited Nickel Tetraamino-phthalocyanine: A Step toward More Efficient Deposition Techniques for Organic Electronics Application.

Phthalocyanines (Pc), with or without metal ligands, are still of high research interest, mainly for the application in organic electronics. Because of rather low solubility, Pc-based films are commonly deposited applying various advanced and demanding vacuum techniques, like physical vapor deposition (PVD). In this work, an alternative straightforward approach of NiPc layer formation is proposed in which NH2-side groups of nickel(II) tetraamino-phthalocyanine (AmNiPc) are engaged in the process of electrochemical deposition of (AmNiPc)layer on indium-tin oxide (ITO) substrates. The resulting layer is widely investigated by cyclic voltammetry, atomic force microscopy, UV-vis, and ATR-IR spectroscopies, X-ray diffraction, and photoemission techniques: X-ray and UV-photoelectron spectroscopies. The chemical and electronic structure of (AmNiPc)layer is characterized. It is shown that the electronic properties of the formed (AmNiPc)layer/ITO hybrid correspond to the ones previously reported for PVD-NiPc films.

Preparation and properties of composite cellulose fibres with the addition of graphene oxide.

The paper presents the results of a study on the preparation of cellulose-based composite fibres (CEL) with graphene oxide addition (GO). Composite fibres (GO/CEL) were prepared via the wet spinning method from CEL solutions in 1-ethyl-3-methylimidazolium acetate (EMIMAc) that contained a nano-addition of GO dispersion in N,N-dimethylformamide (DMF). The GO contents of the composite fibres were 0, 0.21, 0.50, 0.98, and 1.97 % w w. The fibres were coagulated in two solvents: distilled water and methanol. The results demonstrated that the amount of GO additive and the type of coagulant significantly impact the physicochemical, mechanical and structural properties of the CEL and GO/CEL fibres. The use of distilled water in a coagulation bath causes a degree of crystallinity of 31.0-40.8 % (WAXS) and a shift in the thermal decomposition temperature (by approximately 19 °C) towards higher temperatures (TGA). The results demonstrate improvements in the mechanical properties of the GO/CEL fibres, which were at the level of 9.43-14.18 cN/tex. In addition, the GO/CEL fibres exhibit satisfactory GO dispersion throughout their volume.

Supermolecular Structure of Poly(butylene terephthalate) Fibers Formed with the Addition of Reduced Graphene Oxide.

Nanocomposite fibers based on poly(butylene terephthalate) (PBT) and reduced graphene oxide (rGO) were prepared using a method able to disperse graphene in one step into a polymer matrix. The studies were performed for fibers containing four different concentrations of rGO at different take-up velocities. The supermolecular structures of the fibers at the crystallographic and lamellar levels were examined by means of calorimetric and X-ray scattering methods (DSC, WAXS, and SAXS). It was found that the fiber structure is mainly influenced by the take-up velocity. Fibers spun at low and medium take-up velocities contained a crystalline α-form, whereas the fibers spun at a high take-up velocity contained a smectic mesophase. During annealing, the smectic phase transformed into its α-form. The degree of transformation depended on the rGO content. Reduced graphene mainly hindered the crystallization of PBT by introducing steric obstacles confining the ordering of the macromolecules of PBT.

Supramolecular Structure of Polypropylene Fibers Extruded with Addition of Functionalized Reduced Graphene Oxide.

An effective ß-nucleating agent for polypropylene crystallization was obtained by the functionalization of reduced graphene oxide with calcium pimelate. The nucleating ability of the modified reduced graphene oxide (rGO-CP) was confirmed during non-isothermal crystallization. In further examinations, the rGO-CP was used as an additive to modify polypropylene fibers. The fibers were extruded in laboratory conditions. Gravity spun fibers containing three different concentrations of the rGO-CP and fibers taken at three different velocities were obtained. The supramolecular structure of the fibers was examined by means of calorimetric and X-Ray Scattering methods (DSC, WAXS, and SAXS). The considerable amount of -iPP was obtained only in the gravity spun fibers. In the fibers extruded at higher velocities, the diminishing impact of the additive on the fibers structure was revealed. The changes observed in the fiber structure in connection with the impact of the additive on polypropylene crystallization was discussed.

The Influence of Graphene Addition on the Properties of Composite rGO/PAN Membranes and Their Potential Application for Water Disinfection.

The paper presents a method of obtaining composite polyacrylonitrile-based (PAN) membranes with the addition of reduced graphene oxide (rGO). The membranes were obtained using phase inversion method from a homogeneous rGO dispersion in a solution of PAN dissolved in N, N-dimethylformamide (DMF). The impact of the amount of rGO addition to the PAN matrix on the physicochemical, structural, transport, and separation properties and on fouling resistance was studied. Composite membranes, due to the method of preparation used and the addition of rGO, are characterized by very good transport properties (~390 L/m2 h) and by a high degree of protein retention (85%). Reduced graphene oxide has biocidal properties, which, as we have shown, depend on the size of nanoparticles and the type of microorganism. rGO/PAN membranes, on the other hand, show biostatic properties against Gram-negative bacteria (Escherichia coli), Gram-positive bacteria (Staphylococcuc aureus) and fungi (Candida albicans). Thus, the obtained composite membranes can be potentially used in water disinfection.

PET Fibers Modified with Cloisite Nanoclay.

The alternative method of reducing the flammability of polyethylene terephthalate (PET) fibers, analogous to dyeing of PET fibers with dispersed dyes in a high-temperature bath, was proposed. A commercial organophilic montmorillonite Cloisite®15A (C15A) was applied as a flame retardant. The aim of the presented work was to evaluate the effectiveness of the introduced modifier and the improvement of the flame-retardant properties of PET fibers by limiting oxygen index (LOI) and thermogravimetric analysis (TGA) measurements. Evolved gas analysis (EGA) by spectrometric method (FTIR) during coupled thermogravimetric analysis (TGA) was applied in order to confirm no increase in the toxicity of volatile degradation products released from burning modified fibers. The nanocomposite nature of modified fibers was confirmed based on the structural parameters of the fibers determined using wide-angle X-ray scattering (WAXS) and small angle X-ray scattering (SAXS) X-ray diffraction methods.

Structure-Property Relationships of Pure Cellulose and GO/CEL Membranes Regenerated from Ionic Liquid Solutions.

Two types of cellulose membranes were produced by a classical wet phase inversion method from a solution of the polymer in 1-ethyl-3-methylimidazolium acetate (EMIMAc) by coagulation in water and selected primary alcohols. The first type were membranes made from pure cellulose (CEL). The second type were membranes obtained by adding nanosized graphene oxide (GO) to the cellulose solution. The process of precipitation and selection of the coagulant affected the structure of the membranes, which in turn affected their usability and applicability. The results of the presented studies show that the physicochemical properties of the coagulant used (e.g., molecular mass and dipole moment) play important roles in this process. It was found that both the content and dimensions of the pores depended on the molecular mass of the coagulant used. It was also found that the dipole moment of coagulant molecules had a large influence on the volume content of the pores (e.g., the 1-octanol (Oc) membrane had a dipole moment of 1.71 D; Φ = 1.82%). We investigated the effect of the type of coagulant on the porous structure of CEL membranes and how this affected the transport properties of the membranes (e.g., for the distilled water (W) membrane, Jv = 5.24 ± 0.39 L/m2 h; for the Oc membrane, Jv = 92.19 ± 1.51 L/m2 h). The paper presents the results of adding GO nanoparticles in terms of the structure, morphology, and transport properties of GO/CEL membranes (e.g., for composite membrane F (containing 20% GO), Jv = 40.20 ± 2.33 L/m2 h). In particular, it describes their extremely high ability to remove heavy metal ions.

Sodium ascorbate (SA) and l-ascorbic acid (AA) as modifiers of burn affected skin - A comparative analysis.

Proper functioning of living organisms requires controlling the factors which govern the level of oxidative stress in the system, that is presence of free radicals at a given, rather low, level and preventing their excess. In this work it is shown that SA and AA active antioxidants, governing the oxidative stress in the wound, modify standard serum solution as well as burn affected necrotic eschar at the molecular structure level. In the case of incubation of skin fragments in SA and AA, the following findings were reported: modification of serum, that is appearance of low molecular weight oligomer bands in AA and recreation of native serum bands in SA. In frozen serum solutions modified by AA FTIR 1759 and 1420-1053 cm-1 bands are observed, whereas in SA FTIR 1603, 1411-1054 and 536 cm-1 bands appear. In the case of modification of the burn affected necrotic eschar in SA and AA - frequency shifts in the fingerprint region 1780-1000 cm-1 can be biomarkers indicating tissue regeneration process under the influence of antioxidants. 1780-1580 cm-1 and 1418-1250 cm-1 regions on the Raman spectra are particularly rich in spectral information. Modification of samples of skin burnt with AA activates the regions of the ß-sheet aggregates whereas treatment of the samples with SA ascorbate demonstrates changes which testify to reconstruction of α-helix structure (SAXS studies).