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The electrokinetic properties of materials give useful insight into the behavior of surfaces in contact with liquids and other compounds and their quantification is a powerful tool to predict their behavior during further processing and application, especially in textile materials. In this work, we perform a comparative analysis of influence of the two most common selective oxidative protocols for viscose (regenerated cellulose) fabrics on subsequent functionalization with chitosan, and cellulose fabrics’ electrokinetic properties, zeta potential in a pH range of approx. 3–10, and isoelectric point (IEP). For oxidation before deposition of chitosan, sodium periodate and 2,2,6,6-tetramethylpiperidine-1-oxy radical (TEMPO) were used. The content of functional groups in oxidized cellulose fabric (carboxyl and carbonyl groups) was determined by titration methods, while amino functional groups’ availability in samples with chitosan was determined using the CI acid orange 7 dye absorption method. This study reveals that the periodate oxidation (PO) of cellulose is more effective for binding chitosan onto material, which gave rise to higher availability of amino groups onto cellulose/chitosan material, which also influenced the shift in zeta potential curve towards positive values at a pH below 5. Analysis of a relationship between zeta potential increase at pH 4.4 and amino groups’ amount measured using absorption of CI acid orange 7 dye at pH 4.4 revealed dependency that can be fitted linearly or exponentially, with the latter providing the better fit (R2 = 0.75).

Plasma processing of textile materials, especially ones from natural and chemical cellulose fibers, has been the focus of many researchers in the past three decades (1, 2). Plasma treatments, as an alternative to conventional wet treatments in textile processing, such as dewaxing, scouring, bleaching, extraction etc., used to clean fiber surfaces or to tailor fiber surface chemistry and morphology, have many advantages, such are low energy, chemical and water consumption, and short time of treatment, which makes this process environmentally friendly. Among many different plasma configurations available, which can be classified according to several criteria, such as the type of energy supply (direct or alternating with different frequencies), temperature (hot (thermal) and cold (non-thermal) plasma), and pressure (low-pressure and atmospheric pressure plasma), atmospheric pressure plasma, especially dielectric barrier discharge (DBD), is highly promising for textile material modification thanks to its simple arrangements and adaptability of electrodes' shape, more homogeneous surface discharge with lower temperature electrons preventing localized overheating and damage of treated material as well as its potential for up-scaling and implementation in existing industrial facilities (DBD parameters optimized in laboratory conditions can be easily transferred to industrial conditions) and continuous textile processing (1). In this paper, we present a comparative study on the functionalization of natural (cotton and jute) and chemical (viscose) cellulose fibers by DBD treatment with special emphasis on the aging effect as an additional treatment parameter. By controlling the DBD variables, such as the nature of gas (air, oxygen, and nitrogen), discharge power, frequency, and exposure time, a great variety of surface effects can be achieved, such as surface cleaning and etching, introduction of new functional groups, increase or decrease surface energy, cross-linking, etc.

A newly isolated strain Streptomyces sp. BV365 producing high amounts of orange extracellular pigments on mannitol-soy flour agar was identified as Streptomyces anulatus BV365. The producing strain Streptomyces anulatus BV365 was isolated from the ectomycorrhizosphere soil of the black truffle Tuber melanosporum. Crude cell extract of this strain was fractionated and orange pigment fraction showed very strong antimicrobial and cytotoxic activities. On further analysis, the strain was found to produce metabolites actinomycin D, C2 and C3 and nonactin. The application of purified actinomycins in the dyeing of multifiber fabric was assessed. Actinomycins exhibited a high affinity towards protein fibers (silk and wool), but washing durability was maintained only with silk. The morphologies and chemical components of the treated silk fabrics were analyzed using scanning electron microscopy and Fourier transform infrared spectroscopy. In addition, a skin irritation test in 3D-reconstructed human epidermis model was conducted to evaluate the biocompatibility of the tested fabrics. The results showed that the dyed silk had a safe biological properties.

Plasma processing of textile materials, especially ones from cellulose (natural and man-made (or regenerated) cellulose fibers), has been the focus of many researchers in the past three decades (Shishoo 2007, Ul Islam & Haji 2024). Plasma treatments, as an alternative to conventional wet treatments in textile processing used to clean fiber surfaces or to tailor fiber surface chemistry and morphology, have many advantages, such are small energy consumption, short time of treatment, and small chemical consumption, which makes this process environmentally friendly. Among many different plasma configurations available, which can be classified according to several criteria, such as the type of energy supply (direct or alternating with different frequencies), temperature (hot (thermal) and cold (non-thermal) plasma), and pressure (low-pressure and atmospheric pressure plasma), atmospheric pressure plasma, especially dielectric barrier discharge (DBD), is highly promising for textile material modification thanks to its simple arrangements and adaptability of electrodes' shape, more homogeneous surface discharge with lower temperature electrons preventing localized overheating and damage of treated material as well as its potential for up-scaling and implementation in existing industrial facilities and continuous processes. In this paper, we present a comparative study on the functionalization of cellulose fibers by DBD treatment with special emphasis on the aging effect as an additional treatment parameter. By controlling the DBD variables, such as the nature of gas (air, oxygen, and nitrogen), discharge power, frequency, and exposure time, a great variety of surface effects can be achieved, such as surface cleaning and etching, introduction of new functional groups, increase or decrease surface energy, cross-linking, etc.

In this work, the preparation and characterization of composites from cellulose acetate (CA)-poly(ethylene oxide) (PEO) nanofibers (NFs) with incorporated zinc oxide nanoparticles (ZnO-NPs) using solution blow spinning (SBS) is reported. CA-PEO nanofibers were produced by spinning solution that contained a higher CA-to-PEO ratio and lower (equal) CA-to-PEO ratio. Nanoparticles were added to comprise 2.5% and 5% of the solution, calculated on the weight of the polymers. To have better control of the SBS processing conditions, characterization of the spinning suspensions is carried out, which reveals a decrease in viscosity (two- to eightfold) upon the addition of NPs. It is observed that this variation of viscosity does not significantly affect the mean diameters of nanofibers, but does affect the mode of the nanofibers' size distribution, whereby lower viscosity provides thinner fibers. FESEM-EDS confirms ZnO NP encapsulation into nanofibers, specifically into the CA component based on UV-vis studies, since the release of ZnO is not detected for up to 5 days in deionized water, despite the significant swelling of the material and accompanied dissolution of water-soluble PEO. Upon the dissolution of CA nanofibers into acetone, immediate release of ZnO is detected, both visually and by spectrometer. ATR-FTIR studies reveal interaction of ZnO with the CA component of composite nanofibers. As ZnO nanoparticles are known for their bioactivity, it can be concluded that these CA-PEO-ZnO composites are good candidates to be used in filtration membranes, with no loss of incorporated ZnO NPs or their release into an environment.

In this work, plasma pretreatment of raw cotton fibers combined with silver sorption was used for the preparation of antimicrobial fabrics. Special attention was given to the aging effect investigated seven days after plasma treatment. Raw cotton fabrics were modified with atmospheric pressure dielectric barrier discharge (DBD) in air, nitrogen, and oxygen. After plasma treatment, surface morphology and chemistry were characterized by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS), respectively, molecular weight distribution and functional groups profile in cellulose were determined by GPC-MALLS with fluorescence labeling, while sorption properties were evaluated through wettability and moisture sorption measurements. Silver sorption was performed either immediately after treatment or seven days after plasma treatment, in order to investigate the aging effect on the sorption of Ag+. Antimicrobial activity was tested using agar diffusion test against S. aureus, E.coli, and C. albicans. Results have shown that silver sorption is improved and significantly higher when sorption is performed seven days after plasma treatment and consequently antimicrobial activity is also enhanced. This work confirms the significance of plasma aging in natural cellulose fibers' functionalization which presents yet another variable that should be taken into account when planning the procedure for fibers functionalization.

This study aimed to obtain functional viscose textiles based on chitosan coatings with improved antibacterial properties and washing durability. For that reason, before functionalization with chitosan/zinc nanoparticles (NCH+Zn), the viscose fabric was modified by nonthermal gas plasma of dielectric barrier discharge (DBD) to introduce into its structure functional groups suitable for attachment of NCH+Zn. NCH+Zn were characterized by measurements of hydrodynamic diameter and zeta potential and AFM. DBD-plasma-modified and NCH+Zn-functionalized fabrics were characterized by zeta potential measurements, ATR-FTIR spectroscopy, the calcium acetate method (determination of content of carboxyl and aldehyde groups), SEM, breaking-strength measurements, elemental analysis, and ICP-OES. Their antibacterial activity was determined under dynamic contact conditions. In addition to SEM, the NCH+Zn distributions on viscose fabrics were also indirectly characterized by measuring their absorbent capacities before and after functionalization with NCH+Zn. Washing durability was monitored through changes in the zeta potential, chitosan and zinc content, and antibacterial activity after 1, 3, and 5 washing cycles. The obtained results showed that DBD plasma modification contributed to the simultaneous improvement of NCH+Zn sorption and antibacterial properties of the viscose fabric functionalized with NCH+Zn, and its washing durability, making it suitable for the production of high-value-added medical textiles.

This study aimed to obtain functional viscose textiles based on chitosan coatings with improved antibacterial properties and washing durability. For that reason, before functionalization with chitosan/zinc nanoparticles (NCH+Zn), the viscose fabric was modified by nonthermal gas plasma of dielectric barrier discharge (DBD) to introduce into its structure functional groups suitable for attachment of NCH+Zn. NCH+Zn were characterized by measurements of hydrodynamic diameter and zeta potential and AFM. DBD-plasma-modified and NCH+Zn-functionalized fabrics were characterized by zeta potential measurements, ATR-FTIR spectroscopy, the calcium acetate method (determination of content of carboxyl and aldehyde groups), SEM, breaking-strength measurements, elemental analysis, and ICP-OES. Their antibacterial activity was determined under dynamic contact conditions. In addition to SEM, the NCH+Zn distributions on viscose fabrics were also indirectly characterized by measuring their absorbent capacities before and after functionalization with NCH+Zn. Washing durability was monitored through changes in the zeta potential, chitosan and zinc content, and antibacterial activity after 1, 3, and 5 washing cycles. The obtained results showed that DBD plasma modification contributed to the simultaneous improvement of NCH+Zn sorption and antibacterial properties of the viscose fabric functionalized with NCH+Zn, and its washing durability, making it suitable for the production of high-value-added medical textiles.

Cotton yarn was oxidized using the various concentrations and pH of potassium permanganate solutions, in order to investigate the influence of oxidation parameters on chemical, mechanical and sorption properties of cotton. The oxidation progress was monitored through weight loss, carbonyl and carboxyl group content, tensile strength, moisture sorption, crystallinity change, surface charge and morphology of modified samples. The carboxyl groups were introduced into the oxidized cotton up to 0.3 mmol center dot g(-1), while the weight loss was up to 5%. The oxidized samples, compared with untreated cotton, exhibited lower tensile strength, higher moisture sorption and surface roughness. Surface charge was evaluated through measurement of zeta potential at different pH of electrolyte, and the correlation was established between carboxyl group content and zeta values measured at neutral pH, which proved that zeta potential can be a valuable tool for characterizing changes in the structure of oxidized cellulose textile materials.

Halochromic (pH-responsive) material was obtained by dyeing functionalized viscose fabric with a crude extract from Streptomyces sp. strain NP4. The functionalization of the fabric before dyeing was performed to make cellulose susceptible to coloration with NP4 extract. Two combined pre-treatment steps were used, oxidation to obtain dialdehyde cellulose and chitosan deposition after oxidation. Chitosan was deposited onto untreated fabric as well, while only oxidized viscose was also investigated for dyeing. Functionalization by both protocols made viscose susceptible to dyeing with the notion that the deposition of chitosan onto oxidized viscose produced the darkest shade on the material. Dyed fabrics showed visual pH responsiveness in the range pH 4-10, with a color change from pink to red (pH 4-pH 7) and a major color change from red to blue (pH 7-pH 10) whereby fabric was tested and could withstand 10 color-changing cycles. Cytotoxicity assay confirmed the non-toxic nature of dyed material, which indicates its possible use as wound dressing's indicators.

Successful conversion of cellulose hydroxyl (OH) to carboxyl (COOH) groups is the goal of many modification procedures since COOH groups enhance the polarity of the fibers' surface and can be used for further fibers' functionalization. In this work, in order to obtain 2,3-dicarboxycellulose, the regenerated cellulose fibers (viscose) in the form of fabric were functionalized through two-step oxidation: with NaIO4 to introduce CHO groups followed by NaClO2 for CHO conversion to COOH groups. After oxidations, the fibers' morphology, surface chemistry, crystallinity, and surface charge were investigated using scanning electron microscopy (SEM), Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), X-ray diffraction analysis (XRD), and zeta potential measurements, respectively, as well as content of COOH groups determined by volumetric titrations. Sorption properties, i.e. moisture sorption, water retention power, and sorption of silver ions (Ag+) were evaluated and correlated with oxidation parameters. The interaction with model ion - Ag+ revealed that COOH groups, when maximum content obtained in oxidized fibers was 0.27 mmol center dot g(-1), were available for binding Ag+ in nearly 1:1 ratio. The proposed oxidative protocol represents an effective method for COOH groups' introduction into regenerated cellulose fibers, improvement of fibers' sorption properties without deterioration of their crystallinity, and opens up a possibility for further functionalization of 2,3-dicarboxycellulose.

Cotton yarn was oxidized using the various concentrations and pH of potassium permanganate solutions, in order to investigate the influence of oxidation parameters on chemical, mechanical and sorption properties of cotton. The oxidation progress was monitored through weight loss, carbonyl and carboxyl group content, tensile strength, moisture sorption, crystallinity change, surface charge and morphology of modified samples. The carboxyl groups were introduced into the oxidized cotton up to 0.3 mmol center dot g(-1), while the weight loss was up to 5%. The oxidized samples, compared with untreated cotton, exhibited lower tensile strength, higher moisture sorption and surface roughness. Surface charge was evaluated through measurement of zeta potential at different pH of electrolyte, and the correlation was established between carboxyl group content and zeta values measured at neutral pH, which proved that zeta potential can be a valuable tool for characterizing changes in the structure of oxidized cellulose textile materials.

In this work, cellulose (viscose) was functionalized with chitosan and dyed with an extract of Streptomyces sp. NP4 bacterial culture. Cellulose was first converted to dialdehyde cellulose; afterward chitosan was deposited, making fabric susceptible to dyeing. The dyed fabric exhibited pH responsiveness in a broad range of pH, 4-7-10, where colour shade of the fabric, exposed to buffer solutions, was pink, red, and blue, respectively. Response to the pH change was measured in seconds, whereby faster colour shift is from blue to red/pink. The dyed fabrics can withstand 10 cycles of colour change. Due to the broad range of pH activity, the presented cellulose product has the potential to be used as a textile pH sensor, and, more importantly, it is completely made from natural and sustainable resources.

This study aimed to obtain textile based on viscose and chitosan with simultaneously improved sorption and antibacterial properties. For that reason, before functionalization with chitosan, the viscose fabric was modified by nonthermal gas plasma of dielectric barrier discharge (DBD) to introduce into its structure functional groups suitable for improved adsorption of chitosan. Functional groups' content of unmodified and DBD modified viscose fabric was determined by the calcium acetate method, while their influence on the surface charge, as well as the success of the functionalization of viscose fabrics with chitosan, was evaluated by measuring the zeta potential. Morphological, sorption and antibacterial properties of unmodified and DBD modified viscose fabrics, before and after functionalization with chitosan, were characterized by scanning electron microscopy, capillary rise method, and standard test method ASTME 2149-01: 2001, respectively. The obtained results showed that the treatment with DBD contributed to the simultaneous improvement of sorption and antibacterial properties of viscose fabric functionalized with chitosan, making it suitable for the production of high value-added medical textiles.