Natural Fibre Textile Nano-Level Surface Modification

A variety of applications requires production of textile materials with specially designed surface properties. Surface coating by metallic materials have attracted a lot of attention due to their special surface properties, such as UV-absorbsion, antimicrobial, anti-fungicidal and ect. The paper describes the process of vacuum evaporation and magnetron sputtering of copper layers on cotton textile materials and analysis of the metal coated textile surface morphology by laser laboratory complex. The textile samples have been finished by magnetron sputtering and vacuum evaporation technologies and tested for bonding strength, light reflection and light passing properties. The paper presents and discusses the results of the experiment

Straightforward Approach for Preparing Durable Antibacterial ZnO Nanoparticle Coatings on Flexible Substrates

Flexible antibacterial materials have gained utmost importance in protection from the distribution of bacteria and viruses due to the exceptional variety of applications. Herein, we demonstrate a readily scalable and rapid single-step approach for producing durable ZnO nanoparticle antibacterial coating on flexible polymer substrates at room temperature. Substrates used are polystyrene, poly(ethylene-co-vinyl acetate) copolymer, poly(methyl methacrylate), polypropylene, high density polyethylene and a commercial acrylate type adhesive tape. The deposition was achieved by a spin-coating process using a slurry of ZnO nanoparticles in toluene. A stable modification layer was obtained when toluene was a solvent for the polymer substrates, namely polystyrene and poly(ethylene-co-vinyl acetate). These coatings show high antibacterial efficiency causing >5 log decrease in the viable counts of Gram-negative bacteria Escherichia. coli and Gram-positive bacteria Staphylococcus aureus in 120 min. Even after tapping these coated surfaces 500 times, the antibacterial properties remained unchanged, showing that the coating obtained by the presented method is very robust. In contrast to the above findings, the coatings are unstable when toluene is not a solvent for the substrate. © 2022 by the authors. --//-- This is an open access article Šutka A, Mežule L, Denisova V, Meier-Haack J, Kulkarni A, Bitina S, Smits K, Vihodceva S., "Straightforward Approach for Preparing Durable Antibacterial ZnO Nanoparticle Coatings on Flexible Substrates", Molecules, 2022 Nov 8;27(22):7672, doi: 10.3390/molecules27227672 published under the CC BY 4.0 licence.ERA-NET Cofound M-era.Net Project CaFeOx No. ES RTD/2021/11; Institute of Solid-State Physics, University of Latvia has received funding from the European Union's Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-Teaming Phase 2 under grant agreement No. 739508, project CAMART2

Straightforward Approach for Preparing Durable Antibacterial ZnO Nanoparticle Coatings on Flexible Substrates

Flexible antibacterial materials have gained utmost importance in protection from the distribution of bacteria and viruses due to the exceptional variety of applications. Herein, we demonstrate a readily scalable and rapid single-step approach for producing durable ZnO nanoparticle antibacterial coating on flexible polymer substrates at room temperature. Substrates used are polystyrene, poly(ethylene-co-vinyl acetate) copolymer, poly(methyl methacrylate), polypropylene, high density polyethylene and a commercial acrylate type adhesive tape. The deposition was achieved by a spin-coating process using a slurry of ZnO nanoparticles in toluene. A stable modification layer was obtained when toluene was a solvent for the polymer substrates, namely polystyrene and poly(ethylene-co-vinyl acetate). These coatings show high antibacterial efficiency causing >5 log decrease in the viable counts of Gram-negative bacteria Escherichia. coli and Gram-positive bacteria Staphylococcus aureus in 120 min. Even after tapping these coated surfaces 500 times, the antibacterial properties remained unchanged, showing that the coating obtained by the presented method is very robust. In contrast to the above findings, the coatings are unstable when toluene is not a solvent for the substrate

Identifying iron-bearing nanoparticle precursor for thermal transformation into the highly active hematite photo-fenton catalyst

Funding: This reseach was funded by the European Regional Development Fund within the Activity 1.1.1.2 “Post-doctoral Research Aid” of the Specific Aid Objective 1.1.1 “To increase the research and innovative capacity of scientific institutions of Latvia and the ability to attract external financing, investing in human resources and infrastructure” of the Operational Programme “Growth and Employment” (No. 1.1.1.2/VIAA/1/16/157).The hematite photo-Fenton catalysis has attracted increasing attention because it offers strong oxidation of organic pollutants under visible light at neutral pH. In the present work, aqueous synthesis of hematite photo-Fenton catalysts with high activity is demonstrated. We compare photo-Fenton activity for hematite obtained by hydrolyzation at 60◦C or by a thermally induced transformation from iron-bearing nanoparticles, such as amorphous iron oxyhydroxide or goethite. A link between their structure and visible light photo-Fenton reactivity is established. The highest activity was observed for hematite obtained from goethite nanowires due to oblong platelet-like structure, high surface area and the presence of nanopores.European Regional Development Fund 1.1.1.2/VIAA/1/16/157; Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART

Antibacterial Activity of Positively and Negatively Charged Hematite (α-Fe2O3) Nanoparticles to Escherichia coli, Staphylococcus aureus and Vibrio fischeri

In the current study, the antibacterial activity of positively and negatively charged spherical hematite (α-Fe2O3) nanoparticles (NPs) with primary size of 45 and 70 nm was evaluated against clinically relevant bacteria Escherichia coli (gram-negative) and Staphylococcus aureus (gram-positive) as well as against naturally bioluminescent bacteria Vibrio fischeri (an ecotoxicological model organism). α-Fe2O3 NPs were synthesized using a simple green hydrothermal method and the surface charge was altered via citrate coating. To minimize the interference of testing environment with NP’s physic-chemical properties, E. coli and S. aureus were exposed to NPs in deionized water for 30 min and 24 h, covering concentrations from 1 to 1000 mg/L. The growth inhibition was evaluated following the postexposure colony-forming ability of bacteria on toxicant-free agar plates. The positively charged α-Fe2O3 at concentrations from 100 mg/L upwards showed inhibitory activity towards E. coli already after 30 min of contact. Extending the exposure to 24 h caused total inhibition of growth at 100 mg/L. Bactericidal activity of positively charged hematite NPs against S. aureus was not observed up to 1000 mg/L. Differently from positively charged hematite NPs, negatively charged citrate-coated α-Fe2O3 NPs did not exhibit any antibacterial activity against E. coli and S. aureus even at 1000 mg/L. Confocal laser scanning microscopy and flow cytometer analysis showed that bacteria were more tightly associated with positively charged α-Fe2O3 NPs than with negatively charged citrate-coated α-Fe2O3 NPs. Moreover, the observed associations were more evident in the case of E. coli than S. aureus, being coherent with the toxicity results. Vibrio fischeri bioluminescence inhibition assays (exposure medium 2% NaCl) and colony forming ability on agar plates showed no (eco)toxicity of α-Fe2O3 (EC50 and MBC > 1000 mg/L)

Sol-Gel Method for Protective Textiles Processing

Zinc oxide show high absorption in the ultraviolet (UV) region of the light spectrum, while absorption of visible light is quite low. In comparison with organic absorbers conventionally used in the textile industry, inorganic materials show no significant degradation, are therefore extremely stable and the oxides are classified as non-toxic materials. In this research natural textiles were modified by the nanosol to impart UV radiation and antimicrobial protection property to the fabric surface. Nanosols were prepared by using the sol-gel method.The sol-gel method for nanosol preparation used in this research to implement ZnO coating on the fabric surface is a simple process that can be easily transferred to the textile industry, nanosol can be also applied by conventional coatings techniques used in the textile industry – the application can be implemented by simple dipping or spraying process. Scanning electron microscopy was used to examine the nature of the surface modification with ZnO coating by nanosol as also after exploitation of samples; energy dispersive X-ray spectroscopy was used for the analysis of elemental composition of coated fabric samples

Dipping Time Influence on the UV Properties of Natural Textiles Treated via Sol-gel Method

In this study lightweight 100% cotton fabric was successfully modified by the sol-gel method to impart high ultraviolet radiation (UVR) blocking property to the fabric surface. The cotton fabric was dipped in the nanosol solution for 1, 5 and 10 minutes, dried at 90ºC for 10 minutes with thermal post-treatment at 120ºC for 2 minutes. Comparison of coatings of samples prepared using different dipping time was made. The durability of the treatment was investigated by performing repeated home laundering. Excellent durability of the treatment was obtained, which indicates about good adhesion between the coating and the fabric surface. Before and after laundering tests ultraviolet protective properties of the textile samples were determined according to the standard, results of samples with dipping time 10 minutes show that textiles after treatment with nanosol have excellent ultraviolet protection properties, as well after laundering tests (50 washing-drying cycles) still provide excellent ultraviolet protection

Modification of the Cotton Textile Surfaces by the Depositing of Thin Coatings Using the Sol-Gel Method

In the present research the raw and the commercial types of cotton textile were modified by the sol-gel method to evaluate sol-gel technology suitability for different types of cotton textile. The nanosol was de-posited on the cotton textile by dipping process. The evaluation of the dipping process for thin zinc oxide coating deposition was made. The sol-gel method for nanosol preparation used in this research to imple-ment zinc oxide coating on the fabric surface is a simple process that can be easily transferred to the textile industry, nanosol can be also applied by conventional coatings techniques used in the textile industry – the application can be implemented by simple dipping process. The zinc oxide coatings were deposited on the textile surface by sol-gel method without deterioration of textile intrinsic properties, such as flexibility, softness and etc. The analysis of the coated textile surface was carried out by scanning electron microscope (SEM) and energy dispersive X-ray (EDX) spectroscopy. Data received by SEM and EDX analyses evince that the deposited coatings are evenly distributed, not only on surface of yarns but in the depth of textile material as well and resistant to the exploitation impact (laundry test)

Improvement of UV Protection Properties of the Textile from Natural Fibres by the Sol-Gel Method

In this research pure cotton textile has been modified by the sol-gel technology to implement zinc oxide nanolevel coating on textile surface to ensure ultraviolet (UV) radiation protection. One of the advantages of this method is the possibility to obtain thin layers on various materials, as well as the sol-gel layers can cover all fibres with enough high adhesion. Comparison of coatings of samples prepared using different concentrations of TEOS in nano-sols and thermal post-treatment of samples was made. Scanning electron microscopy (SEM) has been used to examine the nature of the surface modification after textile coating and laundering tests. Before and after laundering UV protective properties of the fabric samples were determined according to the standard, results show that textiles after treatment with nano-sol have excellent UV protection properties (UPF rating 50+ according to the standard - excellent protection). Analyses based on the SEM and spectrophotometer measurements show that obtained textile coatings are distributed evenly, not only on surface of yarns but in the depth of textile material as well, and are resistant to exploitation processes. After 50 drying-washing cycles defects of coatings not observed, the UPF ratings are still 50+ UPF that testify that treated fabric after exploitation simulation still provide excellent UV protection