Tarannum Afrin

Application of anisotropic silver nanoparticles: Multifunctionalization of wool fabric

Anisotropic silver nanoparticles (NPs) were successfully employed to color the wool fabrics in this study. The modified wool fabrics exhibited brilliant colors due to the localized surface plasmon resonance (LSPR) properties of silver NPs. The colors of wool fabrics altered with the morphologies of silver NPs. These modified wool fabrics were characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The results indicated that anisotropic silver NPs were effectively assembled on the surface of wool fibers when the solution pH and temperature was about 4 and 40°C, respectively. This assembling of silver NPs on the wool fibers was realized by the electrostatic interaction between wool fibers and silver NPs. This technique was also applied to gold NPs. The fabrics treated with anisotropic silver NPs showed high antibacterial activity against the bacteria of Escherichia coli. This study opens a new approach to color and functionalize conventional textile materials.

Facts and myths of antibacterial properties of silk

Silk cocoons provide protection to silkworm from biotic and abiotic hazards during the immobile pupal phase of the lifecycle of silkworms. Protection is particularly important for the wild silk cocoons reared in an open and harsh environment. To understand whether some of the cocoon components resist growth of microorganisms, in vitro studies were performed using gram negative bacteria Escherichia coli (E. coli) to investigate antibacterial properties of silk fiber, silk gum, and calcium oxalate crystals embedded inside some cocoons. The results show that the previously reported antibacterial properties of silk cocoons are actually due to residues of chemicals used to isolate/purify cocoon elements, and properly isolated silk fiber, gum, and embedded crystals free from such residues do not have inherent resistance to E. coli. This study removes the uncertainty created by previous studies over the presence of antibacterial properties of silk cocoons, particularly the silk gum and sericin.

Self-cleaning wool: effect of noble metals and silica on visible-light-induced functionalities of nano TiO2 colloid

This study intends to enhance the functionality of titanium dioxide (TiO2) nanoparticles applied to wool fabrics under visible light. Herein, TiO2, TiO2/SiO2, TiO2/Metal, and TiO2/Metal/SiO2 nanocomposite sols were synthesized and applied to wool fabrics through a low-temperature sol–gel method. The impacts of three types of noble metals, namely gold (Au), platinum (Pt), and silver (Ag), on the photoefficiency of TiO2 and TiO2/SiO2 under visible light were studied. Different molar ratios of Metal toTiO2 (0.01, 0.1, 0.5, and 1%) were employed in synthesizing the sols. Photocatalytic efficiency of fabrics was analyzed through monitoring the removal of red wine stain and degradation of methylene blue under simulated sunlight and visible light, respectively. Also, the antimicrobial activity against Escherichia coli (E. coli) bacterium and the mechanical properties of fabrics were investigated. Through applying binary and ternary nanocomposite sols to fabrics, an enhanced visible-light-induced self-cleaning property was imparted to wool fabrics. It was concluded that the presence of silica and optimized amount of noble metals had a synergistic impact on boosting the photocatalytic and antimicrobial activities of coated samples. The fabrics were further characterized using attenuated total reflectance, energy-dispersive X-ray spectrometry, and scanning electron microscopy images.

The origin of the antibacterial property of bamboo

Bamboo is an eco-friendly and multifunctional plant. Bamboo clothing has recently entered the textile market with a claim for its antimicrobial properties, but without scientific evidence. In this study, the antibacterial activity of plant extracts from Australian-grown bamboo (Phyllostachys pubescens) is investigated. Bamboo extracts were made using water, dimethyl sulphoxide (DMSO) and dioxane and their antibacterial properties were compared against Gram-negative bacteria, Escherichia coli. It was found that the extract made in 20% DMSO aqueous solution showed weak antibacterial activity, whereas the extract made using 90% dioxane aqueous solution exhibited strong antibacterial activity, even after 20 times dilution. The results indicate that antibacterial agents of P. pubescens are located in lignin, not in hemicellulose or other water-soluble chemical components.

UV absorption property of bamboo

This article describes ultra violet (UV) light shielding behaviour of Australian grown bamboo (Phyllostachys pubescens). Optical reflectance showed that untreated bamboo plant has UV absorption properties. To reveal the origin of the UV absorption property, its chemical components were extracted using several polar and non-polar solvents. The extracts in most of the polar and non-polar solvents showed UV absorption property. Protic polar solvents showed better ability to extract UV absorbing chemicals than aprotic and non-polar solvents, except hexane. The chemical components of bamboo were analysed by FT-IR spectroscopy and the findings were correlated with the UV absorbance characteristics. The results confirmed that the UV absorption ability of bamboo originates from nothing but lignin. It is thus indicated that the conventional methods to manufacture bamboo fibres, such as complete degumming or viscose methods, that involve the removal of lignin, cannot retain the unique UV absorption property of bamboo plant in bamboo fibres.

Enhanced antimicrobial coating on cotton and its impact on UV protection and physical characteristics

This research intends to enhance the antimicrobial activity of cotton fabrics coated with metallized TiO2-based colloids through integrating noble metals (Ag, Au) and silica in the synthesis process. Colloids were synthesized through a low-temperature sol–gel method and applied to the surface of fabrics at ambient temperature. Four molar ratios of metal to TiO2 (0.01, 0.1, 0.5 and 1%) were used in the synthesis process of colloids to elucidate the impacts of metal type and concentration on the antimicrobial activity of fabrics. The antimicrobial property of coated fabrics was studied through monitoring the growth reduction rate of Escherichia coli (E. coli) bacterium in dark. The UV protection property of coated fabrics was analyzed based on the ultraviolet protection factor (UPF) and UV transmittance rates of fabrics. Moreover, the impact of coating process on the mechanical characteristics of fabrics was examined based on changes in fabric tensile strength and air permeability. The surface morphology and elemental composition of coated fabrics were characterized using SEM images and EDS analysis, respectively. It was observed that the presence of noble metals significantly enhanced the antimicrobial property of fabrics particularly for samples coated with Ag-modified colloids. Also, the presence of metals and silica showed positive and negative impacts on UPF values of fabrics, respectively. While the fabrics’ tensile strength improved, the air permeability decreased to some extent after coating. The role of influencing parameters such as the type and concentration of metals, the presence of silica, and the associated mechanisms were discussed.

Properties of bamboo fibres produced using an environmentally benign method

The properties of bamboo fibres extracted from raw bamboo plants in an environmentally benign manner were investigated. To reduce environmental impacts of the manufacturing process, microwave, ultra-sonication and enzyme were used to extract the bamboo fibres, avoiding the use of hazardous chemicals. The new method enabled the extraction of single fibres while retaining a certain quantity of lignin in fibre. The retained lignin allowed the fibre to possess UV absorption and antibacterial properties, which will be advantageous for many textile applications.