A review on the application of inorganic nano-structured materials in the modification of textiles: focus on anti-microbial properties

In vitro and in vivo assessments of inspired Ag/80S bioactive nanocomposites against carbapenem-resistant Klebsiella pneumoniae

In 2017 the World Health Organization listed carbapenem-resistant K. pneumoniae as a critical priority for developing a novel antimicrobial agent. Here we report on our investigation of the antibacterial efficacy of silver nanoparticles (AgNPs), confined to a mesostructured material and designated as an Ag/80S bioactive nanocomposite, against carbapenem-resistant K. pneumoniae. Results from a textural analysis indicate a 7.5 nm mesopore size and 307.6 m²/g surface area for Ag/80S. UV-Vis spectrum and transmission electron microscope images of Ag/80S revealed a uniform AgNP size distribution with an approximately 3.5 nm average. ICP-MS analysis demonstrated a significantly higher silver content in TSB (a protein-rich environment) compared to ultrapure water, suggesting a controllable release of Ag/80S and thus designated as the inspired Ag/80S. Minimum inhibitory concentration (MIC) values against 16 K. pneumoniae isolates ranged from 0.25 to 0.5% (2.5 to 5.0 mg/ml). NIH 3T3 fibroblast viability at 0.25% exceeded 80% and at 0.5% just under 70%, suggesting low cytotoxicity. Mechanistic study results indicate that the inspired Ag/80S attached to and deformed bacterial cells and induced a time-dependent accumulation of reactive oxygen species, leading to bacterial death. Further, inspired Ag/80S significantly extended median survival time in a Caenorhabditis elegans animal model infected with carbapenem-resistant K. pneumoniae ATCC BAA-1705. Combined, we found a novel Ag/80S which could prevent aggregation of AgNP and control its release via a specific environment for medical use against carbapenem-resistant K. pneumoniae.

Altered protein S-glutathionylation depicts redox imbalance triggered by transition metal oxide nanoparticles in a breastfeeding system

Nanosafety has become a public concern following nanotechnology development. By now, attention has seldom been paid to breastfeeding system, which is constructed by mammary physiological structure and derived substances (endogenous or exogenous), cells, tissues, organs, and individuals (mother and child), connecting environment and organism, and spans across mother-child dyad. Thus, breastfeeding system is a center of nutrients transport and a unique window of toxic susceptibility in the mother-child dyad. We applied metabolomics combined with redox proteomics to depict how nanoparticles cause metabolic burden via their spontaneous redox cycling in lactating mammary glands. Two widely used nanoparticles [titanium dioxide (nTiO₂) and zinc oxide (nZnO)] were exposed to lactating mice via intranasal administration. Biodistribution and biopersistence of nTiO₂ and nZnO in mammary glands destroyed its structure, reflective of significantly reduced claudin-3 protein level by 32.1% (P < 0.01) and 47.8% (P < 0.01), and significantly increased apoptosis index by 85.7 (P < 0.01) and 100.3 (P < 0.01) fold change, respectively. Airway exposure of nTiO₂ trended to reduced milk production by 22.7% (P = 0.06), while nZnO significantly reduced milk production by 33.0% (P < 0.01). Metabolomics analysis revealed a metabolic shift by nTiO₂ or nZnO, such as increased glycolysis (nTiO₂: fold enrichment = 3.31, P < 0.05; nZnO: fold enrichment = 3.68, P < 0.05), glutathione metabolism (nTiO₂: fold enrichment = 5.57, P < 0.01; nZnO: fold enrichment = 4.43, P < 0.05), and fatty acid biosynthesis (nTiO₂: fold enrichment = 3.52, P < 0.05; nZnO: fold enrichment = 3.51, P < 0.05) for tissue repair at expense of lower milk fat synthesis (35.7% reduction by nTiO₂; 51.8% reduction by nZnO), and finally led to oxidative stress of mammary glands. The increased GSSG/GSH ratio (57.5% increase by nTiO₂; 105% increase by nZnO) with nanoparticle exposure confirmed an alteration in the redox state and a metabolic shift in mammary glands. Redox proteomics showed that nanoparticles induced S-glutathionylation (SSG) modification at Cys sites of proteins in a nanoparticle type-dependent manner. The nTiO₂ induced more protein SSG modification sites (nTiO₂: 21; nZnO:16), whereas nZnO induced fewer protein SSG modification sites but at deeper SSG levels (26.6% higher in average of nZnO than that of nTiO₂). In detail, SSG modification by nTiO₂ was characterized by Ltf at Cys⁴²³ (25.3% increase), and Trf at Cys^386;395;583 (42.3%, 42.3%, 22.8% increase) compared with control group. While, SSG modification by nZnO was characterized by Trfc at Cys³⁶⁵ (71.3% increase) and Fasn at Cys¹⁰¹⁰ (41.0% increase). The discovery of SSG-modified proteins under airway nanoparticle exposure further supplemented the oxidative stress index and mammary injury index, and deciphered precise mechanisms of nanotoxicity into a molecular level. The unique quantitative site-specific redox proteomics and metabolomics can serve as a new technique to identify nanotoxicity and provide deep insights into nanoparticle-triggered oxidative stress, contributing to a healthy breastfeeding environment.

Cotton decorated with Cu2O-Ag and Cu2O-Ag-AgBr NPs via an in-situ sacrificial template approach and their antibacterial efficiency

Cotton fabrics decorated with Cu₂O-Ag and Cu₂O-Ag-AgBr NPs have been prepared using chemically immobilized Cu₂O NPs as sacrificial templates. The objective is to prepare Cu₂O-Ag heterostructures with Ag being intimately in contact with Cu₂O NPs by galvanic replacement reactions without addition of any external reducing agent. Field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) analysis were used to study the morphology and the chemical composition of the nanocomposites formed on the fabrics. The morphology of the ensuing nanostructures was shown to be dependent on the Ag precursor, AgNO₃, concentration. The antimicrobial activity of the treated fabrics was evaluated against Staphylococcus aureus and Escherichia coli as model strains of gram-negative and gram-positive, respectively. The results showed that the fabrics loaded with Cu₂O-Ag and Cu₂O-Ag-AgBr nanocomposites exhibited enhanced sterilization activity compared to the Cu₂O treated fabric.

Antibacterial activity of an NIR-induced Zn ion release film

Photothermal therapy originated from using gold nanorods (GNRs) and near-infrared (NIR) irradiation has been widely used in the antibacterial field. Zn element exhibits antimicrobial activity against various bacterial and fungal strains. In this study, a bilayer film, consisting of GNRs as the inner layer and a polydopamine layer containing Zn element (PDA@Zn) as the outer layer, was deposited on the Ti surface. The results testified that all the GNR-modified surfaces had the same photothermal conversion efficiency. The Ti surface modified with GNR and PDA@Zn layers had better antibacterial activity against E. coli and S. aureus due to the GNR-induced photothermal effect and the antibacterial Zn element. Moreover, the accelerated release of Zn ions from the PDA@Zn layer was attributed to the GNR-induced high temperature under the NIR irradiation, which caused the concentration of Zn ions to be high enough to kill the surrounding bacteria. This study illustrates that a composite surface possessing both the contact and heat-responsive antibacterial property was constructed on titanium for potential clinical applications.

Analysis of Surface Properties of Ag and Ti Ion-Treated Medical Textiles by Metal Vapor Vacuum Arc Ion Implantation

The study focuses on the effects of Ag (silver) and Ti (titanium) ions on textiles by MEVVA (metal vapor vacuum arc) ion implantation. In order to comprehend this, the research was executed in three parts. In the first part, the antibacterial efficiencies of Ag and TiO2 were investigated in detail since the antibacterial capabilities of Ag and TiO2 are well known. A group of polyester- and cotton-based medical textiles were modified by Ag and TiO2 ions, with doses ranging from 5 × 1015 to 5 × 1016 ion/cm2. To determine the adhesion capabilities of the implanted ions on surfaces, after the first round of antibacterial tests, these medical textiles were washed 30 times, and then antibacterial tests were performed for the second time. The results were also compared with nanoparticle-treated medical textiles. In the second part, the corrosion and friction capabilities of Ag and Ti ion-implanted polyester textiles, with a dose of 5 × 1015 ion/cm2, were investigated. Finally, the UV protection capabilities of Ag and Ti ion-implanted polyester textiles, with a dose of 5 × 1015 ion/cm2, were investigated. The experiments showed that even after 30 washes, the TiO2 ion-implanted polyester textile had almost 85% antibacterial efficiency. In addition, Ti ion implantation reduced the friction coefficiency of a polyester textile by almost 50% when compared with an untreated textile. Finally, the Ag-ion-implanted polyester textile provided a UV protection factor of 30, which is classified as very good protection.

Preparation of pH-Responsive Dual-Compartmental Microcapsules via Pickering Emulsion and Their Application in Multifunctional Textiles

Currently, smart and functional textiles have attracted increasing attention for the research on their application in various fields. In this paper, perfluorooctyltriethoxysilane (FAS13)-loaded silica nanocapsules taken as the Pickering emulsifier was applied to stabilize O/W emulsion for obtaining pH-responsive dual-compartmental microcapsules which show a strawberry-like structure with jasmine essence as the core and pH-responsive polymers and silica nanocapsules as the shell. These microcapsules could endow it with multifunctions by functionalizing the fabric, while the preparation and functionalization process is effortless and environmental friendly. Not only does the treated fabric demonstrate the self-healing superhydrophobicity and ultraviolet (UV) resistance because of the hydrophobic FAS13 getting loaded into silica nanocapsules and the surface modification of UV absorbent, it is also capable of the pH control jasmine essence-releasing performance, which allows over 40% of the fragrance to be preserved for three months through the controlled release of jasmine essence from the microcapsules.

Antibacterial cotton fabric prepared by surface-initiated photochemically induced atom transfer radical polymerization of 2-(dimethylamino)ethyl methacrylate with subsequent quaternization

Antibacterial highly grafted cotton fabric with good laundry resistance was prepared using photoATRP in the presence of air.

Enhancement of antibacterial property of titanium by two-step micro arc oxidation treatment

A customized micro arc oxidation (MAO) treatment technique was developed to obtain desirable antibacterial properties on titanium surfaces. The two-step MAO treatment was applied to fabricate a specimen containing both Ag and Zn in its surface oxide layer. Surface analyses and metal-ion release tests were performed to evaluate the presence of Ag and Zn and the ion release behavior for simulating practical usage, respectively. Additionally, the antibacterial properties of the specimens were also evaluated using gram-negative facultative anaerobic bacteria. The MAO-treated specimens containing both Ag and Zn showed excellent antibacterial properties against Escherichia coli, and the properties were sustained even after 28 days of immersion in physiological saline to simulate the living environment.

Antioxidant, Antimicrobial and Antiviral Properties of Herbal Materials

Recently, increasing public concern about hygiene has been driving many studies to investigate antimicrobial and antiviral agents. However, the use of any antimicrobial agents must be limited due to their possible toxic or harmful effects. In recent years, due to previous antibiotics' lesser side effects, the use of herbal materials instead of synthetic or chemical drugs is increasing. Herbal materials are found in medicines. Herbs can be used in the form of plant extracts or as their active components. Furthermore, most of the world's populations used herbal materials due to their strong antimicrobial properties and primary healthcare benefits. For example, herbs are an excellent material to replace nanosilver as an antibiotic and antiviral agent. The use of nanosilver involves an ROS-mediated mechanism that might lead to oxidative stress-related cancer, cytotoxicity, and heart diseases. Oxidative stress further leads to increased ROS production and also delays the cellular processes involved in wound healing. Therefore, existing antibiotic drugs can be replaced with biomaterials such as herbal medicine with high antimicrobial, antiviral, and antioxidant activity. This review paper highlights the antibacterial, antiviral, and radical scavenger (antioxidant) properties of herbal materials. Antimicrobial activity, radical scavenger ability, the potential for antimicrobial, antiviral, and anticancer agents, and efficacy in eliminating bacteria and viruses and scavenging free radicals in herbal materials are discussed in this review. The presented herbal antimicrobial agents in this review include clove, portulaca, tribulus, eryngium, cinnamon, turmeric, ginger, thyme, pennyroyal, mint, fennel, chamomile, burdock, eucalyptus, primrose, lemon balm, mallow, and garlic, which are all summarized.

Presence of Titanium and Toxic Effects Observed in Rat Lungs, Kidneys, and Central Nervous System in vivo and in Cultured Astrocytes in vitro on Exposure by Titanium Dioxide Nanorods

BACKGROUND

Non-spherical titanium dioxide (TiO2) nanoparticles have been increasingly applied in various biomedical and technological fields. Their toxicological characterization is, however, less complete than that of roundish nanoparticles.

MATERIALS AND METHODS

Anatase form TiO2 nanorods, ca. 15x65 nm in size, were applied to cultured astrocytes in vitro and to the airways of young adult Wistar rats in vivo in 5, 10, and 8 mg/kg BW dose for altogether 28 days. Presence of nanorods and cellular damage was investigated in the astrocytes and in rat lungs and kidneys. Functional damage of the nervous system was studied by electrophysiological methods.

RESULTS

The treated astrocytes showed loss of viability without detectable apoptosis. In rats, TiO2 nanorods applied to the airways reached the blood and various organs including the lungs, kidneys, and the central nervous system. In lung and kidney samples, nanorods were observed within (partly damaged) phagolysosomes and attached to organelles, and apoptotic cell death was also detected. In cortical and peripheral electrophysiological activity, alterations corresponding to energy shortage (resulting possibly from mitochondrial damage) and astrocytic dysfunction were detected. Local titanium levels and relative weight of the investigated organs, apoptotic cell death in the lungs and kidneys, and changes in the central and peripheral nervous activity were mostly proportional to the applied doses, and viability loss of the cultured astrocytes was also dose-dependent, suggesting causal relationship of treatments and effects.

CONCLUSION

Based on localization of the visualized nanorods, on neuro-functional changes, and on literature data, the toxic mechanism involved mitochondrial damage, oxidative stress, and apoptotic cell death. These indicate potential human toxicity and occupational risk in case of exposure to rod-shaped TiO2 nanoparticles.

The application of antimicrobial photodynamic inactivation on methicillin-resistant S. aureus and ESBL-producing K. pneumoniae using porphyrin photosensitizer in combination with silver nanoparticles

As resistance of bacterial strains to antibiotics is a major problem, there is a need to look for alternative treatments. One option is antimicrobial photodynamic inactivation (aPDI). The pathogenic cells are targeted by a nontoxic photosensitizer while the surrounding healthy tissue is relatively unaffected. The photosensitizer is activated by light of t appropriate wavelength resulting in the generation of reactive oxygen species that are cytotoxic for the pathogens. In this work, the photosensitizer TMPyP and silver nanoparticles (AgNPs) were investigated for their synergistic antibacterial effect. We tested these two substances on two bacterial strains, methicillin-resistant Staphylococcus aureus 4591 (MRSA) and extended-spectrum beta-lactamases-producing Klebsiella pneumoniae 2486 (ESBL-KP), to compare their effectiveness. The bacteria were first incubated with TMPyP for 45 min or 5 h, then irradiated with a LED source with the total fluence of 10 or 20 J/cm² and then placed in a microbiological growth medium supplemented with AgNPs. To accomplish the synergistic effect, the optimal combination of TMPyP and AgNPs was estimated as 1.56-25 μM for TMPyP and 3.38 mg/l for AgNPs in case of MRSA and 1.56-50 μM for TMPyP and 3.38 mg/l for AgNPs in case of ESBL-KP at 45 min incubation with TMPyP and fluence of 10 J/cm². Longer incubation and/or longer irradiation led to a decrease in the maximum values of the photosensitizer concentration to produce the synergistic effect. From this work it can be concluded that the combination of antimicrobial photodynamic inactivation with a treatment including silver nanoparticles could be a promising approach to treat bacterial infection.

Inorganic nanomaterials for fighting surface and airborne pathogens and viruses

Nowadays, the deadly viruses (including the latest coronavirus) and pathogens transmission became the major concern worldwide. Efforts have been made to combat with these fatal germs transmitted by the airborne, human-to-human contacts and contaminated surfaces. Thus, the antibacterial and antiviral materials have been widely researched. Meanwhile, the development of diverse nanomaterials with the antiviral traits provided several benefits to counter the threats from the surface and airborne viruses especially during the Covid-19 pandemic. Based on these facts, this paper overviewed the advantages of various nanomaterials that can disinfect and deactivate different lethal viruses transmitted through the air and surfaces. The past development, recent progress, future trends, environmental impacts, biocidal effects and prospects of these nanomaterials for the antiviral coating applications have been emphasized.

Green synthesis of spongy Nano-ZnO productive of hydroxyl radicals for unconventional solar-driven photocatalytic remediation of antibiotic enriched wastewater

Herein, novel green/facile approach to synthesize spongy defective zinc oxide nanoparticles (ZnONPs) is presented using for the first time pomegranate seeds molasses as a green capping fuel/reducing mediator during an aqueous solution combustion process. The developed ZnONPs is characterized by UV-Vis. Spectrophotometry and fluorimetry, XRD, Raman spectroscopy, SEM, TEM and BET. Interestingly, pomegranate seeds molasses within a viable content of bio-capping molecules reveal a defective nanoporous ZnO NPs of smaller particle size, greater pore size/volume, and higher surface area compared to the bulky non-biogenic ZnONPs. Moreover, the biosynthesized defective ZnONPs showed narrowed band gap and higher absorption of visible photons that breed higher density of hydroxyl radicals (^•OH) under Solar-illumination. Even further, the bulk ZnO and the biosynthesized ZnO photocatalysts were examined in photodegrading flumequine (FL) antibiotic. The bulk ZnO gives 41.46% photodegradation efficiency compared to 97.6% for the biosynthesized ZnO. In highly acidic or highly alkaline media, FL photodegradability is greatly retarded. Scavenging experiment infers considerable contribution of holes over electrons in photodegradation reaction. The biosynthesized ZnO shows high durability in FL photodegradation after four reusing cycles. These promising findings highlight new insights for biogenic synthesis of tuned size/controlled morphology semiconductor NPs relevant to environmental remediation applications.

Green Synthesis, Characterization & Antibacterial Studies of Silver (Ag) and Zinc Oxide (Zno) Nanoparticles

Green synthesis nanoparticles were considered as an alternative effective resource instead of chemically engineered metal oxide nanoparticles. Using leaf extracts for green synthesis, essential for the reduction and oxidation process of the metals. Phyllanthus niruri (L.) and Aristolochia indica (L.) leaf extracts were used to synthesize yellowish brown coloured silver (Ag) and white coloured zinc oxide (ZnO) nanoparticles. Synthesized green nanoparticles characterized by different spectroscopic analysis (XRD, XPS, FTIR, PL) and TEM. Characterization results confirmed the particles morphology, size, structure and also their optical and photonic properties. Three different concentrations of Ag and ZnO NPs were analysed against three (gram positive) and five (gram negative) bacteria. Increased levels of green synthesized Ag and ZnO NPs showed increased zone of inhibition than amoxicillin (positive control). Our study proved that the green synthesized Ag and ZnO NPs showed similar unique physical and chemical properties with metal oxide nanoparticles but less toxic while their discharge into the ecosystem.

Microwave assisted urethane grafted nano-apatites for dental adhesives

The objectives were to synthesize urethane grafted nano-apatite in shortest possible time duration using the microwave irradiation method and to utilize them for synthesis of experimental dental adhesives. The structural, morphological, thermal, and mechanical behavior of synthesized grafted nano-apatite were investigated. Then, these grafted nano-apatite particles were incorporated in various concentrations that is, 5wt.%, 10wt.%, and 15wt.% into dimethacrylate resins to develop bioactive adhesives. The weight measurement analysis in deionized water and phosphate buffer saline, Knoop micro-hardness, and degree of conversion were evaluated. The bacterial adhesion was investigated with Streptococcus mutans at 6h, 24h, and 48h. Statistical analysis was conducted using one-way ANOVA. The urethane dimethacrylate was successfully grafted on the nano-apatite surface and spectroscopic analysis confirmed the presence of urethane and phosphate peaks. An inverse relationship was found in both media between the concentration of grafted fillers and weight loss. No significant difference was observed in the micro-hardness and degree of conversion among the groups, whereby the degree of conversion for all groups was in the range of 83% to 86%. The mean number of bacterial colonies was significantly lower in the 15wt.% group compared to 5wt.% and 10wt.%. The grafted nano-apatite presented favorable results for adhesive resin incorporation, where 15wt.% group comparatively showed superior results than other groups.

Surface functionalization of wool via microbial-transglutaminase and bentonite as bio-nano-mordant to achieve multi objective wool and improve dyeability with madder

Recently, natural dyes have a widening scope in various traditional and advanced applications due to their eco-friendly environment. However, improved dyeability of natural dyes still remains a challenging task. This research was aimed to achieve multi-objective wool with improved dyeability using bio-nano-mordant composed of m-Trans-glutaminase, m-TGase, and bentonite nanoclay. Wool fiber was treated through sonochemical method using different concentrations of m-TGase and bentonite. The surface morphology of wool fabric samples was examined by field emission-scanning electron microscopy (FESEM), and Fourier transform Infrared Radiation (FTIR). Further, wool samples treated at different conditions were applied to madder for dyeability examination. The optimum conditions of color coordinates, color strength, K/S, and washing fastness of madder on treated wool fabric with m-TGase and bentonite, were also examined. The results revealed well-made interactions among m-TGase, bentonite, and wool fibers. In addition, surface morphology was strongly influenced by variations in enzyme concentrations so that extra addition of m-TGase lead to clear damage scales or less cuticle surface in SEM images. Moreover, the results showed that the value of K/S for treated wool samples was better than untreated samples. Indeed, amongst all, 5% concentrations of bio-nano-mordant for m-TGase and bentonite have the most constructive K/S values. Similarly, results of ΔE and antibacterial investigations also confirmed its superiority.

Investigation of Biocidal Effect of Microfiltration Membranes Impregnated with Silver Nanoparticles by Sputtering Technique

Silver nanoparticles were loaded in microfiltration membranes by sputtering technique for the development of biocidal properties and biofouling resistance. This technology allows good adhesion between silver nanoparticles and the membranes, and fast deposition rate. The microfiltration membranes (15 wt.% polyethersulfone and 7.5 wt.% polyvinylpyrrolidone in N,N-dimethylacetamide) were prepared by phase inversion method, and silver nanoparticles were deposited on their surface by the physical technique of vapor deposition in a sputtering chamber. The membranes were characterized by Field Emission Scanning Electron Microscopy, and the presence of silver was investigated by Energy-Dispersive Spectroscopy and X-ray Diffraction. Experiments of silver leaching were carried out through immersion and filtration tests. After 10 months of immersion in water, the membranes still presented ~90% of the initial silver, which confirms the efficiency of the sputtering technique. Moreover, convective experiments indicated that 98.8% of silver remained in the membrane after 24 h of operation. Biocidal analyses (disc diffusion method and biofouling resistance) were performed against Pseudomonas aeruginosa and confirmed the antibacterial activity of these membranes with 0.6 and 0.7 log reduction of viable planktonic and sessile cells, respectively. These results indicate the great potential of these new membranes to reduce biofouling effects.

Synthesis of nickel nanoparticles by a green and convenient method as a magnetic mirror with antibacterial activities

In this work, a simple protocol was described for the synthesis of nickel magnetic mirror nanoparticles (NMMNPs) including antibacterial activities. The identification of NMNPs was carried out by field-emission scanning electron microscopy (FESEM) images, energy-dispersive X-ray (EDX) analysis, X-ray diffraction (XRD) pattern, transmission electron microscopy (TEM) images and vibrating sample magnetometer (VSM) curve. The antibacterial activities are investigated against S. aureus and E. coli as the Gram-positive and Gram-negative bacteria, respectively. The UV-Vis absorption was also studied in the present of NMMNPs at different time intervals that disclosed decreasing of the bacterial concentration. More than 80% of the bacteria were disappeared after treating in the presence of NMMNPs for 18 h. The Ni-NPs revealed an excellent mirror attribute with a well-controlled transmission (7%). A better light-reflectivity over conventional glass or a mercury mirror proved their utility for domestic uses in comparison with conventional mirrors as rather toxic materials like mercury. Owing to its magnetic properties, this kind of mirror can be easily made onto glass by using an external magnet. An ordered crystalline structure, admissible magnetic properties, substantial antibacterial activities, tunable mirror properties, mild reaction conditions, and overall, the facile synthesis are the specific features of the present protocol for the possible uses of NMMNPs in diverse applications.

Silver Nanoparticles for Water Pollution Monitoring and Treatments: Ecosafety Challenge and Cellulose-Based Hybrids Solution

Silver nanoparticles (AgNPs) are widely used as engineered nanomaterials (ENMs) in many advanced nanotechnologies, due to their versatile, easy and cheap preparations combined with peculiar chemical-physical properties. Their increased production and integration in environmental applications including water treatment raise concerns for their impact on humans and the environment. An eco-design strategy that makes it possible to combine the best material performances with no risk for the natural ecosystems and living beings has been recently proposed. This review envisages potential hybrid solutions of AgNPs for water pollution monitoring and remediation to satisfy their successful, environmentally safe (ecosafe) application. Being extremely efficient in pollutants sensing and degradation, their ecosafe application can be achieved in combination with polymeric-based materials, especially with cellulose, by following an eco-design approach. In fact, (AgNPs)-cellulose hybrids have the double advantage of being easily produced using recycled material, with low costs and possible reuse, and of being ecosafe, if properly designed. An updated view of the use and prospects of these advanced hybrids AgNP-based materials is provided, which will surely speed their environmental application with consequent significant economic and environmental impact.

Transgenic and Diet-Enhanced Silk Production for Reinforced Biomaterials: A Metamaterial Perspective

Silk fibers, which are protein-based biopolymers produced by spiders and silkworms, are fascinating biomaterials that have been extensively studied for numerous biomedical applications. Silk fibers often have remarkable physical and biological properties that typical synthetic materials do not exhibit. These attributes have prompted a wide variety of silk research, including genetic engineering, biotechnological synthesis, and bioinspired fiber spinning, to produce silk proteins on a large scale and to further enhance their properties. In this review, we describe the basic properties of spider silk and silkworm silk and the important production methods for silk proteins. We discuss recent advances in reinforced silk using silkworm transgenesis and functional additive diets with a focus on biomedical applications. We also explain that reinforced silk has an analogy with metamaterials such that user-designed atypical responses can be engineered beyond what naturally occurring materials offer. These insights into reinforced silk can guide better engineering of superior synthetic biomaterials and lead to discoveries of unexplored biological and medical applications of silk.

Advances in nanomedical applications: diagnostic, therapeutic, immunization, and vaccine production

In the last decades, nanotechnology-based tools started to draw the attention of research worldwide. They offer economic, rapid, effective, and highly specific solutions for most medical issues. As a result, the international demand of nanomaterials is expanding very rapidly. It was estimated that the market of nanomaterials was about $2.6 trillion in 2015. In medicine, various applications of nanotechnology proved their potential to revolutionize medical diagnosis, immunization, treatment, and even health care products. The loading substances can be coupled with a large set of nanoparticles (NPs) by many means: chemically (conjugation), physically (encapsulation), or via adsorption. The use of the suitable loading nanosubstance depends on the application purpose. They can be used to deliver various chemicals (drugs, chemotherapeutic agents, or imaging substances), or biological substances (antigens, antibodies, RNA, or DNA) through endocytosis. They can even be used to deliver light and heat to their target cells when needed. The present review provides a brief overview about the structure and shape of available NPs and discusses their applications in the medical sciences.

Effect of Synthesis Temperature on the Size of ZnO Nanoparticles Derived from Pineapple Peel Extract and Antibacterial Activity of ZnO-Starch Nanocomposite Films

This research investigated the effect of synthesis temperature on the size and shape of zinc oxide (ZnO) nanoparticles (NPs) synthesized using pineapple peel waste and antibacterial activity of ZnO NPs in starch films. Zinc oxide NPs synthesized at different temperatures were characterized by Fourier transform infrared spectroscopy, X-ray diffraction analysis, field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, and transmission electron microscopy. Micrographs of ZnO NPs synthesized at 28 and 60 °C showed that synthesis temperature affected the sizes and shapes of ZnO NPs. The non-heated (28 °C) condition resulted in NPs with diameters in the range of 8-45 nm with a mixture of spherical and rod shapes, whereas the heated (60 °C) condition led to NPs with diameters in the range of 73-123 nm with flower rod shapes. The ZnO-starch nanocomposite films incorporated with 1, 3, and 5 wt.% ZnO NPs were prepared via a film casting method. The antibacterial activity of the films against Gram-positive and Gram-negative bacteria was investigated using the disc diffusion method. The results showed an increase in the inhibition zone for Gram-positive bacteria, particularly Bacillus subtilis, when the concentration of ZnO NPs incorporated in the film was increased from 1 to 5 wt.%.

Development of Durable Antibacterial Textile Fabrics for Potential Application in Healthcare Environment

Recently, efforts at development of functional textiles with antibacterial effect have accelerated, the purpose being to provide protection against airborne bio-particles and micro-organisms. Growth of microbes on surface of textile materials can be inhibited by biocidal approach and biostatic approach. This paper describes the development of a healthcare textile with durable antibacterial properties by optimizing the conventional and commercialized antimicrobial agent polybiguanide derivative—poly(hexamethylenebiguanide) (PHMB). Pad-dry-cure method was used to coat PHMB on cotton fabrics. The durability to simulated healthcare laundering of the fabric samples was evaluated in detail. Specifically, effects of detergent and washing cycles were examined. It was found that the optimum finishing condition can impart to the fabrics excellent durability for simulated healthcare washing. The fabric samples showed 100% bactericidal effect after 52 washing cycles, and 104 washings slightly reduced the bactericidal activity. Nevertheless, both simulated healthcare washing and coating treatment were found to have slightly negative influence on the hand feel and tearing strength properties of cotton fabrics.

Antibacterial cotton fabrics via immobilizing silver phosphate nanoparticles onto the chitosan nanofiber coating

Development of chitosan nanofiber (CNF)/nano‑silver phosphate (Ag3PO4) coatings is reported for the fabrication of antibacterial cotton fabrics. The surface morphology and chemical composition were evaluated by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), respectively. SEM results revealed that Ag3PO4 have formed micron-scale clusters and were not completely deposited on the fabric's surface whereas CNFs properly coated the fabric. However, once the hybrid of CNFs and Ag3PO4 was utilized, nanoparticles were better deposited on the fabric. The porous and nano-fibrous structure of CNFs provided an ideal substrate to which nanoparticles tightly adhered. The antibacterial activity of the as-synthesized Ag3PO4 nanoparticles was demonstrated by measuring the minimum inhibitory concentration (MIC). Moreover, the antibacterial property of the coated fabrics was demonstrated by colony counting method and zone of inhibition (ZOI). The bacterial adhesion reductions for CNF/Ag3PO4 coated fabrics were obtained as 100 and 99.8% against S. aureus and E. coli, respectively. Moreover, ZOI was highly increased in the case of the hybrid coating. The results demonstrated the promising potential of CNF/Ag3PO4 coatings for the fabrication of antibacterial cotton fabrics to be used as antibacterial garments for clinical environments.

Antifungal Activity of Magnesium Oxide Nanoparticles: Effect on the Growth and Key Virulence Factors of Candida albicans

The aim of this research was to study the effects of different concentrations of magnesium oxide nanoparticles (MgO NPs) on the growth and key virulence factors of Candida albicans (C. albicans). The minimum inhibitory concentration (MIC) of MgO NPs against C. albicans was determined by the micro-broth dilution method. A time-kill curve of MgO NPs and C. albicans was established to investigate the ageing effect of MgO NPs on C. albicans. Crystal violet staining, the MTT assay, and inverted fluorescence microscopy were employed to determine the effects of MgO NPs on C. albicans adhesion, two-phase morphological transformation, biofilm biomass, and metabolic activity. The time-kill curve showed that MgO NPs had fungicidal and antifungal activity against C. albicans in a time- and concentration-dependent manner. Semi-quantitative crystal violet staining and MTT assays showed that MgO NPs significantly inhibited C. albicans biofilm formation and metabolic activity, and the difference was statistically significant (p < 0.001). Inverted fluorescence microscopy showed that MgO NPs could inhibit the formation of C. albicans biofilm hyphae. Adhesion experiments showed that MgO NPs significantly inhibited the initial adhesion of C. albicans (p < 0.001). This study demonstrates that MgO NPs can effectively inhibit the growth, initial adhesion, two-phase morphological transformation, and biofilm formation of C. albicans and is an antifungal candidate.

Straw in Clay Bricks and Plasters-Can We Use Its Molecular Decay for Dating Purposes?

Dating of clay bricks (adobe) and plasters is a relevant topic not only for building historians in the Pannonian region. Especially in vernacular architecture in this region, clay with straw amendments is a dominant construction material. The paper presents the potential of the molecular decay of these amendments to establish prediction tools for age based on infrared spectroscopic measurements. Preliminary results revealed spectral differences between the different plant parts, especially culms, nodes, and ear spindles. Based on these results, a first prediction model is presented including 14 historic samples. The coefficient of determination for the validation reached 62.2%, the (RMSE) root mean squared error amounted to 93 years. Taking the limited sample amount and the high material heterogeneity into account, this result can be seen as a promising output. Accordingly, sample size should be increased to a minimum of 100 objects and separate models for the different plant parts should be established.

Advances in photocatalytic self-cleaning, superhydrophobic and electromagnetic interference shielding textile treatments

The use of nanomaterials in textiles provides many new opportunities and advantages for users and manufacturers; however, it comes with some of its downsides and challenges which need to be understood and overcome for enhancing the applicability of these products. This review article discusses the recent progress in developing self-cleaning and conductive textiles as two of the leading research fields of smart textiles. In particular, different aspects of fabricating nanocoatings for photocatalytic self-cleaning, superhydrophobic and electromagnetic interference (EMI) shielding effect will be brought to light. The theoretical concepts, mechanisms, latest fabrication methods along with their potential applications will be discussed. Moreover, the current drawbacks of these fields will be underlined and some recommendations for future research trajectories in terms of performance, current limitations, sustainability and safety will be proposed. This review article provides a comprehensive review on the state-of-the-art achievements in the field, which will be a valuable reference for researchers and decision makers.

Drug delivery system of dual-responsive PF127 hydrogel with polysaccharide-based nano-conjugate for textile-based transdermal therapy

Pluronic F-127 based dual-responsive (pH/temperature) hydrogel drug delivery system was developed involving polysaccharide-based nano-conjugate of hyaluronic acid and chitosan oligosaccharide lactate and applied for loading of gallic acid which is the principal component of traditional Chinese medicine Cortex Moutan recommended in the treatment of atopic dermatitis. The polysaccharide-based nano-conjugate was used as pH-responsive compound in the formulation and its amphiphilic character was determined colorimetrically. Microstructure analysis by SEM and TEM indicated highly porous hydrogel network and well-dispersed micellar structures, respectively, after modification with the nano-conjugate, and so, release property of the hydrogel for drug was significantly improved. Different pH-conditions were applied here to see pH-responsiveness of the formulation and increase in acidity of external environment gradually diminished mechanical stability of the hydrogel and that was reflected on the drug release property. Rheology was performed to observe sol-gel transition of the formulation and showed better rheological properties after modification with nano-conjugate. In this study, the cytotoxicity results of PF127 based formulations loaded with/without gallic acid showed cell viability of > 80.0 % for human HaCaT keratinocytes in the concentration range of 0.0-20.0 μg/ml.

Nano TiO2 Imparting Multifunctional Performance on Dyed Polyester Fabrics with some Disperse Dyes Using High Temperature Dyeing as an Environmentally Benign Method

Polyester fabrics were dyed with prepared disperse dyes using the high temperature dyeing method. The dye exhaustion of the dye baths were compared to the low-temperature dyeing method in an attempt to study the proportion of the dye effluent solution that affects the environment. The dye uptake of the high temperature dyeing method (HT) of polyester fabric was compared with low temperature dyeing, hence (HT) increased the color strength of the investigated dyes by 309 and 265%. This means that the amount of dye present in the dye effluents by using the high-temperature dyeing method is almost non-existent, and this is reflected positively on the environment as these wastes pollute the environment. Post-treated polyester fabric was prepared through a two-step hot process after being immersed in a solution of Titanium (IV) oxide nanoparticle sizeTiO₂ NPs (21 nm primary particle size) at 80 °C followed by curing at 140 °C. The treated fabric realized an optimum UV protection factor of 34.9 and 283.6 degrees. These fabrics also demonstrated a strong ability to improve the light fastness properties. Finally, the potential applications of such value-added fabrics as self-cleaning and antifungal activities were investigated. The results indicated that the treated dyed fabrics with TiO₂ NPs endowed fabrics with the excellent self-cleaning of methylene blue dye. From the above, the treated fabrics with nano-titanium dioxide can be used in some promising fields, for example, medical ones.

Properties of a Plasma-Nitrided Coating and a CrNx Coating on the Stainless Steel Bipolar Plate of PEMFC

PEMFC are considered to be the most promising for automotive energy because of their good working effect, low temperature, high efficiency, and zero pollution. Stainless steel as a PEMFC bipolar plate has unparalleled advantages in strength, cost, and processability, but it is easy to corrode in a PEMFC working environment. In order to improve the corrosion resistance, the surface modification of 316L stainless steel is a feasible solution for PEMFC bipolar plates. In the present study, the plasma-nitrided coating and CrNx coating were prepared by the plasma-enhanced balanced magnetron sputtering technology on the 316L stainless steel surface. The microstructures, phase compositions, and corrosion resistance behavior of the coatings were investigated. The corrosion behavior of the prepared plasma-nitrided coating and CrNx coating was investigated by potentiodynamic polarization, potentiostatic polarization, and electrochemical impedance spectroscopy (EIS) in both cathodic and anodic environments. The experimental results show that corrosion resistance of the CrNx coating was better than the plasma-nitrided coating. It was indicated that the technology process of nitriding first and then depositing Cr was better than nitriding only.

Studies of Polylactic Acid and Metal Oxide Nanoparticles-Based Composites for Multifunctional Textile Prints

A novel approach toward the production of multifunctional printed technical textiles is reported. Three different metal oxides nanoparticles including titanium dioxide, magnesium oxide, and zinc oxide were prepared and characterized. Both natural wool and synthetic acrylic fibers were pretreated with the prepared metal oxide nanoparticles followed by printing using polylactic acid based paste containing acid or basic dyestuffs. Another route was applied via post-treatment of the targeted fabrics with the metal oxide nanoparticles after running the printing process. The color strength (K/S) and colorfastness properties of pretreated and post-treated printed fabrics were evaluated and compared with untreated printed fabrics. The presence of nanoparticles on a fabric surface during the coating process was found to significantly increase the color strength value of the coated textile substrates. The increased K/S value depended mainly on the nature and concentration of the applied metal oxide, as well as the nature of colorant and fabric. In addition, the applied metal oxide nanoparticles imparted the printed fabrics with good antibacterial activity, high ultraviolet protection, photocatalytic self-cleaning, and improved colorfastness properties. Those results suggest that the applied metal oxide-based nanoparticles could introduce ideal multifunctional prints for garments.