Keratin protein nanofibers from merino wool yarn: a top-down approach for the disintegration of hierarchical wool architecture to extract α-keratin protein nanofibers.

We report the extraction of keratin nanofibers from the medulla of a parent yarn after denaturing the cuticle and cortex microstructures of a merino wool yarn. Controlled alkaline hydrolysis, followed by high-speed blending in acetic acid, allowed for the extraction of keratin protein nanofibers with an average diameter of 25 nm and a length of less than 3 µm. SEM and AFM analyses showed the removal of cuticle cells from the yarn. FT-IR and DSC analyses confirmed the hydrolysis and denaturation of the sheet protein matrix of cuticle cells. XPS analysis provided strong evidence for the gradual removal of the epicuticle, cuticle cells, and cortex of the hierarchical wool structure with an increase in alkaline hydrolysis conditions. It was confirmed that the merino wool yarn subjected to hydrolysis under alkaline conditions exposed its internal fibrillar surface. In an acetic acid medium, these fibrillar surfaces obtained a surface charge, which further supported the defibrillation of the structure into its individual nanofibrils during high-speed blending. The extracted nanostructures constitute mainly α-helical proteins. The morphology of the nanofibers is composed of a uniform circular cross-section based on the images obtained using AFM, TEM, and SEM. The extracted nanofibers were successfully fabricated into transparent sheets that can be used in several applications.

Electroless plating of premetalized polyamide fibers for stretchable conductive devices.

A new approach was used to produce electrically conductive polyamide yarns, employing an electroless plating technique, which involved stabilizing silver nanoparticles on the surface of the yarn using Sn2+. First, the [Ag(NH3)2]+ complex was reduced using Sn2+ to produce silver nanoparticle seed layers on the fiber surface, followed by a formaldehyde reduction. The nucleation and growth of silver nanoparticles on the fiber surface were observed through SEM images, demonstrating varying degrees of silver deposition depending on the silver concentration. This deposition variation was confirmed through XRD patterns, TGA data and UV-vis spectra. Additionally, XPS characterization showed the evolution of the chemical state of silver and tin during the silver reduction process. Electrical resistance revealed that the resistance per unit length of the yarn ranged from 3 ± 0.3 Ω cm-1 to 70 ± 6 Ω cm-1, depending on the silver concentration. The resulting silver-plated yarn was incorporated into a stretchable device, demonstrating stable resistance over multiple cycles. This method of fabricating conductive yarn has the potential to open up new possibilities in the design and manufacture of stretchable conductive devices for flexible electronics.

The blending effect of natural polysaccharides with nano-zirconia towards the removal of fluoride and arsenate from water.

Nano-zirconia (ZO) was synthesized using a microwave-assisted one-pot precipitation route. Two biopolymers, chitosan (CTS) and carboxymethyl cellulose were blended with ZO at different w/w ratios. The formulation with 30% w/w chitosan (ZO-CTS) was found to give enhanced uptake of F- and As(V). ZO and the most effective ZO-CTS system were characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. These confirmed the formation of a composite system containing nanoparticles of 50 nm in size, in which ZO was present in the amorphous form. It was observed that the combination of ZO with CTS improved the F- and As(V) adsorption capacity most notably at pH 5.5. Fluoride adsorption by ZO-CTS followed the Freundlich isotherm model, with an adsorption capacity of 120 mg g-1. Adsorption of As(V) by ZO-CTS could be fitted with both the Langmuir and Freundlich isotherm models and was found to have a capacity of 14.8 mg g-1. Gravity filtration studies conducted for groundwater levels indicated the effectiveness of ZO-CTS in adsorbing As(V) and F- at a pH of 5.5. The ability of the ZO-CTS in removing Cd(II) and Pb(II) was also investigated, and no such enhancement was observed, and found the neat ZO was the most potent sorbent here.

Infrared absorbing nanoparticle impregnated self-heating fabrics for significantly improved moisture management under ambient conditions.

Propensity of a textile material to evaporate moisture from its surface, commonly referred to as the 'moisture management' ability, is an important characteristic that dictates the applicability of a given textile material in the activewear garment industry. Here, an infrared absorbing nanoparticle impregnated self-heating (IRANISH) fabric is developed by impregnating tin-doped indium oxide (ITO) nanoparticles into a polyester fabric through a facile high-pressure dyeing approach. It is observed that under simulated solar radiation, the impregnated ITO nanoparticles can absorb IR radiation, which is effectively transferred as thermal energy to any moisture present on the fabric. This transfer of thermal energy facilitates the enhanced evaporation of moisture from the IRANISH fabric surface and as per experimental findings, a 54 ± 9% increase in the intrinsic drying rate is observed for IRANISH fabrics compared with control polyester fabrics that are treated under identical conditions, but in the absence of nanoparticles. Approach developed here for improved moisture management via the incorporation of IR absorbing nanomaterials into a textile material is novel, facile, efficient and applicable at any stage of garment manufacture. Hence, it allows us to effectively overcome the limitations faced by existing yarn-level and structural strategies for improved moisture management.

A magnetically retrievable air and moisture stable gold and palladium nanocatalyst for efficient C-C coupling reactions.

In this study, we report the synthesis of a highly stable, magnetically retrievable gold and palladium nanocatalyst (AuPd@AMNPs), highly active in Suzuki cross-coupling and related homocoupling reactions. The active catalytic component in this system is palladium, which can only be stabilized in the presence of gold nanoparticles. There is no significant loss of activity even after prolonged storage exposed air and moisture. The versatile nature AuPd@AMNPs is demonstrated through the selective catalysis of the homocoupling of phenylboronic acid under low concentrations of O2 and the oxidation of phenylboronic acid to phenol under high O2 concentrations. AuPd@AMNPs also demonstrated Ullmann-type homocoupling of 4-iodotolene with excellent yields. The magnetically retrieved catalyst could be re-used up to six times in Suzuki-Miyaura cross-coupling with consistently high activity and with a minimal loss of the noble metal species. Through these reactions we show that the gold-stabilized AuPd@AMNPs can be used as stable and recyclable palladium reservoir for multiple palladium-catalysed reactions.

Nanofibrous cosmetic face mask for transdermal delivery of nano gold: synthesis, characterization, release and zebra fish employed toxicity studies.

This study involves the generation of gold nanoparticles (Au NPs) via a novel natural/non-toxic methodology using tea and orange-peel extracts. These were then embedded into a novel blend composed of a polyethylene oxide and gelatin (PEO-Gel) fibre mat. The scanning electron microscopy results indicated that the addition of both collagen (COL) and ascorbic acid (AA) into the PEO-Gel system (PEO-Gel-AA-COL system) enhances the Au NP incorporation into nanofibres leading to a diameter of 164.60 ± 20.95 and 192.43 ± 39.14 nm in contrast to the spraying observed with the Au PEO-Gel system alone. Releasing studies conducted over 30 min indicated that the PEO-Gel-AA-COL-orange peel Au (OpAu) system accounts for a higher content of Au release than the green tea Au (GtAu) NP system where a maximum release could be attained within 10-30 min depending on the amount of Au NPs that have been incorporated. Moreover, the transdermal diffusion studies conducted using Strat membrane indicated that Au NPs from both formulations (PEO-Gel-AA-COL-GtAu nanofibre, PEO-Gel-AA-COL-OpAu nanofibre) have diffused through the stratum corneum and trapped in the dermis and epidermis indicating its transdermal deliverability. Additionally, 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay revealed that nanofibres have similar radical scavenging activity like AA standard. Toxicity evaluation on a zebra fish embryo model confirmed that both GtAu NPs and OpAu NPs do not induce any teratogenic activity and are safe to be used in the range of 1.0-167 µg ml-1.

Gold nanoparticle decorated titania for sustainable environmental remediation: green synthesis, enhanced surface adsorption and synergistic photocatalysis.

Developing materials for efficient environmental remediation via cheap, nontoxic and environmentally benign routes remains a challenge for the scientific community. Here, a novel, facile, and green synthetic approach to prepare gold nanoparticle decorated TiO2 (Au/TiO2) nanocomposites for sustainable environmental remediation is reported. The synthesis involved only TiO2, metal precursor and green tea, obviating the need for any solvents and/or harsh chemical reducing or stabilizing agents, and was efficiently conducted at 50 °C, indicating the prominent sustainability of the novel synthetic approach. The synthesis indicated notable atom economy, akin to that observed in a typical chemical mediated synthesis while high-resolution transmission electron microscopy (HRTEM) findings suggest the presence of a pertinent decoration of spherical and homogeneous gold nanoparticles on the titania surface. Notably, the Au/TiO2 nanocomposite demonstrated appreciable stability during preparation, subsequent processing and prolonged storage. Further, the nanocomposite was found to have a superior adsorption capacity of 8185 mg g-1 towards methylene blue (MB) in solution using the Freundlich isotherm model, while the rate constants for the photocatalytic degradation of MB on the nanocomposite under UV irradiation indicated a 4.2-fold improvement compared to that of bare TiO2. Hence, this novel green synthesized Au/TiO2 nanocomposite shows promising potential for sustainable environmental remediation via efficient contaminant capture and subsequent synergistic photocatalysis.

Akaganeite nanorices deposited muscovite mica surfaces as sunlight active green photocatalyst.

Thin films of akaganeite [FeO(OH)] nanorices deposited muscovite mica (ANPM) surfaces are synthesized using the facile urea assisted controlled self-assembly technique. The synthesized materials are characterized using scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy, atomic force microscopy, X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy and thermogravimetric analysis (TGA). The prepared nanorices on mica surfaces show average particle length and width of 200 and 50 nm, respectively. Synthesized material acts as an efficient photocatalyst under UV and sunlight conditions as demonstrated by the degradation of standard methylene blue (MB) solution. The MB degradation efficiencies of the catalyst under exposure to 180 min sunlight and UV are 89% and 87.5%, respectively, which shows that the catalyst is more highly active under sunlight than under UV light. Therefore, the synthesized material is a potential green photocatalyst in efficient treatment of industrial dye effluents under direct sunlight.

Facile and low-cost synthesis of pure hematite (α-Fe2O3) nanoparticles from naturally occurring laterites and their superior adsorption capability towards acid-dyes.

Hematite nanoparticles have a broad range of outstanding applications such as in wastewater treatment, electrolytic studies, and photoelectrochemical and superparamagnetic applications. Therefore, the development of facile and novel methods to synthesize hematite nanoparticles using low-cost raw materials is an important and timely requirement. In this study, we have developed a facile economical route to synthesize hematite nanoparticles, directly from the naturally occurring material laterite. Laterite is a rock that is rich in Fe and Al with extensive distribution in large mineable quantities in many countries around the world, though not yet utilized for major industrial applications. In this method, ferric ions in the laterite were leached out using acid and the solution obtained was hydrolyzed with slow-release hydroxyl ions which were acquired by aqueous decomposition of urea. The resulted precursor was calcined to obtain hematite nanoparticles. Characterization data shows that the final product is comprised of spherical hematite nanoparticles with a narrow particle size vs. frequency distribution with an average particle diameter of 35 nm. The synthesized product has a purity of over 98%. Furthermore, the synthesized nanoparticles show an excellent adsorption percentage as high as 70%, even when the initial dye concentration in water is 5000 ppm and the amount of material is minimal, towards acid dyes which are excessively used in textile based industries. Such acid dyes are a threat to the environment when they are released into water bodies by industries in massive quantities. Therefore synthesized hematite nanoparticles are ideal to treat dye wastewater in industrial effluents because such nanoparticles are low cost and economical, and the synthesis procedure is rather facile and effective.

Metal and polymer-mediated synthesis of porous crystalline hydroxyapatite nanocomposites for environmental remediation.

This study was focused on the preparation of metal and polymer-mediated porous crystalline hydroxyapatite (HAp) nanocomposites for environmental applications. Four different nano HAp systems were synthesized, namely, microwave irradiated HAp (M1), Zn doped HAp (M2), Mg-doped HAp (M3) and sodium alginate incorporated HAp (M4), and characterized using X-ray diffraction (XRD), Fourier transform infra-red spectroscopy, scanning electron microscopy, transmission electron microscopy, atomic force microscopy, nuclear magnetic resonance (NMR), X-ray fluorescence, thermogravimetric analysis and Brunauer-Emmett-Teller (BET) analyses. Systems M1-M4 showed morphologies similar to coral shapes, polymer-like interconnected structures, sponges and feathery mycelium assemblies. Using XRD, selected area electron diffraction patterns and 1H and 31P CP/MAS solid-state NMR studies, crystallinity variation was observed from highest to lowest in the order of M4 > M1 > M3 > M2. Surface area estimates using BET isotherm reflected the highest surface area for M3, and M1 > M2 > M4. Four systems of M1-M4 were used as potential adsorbent materials for the removal of metal containing azo dye from aqueous system. Adsorption data were correlated to Freundlich and Langmuir isotherm models. According to the results, the highest capacity of 212.8 mg g-1 was exhibited by M4 having mycelium like morphology with alginate groups. This study highlights the possibility of developing HAp nanocomposites for the effective removal of dye contaminants in the environment.

Magnetofection and isolation of DNA using polyethyleneimine functionalized magnetic iron oxide nanoparticles.

This study was carried out to develop a simple and efficient method to isolate DNA directly from biological samples using iron oxide nanoparticles (IONPs) functionalized with polyethyleneimine (PEI). IONPs were synthesized via co-precipitation method followed with direct attachment of branched PEI. Nanoparticles were characterized using STEM, FT-IR spectroscopy and XRD analysis. The binding capacity of synthesized PEI-IONPs for plasmid and genomic DNA was assessed using purified DNA samples. In order to elute bound DNA, elution conditions were optimized, changing pH, salt concentration and temperature. Synthesized PEI-IONPs were subjected to isolation of DNA from bacterial cell culture and from human blood. PCR and magnetofection of the enhanced green fluorescence protein (EGFP) were carried out to verify the downstream applications of isolated DNA. The results indicated that the synthesized nanoparticles were of 5-10 nm. The binding capacity of PEI-IONPs for plasmid DNA and genomic DNA were 5.4 and 8.4 µg mg-1, respectively, which were even higher than the commercially available kits such as Mag-bind, MagJET and Magmax. The optimized condition for plasmid DNA elution was 0.1 M Tris HCl (pH 10.0), 1.5 M NaCl and 5% formamide, maintained at the temperature of 60°C. The optimized condition for genomic DNA elution was 0.1 M Tris HCl (pH 10.0), 1.5 M NaCl and 10% formamide, maintained at 60°C. PCR and magnetofection processes were successful. This study revealed that the magnetic separation of DNA using PEI-IONPs is a simple and efficient method for direct isolation of DNA from biological samples which can be then used in various downstream applications.

Facile Synthesis of Colored and Conducting CuSCN Composite Coated with CuS Nanoparticles.

Conductivity-tunable, different colored CuS nanoparticle-coated CuSCN composites were synthesized in a single pot using a mixture of copper sulfate and sodium thiosulfate in the presence of triethyl amine hydrothiocyanate (THT) at the ambient condition. When these reagents are mixed in 1:1:1 molar ratio, white-gray-colored CuSCN was produced. In the absence of THT, microsized dark blue-colored CuS particles were produced. However, when THT is present in the solution mixture by different amounts, colored conducting CuS nanoparticle-coated CuSCN composite was produced. CuS nanoparticles are not deposited on CuSCN soon after mixing these regents, but it takes nearly overnight to see the color change (CuS production) in the white CuSCN dispersed mixture. TEM analysis shows that composite consists of hexagonal CuS nanoparticles in the range of ~ 3-10 nm in size. It is interesting to note that CuS-coated CuSCN possesses higher conductivity than neat CuS or CuSCN. Moreover, strong IR absorption was observed for CuS-coated CuSCN composite compared to neat CuS (absence of THT) or CuSCN. Lowest resistivity of 0.05 Ω cm was observed for annealed (250 °C) CuS-coated CuSCN particles (adding 10 ml of THT) under nitrogen atmosphere. Also, this simple method could be extended to be used in the synthesis of CuS-coated composites on the other nanomaterials such as metal oxides, polymers, and metal nanoparticles.