Zirconia based superhydrophobic coatings on cotton fabrics exhibiting excellent durability for versatile use

A fluorinated silyl functionalized zirconia was synthesized by the sol-gel method to fabricate an extremely durable superhydrophobic coating on cotton fabrics by simple immersion technique. The fabric surfaces firmly attached with the coating material through covalent bonding, possessed superhydrophobicity with high water contact angle approximate to 163 +/- 1 degrees, low hysteresis approximate to 3.5 degrees and superoleophilicity. The coated fabrics were effective to separate oil/water mixture with a considerably high separation efficiency of 98.8 wt% through ordinary filtering. Presence of highly stable (chemically and mechanically) superhydrophobic zirconia bonded with cellulose makes such excellent water repelling ability of the fabrics durable under harsh environment conditions like high temperature, strong acidic or alkaline solutions, different organic solvents and mechanical forces including extensive washings. Moreover, these coated fabrics retained self-cleanable superhydrophobic property as well as high water separation efficiency even after several cycles, launderings and abrasions. Therefore, such robust superhydrophobic ZrO2 coated fabrics have strong potential for various industrial productions and uses

Durable superhydrophobic ZnO-SiO2 films: a new approach to enhance the abrasion resistant property of trimethylsilyl functionalized SiO2 nanoparticles on glass

Although trimethylsilyl functionalized SiO2 derived films show excellent superhydrophobicity, their adhesion and abrasion resistant properties are extremely poor. In this study, a new approach has been shown to improve the adhesion and abrasion properties of such films. A neutral and relatively hydrophobic Zn(CH3OO)(2)(H2O)(2)] complex solution has been used to interact with the superhydrophobic silica gel nanoparticle dispersion. After dip-coating, the composite sol yielded films of a zinc acetate/superhydrophobic silica composite network while the hydrophilic part (bonded water) associated with Zn helps in binding the hydroxyl groups (silanols) present on the glass surface. The composite films were heat-treated at 300-400 degrees C in a nitrogen atmosphere in order to obtain transparent and superhydrophobic ZnO-SiO2 nanocomposite films. The decomposition of zinc acetate formed ZnO nanocrystallites and remained attached with the hybrid silica matrix. These films showed excellent water repellency (water contact angle, CA approximate to 158 +/- 7 degrees; hysteresis approximate to 4 degrees) with good adhesion and abrasion resistant properties. XRD, Raman and TEM studies confirm the existence of ZnO nanocrystallites in the composite films. Owing to the stability of hydrophobic methyl groups attached with silicon at relatively high temperature in a nitrogen atmosphere, these ZnO-SiO2 nanocomposite films remain superhydrophobic even after a heat-treatment at 400 degrees C

Pd-Ni alloy nanoparticle doped mesoporous SiO2 film: the sacrificial role of Ni to resist Pd-oxidation in the C-C coupling reaction

A Pd-Ni alloy nanoparticle (NP) doped mesoporous SiO2 film was synthesized using a one pot inorganic-organic sol-gel process in the presence of structure director P123. Pure Pd and Ni NP containing films were also synthesized as controls. Overall a composition of 10 mol% metal (in the case of Pd-Ni, 5 mol% of each metal) and 90 equivalent mol% SiO2 was maintained in the heat-treated films. Grazing incidence X-ray diffraction and transmission electron microscopy studies of the final heat-treated Pd-Ni doped films revealed the (111) oriented growth of the Pd-Ni alloy NPs, with an average size of 5.3 nm, residing inside the mesopores of the SiO2 film. We performed the C-C coupling reaction employing the film-catalysts and the progress of the reaction was monitored using a fluorimeter. Overall, only the Pd-Ni alloy NP doped film showed good catalytic activity with excellent recyclability. It has been determined that the higher oxidising ability of metallic Ni restricted the oxidation of Pd in the Pd-Ni alloy catalyst under the reaction conditions, leading to the maintained reusability in consecutive cycles

Porous SiO2 nanofiber grafted novel bioactive glass-ceramic coating: A structural scaffold for uniform apatite precipitation and oriented cell proliferation on inert implant

A composite bioactive glass-ceramic coating grafted with porous silica nanofibers was fabricated on inert glass to provide a structural scaffold favoring uniform apatite precipitation and oriented cell proliferation. The coating surfaces were investigated thoroughly before and after immersion in simulated body fluid. In addition, the proliferation behavior of fibroblast cells on the surface waslthserved for several culture times. The nanofibrous exterior of this composite bioactive coating facilitated homogeneous growth of flake-like carbonated hydroxyapatite layer within a short period of immersion. Moreover, the embedded porous silica nanofibers enhanced hydrophilicity which is required for proper cell adhesion on the surface. The cells proliferated well following a particular orientation on the entire coating by the assistance of nanofibrous scaffold-like structural matrix. This newly engineered composite coating was effective in creating a biological structural matrix favorable for homogeneous precipitation of calcium phosphate, and organized cell growth on the inert glass surface. (C) 2016 Elsevier B.V. All rights reserved

Fabrication of a cubic zirconia nanocoating on a titanium dental implant with excellent adhesion, hardness and biocompatibility

A crystalline cubic zirconia (ZrO2) nanocoating was fabricated in situ on commercially pure titanium metal (cpTi) as a superior dental implant with enhanced biocompatibility. The crystallinity of the nanocoating was achieved at a moderately lower annealing temperature (350 degrees C) in air using a simple sol-gel method applying a successive layer-by-layer dip-coating technique. Such a procedure facilitates the growth of cubic phase zirconia without noticeable deterioration of the metallic Ti. The bioactivity and biocompatibility of this ZrO2 coated cpTi (Z-cpTi) were assessed in terms of apatite precipitation through immersion in simulated body fluid, and cell proliferation, respectively for several periods of time. The newly designed Z-cpTi showed unique apatite forming ability, better biocompatibility and tissue attachment properties, and is expected to reduce inflammatory response compared to the bare Ti implants. Moreover, the chemical inertness, corrosion and wear resistant properties, high strength, and appearance of this ZrO2 nanocoating suggest the probable expediency of Z-cpTi as an advanced oral implant for long-standing performance

Electrospun TiO2–rGO Composite Nanofibers with Ordered Mesopores by Molecular Level Assembly: A High Performance Anode Material for Lithium-Ion

The authors report a novel strategy to fabricate electrospun anatase TiO2–rGO composite nanofibers with 3D cubic ordered mesoporosity. Such synthesis route not only ensures molecular level composite formation between rGO and TiO2 but also retains the rGO content and orders mesostructure after calcination of the nascent fiber at an optimum condition that only removes the surfactant and polymer. Transmission electron microscopic and low angle X-ray diffraction studies confirm the presence of ordered mesoporosity within the nanofibers. Raman and X-ray photoelectron spectroscopy studies reveal the molecular level composite formation between rGO and TiO2 with chemical bonding. This composite nanofiber with high surface area (155 m2 g–1) is tested as an anode material in lithium-ion batteries. Intrinsically formed TiO2–rGO composite structural features with channel like interconnected 3D order mesopores within 1D fibrous morphology help in achieving 94% of the theoretical capacity (335 mAh g–1 for one electron transfer) at a current density of 16.75 mA g–1, the highest reported so far. It shows specific capacity of 212 and 168 mAh g–1 even at moderately high current densities of 335 and 838 mA g–1, respectively. Moreover, 85.3% of capacity retains after 500 continuous discharge/charge cycles at 335 mA g–1

Hierarchically Designed Bioactive Glassy Nanocoatings for the Growth of Faster and Uniformly Dense Apatite

Crack-free bioactive nanocoatings embedded with uniformly distributed silica-rich bioactive spherical aggregates were successfully prepared insitu by controlling the micellization of a SiO2-CaO-P2O5 sol using the tri-block copolymer P123 followed by dip-coating onto a bio-inert glass substrate and calcined. These hierarchically designed nanocoatings embedded with such bioactive glassy nanospheres (BGNS) enabled to induce the deposition of a densely populated, uniform, and well-developed needlelike crystalline carbonated hydroxyapatite coating reminiscence of the mineral phase of natural bone within a short immersion time in simulated body fluid. The BGNS nanocoatings also supported the growth and attachment of human gingival fibroblasts. The results suggest that these newly designed composite nanocoatings are noncytotoxic, capable of supporting rapid and homogeneous calcium phosphate deposition as well as subsequent crystallization, and likely to be promising candidates for inert glass reinforced bone implants

Understanding the Effect of Single Cysteine Mutations on Gold Nanoclusters as Studied by Spectroscopy and Density Functional Theory Modeling

Fluorescent metal nanoclusters have generated considerable excitement in nanobiotechnology, particularly in the applications of biolabeling, targeted delivery, and biological sensing. The present work is an experimental and computational study that aims to understand the effects of protein environment on the synthesis and electronic properties of gold nanoclusters. MPT63, a drug target of <i>Mycobacterium tuberculosis</i>, was used as the template protein to synthesize, for the first time, gold nanoclusters at a low micromolar concentration of the protein. Two single cysteine mutants of MPT63, namely, MPT63Gly20Cys (mutant I) and MPT63Gly40Cys (mutant II) were employed for this study. The experimental results show that cysteine residues positioned in two different regions of the protein induce varying electronic states of the nanoclusters depending on the surrounding amino acids. A mixture of five-atom and eight-atom clusters was generated for each mutant, and the former was found to be predominant in both cases. Computational studies, including density functional theory (DFT), frontier molecular orbital (FMO), and natural bond orbital (NBO) calculations, validated the experimental observations. The as-prepared protein-stabilized nanoclusters were found to have applications in the imaging of live cells

Development of nano-porous hydroxyapatite coated e-glass for potential bone-tissue engineering application: An in vitro approach

To reconstruct the defects caused by craniectomies autologous, bone grafting was usually used, but they failed most commonly due to bone resorption, infections and donor-site morbidity. In the present investigation, an effort has been made for the first time to check the feasibility and advantage of using hydroxyapatite (HAp) coated e-glass as component of bone implants. Sol-gel synthesized coatings were found to be purely hydroxyapatite from XRD with graded and interconnected pores all over the surface observable in TEM. The interconnected porous nature of ceramics are found to increase bioactivity by acting to up-regulate the process of osseointegration through enhanced nutrient transfer and induction of angiogenesis. From TEM studies and nano indentation studies, we have shown that pores were considered to be appropriate for nutrient supply without compromising the strength of sample while in contact with physiological fluid. After SBF immersion test, porous surface was found to be useful for nucleation of apatite crystals, hence increasing the feasibility and bioactivity of sample. However, our quasi-dynamic study showed less crystallization but had significant formation of apatite layer. Overall, the in vitro analyses show that HAp coated e-glass leads to significant improvement of implant properties in terms of biocompatibility, cell viability and proliferation, osteoinductivity and osteoconductivity. HAp coating of e-glass can potentially be utilized in fabricating durable and strong bioactive non-metallic implants and tissue engineering scaffolds