Mixed oxide nanotubes in nanomedicine: A dead-end or a bridge to the future?

Nanomedicine has seen a significant rise in the development of new research tools and clinically functional devices. In this regard, significant advances and new commercial applications are expected in the pharmaceutical and orthopedic industries. For advanced orthopedic implant technologies, appropriate nanoscale surface modifications are highly effective strategies and are widely studied in the literature for improving implant performance. It is well-established that implants with nanotubular surfaces show a drastic improvement in new bone creation and gene expression compared to implants without nanotopography. Nevertheless, the scientific and clinical understanding of mixed oxide nanotubes (MONs) and their potential applications, especially in biomedical applications are still in the early stages of development. This review aims to establish a credible platform for the current and future roles of MONs in nanomedicine, particularly in advanced orthopedic implants. We first introduce the concept of MONs and then discuss the preparation strategies. This is followed by a review of the recent advancement of MONs in biomedical applications, including mineralization abilities, biocompatibility, antibacterial activity, cell culture, and animal testing, as well as clinical possibilities. To conclude, we propose that the combination of nanotubular surface modification with incorporating sensor allows clinicians to precisely record patient data as a critical contributor to evidence-based medicine.     

Synthesis and Characterization of Zinc/Polypyrrole Nanotube as a Protective Pigment in Organic Coatings

This study deals with the synthesis and characterization of zinc/polypyrrole nanotube (Zn/PPy) as a protective pigment in organic coatings. The PPy nanotube is synthesized by chemical oxidative polymerization, and zinc nanoparticles are deposited onto the surface of the synthesized PPy nanotube in the presence of sodium dodecyl sulfate. Field emission scanning electron microscopy, transmission electron microscopy, and X-ray diffraction results confirm the existence of the nanotube morphology and the zinc nanoparticles. Electrochemical impedance spectroscopy and potentiodynamic polarization are performed on steel plates coated with polyvinyl butyral incorporated with the Zn/PPy nanotube. The results show that the existence of zinc can improve the protective properties of the pigment. The existence of zinc leads to a cathodic protection and the main product of zinc corrosion is the stale zinc hydroxide which can block the pores in the coating. In addition, the zinc nanoparticles can increase conductivity of the PPy nanotube leading to increasing nanotube’s ability to form protective layers of metal oxides on the steel surface.     

Effect of KOH concentration in the gel polymer electrolyte for direct borohydride fuel cell

The performance of a direct borohydride fuel cell (DBFC) based on a polyacrylamide (PAAm) gel polymer electrolyte system is investigated at different electrolyte concentrations. The DBFC, constructed using 2M sodium borohydride (NaBH₄) as the fuel and potassium hydroxide (KOH) solution gelled with PAAm as the electrolytes yield the highest electrical conductivity of 2.73 × 10^?1 S cm^?1 at 6M KOH. The optimized composition, PAAm + 2M NaBH₄ + 6M KOH, and the selected composition, PAAm + 2M NaBH₄ + 3M KOH are then used in preparing the cells. Open‐circuit voltages for fuel cells is about 0.85–0.92 V, and the discharge characteristic produce discharge capacities of about 257.12–273.12 mAh cm^?2 for cells with PAAm‐6M KOH. Current‐voltage and current density‐power density plots and internal resistance for both cells are almost the same. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Window and roof configurations for comfort ventilation

This paper assesses the applicability of some architectural design elements to provide comfort ventilation in humid tropical regions: size and location of windows, building eaves and roof shapes for a single unit house. Most window and roof configurations are sufficent to produce only a slightly more comfortable level although they can certainly increase the indoor air velocity. The improvement of indoor air velocity can minimize the physiological effect of the high humidity. Among the tested models, the room with a high gable roof combining with eaves improves significantly the indoor air velocity. Cet expose evalue l'applicabilite de certains elements de configuration visant a assurer une ventilation de confort daus les regions tropicales humides: dimensions et emplacement des fenetres, formes d'avant-toit et de toiture pour une maison individuelle. La plupart des configurations de fenetre et de toiture suffisent seulement a fournir un minime supplement de confort, bien qu'elles puissent effectivement ameliorer la circulation interieure de l'air. Une amelioration de circulation interieure de l'air peut attenuer les effets physiologiques d'une forte humidite. Parmi les modeles essayes, le local comportant une toiture a pignon eleve associee a des avant-toits offre une nette amelioration de circulation interieure de l'air.     

Immobilized copper ions on MWCNTS-Chitosan thin film: Enhanced amperometric sensor for electrochemical determination of diclofenac sodium in aqueous solution

A simple and effective electrochemical sensor was designed by the drop cast method for the detection of Diclofenac Sodium (DS), a widely used painkiller, by combining the significant catalytic property of multi-walled carbon nanotubes (MWCNTs), excellent adsorption capacity and film forming ability of Chitosan and synergistic catalytic effect of Chitosan-copper complex. The characteristics of newly proposed composite (MWCNTs/CTS-Cu/GCE) were investigated by different techniques like Fourier Transform Infrared Spectroscopy (FTIR), Field emission scanning electron microscopy (FESEM) and Energy dispersive X-ray analysis (EDX). The electrochemical performance of the newly modified composite was studied by using Cyclic voltammetry (CV), Electrochemical impedance spectroscopy (EIS), Square wave voltammetry (SWV). Under the optimum conditions, the anodic peak current for Diclofenac sodium (DS) was linear and the range is between 0.3 and 200 μmol L^?1 with the detection limit of 0.021 μmol L^?1 at pH 4.0. Finally, this modified composite exhibit good selectivity, sensitivity and stability for the detection of Diclofenac sodium (DS) from the pharmaceutical dosage form and real samples.     

Preparation,scratch adhesion and anti-corrosion performance of TiO2-MgO-BHA coating on Ti6Al4V implant by plasma electrolytic oxidation technique

Bovine hydroxyapatite (BHA) (from cortical bone), was selected as the main electrolyte for plasma electrolytic oxidation (PEO) on Ti6Al4V implant. The prepared PEO coatings were examined by X-ray diffraction, field emission scanning electron microscope and energy-dispersive X-ray spectroscopy. The surface roughness, adhesion strength, wettability, surface energy and corrosion behaviour of the film were also investigated. The results show that the oxide layer (26 μm) formation on the Ti6Al4V was rough and porous. The micro-pores were filled with anatase TiO₂, cubic MgO and hexagonal BHA particles. The porous structures and the compound particles were mainly composed of Mg, O, Ca, P, Ti, Na and Al. Unlike previous coatings produced from calcium and phosphorus inorganic solutions, the coating formation from a newly developed bovine bone-derived HA electrolyte revealed an additional MgO phase in the coating layer. Moreover, higher amount of single phase hexagonal crystalline BHA phase with a Ca/P ratio of 1.1 was achieved with a single PEO process. A film-to-substrate adhesion strength of 1862.24 mN and scratch hardness of about 4.1 GPa was achieved from this method. The TiO₂/MgO/BHA film exhibited better wettability, higher surface energy and superior corrosion resistance compared to the bare Ti6Al4V substrate.     

Low earth orbit resistant siloxane copolymers

Two classes of siloxane copolymers were evaluated for their resistance to the low earth orbit (LEO) environment. Poly(imide–siloxane) (PISX) copolymers were used as the resin for PISX–carbon fiber composites. These composites were exposed to the LEO environment, for 50 h, as part of the “Effect of Oxygen Interaction with Materials” (EOIM-III) experiment aboard the space shuttle STS-46. XPS analysis showed primarily silicon oxides on the LEO-exposed surfaces and evidence of a thermally accelerated oxidation. The results of simulated LEO exposure of the PISX composites show that they are one to two orders of magnitude more resistant than are homopolyimide-based composites. Furthermore, we found, surprisingly, that these materials erode slower when far-UV radiation is combined with the atomic oxygen. XPS analysis of PISX exposed only to far-UV allowed a partial mechanism to be proposed for the effect of far-UV radiation on the PISX copolymers. Polyhedral oligosilsequioxane (POSS)–siloxane copolymers were evaluated in a simulated LEO environment and results indicate that the POSS–siloxane copolymers are even more resistant to the simulated LEO environment than are the PISX copolymers; POSS–siloxanes actually gained weight during the exposure and healed the microcracks present. © 1996 John Wiley Sons, Inc.