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ABSTRACT: Various approaches have been studied to engineer the implant surface to enhance bone in-growth properties, particularly using micro- and nano-topography. In this study, the behavior of osteoblast (bone) cells was analyzed in response to a titanium oxide (TiO2) nanotube-coated commercial zirconia femoral knee implant consisting of a combined surface structure of a micro-roughened surface with the nanotube coating. The osteoblast cells demonstrated high degrees of adhesion and integration into the surface of the nanotube-coated implant material, indicating preferential cell behavior on this surface when compared to the bare implant. The results of this brief study provide sufficient evidence to encourage future studies. The development of such hierarchical micro- and nano-topographical features, as demonstrated in this work, can provide insightful designs for advanced bone-inducing material coatings on ceramic orthopedic implant surfaces.
Materials science & engineering. C, Materials for biological applications. 07/2013; 33(5):2752-6.
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ABSTRACT: The structure and properties of nanoscale magnetic island arrays for bit patterned media (BPM) have been studied. A periodic
Si nano-island array was fabricated by nano-imprint-lithography (NIL), with the trenchfilling and flattening achieved by resist
spin coating followed by reactive ion back-etching. A Co/Pd multilayer magnetic media with a perpendicular anisotropy was
then sputtered and lifted-off so that the processed nanostructure array now has the magnetic material only on the top of the
pillars. This process significantly improved the magnetic characteristics of BPM. A planarization by hydrogen silsesquioxane
filling reduced the tribological interference of the protruding nanoisland heights in BPM.
Keywordsbit patterned media–nano imprint lithography–filling and planarization
Electronic Materials Letters 04/2012; 6(3):113-116. · 1.82 Impact Factor
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ABSTRACT: This paper reports on the extremely superhydrophobic behavior of supercritical CO2 processed silicon nanowires SiNWs) with a contact angle in excess of ∼177°. Vertically aligned silicon nanowires with 10
nm to 40 nm diameter and 1 mm to 3 mm in length were obtained by electroless etching (EE) technique. The asfabricated SiNWs
were superhydrophilic with no water droplet formation (zero contact angle), and were then completely transformed to an extreme
superhydrophobic state when their nanoscale surface roughness is combined with trichlorosilane hydrophobic coating. The processed
SiNW array was so hydrophobic that water droplets always bounced off the surface and did not allow contact angle measurements
to be obtained unless the substrate was intentionally given a concave-curvature by vacuum suction. Utilization of a hydrophobically
surface-treated micro-pipette syringe enabled the release of a water droplet onto this extremely superhydrophobic surface
for contact angle measurement. To prevent severe nanowire agglomeration during the drying process of wet etched SiNWs, supercritical
CO2 drying was utilized, which process significantly improved the nano configuration and enhanced hydrophobicity.
Keywordssuperhydrophobic surface–electroless etching–silicon nanowires–contact angle
Electronic Materials Letters 04/2012; 6(2):59-64. · 1.82 Impact Factor
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ABSTRACT: Co/Pd multilayer media with an antidot structure have been fabricated on hole-patterned Si substrates. Si nanoholes were created by dry etching using a self-assembled diblock copolymer (DBCP) pattern as an etch mask. To enhance dry etching selectivity, thin Cr film was vacuum deposited on DBCP surface at an oblique incident angle. In comparison with the Co/Pd multilayer on a flat Si substrate, the magnetic hysteresis loop of the antidot structured Co/Pd multilayer revealed an enhanced coercive force largely independent of the amount of reactive etching time, while the shape of hysteresis loop was substantially altered as a function of dry etching time. In an optimized condition, high perpendicular magnetic anisotropy was obtained while no significant parallel magnetic anisotropy was seen, which is desirable for perpendicular recording media or pseudobit-patterned media application.
IEEE Transactions on Magnetics 11/2011; · 1.36 Impact Factor
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ABSTRACT: We report unprecedented superomniphobic characteristics of nanotube-structured TiO(2) surface fabricated by electrochemical etching and hydrothermal synthesis process, with the wettability contact angles for water and oil both being ∼174° or higher. A tangled forest of ∼8-nm-diameter, multiwalled nanotubes of TiO(2) was produced on the microtextured Ti surface, with the overall nanotube length controlled to 150 nm by adjusting the processing time. Wettability measurements indicate that the nanotube surface is extremely nonwettable to both water and oil. The contact angle of the 8 nm TiO(2) nanotube surface after perfluorosilane coating is extremely high (178°) for water droplets indicating superhydrophobic properties. The contact angle for oil, measured using a glycerol droplet, is also very high, about 174°, indicating superoleophobic characteristics. These dual nonwetting properties, superomniphobic characteristics, are in sharp contrast to the as-made TiO(2) nanotubes which exhibit superhydrophilic properties with a contact angle of essentially ∼0°. Such an extreme superomniphobic material made by a simple and versatile method can be useful for a variety of technical applications. It is interesting to note that all three properties can be obtained with identical nanotube structures. A nanometer-scaled structure introduced by hydrothermally grown TiO(2) nanotubes is an effective air trapping nanostructure in enhancing the amphiphobic (superomniphobic) wettability.
Langmuir 08/2011; 27(16):10191-6. · 4.19 Impact Factor
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Angewandte Chemie International Edition 06/2011; 50(30):6771-5. · 13.45 Impact Factor
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ABSTRACT: Anodized aluminum oxide (AAO), well-known hexagonally ordered vertical pore nanostructure, can be altered to form nanotubular AAO arrays potentially having many favorable properties due to its large surface area and unique geometry. We present here a creation of novel nanotubular AAO structure by the hard anodization technique. Because of the guided formation of void channels at triple cell junctions during the course of the controlled anodization process, periodically spaced-apart aluminum oxide nanotubular geometry could be achieved over large areas. Further separation to well-defined individual AAO nanotube arrays was obtained when etched in a mixed CuCl2/HCl solution during Al substrate removal. Nanotubular geometry AAO with periodic and mechanically robust structure can be useful not only for biomedical applications such as to enhance cell adhesion and viability or drug delivery vehicles, but also as a large-surface-area catalyst support or sensor elements.
Journal of Materials Research. 01/2011; 26(02):186 - 193.
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Advanced Engineering Materials 01/2011; 13(3):B88 - B94. · 1.18 Impact Factor
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ABSTRACT: Nanotubular materials have many favorable properties for drug delivery. We present here a pioneering study of con-trolled release of a model drug, amoxicillin, from the internal nanopore structure of self-ordered, periodically spaced-apart aluminum oxide with an innovative, nanotubular geometry. This aluminum oxide nanotube geometry has not yet been revealed for biological applications, thus we have selected this oxide nanotube structure and demonstrated its ability as a drug carrier. Controlled, sustained release was achieved for over 5 weeks. The release kinetics from the nanotube layer was thoroughly characterized and it was determined that the amount of drug released was proportional to the square root of time. This type of controlled release and longevity from the nanotube layer has potential for therapeutic surface coatings on medical implants. Furthermore, this type of geometry has many features that are ad-vantageous and biologically relevant for enhancing tissue biointegration.
Journal of Biomaterials and Nanobiotechnology. 01/2011; 2:226-233.
