Metal Oxide Nanoarchitectures for Environmental Sensing

Varghese, Oomman K.; Grimes, Craig A.

doi:10.1166/jnn.2003.158

Cited by 222 publications

(136 citation statements)

References 99 publications

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“…Fabrication of the nanostructured titanium dioxide (TiO 2 ) nanotube arrays has been a primary subject of investigation lately because of the wide range of TiO 2 applications in the fields of solar cells (13)(14)(15)(16), photocatalysis (17)(18)(19), photoelectrolysis (20), sensors (21,22), and biomaterials (23)(24)(25). The presence of a vertically aligned TiO 2 nanotube surface on Ti foils had a critical effect that improved the proliferation and mineralization of osteoblasts (24) and enhanced the mobility, vasodilation, and monolayer formation of endothelial cells (25) because of the unique nanotopographical features and high biocompatibility of the TiO 2 nanotube surface.…”

mentioning

confidence: 99%

Stem cell fate dictated solely by altered nanotube dimension

Oh¹,

Brammer²,

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

1,097

914

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Two important goals in stem cell research are to control the cell proliferation without differentiation and to direct the differentiation into a specific cell lineage when desired. Here, we demonstrate such paths by controlling only the nanotopography of culture substrates. Altering the dimensions of nanotubular-shaped titanium oxide surface structures independently allowed either augmented human mesenchymal stem cell (hMSC) adhesion or a specific differentiation of hMSCs into osteoblasts by using only the geometric cues, absent of osteogenic inducing media. hMSC behavior in response to defined nanotube sizes revealed a very dramatic change in hMSC behavior in a relatively narrow range of nanotube dimensions. Small (Ϸ30-nm diameter) nanotubes promoted adhesion without noticeable differentiation, whereas larger (Ϸ70-to 100-nm diameter) nanotubes elicited a dramatic stem cell elongation (Ϸ10-fold increased), which induced cytoskeletal stress and selective differentiation into osteoblast-like cells, offering a promising nanotechnology-based route for unique orthopedics-related hMSC treatments.differentiation ͉ mesenchymal ͉ nanotopography ͉ osteogenesis ͉ proliferation N anostructures are of particular interest because they have the advantageous feature of a high surface-to-volume ratio, and they elicit a higher degree of biological plasticity compared with conventional micro-or macrostructures. In the field of biomaterial development and in vivo implant technology, the nanoscale structure and morphologenic factor of the surface have played a critical role in accelerating the rate of cell proliferation and enhancing tissue acceptance with a reduced immune response (1, 2). In terms of in vitro cell biology, there has also been much attention placed on cellular responses to their structural surroundings (3). In fact, it has been observed that macro-, micro-and nano-sized topographical factors stimulate behavioral changes in both cells and tissues. Recent studies related to the effect of nanotopography on cellular behavior indicated that osteoblast adhesion and functionality was enhanced by 30% when cultured on a nanograined Al 2 O 3 and TiO 2 substrate (4-6) compared with those cultured on a micrograined surface, and nanostructures such as TiO 2 nanotubes with Ͻ100-nm spacing showed superior characteristics in bone mineral synthesis (5). However, most of the previous studies on nanostructures and cell responses have mainly used oriented, patterned, or semiordered polymer arrays (7-9) and alumina/ polymer hybrid patterned arrays (10).The material and mechanical characteristics of titanium (Ti) metal, which has a thin native oxide layer of TiO 2 , make it an ideal orthopedic material that bonds directly to the adjacent bone surface (11,12). Fabrication of the nanostructured titanium dioxide (TiO 2 ) nanotube arrays has been a primary subject of investigation lately because of the wide range of TiO 2 applications in the fields of solar cells (13-16), photocatalysis (17-19), photoelectrolysis (20), sensors (21,22), and b...

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mentioning

confidence: 99%

Stem cell fate dictated solely by altered nanotube dimension

Oh¹,

Brammer²,

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

1,097

914

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“…These films sense the changes in humidity through its pores, which are filled with water molecules, and thus its dielectric constant and capacitance changes. This is due to capillary condensation in the pores and adsorption of water on the surface of the film [2], which causes the electrical properties of the device to change as shown in the change in capacitance. A schematic for capillary condensation and adsorption is shown in Figure 1.…”

Section: Introductionmentioning

confidence: 99%

Fabrication of a capacitive relative humidity sensor using aluminum thin films deposited on etched printed circuit board

Lee

Culaba

2016

MATEC Web of Conferences

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Abstract.A capacitive humidity-sensing device was created by thermal evaporation of 99.999% aluminum. The substrate used for the coating was etched double-sided printed circuit board. The etched printed circuit board serves as the dielectric of the capacitor while the aluminum thin films deposited on either side serve as the plates of the capacitor. The capacitance was measured before and after exposure to humidity. The device was then calibrated by comparing the readings of capacitance with that of the relative humidity sensor of the Vernier LabQuest2. It was found that there is a linear relationship between the capacitance and relative humidity given by the equation C=1.418RH+29.139 where C is the capacitance and RH is the relative humidity. The surface of the aluminum films is porous and it is through these pores that water is adsorbed and capillary condensation occurs, thereby causing the capacitance to change upon exposure to humidity.

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“…An example of such catalysts is given by ordered arrays of vertically aligned 1D nanostructures prepared by anodic oxidation [4][5][6]. The technique has a relatively low cost and is potentially scalable, while other techniques, such as electron beam lithography show limitations for scale-up and may be mainly used to prepare ordered patterns of metal nanoparticles [7][8][9].…”

Section: Introductionmentioning

confidence: 99%

“…In addition, often results on a systematic control of the surface nanostructure are missing. For example, several studies on the preparation of titania nanotubes has been published [14][15][16][17][18][19][20][21][22][23][24][25], but often a more specific correlation between the nanostructure and synthesis parameters is missing.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of TiO2 Thin Films: Relationship Between Preparation Conditions and Nanostructure

et al. 2008

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The influence of the synthesis conditions (pH, HF concentration, procedure of application of the voltage) during the anodization of Ti foils to produce TiO 2 thin films characterized by an ordered arrays of 1D nanostructures (nanorods, nanotubes) is discussed. Different types of 1D nanostructures could be obtained by changing the procedure of synthesis, as shown by field emission scanning electron microscopy images. The analysis of the current versus time curves during the procedure of synthesis provides indications on the sequence of processes occurring during the synthesis. It is also suggested that different growing mechanisms occur depending on the preparation, leading in turn to the different type of nanostructures observed. The relevance of this preparation method is related to the analysis of the relationship for oxide materials between nano-architecture and reactivity and gives the opportunity to prepare materials with an intermediate degree of complexity between model and applied catalysts.

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Metal Oxide Nanoarchitectures for Environmental Sensing

Cited by 222 publications

References 99 publications

Stem cell fate dictated solely by altered nanotube dimension

Stem cell fate dictated solely by altered nanotube dimension

Fabrication of a capacitive relative humidity sensor using aluminum thin films deposited on etched printed circuit board

Synthesis of TiO2 Thin Films: Relationship Between Preparation Conditions and Nanostructure

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