Structure of alumina oxide coatings deposited by impulse plasma method

Zdunek, Krzysztof; Mizera, J.; Wiencek, P.; Gȩbicki, W.; Możdżonek, M.

doi:10.1016/s0040-6090(98)01594-6

Cited by 6 publications

(3 citation statements)

References 9 publications

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“…In the IR absorption spectra of the AlO x films, shown in Figure 2, two broad absorbance bands can be identified. The first one is located in the 1 200–600 cm −1 region, and it is the result of different contributions21, 22: the OAlO bending mode (≈650–700 cm −1 ), the AlO stretching mode (≈750–850 cm −1 ) and the AlCH 3 stretching mode (≈1 000–1 200 cm −1 ). The deconvolution of this band is not possible because of the lack of information available in literature on the exact absorption frequencies of the IR peaks.…”

Section: Resultsmentioning

confidence: 99%

Remote Plasma‐Enhanced Metalorganic Chemical Vapor Deposition of Aluminum Oxide Thin Films

Volintiru

Creatore

Hemmen

et al. 2008

Plasma Processes & Polymers

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Aluminum oxide films were deposited using remote plasma-enhanced metalorganic chemical vapor deposition from oxygen/trimethylaluminum mixtures. Initial studies by in situ spectroscopic ellipsometry demonstrated that the aluminum oxide films deposited at temperatures <150 8C were porous. The low refractive index of 1.38 was found to increase to 1.52 under ambient conditions, due to ageing. In order to improve the film properties, two routes were explored. First, by increasing the substrate temperature films with a refractive index of 1.48 were obtained at 400 8C, accompanied by a strong decrease in OH concentration, as shown by infrared spectroscopy. Second, by applying an additional rf bias to the substrate the in situ refractive index increased up to 1.60 and the OH groups were quantitatively removed.

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Section: Resultsmentioning

confidence: 99%

Remote Plasma‐Enhanced Metalorganic Chemical Vapor Deposition of Aluminum Oxide Thin Films

Volintiru

Creatore

Hemmen

et al. 2008

Plasma Processes & Polymers

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“…The FT-IR spectrum of the alumina nanoparticles exhibits strong absorption in the range of 500-900 cm -1 , characteristic for Al 2 O 3 . 17 It also has peaks at 1630 and 3422 cm -1 that can be attributed to physically adsorbed water molecules. 18 The pepsin FT-IR spectrum exhibits a peak at 1655 cm -1 , characteristic of an amide I bond.…”

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confidence: 99%

“…In that regard, there are 10 sulfur atoms from cysteine and methionine residues per pepsin molecule. The FT-IR spectrum of the alumina nanoparticles exhibits strong absorption in the range of 500−900 cm -1 , characteristic for Al 2 O 3 . It also has peaks at 1630 and 3422 cm -1 that can be attributed to physically adsorbed water molecules .…”

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confidence: 99%

Alumina−Pepsin Hybrid Nanoparticles with Orientation-Specific Enzyme Coupling

Wang

Gavalas

et al. 2002

Nano Lett.

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Hybrid alumina nanoparticles with pepsin were prepared in a controlled and efficient manner. Phosphorylated pepsin can be coupled to alumina through the interaction between phosphoserine on pepsin and the alumina surface in an orientation-specific manner. A comparison of data obtained with nanoparticles and microsized alumina particles reveals that the conjugated pepsin retained much higher enzymatic activity when it was immobilized on nanoparticles mainly because of the lack of diffusion limitations of the substrate. Additionally, upon attachment to the alumina nanoparticles, the thermal stability of pepsin is enhanced. The coupled enzyme can be quantitatively released by simply incubating the hybrid nanoparticles with phosphate buffer.Introduction. Nanotechnology has emerged as a powerful tool in the fabrication of materials having superior and often unique properties. 1-4 The incorporation of biological molecules into these materials should expand the range of potential applications to include nanoscale biosensors and biocatalysts. 5 Previous studies on the conjugation of nanoparticles with biomolecules such as proteins and DNA used mainly gold-, silver-, silica-, and nickel-based nanoparticles as well as quantum dots. 6 Several methods have been employed for the attachment of biomolecules on nanoparticles including binding through a thiol group to gold 7,8 and maleimido-modified fullerenes, 9 through amino groups to carboxyl-functionalized paricles, 10 through a polyhistidine tag to nickel, 11 or through electrostatic interactions to charged nanoparticles. 12 Herein, we report a new class of hybrid nanoparticles composed of nanosized alumina functionalized with an enzyme. We demonstrate, using pepsin as a model enzyme, an orientation-specific, efficient, and reversible means to couple phosphorylated proteins to alumina nanoparticles through the interaction between the phosphoryl group and the alumina surface. When alumina nanoparticles are used in this manner, the decrease in enzymatic activity is minimal. A unique property of these hybrid nanoparticles is the ability to release the coupled pepsin quantitatively (98%) in a controlled manner.Pepsin is an enzyme essential to the digestion process in animals. The optimal pH for its activity is 2.0, which is compatible with that of alumina. The enzyme has a total of

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