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Journal of Toxicology and Environmental... 2007
Review
Topics: Aluminum; Aluminum Compounds; Aluminum Hydroxide; Aluminum Oxide; Animals; Environmental Exposure; Humans; Occupational Exposure; Risk Assessment; Tissue Distribution; Toxicity Tests
PubMed: 18085482
DOI: 10.1080/10937400701597766 -
Langmuir : the ACS Journal of Surfaces... Oct 2015Nanoporous anodic aluminum oxide layers were fabricated on aluminum substrates with systematically varied pore diameters (20-80 nm) and oxide thicknesses (150-500 nm) by...
Nanoporous anodic aluminum oxide layers were fabricated on aluminum substrates with systematically varied pore diameters (20-80 nm) and oxide thicknesses (150-500 nm) by controlling the anodizing voltage and time and subsequent pore-widening process conditions. The porous nanostructures were then coated with a thin (only a couple of nanometers thick) Teflon film to make the surface hydrophobic and trap air in the pores. The corrosion resistance of the aluminum substrate was evaluated by a potentiodynamic polarization measurement in 3.5 wt % NaCl solution (saltwater). Results showed that the hydrophobic nanoporous anodic aluminum oxide layer significantly enhanced the corrosion resistance of the aluminum substrate compared to a hydrophilic oxide layer of the same nanostructures, to bare (nonanodized) aluminum with only a natural oxide layer on top, and to the latter coated with a thin Teflon film. The hydrophobic nanoporous anodic aluminum oxide layer with the largest pore diameter and the thickest oxide layer (i.e., the maximized air fraction) resulted in the best corrosion resistance with a corrosion inhibition efficiency of up to 99% for up to 7 days. The results demonstrate that the air impregnating the hydrophobic nanopores can effectively inhibit the penetration of corrosive media into the pores, leading to a significant improvement in corrosion resistance.
Topics: Air; Aluminum; Aluminum Oxide; Corrosion; Electrodes; Hydrophobic and Hydrophilic Interactions; Microscopy, Electron, Scanning; Nanopores
PubMed: 26393523
DOI: 10.1021/acs.langmuir.5b02392 -
Journal of Biomedical Materials... May 2020The use of nanoscale surface modifications offers a possibility to regulate the bacterial adherence behavior. The aim of this study was to evaluate the influence of...
The use of nanoscale surface modifications offers a possibility to regulate the bacterial adherence behavior. The aim of this study was to evaluate the influence of nanoporous anodic aluminum oxide of different pore diameters on the bacterial species Streptococcus mitis and Streptococcus mutans. Nanoporous anodic aluminum oxide (AAO) surfaces with an average pore diameter of 15 and 40 nm, polished pure titanium and compact aluminum oxide (alumina) samples as reference material were investigated. S. mitis and mutans were evaluated for initial adhesion and viability after an incubation period of 30 and 120 min. After 30 min a significantly reduced growth of S. mitis and mutans on 15 nm samples compared to specimens with 40 nm pore diameter, alumina and titanium surfaces could be observed (p < .001). Even after 120 min incubation there was a significant difference between the surfaces with 15 nm pore diameter and the remaining samples (p < .001). AAO surfaces with a small pore diameter have an inhibitory effect on the initial adhesion of S. mitis and mutans. The use of such pore dimensions in the area of the implant shoulder represents a possibility to reduce the adhesion behavior of these bacterial species.
Topics: Aluminum Oxide; Bacterial Adhesion; Electrodes; Porosity; Streptococcus mitis; Streptococcus mutans
PubMed: 31763773
DOI: 10.1002/jbm.b.34514 -
International Journal of Toxicology Nov 2016This is a safety assessment of alumina and aluminum hydroxide as used in cosmetics. Alumina functions as an abrasive, absorbent, anticaking agent, bulking agent, and... (Review)
Review
This is a safety assessment of alumina and aluminum hydroxide as used in cosmetics. Alumina functions as an abrasive, absorbent, anticaking agent, bulking agent, and opacifying agent. Aluminum hydroxide functions as a buffering agent, corrosion inhibitor, and pH adjuster. The Food and Drug Administration (FDA) evaluated the safe use of alumina in several medical devices and aluminum hydroxide in over-the-counter drugs, which included a review of human and animal safety data. The Cosmetic Ingredient Review (CIR) Expert Panel considered the FDA evaluations as part of the basis for determining the safety of these ingredients as used in cosmetics. Alumina used in cosmetics is essentially the same as that used in medical devices. This safety assessment does not include metallic or elemental aluminum as a cosmetic ingredient. The CIR Expert Panel concluded that alumina and aluminum hydroxide are safe in the present practices of use and concentration described in this safety assessment.
Topics: Aluminum Hydroxide; Aluminum Oxide; Animals; Consumer Product Safety; Cosmetics; Equipment and Supplies; Government Regulation; Humans; Molecular Structure; Toxicity Tests; Toxicokinetics; United States; United States Food and Drug Administration
PubMed: 27913785
DOI: 10.1177/1091581816677948 -
International Journal of Biological... Oct 2019Herein, we explored the interaction of AlO NPs with RBCs and Hb to determine the effect of AlO NPs on hemolytic activity and Hb denaturation. The percentage of hemolysis...
Herein, we explored the interaction of AlO NPs with RBCs and Hb to determine the effect of AlO NPs on hemolytic activity and Hb denaturation. The percentage of hemolysis of extracts and direct contact assays triggered by AlO NPs was calculated by determining supernatant Hb concentration at 540 nm. Far-UV CD and Trp/ANS/acrylamide fluorescence spectroscopic methods were used to determine the structural changes of Hb upon interaction with AlO NPs. Theoretical studies were carried out to display the residues involved in the binding site of Hb with AlO nanocluster as well as the structural changes of Hb after interaction. The results showed that the percentage of hemolysis of extract and direct contact assays induced by AlO NPs were 1.16 and 0.46, respectively. Fluorescence spectroscopy revealed that AlO NPs alter the quaternary structure of the protein; however, CD spectroscopy indicated that the secondary structure of Hb remains almost unchanged. Theoretical study displayed that AlO nanocluster interacts with different residues of protein, and Hb tends to be destabilized at the binding site with nanocluster. This study may be significant in exploring the toxicity profile of AlO NPs for their in vivo implementations.
Topics: Aluminum Oxide; Erythrocytes; Hemoglobins; Hemolysis; Humans; Models, Molecular; Molecular Conformation; Nanoparticles; Protein Conformation; Spectrum Analysis
PubMed: 31351960
DOI: 10.1016/j.ijbiomac.2019.07.154 -
Small (Weinheim An Der Bergstrasse,... Jun 2007Nanoporous aluminum oxide membranes with high open porosity are prepared by anodic oxidation. Conventional self-supporting as well as mechanically stabilized nanoporous...
Nanoporous aluminum oxide membranes with high open porosity are prepared by anodic oxidation. Conventional self-supporting as well as mechanically stabilized nanoporous membranes are produced from aluminum plates and microimprinted aluminum foils, respectively. The mechanically stabilized membranes are characterized by very thin membrane parts stabilized by surrounding thick bridges. The minimal thickness of these thin membranes with open pores on both sides is 1 microm, with a mean pore size of the parallel open pores of 185 nm. With these two kinds of membrane the flow rates for cross filtration can be tuned over a wide range. With the mechanically stabilized membranes, substantially higher flow rates are achieved and experiments that cannot be performed with thicker membranes become possible. The biofunctionalization of the pore walls with archaebacterial tetraether lipids is realized and proved using aminated semiconductor nanocrystals. The lipid layer deposited on the pore walls also changes the filtration properties.
Topics: Aluminum Oxide; Filtration; Lipids; Membranes, Artificial; Microscopy, Electron, Scanning; Nanoparticles; Porosity
PubMed: 17492744
DOI: 10.1002/smll.200600582 -
Journal of Biomedical Materials... Mar 2022For cardiopulmonary bypass, the polyvinyl chloride (PVC) circuit which can initiate the activation of platelets and the coagulation cascade after blood cell contacting...
Enhancement of the anticoagulant capacity of polyvinyl chloride tubing for cardiopulmonary bypass circuit using aluminum oxide nanoscale coating applied through atomic layer deposition.
For cardiopulmonary bypass, the polyvinyl chloride (PVC) circuit which can initiate the activation of platelets and the coagulation cascade after blood cell contacting is the possible detrimental effect. Surface coating of the PVC tubing system can be an effective approach to enhance circuit's hemocompatibility. In this study, aluminum oxide (Al O ) thin films were deposited through thermal atomic layer deposition (T-ALD) or plasma-enhanced ALD (PE-ALD) on PVC samples, and the anticoagulation of the Al O -coated PVC samples was demonstrated. The results revealed that Al O deposition through ALD increased surface roughness, whereas T-ALD had a relative hydrophilicity compared with blank PVC and PE-ALD. Whole blood immersion tests showed that blood clots formed on blank PVC and that a large amount of red blood cells was found on PE-ALD substrates, whereas less blood cells were noted in T-ALD samples. Both T-ALD and PE-ALD Al O films did not cause activation of blood cells, as evidenced in CD3 /CD4 /CD8 , CD61 /CD62P , and CD45 /CD42b populations. Analysis of serum coagulation factors showed that a lower amount of prothrombin was absorbed on T-ALD Al O samples than that on blank PVC. For albumin and fibrinogen immersion tests, immunostaining and scanning electron microscopy further revealed that a thin albumin layer was absorbed on T-ALD Al O substrates but not on PVC samples. This study revealed that deposition of Al O films by T-ALD can improve anticoagulation of the PVC tubing system.
Topics: Aluminum Oxide; Anticoagulants; Cardiopulmonary Bypass; Polyvinyl Chloride
PubMed: 34492134
DOI: 10.1002/jbm.b.34932 -
Langmuir : the ACS Journal of Surfaces... Dec 2015The interaction of water vapor with amorphous aluminum oxide films on Al(111) is studied using X-ray photoelectron spectroscopy to elucidate the passivation mechanism of...
The interaction of water vapor with amorphous aluminum oxide films on Al(111) is studied using X-ray photoelectron spectroscopy to elucidate the passivation mechanism of the oxidized Al(111) surfaces. Exposure of the aluminum oxide film to water vapor results in self-limiting Al2O3/Al(OH)3 bilayer film growth via counter-diffusion of both ions, Al outward and OH inward, where a thinner starting aluminum oxide film is more reactive toward H2O dissociation-induced oxide growth because of the thickness-dependent ionic transport in the aluminum oxide film. The aluminum oxide film exhibits reactivity toward H2O dissociation in both low-vapor pressure [p(H2O) = 1 × 10(-6) Torr] and intermediate-vapor pressure [p(H2O) = 5 Torr] regimes. Compared to the oxide film growth by exposure to a p(H2O) of 1 × 10(-6) Torr, the exposure to a p(H2O) of 5 Torr results in the formation of a more open structure of the inner Al(OH)3 layer and a more compact outer Al2O3 layer, demonstrating the vapor-pressure-dependent atomic structure in the passivating layer.
Topics: Aluminum Oxide; Diffusion; Photoelectron Spectroscopy; Surface Properties; Water
PubMed: 26550986
DOI: 10.1021/acs.langmuir.5b02769 -
Archives of Toxicology Oct 2015Aluminum oxide nanoparticles are listed among 14 high-priority nanomaterials published by the Organization for Economic Co-operation and Development, but limited... (Comparative Study)
Comparative Study
Aluminum oxide nanoparticles are listed among 14 high-priority nanomaterials published by the Organization for Economic Co-operation and Development, but limited information is available on their potential hazards. In this study, we compared the toxicity of two different aluminum oxide nanorods (AlNRs) commercially available in vivo and in vitro. Considering aspect ratio, one was 6.2 ± 0.6 (long-AlNRs) and the other was 2.1 ± 0.4 (short-AlNRs). In mice, long-AlNRs induced longer and stronger inflammatory responses than short-AlNRs, and the degree reached the maximum on day 7 for both types and decreased with time. In addition, in vitro tests were performed on six cell lines derived from potential target organs for AlNPs, HEK-293 (kidney), HACAT (skin), Chang (liver), BEAS-2B (lung), T98G (brain), and H9C2 (heart), using MTT assay, ATP assay, LDH release, and xCELLigence system. Long-AlNRs generally produced stronger toxicity than short-AlNRs, and HEK-293 cells were the most sensitive for both AlNRs, followed by BEAS-2B cells, although results from 4 kinds of toxicity tests conflicted among the cell lines. Based on these results, we suggest that toxicity of AlNRs may be related to aspect ratio (and resultant surface area). Furthermore, novel in vitro toxicity testing methods are needed to resolve questionable results caused by the unique properties of nanoparticles.
Topics: Aluminum Oxide; Animals; Cell Line; Cell Line, Tumor; HEK293 Cells; Humans; Inflammation; Male; Mice; Mice, Inbred ICR; Nanotubes; Rats; Toxicity Tests
PubMed: 25155191
DOI: 10.1007/s00204-014-1332-5 -
ACS Combinatorial Science May 2019The present study reports a two-level multivariate analysis to optimize the production of anodized aluminum oxide (AlO) dielectric films for zinc oxide thin-film...
The present study reports a two-level multivariate analysis to optimize the production of anodized aluminum oxide (AlO) dielectric films for zinc oxide thin-film transistors (TFTs). Fourteen performance parameters were measured and analysis of variance (ANOVA) of the combined responses has been applied to identify how the AlO dielectric fabrication process influences the electrical properties of the TFTs. Using this approach, the levels for the manufacturing factors to achieve optimal overall device performance have been identified and ranked. The cross-checked analysis of the TFT performance parameters demonstrated that the appropriate control of the anodization process can have a higher impact on TFT performance than the use of traditional methods of surface treatment of the dielectric layer. Flexible electronics applications are expected to grow substantially over the next 10 years. Given the complexity and challenges of new flexible electronics components, this "multivariate" approach could be adopted more widely by the industry to improve the reliability and performance of such devices.
Topics: Aluminum Oxide; Combinatorial Chemistry Techniques; Electrochemical Techniques; Electrodes; Multivariate Analysis; Transistors, Electronic; Zinc Oxide
PubMed: 30892872
DOI: 10.1021/acscombsci.8b00195