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Sensors (Basel, Switzerland) Nov 2023Optical sensors excel in performance but face efficacy challenges when submerged due to potential surface colonization, leading to signal deviation. This necessitates...
Optical sensors excel in performance but face efficacy challenges when submerged due to potential surface colonization, leading to signal deviation. This necessitates robust solutions for sustained accuracy. Protein and microorganism adsorption on solid surfaces is crucial in antibiofilm studies, contributing to conditioning film and biofilm formation. Most studies focus on surface characteristics (hydrophilicity, roughness, charge, and composition) individually for their adhesion impact. In this work, we tested four materials: silica, titanium dioxide, aluminum oxide, and parylene C. Bovine Serum Albumin (BSA) served as the biofouling conditioning model, assessed with X-ray photoelectron spectroscopy (XPS). Its effect on microorganism adhesion (modeled with functionalized microbeads) was quantified using a shear stress flow chamber. Surface features and adhesion properties were correlated via Principal Component Analysis (PCA). Protein adsorption is influenced by nanoscale roughness, hydrophilicity, and likely correlated with superficial electron distribution and bond nature. Conditioning films alter the surface interaction with microbeads, affecting hydrophilicity and local charge distribution. Silica shows a significant increase in microbead adhesion, while parylene C exhibits a moderate increase, and titanium dioxide shows reduced adhesion. Alumina demonstrates notable stability, with the conditioning film minimally impacting adhesion, which remains low.
Topics: Aluminum Oxide; Silicon Dioxide; Surface Properties; Serum Albumin, Bovine; Titanium; Adsorption
PubMed: 38067919
DOI: 10.3390/s23239546 -
Molecules (Basel, Switzerland) Feb 2016Optical absorption measurements are combined with electronic structure calculations to explore photochemistry of an α-Al₂O₃-PETN interface formed by a nitroester...
Optical absorption measurements are combined with electronic structure calculations to explore photochemistry of an α-Al₂O₃-PETN interface formed by a nitroester (pentaerythritol tetranitrate, PETN, C₅H₈N₄O12) and a wide band gap aluminum oxide (α-Al₂O₃) substrate. The first principles modeling is used to deconstruct and interpret the α-Al₂O₃-PETN absorption spectrum that has distinct peaks attributed to surface F⁰-centers and surface-PETN transitions. We predict the low energy α-Al₂O₃ F⁰-center-PETN transition, producing the excited triplet state, and α-Al₂O₃ F⁰-center-PETN charge transfer, generating the PETN anion radical. This implies that irradiation by commonly used lasers can easily initiate photodecomposition of both excited and charged PETN at the interface. The feasible mechanism of the photodecomposition is proposed.
Topics: Aluminum Oxide; Models, Molecular; Pentaerythritol Tetranitrate; Photochemical Processes; Photochemistry
PubMed: 26938517
DOI: 10.3390/molecules21030289 -
International Journal of Molecular... Jul 2023The dental prophylactic cleaning of a damaged resin-based composite (RBC) restoration with sodium bicarbonate can change the surface characteristics and influence the...
The dental prophylactic cleaning of a damaged resin-based composite (RBC) restoration with sodium bicarbonate can change the surface characteristics and influence the repair bond strength. The purpose of this study was to compare the effect of sodium bicarbonate (SB) and aluminum oxide (AO) surface treatments on the microtensile bond strength (µTBS) of repaired, aged RBC. Bar specimens were prepared from microhybrid RBC and aged in deionized water for 8 weeks. Different surface treatments (AO air-abrasion; SB air-polishing), as well as cleaning (phosphoric acid, PA; ethylene-diamine-tetraacetic-acid, EDTA) and adhesive applications (single bottle etch-and-rinse, ER; universal adhesive, UA), were used prior to the application of the repair RBC. Not aged and aged but not surface treated RBCs were used as positive and negative controls, respectively. The repaired blocks were cut into sticks using a precision grinding machine. The specimens were tested for tensile fracture and the µTBS values were calculated. Surface characteristics were assessed using scanning electron microscopy. AO-PA-UA (62.6 MPa) showed a 20% increase in µTBS compared to the NC (50.2 MPa), which proved to be the most significant. This was followed by SB-EDTA-UA (58.9 MPa) with an increase of 15%. In addition to AO-PA-UA, SB-EDTA-UA could also be a viable alternative in the RBC repair protocol.
Topics: Composite Resins; Aluminum Oxide; Sodium Bicarbonate; Edetic Acid; Surface Properties; Microscopy, Electron, Scanning; Dental Materials; Dental Bonding; Tensile Strength; Materials Testing; Resin Cements
PubMed: 37511327
DOI: 10.3390/ijms241411568 -
Molecules (Basel, Switzerland) Apr 2022The development of green and sustainable materials for use as heterogeneous catalysts is a growing area of research in chemistry. In this paper, mesoporous SiO-AlO mixed...
The development of green and sustainable materials for use as heterogeneous catalysts is a growing area of research in chemistry. In this paper, mesoporous SiO-AlO mixed oxide catalysts with different Si/Al ratios were prepared via hydrolytic (HSG) and nonhydrolytic sol-gel (NHSG) processes. The HSG route was explored in acidic and basic media, while NHSG was investigated in the presence of diisopropylether as an oxygen donor. The obtained materials were characterized using EDX, N-physisorption, powder XRD, Si, Al MAS-NMR, and NH-TPD. This approach offered good control of composition and the Si/Al ratio was found to influence both the texture and the acidity of the mesoporous materials. According to Al and Si MAS NMR analyses, silicon and aluminum were more regularly distributed in NHSG samples that were also more acidic. Silica-alumina catalysts prepared via NHSG were more active in esterification of acetic acid with n-BuOH.
Topics: Aluminum Oxide; Catalysis; Esterification; Gels; Oxides; Silicon Dioxide
PubMed: 35458732
DOI: 10.3390/molecules27082534 -
International Orthopaedics Apr 2009Pure alumina ceramic has been in clinical use in orthopaedics since 1971 and, currently, up to 5 million components have been implanted. Alumina offers advantages like... (Review)
Review
Pure alumina ceramic has been in clinical use in orthopaedics since 1971 and, currently, up to 5 million components have been implanted. Alumina offers advantages like stability, biocompatibility and low wear; however, it has limited strength. Applications are limited by design considerations. Engineers in biomaterials have worked on improving the performance of the material by optimising the manufacturing process. To fulfil surgeons' and patients' increasingly exacting requirements, ceramists have also developed a new ceramic composite, the alumina matrix composite (AMC). This material combines the great principles of the reinforcement of ceramics with its tribological qualities and presents a better mechanical resistance than alumina. The examination of the tribological situation of AMC, especially under the challenging conditions of hydrothermal ageing, shows the aptitude of this material in wear applications. The US Food and Drug Administration (FDA) has approved ceramic ball heads articulating against polyethylene inserts. Since its introduction, more than 65,000 ball heads and 40,000 inserts of AMC have been implanted. With a 6-year follow up, no complication has been reported to the manufacturer. Improved toughness and the excellent wear of AMC makes it a potentially more flexible alternative to the more traditional alumina for hip prostheses.
Topics: Aluminum Oxide; Arthroplasty, Replacement, Hip; Biomechanical Phenomena; Ceramics; Coated Materials, Biocompatible; Hip Prosthesis; Humans; Materials Testing; Prosthesis Design; Prosthesis Failure; Sensitivity and Specificity; Stress, Mechanical; Surface Properties; Tensile Strength
PubMed: 18043920
DOI: 10.1007/s00264-007-0484-9 -
International Journal of Molecular... Apr 2017In recent years, zirconia has been a recognized implant material in clinical dentistry. In the present study, we investigated the performance of an alkali-modified...
In recent years, zirconia has been a recognized implant material in clinical dentistry. In the present study, we investigated the performance of an alkali-modified ceria-stabilized tetragonal ZrO₂ polycrystalline ceramic-based nanostructured zirconia/alumina composite (NANOZR) implant by assessing surface morphology and composition, wettability, bovine serum albumin adsorption rate, rat bone marrow (RBM) cell attachment, and capacity for inducing bone differentiation. NANOZR surfaces without and with alkali treatment served as the control and test groups, respectively. RBM cells were seeded in a microplate with the implant and cultured in osteogenic differentiation medium, and their differentiation was evaluated by measuring alkaline phosphatase (ALP) activity, osteocalcin (OCN) production, calcium deposition, and osteogenic gene expression. The alkali-treated NANOZR surface increased ALP activity, OCN production, calcium deposition, and osteogenesis-related gene expression in attached RBM cells. These data suggest that alkali treatment enhances the osteogenesis-inducing capacity of NANOZR implants and may therefore improve their biointegration into alveolar bone.
Topics: Aluminum Oxide; Animals; Bone Marrow Cells; Cell Differentiation; Cell Proliferation; Cells, Cultured; Dental Implants; Dental Materials; Nanoparticles; Osteogenesis; Rats; Surface Properties; Wettability; Zirconium
PubMed: 28383491
DOI: 10.3390/ijms18040780 -
Particle and Fibre Toxicology Jun 2012Aluminum oxide-based nanowhiskers (AO nanowhiskers) have been used in manufacturing processes as catalyst supports, flame retardants, adsorbents, or in ceramic, metal...
BACKGROUND
Aluminum oxide-based nanowhiskers (AO nanowhiskers) have been used in manufacturing processes as catalyst supports, flame retardants, adsorbents, or in ceramic, metal and plastic composite materials. They are classified as high aspect ratio nanomaterials. Our aim was to assess in vivo toxicity of inhaled AO nanowhisker aerosols.
METHODS
Primary dimensions of AO nanowhiskers specified by manufacturer were 2-4 nm x 2800 nm. The aluminum content found in this nanomaterial was 30% [mixed phase material containing Al(OH)3 and AlOOH]. Male mice (C57Bl/6 J) were exposed to AO nanowhiskers for 4 hrs/day, 5 days/wk for 2 or 4 wks in a dynamic whole body exposure chamber. The whiskers were aerosolized with an acoustical dry aerosol generator that included a grounded metal elutriator and a venturi aspirator to enhance deagglomeration. Average concentration of aerosol in the chamber was 3.3 ± 0.6 mg/m3 and the mobility diameter was 150 ± 1.6 nm. Both groups of mice (2 or 4 wks exposure) were necropsied immediately after the last exposure. Aluminum content in the lung, heart, liver, and spleen was determined. Pulmonary toxicity assessment was performed by evaluation of bronchoalveolar lavage (BAL) fluid (enumeration of total and differential cells, total protein, activity of lactate dehydrogenase [LDH] and cytokines), blood (total and differential cell counts), lung histopathology and pulmonary mechanics.
RESULTS
Following exposure, mean Al content of lungs was 0.25, 8.10 and 15.37 μg/g lung (dry wt) respectively for sham, 2 wk and 4 wk exposure groups. The number of total cells and macrophages in BAL fluid was 2-times higher in animals exposed for 2 wks and 6-times higher in mice exposed for 4 wks, compared to shams (p < 0.01, p < 0.001, respectively). However no neutrophilic inflammation in BAL fluid was found and neutrophils were below 1% in all groups. No significant differences were found in total protein, activity of LDH, or cytokines levels (IL-6, IFN-γ, MIP-1α, TNF-α, and MIP-2) between shams and exposed mice.
CONCLUSIONS
Sub-chronic inhalation exposures to aluminum-oxide based nanowhiskers induced increased lung macrophages, but no inflammatory or toxic responses were observed.
Topics: Administration, Inhalation; Aerosols; Aluminum Oxide; Animals; Bronchoalveolar Lavage Fluid; Cell Count; Cytokines; Inhalation Exposure; L-Lactate Dehydrogenase; Lung; Macrophages; Male; Metal Nanoparticles; Mice; Mice, Inbred C57BL; Particle Size; Tissue Distribution; Toxicity Tests
PubMed: 22713230
DOI: 10.1186/1743-8977-9-22 -
Science (New York, N.Y.) Dec 2008The notion of mimicking natural structures in the synthesis of new structural materials has generated enormous interest but has yielded few practical advances. Natural...
The notion of mimicking natural structures in the synthesis of new structural materials has generated enormous interest but has yielded few practical advances. Natural composites achieve strength and toughness through complex hierarchical designs that are extremely difficult to replicate synthetically. We emulate nature's toughening mechanisms by combining two ordinary compounds, aluminum oxide and polymethyl methacrylate, into ice-templated structures whose toughness can be more than 300 times (in energy terms) that of their constituents. The final product is a bulk hybrid ceramic-based material whose high yield strength and fracture toughness [ approximately 200 megapascals (MPa) and approximately 30 MPa.m(1/2)] represent specific properties comparable to those of aluminum alloys. These model materials can be used to identify the key microstructural features that should guide the synthesis of bio-inspired ceramic-based composites with unique strength and toughness.
Topics: Aluminum Oxide; Animals; Calcium Carbonate; Ceramics; Elasticity; Freezing; Gastropoda; Materials Testing; Mechanical Phenomena; Polymethyl Methacrylate
PubMed: 19056979
DOI: 10.1126/science.1164865 -
Biosensors & Bioelectronics Aug 2022Chronic wounds represent an important healthcare challenge in developed countries, being wound infection a serious complication with significant impact on patients' life...
Chronic wounds represent an important healthcare challenge in developed countries, being wound infection a serious complication with significant impact on patients' life conditions. However, there is a lack of methods allowing an early diagnosis of infection and a right decision making for a correct treatment. In this context, we propose a novel methodology for the electrical monitoring of infection biomarkers in chronic wound exudates, using nanoporous alumina membranes. Lysozyme, an enzyme produced by the human immune system indicating wound infection, is selected as a model compound to prove the concept. Peptidoglycan, a component of the bacterial layer and the native substrate of lysozyme, is immobilized on the inner walls of the nanochannels, blocking them both sterically and electrostatically. The steric blocking is dependent on the pore size (20-100 nm) and the peptidoglycan concentration, whereas the electrostatic blocking depends on the pH. The proposed analytical method is based on the electrical monitoring of the steric/electrostatic nanochannels unblocking upon the specific degradation of peptidoglycan by lysozyme, allowing to detect the infection biomarker at 280 ng/mL levels, which are below those expected in wounds. The low protein adsorption rate and thus outstanding filtering properties of the nanoporous alumina membranes allowed us to discriminate wound exudates from patients with both sterile and infected ulcers without any sample pre-treatment usually indispensable in most diagnostic devices for analysis of physiological fluids. Although size and charge effects in nanochannels have been previously approached for biosensing purposes, as far as we know, the use of nanoporous membranes for monitoring enzymatic cleavage processes, leading to analytical systems for the specific detection of the enzymes has not been deeply explored so far. Compared with previously reported methods, our methodology presents the advantages of no need of neither bioreceptors (antibodies or aptamers) nor competitive assays, low matrix effects and quantitative and rapid analysis at the point-of-care, being also of potential application for the determination of other protease biomarkers.
Topics: Aluminum Oxide; Biomarkers; Biosensing Techniques; Humans; Muramidase; Peptidoglycan; Wound Infection
PubMed: 35421671
DOI: 10.1016/j.bios.2022.114243 -
BioMed Research International 2019Aluminum oxide nanoparticles were supplemented to ATCC 20542 precultures and the outcomes of the process were evaluated relative to the results of...
Aluminum oxide nanoparticles were supplemented to ATCC 20542 precultures and the outcomes of the process were evaluated relative to the results of microparticle-enhanced and standard cultivations. The selected morphological parameters of fungal pellets (projected area, elongation, convexity, and shape factor) were monitored throughout the experiment, together with biomass, lactose, and lovastatin concentration. The qualitative and quantitative chemical analysis was performed with the use of liquid chromatography coupled with high resolution mass spectrometry. The results of the study indicated that the application of nanoparticles was indeed associated with morphological consequences, most notably the decreased pellet size. However, it turned out that the term "nanoparticle-enhanced cultivation" could not be used in the context of lovastatin production, as no marked increase of product titer was observed in nanoparticle-influenced variants relative to standard and microparticle-enhanced cultivation. In addition, the concentration of biomass in the nanoparticle-influenced runs was relatively low. Comparative analysis of total ion chromatograms revealed the presence of a molecule of unknown structure that could be detected solely in broths from standard and microparticle-containing cultures. This study represents the first evaluation of nanoparticles as the tools of morphological engineering aimed at enhanced lovastatin biosynthesis in cultures.
Topics: Aluminum Oxide; Aspergillus; Biomass; Lactose; Lovastatin; Nanoparticles; Time Factors
PubMed: 30733961
DOI: 10.1155/2019/5832496