Commercial Aluminum Hydroxide Research Articles

Water-Soluble and Freezable Aluminum Salt Vaccine Adjuvant.

Particulate aluminum salts have long occupied a central place worldwide as inexpensive immunostimulatory adjuvants that enable induction of protective immunity for vaccines. Despite their huge benefits and safety, the particulate structures of aluminum salts require transportation and storage at temperatures between 2 °C and 8 °C, and they all have exquisite sensitivity to damage caused by freezing. Here, we propose to solve the critical freezing vulnerability of particulate aluminum salt adjuvants by introducing soluble aluminum salts as adjuvants. The solubility properties of fresh and frozen aluminum chloride and aluminum triacetate, each buffered optimally with sodium acetate, were demonstrated with visual observations and with UV-vis scattering analyses. Two proteins, A244 gp120 and CRM197, adjuvanted either with soluble aluminum chloride or soluble aluminum triacetate, each buffered by sodium acetate at pH 6.5-7.4, elicited murine immune responses that were equivalent to those obtained with Alhydrogel®, a commercial particulate aluminum hydroxide adjuvant. The discovery of the adjuvanticity of soluble aluminum salts might require the creation of a new adjuvant mechanism for aluminum salts in general. However, soluble aluminum salts might provide a practical substitute for particulate aluminum salts as vaccine adjuvants, thereby avoiding the risk of inactivation of vaccines due to accidental freezing of aluminum salt particles.

Autoclave-Induced Changes in the Physicochemical Properties and Antigen Adsorption of Aluminum Adjuvants

Aluminum hydroxide adjuvants are widely used in human vaccines, such as diphtheria, tetanus, hepatitis A and hepatitis B vaccines. The adsorption of antigens on aluminum hydroxide adjuvants determines the immune boosting effect of vaccines, but it is not clear how changes in physicochemical properties resulting from the production and formulation processes affect the adsorption of aluminum hydroxide adjuvants with antigens. In this study, the commercial aluminum hydroxide adjuvant Alhydrogel® was pretreated by commonly used processes such as autoclaving and calcination, and the changes of aluminum hydroxide adjuvant in physicochemical properties during the treatment were then comprehensively characterized. The adsorption of ovalbumin (OVA) with treated Alhydrogel®, was also investigated, it was found that the decrease in specific surface area caused by the autoclaving process reduced the adsorptive capacity of the antigen, and the adsorptive strength of antigen was decreased only when the surface hydroxyl groups and chemically bound water of adjuvant were reduced by calcination. These findings help to optimize the production and formulation process of adjuvants for the rational regulation of antigen adsorption in vaccines.

Synthesis of Nucleoshell γ-AlOOH as an ultra-high-capacity adsorbent for organic pollutants removal

To solve the problem of effective and low cost of dye removal treatment methods. In this paper, a simple and efficient ionic liquid method for Nucleoshell γ-AlOOH (NA) synthesis is proposed. Hollow γ-AlOOH (HA) prepared by the template method and commercial aluminum hydroxide was also discussed. NA formed a core-shell layered structure with small particle size and large specific surface area, for which the surface space of the adsorbent is fully utilized. The maximum adsorption capacities of Congo red and Methylene blue were 3881.46 mg/g and 1514.66 mg/g, compared to 2544.26 mg/g and 920.52 mg/g for HA. The adsorption process of NA shows a good correlation with pseudo-second-order and the Langmuir model. The adsorption reaction is an exothermic spontaneous reaction. Subsequent treatment can be accomplished by roasting to achieve green recycling. It is shown that NA, as an effective adsorbent, has great potential in the field of wastewater treatment.

Mg/Al-LDH as a nano-adjuvant for pertussis vaccine: a evaluation compared with aluminum hydroxide adjuvant

Background. Layered double hydroxide (LDH) has been demonstrated as a highly efficient antigen platform to induce effective and durable immune response. However, whether LDH nanoparticles could act as an adjuvant for pertussis vaccines is still unknown. Here we evaluated the potential of Mg/Al-LDH as a nano-adjuvant to improve immune response against pertussis and compared it with commercial aluminum hydroxide (AH) adjuvant. Method. The Mg/Al-LDH nanoparticles were synthesized by a hydrothermal reaction. The morphology, structure and size of Mg/Al-LDH were characterized by transmission electron microscope, x-ray diffraction and MALVERN particle analysis. The ovalbumin and Pertussis toxin (PTd) was adsorbed to Mg/Al-LDH. The immune response of antigen-LDH complex was evaluated in mice, compared with commercial adjuvant alum. Hematoxylin-eosin staining was used to evaluate the inflammatory response at injection site. Results. The synthetic Mg/Al-LDH nanoparticles showed a typical hexagonal lamellar structure. The average size of synthetic nanoparticles was 102.9 nm with PDI of 0.13 and zeta potential was 44.4 mV. Mg/Al-LDH nanoparticles effectively adsorbed protein antigen and mediated antigen uptake by DC cells. Animal experiments showed that Mg/Al-LDH gave enhancement in anti-pertussis toxin (PTd) humoral immune response, which was considerable to commercial AH adjuvant. Finally, Mg/Al-LDH produced a slighter inflammatory response than AH at injection site and this injury was quickly recovered. Conclusion. Our study demonstrated the potential of Mg/Al-LDH as an effective adjuvant for pertussis vaccine, which induced comparable antibody response and had a better safety compared with commercial AH adjuvant.

Processing of Hydro-Mineral Lithium Raw Material of Kazakhstan Using Inorganic Sorbents

The article presents the results of studies on recovery of lithium from reservoir brines using both commercial and synthesized aluminum hydroxide and hydrated manganese oxide as sorbents. The research results showed that, when using commercial aluminum hydroxide and synthesized hydrated manganese oxide as sorbents, lithium recovery from brine was 21.8 and 20.1%, respectively. Studies were conducted on lithium chemisorption on freshly precipitated aluminum hydroxide, which was obtained by adding aluminum chloride solution and tri-calcium hydro-aluminate to the brine. Chemisorption of lithium was carried out under the following conditions: T = 50 °C; AlCl3 solution concentration - 120 g/dm3; molar ratio Li/Al = 7; pH equal = 8.0-8.8; holding time with stirring 1 h. The degree of lithium extraction from brine was 71%; lithium capacity of freshly precipitated Al (OH)3 was 5.9 mg/g. During calcareous leaching of lithium-aluminum precipitate, lithium was extracted into a solution by 74.7%.

High activity AlOOH catalyzed Al hydrolysis for hydrogen generation

Previous works indicated that aluminum hydroxide could act as catalyst to assist the hydrolysis reaction of Al, but the catalytic activity of commercial aluminum hydroxide was very poor. In the present research, an AlOOH catalyst with high activity and excellent stability is synthesized using hydrothermal method, and the catalytic effect of this AlOOH catalyst on Al hydrolysis is researched systematically. The results show that AlOOH not only significantly shortens the induction time but also accelerates Al hydrolysis, and the catalytic activity of AlOOH depends on its preparation conditions. The SEM and XRD analyses reveal that the hydrothermal temperature and hydrothermal time have great influence on the crystallinity and grain size of AlOOH, which in turn impact the catalytic activity of AlOOH. The AlOOH catalyst prepared at the hydrothermal temperature of 165 °C for 24 h has the best activity, and it shortens the induction time from 5.00 h to 0.58 h. This work provides a novel and feasible way to generate hydrogen for portable devices.

<p>Crystalline and Amorphous Preparation of Aluminum Hydroxide Nanoparticles Enhances Protective Antigen Domain 4 Specific Immunogenicity and Provides Protection Against Anthrax</p>

IntroductionAluminum salts, although they have been used as adjuvants in many vaccine formulations since 1926, exclusively induce a Th2-biased immune response, thereby limiting their use against intracellular pathogens like Mycobacterium tuberculosis.Methods and ResultsHerein, we synthesized amorphous and crystalline forms of aluminum hydroxide nanoparticles (AH nps) of 150–200 nm size range. Using Bacillus anthracis protective antigen domain 4 (D4) as a model antigen, we demonstrated that both amorphous and crystalline forms of AH nps displayed enhanced antigen D4 uptake by THP1 cells as compared to commercial adjuvant aluminum hydroxide gel (AH gel). In a mouse model, both amorphous and crystalline AH nps triggered an enhanced D4-specific Th2- and Th1-type immune response and conferred superior protection against anthrax spore challenge as compared to AH gel. Physicochemical characterization of crystalline and amorphous AH nps revealed stronger antigen D4 binding and release than AH gel.ConclusionThese results demonstrate that size and crystallinity of AH nps play important roles in mediating enhanced antigen presenting cells (APCs) activation and potentiating a strong antigen-specific immune response, and are critical parameters for the rational design of alum-based Th1-type adjuvant to induce a more balanced antigen-specific immune response.

Effect of metal-metal and metal-support interaction on activity and stability of Pd-Rh/alumina in CO oxidation

A series of Pd-Rh/alumina catalysts with total precious metals loading of 0.2wt.% was prepared by means of mechanical mixing of monometallic precursors and incipient wetness impregnation of the support with dual complex salt. Gamma and delta alumina supports were obtained from commercial aluminum hydroxide by calcinations at 720 and 1000°C respectively. Supports were examined by electron paramagnetic resonance spectroscopy, low-temperature nitrogen adsorption, X-ray diffraction analysis and photoluminescence spectroscopy. It was shown that concentration of donor sites of the supports differs according to distinctions between values of their specific surface areas. Finally, the strength of metal-support interaction is getting much weaker in the case of δ-Al2O3. Bimetallic Pd-Rh species with strong metal-metal interaction supported on γ-Al2O3 were found to be characterized by superior high-temperature stability. Pd/Rh ratios of 3:2 and 7:3 were shown to be the most appropriate for this purpose.

Clay-lipid nanohybrids: towards influenza vaccines and beyond

AbstractThe design of nanostructured materials based on natural components, such as clay minerals, offers new solutions to biomedical challenges such as more efficient and storage-stable vaccines. Clay-lipid hybrid materials have proved useful as adjuvants in influenza vaccines and with a possible projection to leishmaniasis vaccines and other pathogens. Self-assembly of phospholipid molecules on the surface of microfibrous sepiolite and lamellar Mg/Al layered double hydroxide renders a biocompatible lipid bilayer membrane that ensures non-degrading immobilization of proteins and other biological species including viral particles and DNA (deoxyribonucleic acid). Immunization tests in mice showed the superior immunogenicity of a clay-lipid-supported virus compared to a commercial aluminium hydroxide adjuvant.

Flame Retardant Low Density Polyethylene with Aluminium Hydroxide/ Commercial Fire Retardants FR01 Synergistic System

Low density polyethylene (LDPE) was modified by the addition of commercial fire retardants FR01 and aluminium hydroxide (ATH). ATH/FR01/LDPE composites were prepared by melt blending and extrusion in a twin-screw extruder. ATH was first modified by a silane coupling agent KH550 then added to LDPE. The flame retardancy, electrical property and thermal behavior of the LDPE composites were investigated by limiting oxygen index (LOI), volume resistivity and thermogravimetric analysis (TGA), respectively. The results indicated that the surface modification of ATH (M-ATH) could greatly improve the dispersibility and compatibility with LDPE matrix. The mechanical property tests showed good mechanical properties of composite, compared with unmodified one, tensile strength and elongation of M-ATH/LDPE were all improved, and the addition of FR01 improved the flame retardancy of ATH/LDPE remarkably. TGA results demonstrate that char yield of M-ATH/FR01/LDPE (30/15/70) reaches 27 wt% at 600 °C in Ar atmosphere.

Inhibition of Aggregation of Aluminum Hydroxide Adjuvant During Freezing and Drying

Aluminum-salt adjuvants are widely used to increase immunogenicity of recombinant protein vaccines. However, when vaccines formulated with these adjuvants are frozen or lyophilized, losses of efficacy are often reported. This loss of potency is usually attributed to the aggregation of adjuvant particles during processing. In this study, we examine the aggregation behavior of Alhydrogel™, a commercial aluminum hydroxide adjuvant, during freeze-thawing and freeze-drying. By cooling Alhydrogel™ formulations at faster rates or by the addition of sufficient amounts of a glass forming excipient such as trehalose, aggregation of Alhydrogel™, can be prevented or minimized. We propose that freeze-concentration of buffer salts induces modifications in adjuvant surface chemistry and crystallinity, which in turn favor aggregation. These modifications, and the resulting aggregation of Alhydrogel™ particles can be minimized through choice of buffer ions, or kinetically inhibited by rapidly forming a glassy state during freezing.

TSEFLAR™ – the centrifugal flash reactor for rapid thermal treatment of powdered materials

The concept of the centrifugal thermal activation (CTA) of powdered materials on a rotating solid heat carrier is developed. A compact centrifugal flash reactor has been manufactured and tested. The tested set-up provided: the heating of gibbsite powder to the temperature of 400–900 K with the rate more than 103 K/s; the duration of the powder thermal treatment less than 1.5 s; the regulation of the treatment duration by changing the speed of the plate rotation and the shape of the rotating heat carrier; the product output up to 40 dm3/h; the removal of the extracted steam containing gases and rapid quenching of the thermally activated solid products. The device tested has been used for the thermal activation of commercial aluminium hydroxide Al(OH)3 (gibbsite). The obtained thermally activated product possesses a high reactivity and can be used for the preparation of various alumina-based compounds.

Synthesis, evaluation and characterization of alumina ceramics with elongated grains

Alumina ceramics with high fracture toughness were synthesised by introducing seeds and controlling processing using the in situ self-toughening technique. The preparation of the high tough alumina materials started with cheap commercial aluminum hydroxide as raw materials. α-Alumina powder was gained by low temperature calcination of the aluminum hydroxide with seeds, which were introduced by high purity alumina ball medium during grinding. The alumina powders were hot-pressed, then, the high tough alumina ceramics with elongated grains were obtained. The elongated grain structure is originally considered to play a significant role in the increment of fracture toughness. Meanwhile, in order to investigate in situ toughening mechanism of elongated alumina grains, which can produce crack bridging, crack deflection and pull-out as dominant toughening mechanisms to greatly increase toughness, fractal characteristics and model were studied in detail.

Fabrication of low cost fine-grained alumina powders by seeding for high performance sintered bodies

The effect of seeding into commercial aluminum hydroxide on the α-alumina transition temperature, powder characteristics and properties of sintered bodies was investigated, with the purpose of obtaining high performance sintered bodies from low cost raw material. A small amount of fine α-alumina seed addition, which was worn from wet ball milling, drastically lowered the α-alumina transition temperature. The particle size of the low temperature transformed seeded powder was smaller than non-seeded powder. This powder could be sintered to full dense at lower temperature. The abnormal grain growth, which is often observed in high temperature sintered usual purity alumina, occurred at lower temperature in the sintered low temperature transformed seeded powder. However, the abnormal grain size was small and the number of the grains was high. The sintered bodies with these microstructures show high bending strength and very high fracture toughness.

High toughness alumina ceramics with elongated grains developed from seeds

In the present paper, the influence of α-Al2O3 seeds and sintering methods on elongated grain growth and fracture toughness is investigated. The preparation of alumina ceramics started with commercial aluminum hydroxide. Abrasives were introduced to the starting materials by wet-grinding of high-purity alumina milling balls. Abrasives, playing the role of seeds, lowered the transformation temperature of aluminum hydroxide to alumina. Microstructures with elongated grains were developed by hot-pressing for the above calcined powders containing α-Al2O3 seeds, and alumina grain shapes changed with the amount of seeds introduced. However, only equiaxed grains were observed for the samples pressureless sintered. Fracture toughness of the alumina ceramics was dramatically improved by elongated grains. For the sample hot-pressed at 1600°C for 2 h under 40 MPa pressure, fracture toughness reached 7.1 MPa·m1/2, which is much higher than that of normal alumina ceramics without elongated grains. In addition, high flexural strength of 630 MPa for the hot-pressed samples was also obtained.

Influence of α-alumina seed on the morphology of grain growth in alumina ceramics from Bayer aluminum hydroxide

The preparation of alumina ceramics started with commercial aluminum hydroxide from the Bayer process. Abrasives were introduced to the starting materials by the wet grinding of high-purity alumina milling balls. Abrasives played the role of seeds, lowering the transformation temperature of aluminum hydroxide to alumina. The phase transformation from aluminum hydroxide to α-Al 2O 3 was completed at 1100 °C in 2 h with a certain amount of seeds added. Seed also changed the sintering behavior and microstructure of calcined powders. In this paper, the relationship between seed concentrations and grain morphology was investigated. The alumina grain morphology showed a trend of change from equiaxed grain to hexagonal platelets, and finally to elongated grains with increase of the seed concentration.

Measuring the surface area of aluminum hydroxide adjuvant

The traditional method of determining surface area, nitrogen gas sorption, requires complete drying of the sample prior to analysis. This technique is not suitable for aluminum hydroxide adjuvant because it is composed of submicron, fibrous particles that agglomerate irreversibly upon complete removal of water. In this study, the surface area of a commercial aluminum hydroxide adjuvant was determined by a gravimetric/FTIR method that measures the water adsorption capacity. This technique does not require complete drying of the adjuvant. Five replicate determinations gave a mean surface area of 514 m2/g and a 95% confidence interval of 36 m2/g for a commercial aluminum hydroxide adjuvant. The X‐ray diffraction pattern and the Scherrer equation were used to calculate the dimensions of the primary crystallites. The average calculated dimensions were 4.5 × 2.2 × 10 nm. Based on these dimensions, the mean calculated surface area of the commercial aluminum hydroxide adjuvant was 509 m2/g, and the 95% confidential interval was 30 m2/g. The close agreement between the two surface area values indicates that either method may be used to determine the surface area of aluminum hydroxide adjuvant. The high surface area, which was determined by two methods, is an important property of aluminum hydroxide adjuvants, and is the basis for the intrinsically high protein adsorption capacity. © 2002 Wiley‐Liss Inc. and the American Pharmaceutical Association J Pharm Sci 91:1702–1706, 2002

Preparation of High Fracture Toughness Alumina Sintered Bodies from Bayer Aluminum Hydroxide

The mechanical properties of hot-pressed, low-temperature-calcined α-alumina powder made from commercial aluminum hydroxide by seeding of wet grinding abrasion powder were investigated. The microstructure of samples sintered at low temperature is composed of very fine equiaxial grains and its bending strength is higher than 800MPa. As the sintering temperature increases, the grains become large and uniaxially elongated, the bending strength of sintered bodies decreases, and the fracture toughness increases. A sample sintered at 1400°C shows a bending strength of 600MPa and a fracture toughness of 7.9MPa⋅m1/2 (SEPB method). A maximum fracture toughness of 9.0MPa⋅m1/2 is achieved in a sample sintered at 1600°C. This high fracture toughness is caused by a uniform and elongated grain structure, and by increment of grain boundary fracture.

Strength of Sintered Alumina at Low Temperature Due to Ball Mill Abrasion Powder Seeding

Sinterability of low-temperature calcined α-alumina powder and the bending strength of sintered bodies were investigated. The α-alumina powder was made from commercial aluminum hydroxide with seeding of abrasion powder worn in the wet ball milling. The low-temperature calcined α-alumina powder was very fine and achieved the density of more than 3.8Mg/m3 by hot pressing at 1200°C. The microstructure of the sample sintered at low temperature was composed of very fine equiaxial gains in spite of low purity. The bending strength of this sample was more than 800MPa.

Formation of α-Al<sub>2</sub>O<sub>3</sub> from Al(OH)<sub>3</sub> in the Presence of Seed Particles and Its Sinterability

Effect of wet grinding of commercial aluminum hydroxide on the transformation to α-alumina during heating was investigated using vibration ball mill. The grinding with high purity alumina balls reduced the transformation temperature to α-alumina by 300°C. Such significant reduction in the transformation temperature was not observed in the samples obtained by the grindings with zirconia and low purity alumina balls. The formation of α-alumina from ground aluminum hydroxide at such a low temperature was possibly attributed to a seed-effect of fine α-alumina powder worn from the balls and its uniform mixing with the mother powder during grinding. The α-alumina powder made from ground aluminum hydroxide consisted of very fine particles, which enabled us to sinter at a relatively low temperature. The sintered bodies had fine-grained structure without abnormal grain growth.