Search Results (29)

Adjuvants are chemical substances used in vaccines to enhance immunogenicity. Among them, aluminum-based nanoparticles are some of the oldest and most widely employed adjuvants in vaccine formulations. A key function of aluminum adjuvants is thought to involve acting as an antigen depot, enabling slow antigen release and providing sufficient time for effective immune activation. Therefore, understanding antigen–adjuvant interactions is essential, as these interactions influence antigen stability, release kinetics, and overall vaccine performance. In this study, we investigated how the physicochemical properties of aluminum hydroxide nanoparticles modulate antigen–protein interactions and affect protein stability. Nanoparticles synthesized under acidic (pH » 5.0) to near-neutral (pH » 7.1) conditions exhibited lower crystallinity, reduced hydroxyl density, and higher interfacial hydration, whereas those prepared under basic conditions (pH » 9.0) displayed increased crystallinity, enriched surface hydroxyl groups, and markedly reduced hydration. Antigen proteins bound to low-crystallinity aluminum hydroxide nanoparticles showed improved thermal stability, while those associated with highly crystalline nanoparticles exhibited reduced thermal stability. Complementary ITC study further suggests that these stability differences are accompanied by changes in their interaction behavior. These findings indicate that the structural and interfacial properties of aluminum hydroxide nanoparticles strongly influence their interactions with antigen proteins and the resulting physical stability. Together, our results demonstrate that the balance among crystallinity, hydroxyl organization, and interfacial hydration governs the thermal behavior of antigen proteins adsorbed onto aluminum hydroxide. This work provides a rational design principle for engineering aluminum-based adjuvants that optimize antigen–protein stability in vaccine formulations. Full article

The present work deals with the preparation and characterization of fire-retardant acrylonitrile–butadiene–styrene (ABS) foams incorporating 25 wt% of a phosphorus flame-retardant (PFR) system formed by 50% of ammonium polyphosphate (APP) and 50% of aluminum diethylphosphinate (AlPi). To further enhance performance, 5 wt% of the PFR was replaced by either montmorillonite (MMT) or layered double hydroxide (LDH) nanoparticles, maintaining the overall FR content constant. The formulations were prepared by melt blending, and foams were produced using a one-step supercritical carbon dioxide (sCO₂) dissolution foaming process. The incorporation of the PFR, alone or partially replaced by nanoclays, resulted in foams with smaller cell sizes and higher cell nucleation densities compared to pure ABS, with cell sizes reducing from 60 μm to as low as 40 μm and cell densities reaching values > 10⁷ cells/cm³. The presence of LDH notably modified the thermal decomposition of ABS–PFR, increasing the temperature at 5% mass loss (T_5%) by more than 10 °C and the amount of formed residue by more than 15%. The ABS–PFR/LDH foam also showed a higher glass transition temperature (3 °C increase) and a higher specific storage modulus (920 MPa·cm³/g, a more than 40% increase). Cone calorimetry revealed a very significant reduction in the peak of the heat release rate (PHRR) and increased residue formation for ABS–PFR compared to ABS (from 1672 kW·m⁻² to as low as 483 kW·m⁻²). LDH nanoparticles further decreased HRR during the early quasi-static combustion stage of foams, indicating a more effective condensed-phase flame-retardant action than MMT. Full article

The use of vaccines incorporating subunit proteins and viral components has significantly increased in recent decades, emphasizing the need for more effective and modular adjuvants. This study examined saponins from Saponaria officinalis, regarded as one of the most promising plant sources for developing an adjuvant platform using nanocomplex formation. A nanoparticle adjuvant containing saponins from Saponaria officinalis can be used to stimulate a humoral immune response; this ability was demonstrated using a model that included various viral proteins. The humoral immune response enhanced by saponin-containing adjuvants can increase from four to sixteen times, depending on the type of antigen used. Additionally, this response surpasses that triggered by antigens paired with aluminum hydroxide and is comparable to responses induced by adjuvants that contain Quil A. The further investigation of these platforms may yield a broader range of immunostimulants that can enhance vaccine effectiveness. Full article

Background: Chitosan, a family of polysaccharides composed of glucosamine and N-acetyl glucosamine, is a promising adjuvant candidate for eliciting potent immune response. Methods: This study compared the adjuvant effects of chitosan to those of empty lipid nanoparticles (eLNPs) and aluminum hydroxide (alum) following administration of recombinant SARS-CoV-2 spike immunogen in adult mice. Mice received the adjuvanted recombinant protein vaccine in a prime-boost regimen with four weeks interval. Subsequent analyses included serological assessment of antibody responses, evaluation of T cell activity, immune cell recruitment and cytokine profiles at injection site. Results: Compared to alum, chitosan induced a more balanced Th1/Th2 response, akin to that observed with eLNPs, demonstrating its ability to modulate both the humoral and cellular immune pathways. Chitosan induced a different proinflammatory cytokine (e.g., IL-1⍺, IL-2, IL-6, and IL-7) and chemokine (e.g., Eotaxin, IP-10, MIP-1a) profile compared to eLNPs and alum at the injection site and in the draining lymph nodes. Moreover, chitosan potentiated the recruitment of innate immune cells, with neutrophils accounting for about 40% of the infiltrating cells in the muscle, representing a ~10-fold increase compared to alum and a comparable level to eLNPs. Conclusions: These findings collectively indicate that chitosan has the potential to serve as an effective adjuvant, offering comparable, and potentially superior, properties to those of currently approved adjuvants. Full article

The synthesis of oxide nanopowders through ultrasonic spray pyrolysis (USP) represents a sustainable method for producing high-purity, spherical particles tailored for advanced material applications. Recent developments in USP synthesis leverage the continuous transport of aerosols from an ultrasonic generator to a high-temperature furnace, with nanopowders collected efficiently using an electrostatic precipitator. This study explored the use of USP for titanium oxysulfate and aluminum nitrate solutions derived from the aluminum industry, focusing on resource recovery and waste reduction. Titanium oxysulfate was synthesized by leaching slag, generated during the reduction of red mud, with sulfuric acid under oxidizing, high-pressure conditions. After purification, the titanium oxysulfate solution was processed using USP in a hydrogen reduction atmosphere to yield spherical titanium dioxide (TiO₂) nanopowders. The hydrogen atmosphere enabled precise control over the nanoparticles’ morphology and crystallinity, enhancing their suitability for use in applications such as photocatalysis, pigments, and advanced coatings. In parallel, both synthetic and laboratory solutions of aluminum nitrate [Al(NO₃)₃] were prepared. The laboratory solution was prepared by leaching aluminum hydroxide oxide (AlOOH) with hydrochloric acid to form aluminum chloride (AlCl₃), followed by a conversion to aluminum nitrate through the addition of nitric acid. The resulting aluminum nitrate solution was subjected to USP, producing highly uniform, spherical alumina (Al₂O₃) nanopowders with a narrow size distribution. The resulting nanopowders, characterized by their controlled properties and potential applicability, represent an advancement in oxide powder synthesis and resource-efficient manufacturing techniques. Full article

Nanoclays have gained attention in biological applications due to their biocompatibility, low toxicity, and cost-effectiveness. Layered double hydroxides (LDHs) are synthetic nanoclays that have been used as adjuvants and antigen carriers in nanovaccines developed through passive bioconjugation. However, performing active bioconjugation to bind antigens covalently and generate subunit nanovaccines remains unexplored. In this study, we investigated the synthesis, functionalization, and active conjugation of LDH nanoparticles to produce subunit nanovaccines with peptides from SARS-CoV-2. The synthesis of Mg-Al LDHs via a coprecipitation and hydrothermal treatment rendered monodisperse particles averaging 100 nm. Their functionalization with (3-aminopropyl)triethoxysilane was better than it was with other organosilanes. Glutaraldehyde was used as a linker to bind lysine as a model biomolecule to establish the best conditions for reductive amination. Finally, two peptides, P₂ and P₅ (epitopes of the SARS-CoV-2 spike protein), were bound on the surface of the LDH to produce two subunit vaccine candidates, reaching peptide concentrations of 125 and 270 µg/mL, respectively. The particles were characterized using DLS, TEM, XRD, TGA, DSC, and FTIR. The cytotoxicity studies revealed that the conjugate with P₂ was non-toxic up to 250 µg/mL, while the immunogenicity studies showed that this conjugate induced similar IgG titers to those reached when aluminum hydroxide was used as an adjuvant. Full article

Vaccines usually contain an adjuvant that activates innate immunity to promote the acquisition of adaptive immunity. Aluminum and lipid nanoparticles have been used for this purpose, but their accumulation or widespread circulation in the body can lead to adverse effects. In contrast, physical adjuvants, which use physical energy to transiently stress tissues, do not persist in exposed tissues or cause lasting adverse effects. Herein, we investigate the effects of intradermal injection of endotoxin-free ovalbumin (OVA) protein alone without additional adjuvants using a needle-free pyro-drive jet injector (PJI) on tumor vaccination efficacy. Intradermal injection of OVA protein alone using PJI significantly increased OVA-specific CD8⁺ T cell expansion in the lymph node, although lymph node swelling was much less than when aluminum hydroxide was used. The injection also induced OVA-specific killing activity and antibody production and showed strong CD8⁺ T cell-dependent prophylactic antitumor effects against transplanted E.G7-OVA tumors. In particular, intradermal injection of the fluorescent OVA protein significantly enhanced its uptake by XCR1⁺ dendritic cells, which have a strong ability to cross-present extracellular proteins in the skin and draining lymph nodes. In addition, the injection increased the expression of HMGB1, one of the potent danger signals whose expression has been reported to increase in response to shear stress. Thus, intradermal injection of OVA protein alone without any additional adjuvants using PJI induces potent CD8⁺ T cell-mediated antitumor immunity by enhancing its uptake into XCR1⁺ dendritic cells, which have a high cross-presentation capacity accompanied by an increased expression of shear stress-induced HMGB1. Full article

The Varicella zoster virus (VZV), responsible for both varicella (chickenpox) and herpes zoster (shingles), presents significant global health challenges. While primary VZV infection primarily affects children, leading to chickenpox, reactivation in later life can result in herpes zoster and associated post-herpetic neuralgia, among other complications. Vaccination remains the most effective strategy for VZV prevention, with current vaccines largely based on the attenuated vOka strains. Although these vaccines are generally effective, they can induce varicella-like rashes and have sparked concerns regarding cell virulence. As a safer alternative, subunit vaccines circumvent these issues. In this study, we developed a nanoparticle-based vaccine displaying the glycoprotein E (gE) on ferritin particles using the SpyCatcher/SpyTag system, termed FR-gE. This FR-gE nanoparticle antigen elicited substantial gE-specific binding and VZV-neutralizing antibody responses in BALB/c and C57BL/6 mice—responses that were up to 3.2-fold greater than those elicited by the subunit gE while formulated with FH002C, aluminum hydroxide, or a liposome-based XUA01 adjuvant. Antibody subclass analysis revealed that FR-gE produced comparable levels of IgG1 and significantly higher levels of IgG2a compared to subunit gE, indicating a Th1-biased immune response. Notably, XUA01-adjuvanted FR-gE induced a significant increase in neutralizing antibody response compared to the live attenuated varicella vaccine and recombinant vaccine, Shingrix. Furthermore, ELISPOT assays demonstrated that immunization with FR-gE/XUA01 generated IFN-γ and IL-2 levels comparable to those induced by Shingrix. These findings underscore the potential of FR-gE as a promising immunogen for the development of varicella and herpes zoster vaccines. Full article

Aluminum oxide production from aluminum filings, which are a byproduct of several industrial machining processes and cannot be recycled to attain bulk aluminum (Al), is vital due to its wide use in scientific research and industry. The goal of this paper is to produce ultrafine and down-to-the-nanoscale alumina powder (Al₂O₃), starting from a waste Al filings. The microstructure and composition of the starting Al used were investigated using scanning electron microscopy (SEM), which was equipped with an attached energy dispersive spectrometer (EDS) unit. The results of this investigation confirmed that the starting Al was mainly Al–Mg alloy. Al₂O₃ was produced using two routes: The first involved the burning of aluminum hydroxide Al(OH)₃ that was precipitated from aluminum chloride solution (AlCl₃) resulting from dissolving the Al filings in 2M HCl. The second route involved direct precipitation as a reaction product of aluminum chloride with sodium carbonate solution. The Al₂O₃ produced using both routes, as well as the intermediate product Al(OH)₃, were studied by SEM. The results demonstrate that the nanoscale range size was reached after milling of the produced Al₂O₃. Following thorough washing with distilled water, the EDS and the XRD techniques confirmed the formation of Al₂O₃, with no residual salt detected. The EDS results showed that the ratios of Al and O in the produced Al₂O₃ were about 96% of the ideal compound ratios. The XRD analysis also revealed the amorphous structure of the standard and the produced Al(OH)₃, whereas the phases of the produced Al₂O₃ were either crystalline or amorphous. In our study, the Al₂O₃ percentage yield was about 77%, and this value obviously depends on the percentage of Al dross in the original Al filings. Overall, this research provides a novel contribution to the production of alumina powder in the nano-range starting from an aluminum filings byproduct, thereby reducing the dependence on known sources of aluminum. Full article

This study investigates the influence of silane-treated aluminum hydroxide on the mechanical performance of flame-retardant composites. These composites have potential applications for luggage bags, as a replacement for conventional plastics, offering more durability and lighter weight. Glass fabric was used as the reinforcement, while epoxy was used as the matrix material. To impart flame retardancy, aluminum hydroxide nanoparticles were used as fillers in different weight % age (5%, 10% and 15%). As these are inorganic particles and have compatibility issues with the matrix material, silane-coupling agents (Dynasylan^® 6490 and Dynasylan Glymo) were used to treat these filler particles. Both the silane-coupling agents fraction used for treatment and the fillers fraction added to the composites were varied to determine the most optimum combination. The mechanical properties of the developed composites such as tensile, flexural, and short beam shear strength were investigated. The best results were exhibited by 10% aluminum hydroxide fillers treated with 1% (by weight) coupling agent (Dynasylan Glymo). Full article

A layered double hydroxide (LDH) calcined-framework adsorbent was investigated for the rapid removal of heavy metal cations from plating wastewater. Li–Al–CO₃ LDH was synthesized on an aluminum lathe waste frame surface to prepare the sorbent. The calcination treatment modified the LDH surface properties, such as the hydrophilicity and the surface pH. The change in surface functional groups and the leaching of lithium ions affected the surface properties and the adsorption capacity of the heavy metal cations. A zeta potential analysis confirmed that the 400 °C calcination changed the LDH surface from positively charged (+10 mV) to negatively charged (−17 mV). This negatively charged surface contributed to the sorbent instantly bonding with heavy metal cations in large quantities, as occurs during contact with wastewater. The adsorption isotherms could be fitted using the Freundlich model. The pseudo-second-order model and the rate-controlled liquid-film diffusion model successfully simulated the adsorption kinetics, suggesting that the critical adsorption step was a heterogeneous surface reaction. This study also confirmed that the recovered nickel and/or copper species could be converted into supported metal nanoparticles with a high-temperature hydrogen reduction treatment, which could be reused as catalysts. Full article

Nanoparticles, by virtue of their amorphous nature and high specific surface area, exhibit ideal pozzolanic activity which leads to the formation of additional C-S-H gel by reacting with calcium hydroxide, resulting in a denser matrix. The proportions of ferric oxide (Fe₂O₃), silicon dioxide (SiO₂), and aluminum oxide (Al₂O₃) in the clay, which interact chemically with the calcium oxide (CaO) during the clinkering reactions, influence the final properties of the cement and, therefore, of the concrete. Through the phases of this article, a refined trigonometric shear deformation theory (RTSDT), taking into account transverse shear deformation effects, is presented for the thermoelastic bending analysis of concrete slabs reinforced with ferric oxide (Fe₂O₃) nanoparticles. Thermoelastic properties are generated using Eshelby’s model in order to determine the equivalent Young’s modulus and thermal expansion of the nano-reinforced concrete slab. For an extended use of this study, the concrete plate is subjected to various mechanical and thermal loads. The governing equations of equilibrium are obtained using the principle of virtual work and solved using Navier’s technique for simply supported plates. Numerical results are presented considering the effect of different variations such as volume percent of Fe₂O₃ nanoparticles, mechanical loads, thermal loads, and geometrical parameters on the thermoelastic bending of the plate. According to the results, the transverse displacement of concrete slabs subjected to mechanical loading and containing 30% nano-Fe₂O₃ was almost 45% lower than that of a slab without reinforcement, while the transverse displacement under thermal loadings increased by 10%. Full article

Snakebite envenoming represents a worldwide public health issue. Suitable technologies have been investigated for encapsulated recombinant or native proteins capable of inducing an effective and long-lasting adaptive immune response. Nanoparticles are colloidal dispersions that have been used as drug delivery systems for bioactive biological compounds. Venom-loaded nanoparticles modulate the protein release and activate the immune response to produce specific antibodies. In this study, biocompatible cationic nanoparticles with Bothrops jararaca venom were prepared to be used as a novel immunoadjuvant that shows a similar or improved immune response in antibody production when compared to a conventional immunoadjuvant (aluminum hydroxide). We prepared stable, small-sized and spherical particles with high Bothrops jararaca venom protein association efficiency. The high protein loading efficiency, electrophoresis, and zeta potential results demonstrated that Bothrops jararaca venom is adsorbed on the particle surface, which remained as a stable colloidal dispersion over 6 weeks. The slow protein release occurred and followed parabolic diffusion release kinetics. The in vivo studies demonstrated that venom-loaded nanoparticles were able to produce an immune response similar to that of aluminum hydroxide. The cationic nanoparticles (CNp) as carriers of bioactive molecules, were successfully developed and demonstrated to be a promising immunoadjuvant. Full article

The initial stages of AM60-AlN nanocomposite and AM60 corrosion behaviors were compared over 30 days of exposure to solution ($\mathrm{NaCl}$, ${\mathrm{Na}}_2{\mathrm{SO}}_4$ and ${\mathrm{NaHCO}}_3$), simulating the marine-coastal environment (SME). The incorporation of AlN nanoparticles (1.0 wt.%) in the AM60 alloy matrix favored the lower roughness of the AM60-AlN, associated with the grain refinement in the matrix. During the immersion of the alloys, pH of the SME solution shifted to alkaline values >9, and therefore, the solubility of AlN aluminum hydroxide phases were raised, followed by a slightly higher release of Mg-ions and corrosion rate increase. The chloride ions attributed to the unstability of the Al-Mn phase and $\mathrm{Al}{\left(\mathrm{OH}\right)}_3$ corrosion product was formed in a low content. The composite AM60-AlN presented lower value of the electrochemical noise resistance $\left({\mathrm{R}}_{\mathrm{n}}\right)$, suggesting that the corrosion process occurs with less difficulty. The localized corrosion near the Al-Mn cathodes seems to be stronger on the composite surface, in area and depth of penetration. The corrosion current fluctuations suggested that the corrosion is a weakly persistent process, dominated by the fractional Gaussian noise (fGn). Full article

SAPO-34 nanocrystals with sizes of 50–150 nm were obtained via steam-assisted crystallization (SAC) for 5 h at 200 °C from two types of aluminum precursors—aluminum isopropoxide and boehmite. A reaction mixture composition with a small amount of organic template tetraehylammonium hydroxide (TEAOH) was used with the molar ratio TEAOH/Al₂O₃ = 1/1. The alumina precursor type and duration of the SAC (5 and 24 h) on the crystal size, texture, and acid properties were investigated. The SAPO-34 nanocrystals that we obtained possess a large micropore volume of 0.22–0.24 cm³/g and a specific surface area of 651–695 m²/g. When the crystallization was prolonged for up to 24 h, a SAPO-18 structure appeared, but the micropore and mesopore volumes changed insignificantly. Using boehmite as the aluminum precursor led to higher mesoporosity of the material but a little bit lower acidity when compared with the samples prepared from aluminum isopropoxide. In addition, the method proposed was used for preparing a SAPO-34-coated aluminum adsorber heat exchanger. Thus, the synthesis method proposed is affordable and effective to prepare SAPO-34 highly crystalline nanoparticles, with no need for post-synthetic procedures as the mother liquor separation from nanocrystals. Full article