Dispersion Stability Research Articles

Characteristics of Tylvalosin Tartrate Enteric Amorphous Pellets Prepared by Liquid Layering.

Tylvalosin Tartrate (TAT), a new-generation macrolide antibiotic, undergoes significant degradation in the stomach and in vivo rapid elimination upon oral administration, resulting in poor bioavailability. This study developed TAT enteric amorphous pellets by liquid layering (TAT/EAP-LL) with pH-sensitive and burst release characteristics, to enhance drug stability in the stomach and concentration enrichment in the duodenum. The drug loading layer, isolation layer and enteric layer were formed on the surface of the blank core pellets. Investigation into the characteristics of TAT/EAP-LL revealed that stable amorphous solid dispersions in the drug loading layer were formed by liquid layering. Then, DSC analysis confirmed that triethyl citrate significantly improved the film-forming properties of Methacrylic-ethyl acrylate copolymer. Additionally, TAT/EAP-LL was confirmed to exist in the amorphous state by DSC、PXRD and PLM. In vitro, TAT/EAP-LL demonstrated a similar 4.07% release within 2h at pH 1.0 as TAT enteric pellets (TAT/EP-LL) and a much faster burst release at pH 6.8, with complete release within 15min. In vivo, the oral bioavailability of TAT/EAP-LL was improved to 1.71 times compared to commercial formulations and 1.47 times compared to TAT/EP-LL. This study offers a novel platform for the enhanced oral delivery of TAT and proposes effective formulation strategies for pulsatile drug delivery.

Molecular miscibility of ASD blend components: an evaluation of (the added value of) solid state NMR spectroscopy and relaxometry.

In order to evaluate the stability of an amorphous solid dispersion (ASD) it is crucial to be able to accurately determine whether the ASD components are homogeneously mixed or not. Several solid-state analysis techniques are at the disposal of the formulation scientist, such as for example modulated differential scanning calorimetry (mDSC) and solid-state nuclear magnetic resonance spectroscopy (ssNMR). ssNMR is a robust, versatile, and accurate analysis technique with a large number of application possibilities. Especially ssNMR relaxometry, which allows the measurement of the proton relaxation times T1H and T1ρH, is very useful for evaluating the miscibility of ASDs. In this paper, the miscibility of a model ASD, composed of indomethacin (IND) and poly(vinylpyrrolidone-co-vinyl acetate) (PVPVA), was assessed using mDSC and various ssNMR techniques, in order to compare the different techniques and to evaluate the advantages and disadvantages of each. It was found that measuring the relaxation times via the chemical shift selective carbon signals using 13C-cross-polarization magic angle spinning (13C-CPMAS) is still the golden standard to evaluate miscibility, even giving information about the miscibility at the nm scale. Although non-chemical shift selective 1H-wideline measurements are significantly faster than 13C-CPMAS measurements to determine the relaxation times, the results are often hard to interpret, especially with regard to the T1ρH relaxation times. 2D 1H-13C dipolar heteronuclear correlation (dipolar HETCOR) NMR is an additional technique that can be used, and which provides information about the special proximity of 1H and 13C nuclei with respect to each other and therefore about the miscibility of the components at the nm scale. Additionally, it often allows to acquire information regarding the intermolecular interactions and the functional groups involved. Nevertheless, optimalization of the experiments, data processing and interpretation of the results require some expertise. Compared to mDSC, the ssNMR techniques are more sensitive and robust and can often provide information about the miscibility at nm scale. However, mDSC is a very fast analysis technique that requires less optimalization. Therefore, it remains recommended to use mDSC always for a first screening and as a complementary analysis technique.

Selective hydrogenation of anisole over Pt/SBA-15 catalysts: Effect of Pt loading on catalytic efficiency

Abstract Pt catalysts (0.1–2 wt.% of platinum) supported on SBA-15 were used for the selective hydrogenation of the aromatic ring of anisole with the formation of cyclohexyl methyl ether product. The catalysts were characterized by N2 physisorption, UV–vis diffuse reflectance spectroscopy, powder X-ray diffraction, and scanning and transmission electron microscopies. The reaction progress and the impact of Pt loading in the catalysts were analyzed by gas chromatography. All the catalysts demonstrated high catalytic activity for the hydrogenation of anisole to cyclohexyl methyl ether (CME), reaching 90–98% anisole conversion at 6-h reaction time with near 90% selectivity to CME (280 °C, 6.9 MPa total pressure). An increase in the Pt content led to a slight decrease in the selectivity to CME due to its transformation to cyclohexane. 1%Pt/SBA-15 catalyst was tested in three repeated catalytic cycles showing high stability and preservation of Pt nanoparticle dispersion. Graphical abstract

Tribological performance of carbon nanospheres as lubricant additives: insights from molecular dynamics simulation and experimental analysis

Abstract To investigate the lubrication mechanism of carbon nanospheres and compare their tribological performance with carbon powder, this study presented a comprehensive analysis of their potential as lubricant additives through both experimental testing and molecular dynamics simulations. Carbon nanospheres were synthesized using the hydrothermal method. Extensive comparisons were conducted between carbon powder and carbon nanospheres, focusing on material characterization, dispersion stability, antifriction performance, and antiwear capability. Findings revealed that carbon nanospheres outperformed carbon powder as lubricant additives in PAO 10 owing to their smaller particle size and spherical shape. Specifically, at a concentration of 1wt%, a load of 50 N, a disk speed of 10 rpm, and a temperature of 25 °C, the addition of carbon nanospheres reduced the friction coefficient by 34% and wear volume by 35%. The improved tribological performance was linked to the ability of carbon nanospheres to fill the pits, improving the interface smoothness. Molecular dynamics simulation of carbon nanospheres effectively reflected substrate roughness in the bulk region and further confirmed that this filling effects increased the lubricant's load-bearing capacity, which contributed to the reduction of friction and wear. This study provided significant insights into the development of innovative high-performance lubricant additives for oil-based lubrication in metal friction pairs.

Microwave-Assisted Synthesis of Carbon Nanospheres and Their Application as Plugging Agents for Oil-Based Drilling Fluids

Wellbore instability caused by the invasion of drilling fluids into formations remains a significant challenge in the application of oil-based drilling fluids (ODFs). In this study, carbon nanospheres (CNSs) were synthesized using glucose as the carbon source through a microwave-assisted method. The effects of the reaction temperature, carbon source concentration, and reaction time on the particle size of CNSs were systematically investigated. The results revealed that under optimal conditions, CNSs with an average particle size of 670 nm were successfully synthesized, exhibiting high sphericity and excellent dispersibility. CNSs demonstrated stable dispersion in mineral oil when lecithin was used as a dispersant. The plugging performance of CNSs in ODFs was evaluated through low-pressure filtration and high-temperature, high-pressure (HTHP) filtration tests. After aging at 180 °C for 16 h, the addition of 2% CNSs reduced the filtration volume from 10.6 mL to 2.5 mL on standard filter paper (average pore size: 3 μm) and from 8.5 mL to 1.6 mL on microporous membranes (average pore size: 0.5 μm). Additionally, the HTHP filtration volume decreased from 73 mL to 18 mL, and the permeability of the filter cake formed during HTHP filtration was reduced from 26.5 × 10−3 mD to 1.2 × 10−3 mD. Furthermore, CNSs improved the rheological properties and emulsion stability of ODFs. With excellent compatibility and applicability, CNSs offer a promising solution for enhancing the performance of oil-based drilling fluids.

The Impact of High-Speed Crushing Process of Fibrous Polytetrafluoroethylene on Pyrolyzed Carbon Black/Natural Rubber Composites.

This study employed a high-speed rotating crushing process to modify pyrolyzed carbon black (CBp) using self-lubricating and low-friction polytetrafluoroethylene (PTFE). The effects of PTFE content on the dispersion, mechanical properties, wear resistance, and thermal stability of modified PTFE-CBp/natural rubber (NR) composites were investigated. The rotating crushing process from the high-speed grinder altered the physical structure of PTFE, forming tiny fibrous structures that interspersed among the CBp particles. This arrangement encouraged the alignment of CBp particles in specific directions and improved the surface activity of CBp, enhancing the dispersion of CBp within the NR matrix and consequently improving wear resistance. The experimental results indicated that as the amount of PTFE fibers increased, the hardness, wear resistance, and thermal stability of the PTFE-CBp/NR composite significantly improved. Compared to untreated CBp/NR composites, the hardness, modulus at 300%, and wear resistance of the 3 phr PTFE-CBp/NR composites increased by 20%, 24%, 21%, respectively, achieving the preparation of highly wear-resistant CBp/NR composites.

On the Stability of Graphene-Based Aqueous Dispersions and Their Performance in Cement Mortar

On the Stability of Graphene-Based Aqueous Dispersions and Their Performance in Cement Mortar

The Role of Dendritic Cells in Adaptive Immune Response Induced by OVA/PDDA Nanoparticles.

Background/Objective: Cationic polymers were shown to assemble with negatively charged proteins yielding nanoparticles (NPs). Poly-diallyl-dimethyl-ammonium chloride (PDDA) combined with ovalbumin (OVA) yielded a stable colloidal dispersion (OVA/PDDA-NPs) eliciting significant anti-OVA immune response. Dendritic cells (DCs), as sentinels of foreign antigens, exert a crucial role in the antigen-specific immune response. Here, we aimed to evaluate the involvement of DCs in the immune response induced by OVA/PDDA. Methods: In vivo experiments were used to assess the ability of OVA/PDDA-NPs to induce anti-OVA antibodies by ELISA, as well as plasma cells and memory B cells using flow cytometry. Additionally, DC migration to draining lymph nodes following OVA/PDDA-NP immunization was evaluated by flow cytometry. In vitro experiments using bone marrow-derived DCs (BM-DCs) were used to analyze the binding and uptake of OVA/PDDA-NPs, DC maturation status, and their antigen-presenting capacity. Results: Our data confirmed the potent effect of OVA/PDDA-NPs inducing anti-OVA IgG1 and IgG2a antibodies with increased CD19+CD138+ plasma cells and CD19+CD38+CD27+ memory cells in immunized mice. OVA/PDDA-NPs induced DC maturation and migration to draining lymph nodes. The in vitro results showed higher binding and the uptake of OVA/PDDA-NPs by BM-DCs. In addition, the NPs were able to induce the upregulation of costimulatory and MHC-II molecules on DCs, as well as TNF-α and IL-12 production. Higher OVA-specific T cell proliferation was promoted by BM-DCs incubated with OVA/PDDA-NPs. Conclusions: The data showed the central role of DCs in the induction of antigen-specific immune response by OVA-PDDA-NPs, thus proving that these NPs are a potent adjuvant for subunit vaccine design.

Effect of Lipid Composition and Stirring Dynamics on Oxygen Microbubble Stability and Oxygen Release.

Lipid-coated oxygen microbubbles (OMBs) are being investigated for biomedical applications to alleviate hypoxia such as systemic oxygenation and image-guided radiosensitization therapy. Additionally, they hold potential for boarder application as oxygen carriers beyond the biomedical filed. Understanding the stability and oxygen release properties of OMBs in dynamic aqueous environments is critical for these applications. In this study, we found that OMBs composed of longer acyl chain phospholipids (DSPC and DBPC) were stable in storage for at least 1 week, unlike the shorter acyl chain phospholipid (DPPC). OMBs were also more stable with a diacyl PEG-PE emulsifier compared with single-chain PEG-40 stearate. Dilution of OMBs did not alter the average diameter. While previous studies have examined the theoretical and experimental aspects of oxygen release from OMBs under static conditions, quantitative evaluations of OMB dispersions under dynamic stirring conditions remain limited. Here, we introduce a novel oxygen measurement method that quantitatively tracks the transition of the dissolved oxygen concentration in an aqueous medium upon mixing with a bolus of OMBs. Our results indicate that a 50 vol % OMB dispersion releases more than 330 mg/L of oxygen, surpassing arterial oxygen levels, and that more than 95% of this oxygen is released within 30 s. The rate of oxygenation of the OMB dispersions was comparable to that of a bolus injection of oxygen-saturated water under sufficient agitation, indicating that convection in the aqueous medium is the limiting transport mechanism. However, the lipid shell had a measurable effect on the oxygen release rate, which correlated with its oxygen permeability. Increasing the stirring speed increased both oxygen release rate and total amount of oxygen released. Overall, this study elucidates the fundamental stability and mass transport properties of the OMB dispersions under practical stirring conditions.

Fabrication of nanoparticles with precisely controllable plasmonic properties as tools for biomedical applications.

Metal nanoparticles are established tools for biomedical applications due to their unique optical properties, primarily attributed to localized surface plasmon resonances. They show distinct optical characteristics, such as high extinction cross-sections and resonances at specific wavelengths, which are tunable across the wavelength spectrum by modifying the nanoparticle geometry. These attributes make metal nanoparticles highly valuable for sensing and imaging in biology and medicine. However, their widespread adoption is hindered due to challenges in consistent and accurate nanoparticle fabrication and functionality as well as due to nanotoxicological concerns, including cell damage, DNA damage, and unregulated cell signaling. In this study, we present a fabrication approach using nanoimprint lithography in combination with thin film deposition which yields highly homogenous nanoparticles in size, shape and optical properties with standard deviations of the main geometry parameters of less than 5% batch-to-batch variation. The measured optical properties closely match performed simulations, indicating that pre-experimental modelling can effectively guide the design of nanoparticles with tailored optical properties. Our approach also enables nanoparticle transfer to solution. Particularly, we show that the surface coating with a PEG polymer shell ensures stable dispersions in buffer solutions and complex cell media for at least 7 days. Furthermore, our in vitro experiments demonstrate that these nanoparticles are internalized by cells via endocytosis, exhibit good biocompatibility, and show minor cytotoxicity, as evidenced by high cell viability. In the future, our high-precision nanoparticle fabrication method together with tunable surface plasmon resonance and reduced nanotoxicity will offer the possibility to replace conventional nanomaterials for biomedical applications that make use of an optical response at precise wavelengths. This includes the use of the nanoparticles as contrast agents for imaging, as probes for targeted photothermal cancer therapy, as carriers for controlled drug delivery, or as probes for sensing applications based on optical detection principles.

Permanent Nanobubbles in Water: Liquefied Hollow Carbon Spheres Break the Limiting Diffusion Current of Oxygen Reduction Reaction.

Porous liquids have traditionally been designed with sterically hindered solvents. Alternatively, recent efforts rely on dispersing microporous frameworks in simpler solvents like water. Here we report a unique strategy to construct macroporous water by selectively incorporating hydrophilicity on the surfaces of hydrophobic hollow carbon spheres (HCS). Specifically, we show that the stable dispersion surface ionized HCS in water while retaining the inherent porosity. The electrocatalytic conversion of small gas molecules in aqueous electrolytes is limited by the concentration and diffusion rates of gas molecules in water. In this case, macroporous water exhibited 6 times gas uptake compared to nonporous (pure) water. By leveraging the high gas capacity and enhanced diffusion kinetics, the limiting diffusion current of oxygen reduction reaction (ORR) in macroporous water is 2 times that in nonporous water, offering promising prospects for sustainable energy conversion technologies.

Easy to use particle-mediated transport of various dissolved active agents into the hair follicles - A novel platform technology.

The use of nanoparticulate systems for the transport of active ingredients into hair follicles has been researched for almost two decades, resulting in countless publications with a wide variety of particle types, release mechanisms and active ingredients. The production of a stable dispersion is often time-consuming and costly. In this publication, we demonstrate for the first time that simply adding diverse submicron particles to a drug solution significantly increases follicular penetration depth by over 160% to 190%, allowing the targeting of subinfundibular structures. Our results indicate that the increase in follicular penetration is independent of the type or sphericity of the particles (nanocrystals (NC) or lipid submicron particles (LN)). Furthermore, this principle can be used with both small molecules and large molecule therapeutics, as demonstrated with the model drugs fluorescein sodium, 6-carboxyfluorescein, green fluorescent protein and FITC-BSA. This highlights the high versatility of this new formulation principle. The system may be used for various hair follicle-associated diseases such as alopecia or for the preoperative disinfection of hair follicles and the transfollicular transport of active pharmaceutical and/or cosmetic ingredients.

Study of Corrosion of Portland Cement Embedded Steel with Addition of Multi-Wall Carbon Nanotubes.

In this study, we research the innovative application of multi-walled carbon nanotubes (MWCNTs) as corrosion inhibitors in Portland cement embedded steel. The physicochemical properties of the dispersion solutions were evaluated, varying the storage time, to analyze their effect on corrosion resistance. Using a dispersion energy of 440 J/g and a constant molarity of 10 mM, stable dispersions were achieved for up to 3 weeks. These dispersions were characterized using Raman spectroscopy, UV-Vis spectroscopy and Zeta potential spectroscopy to assess the stability and structural damage of the MWCNTs. These results show that the addition of MWCNTs not only reduces the porosity of the cement matrix, but also forms an effective barrier against chloride ion intrusion, protecting the reinforcing steel. This approach stands out for combining improved mechanical properties and significant corrosion resistance, representing a promising innovation in the development of more durable construction materials.

Influence of polymer and surfactant-based precipitation inhibitors on supersaturation-driven absorption of Ibrutinib from high-dose lipid-based formulations.

There is a growing pharmaceutical interest in supersaturated lipid-based formulations (Super-LbF) as an innovative strategy to enhance drug loading capacities while simultaneously reducing pill burden. This approach involves increasing the drug concentration above its equilibrium solubility in a lipid solution, achieved through temperature-induced supersaturation or the dissolution of lipophilic ionic salts. However, the physical instability and potential drug precipitation upon the dispersion of LbF remain critical. The focus of this work was to assess the impact of polymer and surfactant as precipitation inhibitors (PIs) in Super-LbF and investigate whether PIs can effectively address the aforementioned challenges. Ibrutinib (Ibr) was selected as a model drug due to its limited solubility and dissolution characteristics. The optimized formulations were characterized with a focus on dispersibility, lipolysis-permeation, and physical stability during storage. The inclusion of PIs in Super-LbF significantly enhanced physical stability by increasing viscosity and reducing the degree of supersaturation through elevated equilibrium solubility. During the dispersion and digestion study, varying levels of transient supersaturation were observed for both Super-LbF and PI-loaded Super-LbF. A noteworthy 2.5 to 3-fold increase in the solubilization ratio was observed for PI-loaded Super-LbF in comparison to Super-LbF without PI. This increase indicates a significant rise in transient drug supersaturation through kinetic and thermodynamic precipitation inhibition mechanisms. Moreover, lipolysis-permeation studies revealed increased flux values with enhanced solubilization, except in the case of Pluronic® F68, which exhibited a reduced free drug concentration near the Permeapad® barrier. Further, the in vivo absorption study confirmed that prolonged supersaturation, facilitated by PIs, contributed to enhancement in drug exposure in rats. PI-loaded Super-LbFs demonstrated a significant improvement (5.1 to 8.9-fold) in the absorption profile compared to Super-LbF without PI (p<0.001). The study results indicate that incorporating PIs into Super-LbF enhances physical stability and maintains transient drug supersaturation under digestive conditions. Overall, this formulation approach shows promise for expanding the application of LbF to enable the successful oral delivery of high-dose regimen drugs.

Effect of ultrasound-assisted phosphates treatment on solubilization and stable dispersion of rabbit Myofibrillar proteins at low ionic strength.

The effects of high-intensity ultrasound (HIU) on the dispersibility of myofibrillar proteins (MPs) in low-salt medium were investigated. HIU-assisted STPP or TSPP could sharply improve the solubility and dispersibility of MPs (from 38.12% to 94.08% and 37.80% to 89.91%, respectively), whereas the use of NaCl or SHMP had negligible effects. MPs in STPP and TSPP medium had higher surface charge and stronger hydrophilic ability than those in NaCl and SHMP medium. The results of CLSM and SDS-PAGE showed MP depolymerization in STPP and TSPP medium. MPs in STPP and TSPP displayed a flexible α-helix conformation. HIU could induce the rearrangement of myosin and actin in STPP and TSPP medium and generated soluble oligomers by disulfide bonds. By contrast, MPs in SHMP and NaCl exhibited a stable β-sheet conformation, hindering the modification effect of HIU. Medium could affect the modification effect of HIU on MPs by changing surface charge and hydrophilicity.

Osteogenic potential of esculetin-loaded chitosan nanoparticles in microporous alginate/polyvinyl alcohol scaffolds for bone tissue engineering.

Bone tissue engineering (BTE) is an emerging strategy for the treatment of critical bone defects using biomaterials and cells. Esculetin (ES), a coumarin phytocompound, has demonstrated therapeutic potential, although its osteogenic effects remain insufficiently explored. Owing to its hydrophobic nature, which limits its bioavailability, this study developed a drug delivery system using chitosan nanoparticles (nCS) to achieve sustained release of ES. These ES-loaded nCS nanoparticles were incorporated into biocomposite scaffolds composed of alginate (Alg) and polyvinyl alcohol (PVA) using freeze-drying. The synthesized nCS-ES nanoparticles exhibited spherical morphology with a uniform size distribution, ranging from 105 to 117nm, and demonstrated excellent entrapment efficiencies (94.07 to 97.61%). The nanoparticles displayed high zeta potential values (+27.8 to +33.2mV), ensuring stable dispersion. The biocomposite scaffolds exhibited a uniform distribution of pores, with pore diameters ranging from 106±14μm to 112±14μm. The biocomposite scaffolds exhibited excellent swelling, protein adsorption, biodegradation, and biomineralization properties. The ES-loaded scaffolds showed sustained ES release, promoting osteogenesis in vitro, with the activation of the Wnt/β-catenin signaling pathway. In vivo studies using a rat tibial bone defect model further confirmed that these scaffolds stimulated new bone formation, highlighting the ES's potential for BTE applications.

Enhanced dispersion stability of shear thickening fluid based on PS@ZIF-8 core-shell nanospheres and ionic liquids for functional applications

Enhanced dispersion stability of shear thickening fluid based on PS@ZIF-8 core-shell nanospheres and ionic liquids for functional applications

Polymer encapsulation of TiO2 by seeded emulsion polymerization to improve the dispersion stability and reflectance

Polymer encapsulation of TiO2 by seeded emulsion polymerization to improve the dispersion stability and reflectance

An environmentally friendly, rainfall-resistant suspension prepared based on halloysite nanotubes for the delivery of hydrophobic pesticides

The application of nanomaterials in pesticide system shows many advantages such as enhanced dispersion stability, high foliar affinity, improved insecticidal effect, and reduced environmental risks. In the study, a simple wet grinding method was used to decrease the particles size of the pesticides chlorobenzuron and indoxacarb (CI) in presence of halloysite nanotubes (HNTs). The irregularly shaped suspension pesticide system (CI@HNTs) in size of ∼ 2 μ m is obtained via HNTs and xanthan gum (XG) encapsulation of the hydrophobic pesticides. Attributed to the small size and interfacial interactions of HNTs, CI@HNTs have excellent stability, dispersion and slow release behavior. CI@HNTs exhibit enhanced foliar wettability, spreading and topological effect on plant leaves compare to commercial suspension concentrate (SC) product and CI (without HNTs), which results in high resistance to rainfall washout. In the crop model treated by fall armyworm, the mortality rate is 53.3 % in CI group, while the mortality is 75.0 % in CI@HNTs-8 which is 1.41 times that of CI. In addition, the safety of CI@HNTs is systematically evaluated, and the results show that the toxicity of CI@HNTs to the wheat and the aquatic organism zebrafish is lower than that of the SC. This study develops an economical, efficient and environmentally friendly pesticide system based on natural clay nanotubes, which shows promising applications in sustainable agricultural production.

Influence factors and mechanism of dispersion stability of organoclay for Antarctic drilling fluid under ultra-low temperature conditions

Influence factors and mechanism of dispersion stability of organoclay for Antarctic drilling fluid under ultra-low temperature conditions