Stable Suspension Research Articles

Physicochemical characteristics of highly concentrated suspensions with some types of Ukrainian coal

ABSTRACT The investigation results of granulometric composition, zeta potential, sedimentation stability, and viscosity of some water-coal suspensions made of Ukrainian coal from the “Stepova” mine, Lviv-Volyn region, are reported. The most effective granulometric composition of the water-coal suspension consisting of the rough and fine fractions is found from the analysis of the abovementioned physicochemical characteristics of the suspensions. Based on the complex investigation of the zeta potential of the dispersed phase particles, viscosity, and sedimentation stability of the suspensions, it was established that the best technological effectiveness can be expected for the suspensions containing 60% of the rough fraction (sized between 100 and 250 µm) and fine particles sized between 20 and 40 µm. In such systems, the particles form a quasi-stable structure, where the lower-charged small particles are located in the interparticle space between the highly charged bigger particles. All particles bear the same charge, increasing the system’s sedimentation stability and avoiding decomposition for at least 5 days. This time seems reasonable for the preparation, storage, and pumping of the suspensions while their viscosity and stability meet the relevant technological requirements.

Chitosan/Silica Hybrid Nanogels by Inverse Nanoemulsion for Encapsulating Hydrophilic Substances

AbstractA strategy for the preparation of a hybrid chitosan/silica nanohydrogel is reported, which combines the gelation of chitosan in a nanoemulsion system with a sol–gel process to produce silica. Chitosan is used as a biopolymer matrix, while silica acts as a structuring additive. Hydrogel nanocapsules are obtained through the ionic interaction of the cationic groups of chitosan with the anionic groups of sodium triphosphate (STP), which is used as a physical cross‐linker. Two alternative preparation methods are compared in this work: in the first one, STP is added to the continuous phase of an inverse emulsion of chitosan; in the second one, the fusion of droplets of two emulsions containing separate chitosan and STP takes place. The size of the obtained nanocapsules ranges from 50 to 200 nm. The efficiency of the formed hydrogel for entrapping a hydrophilic model substance (erioglaucine disodium salt) is investigated for the two systems by studying the release in a neutral aqueous medium. The results indicate that the hydrophilic cargo is efficiently encapsulated by both preparation methods, although the droplet‐fusion method yields more stable suspensions. As a general observation, the release behavior of erioglaucine is systematically retarded when silica is present in the systems.

Preparation and systematic study of mechanical properties and suspension stability of polyurethane-polyurea double-shell perfume oil microcapsules

The perfume oil microcapsules are of considerable significance in personal care and household products due to their ability to control the targeted release of perfume oil under specific conditions, which enhances the longevity and overall performance of the product. In this study, double-shell perfume oil microcapsules were prepared using polyurea (PUA) and polyurethane (PU) as wall materials. The first PUA shell was formed at room temperature to encapsulate the perfume oil by adjusting the agitation speed, protective colloid concentration, and polymethylene polyphenyl isocyanate (PAPI) content. Subsequently, the second PU shell was formulated. Mechanical property analysis revealed that PU/PUA microcapsules exhibited superior characteristics, showing a threefold increase in mechanical strength compared to PUA microcapsules. Thermogravimetric analysis and dynamic release experiments in ethanol demonstrated that the PU/PUA microcapsules possessed higher thermal stability and greater compactness compared to the PUA microcapsules. Finally, by incorporating bacterial cellulose (BC) microgels and hydroxypropyl methylcellulose (HPMC) as stabilizing agents into the laundry detergent matrix (JJ), a stable suspension of PU/PUA microcapsules was achieved for over 180 days.

Surfactant-Driven Dynamic Changes in Rheology of Activated Carbon Slurry Electrodes.

Carbon black slurry electrodes are an effective means to improve flow battery performance by increasing the active surface area necessary for electrochemical reactions with a cost-effective material. Current challenges with this specific flow battery chemistry include the stability and flowability of the carbon black suspensions, especially in response to formulation choices. Advancing the manufacturing, operation, and performance of these redox flow batteries requires a deeper understanding of how slurry formulation impacts its rheological profile and ultimately battery performance. In response to this need, the linear and nonlinear rheological responses of activated carbon (AC) based slurry electrode materials used in an all-iron flow battery in the presence of a nonionic surfactant (Triton X-100) were measured. Results from these measurements show the slurry is a colloidal gel with elasticity remaining constant despite increasing surfactant concentration until α (= Csurf/CAC) < 0.65. However, at α ≥ 0.65, the slurry abruptly transitions to a fluid with no measurable yield stress. This critical surfactant concentration at which the rheological profile undergoes a dynamic change matches the concentration found previously for gel collapse of this system. Moreover, this transition is accompanied by a complete loss of electrical conductivity. From these data we conclude the site specific adsorption of surfactant molecules often used in slurry formulation has a significant and dramatic impact on the stability and flowability of these suspensions. Work presented herein demonstrates the importance of additive choices when formulating a slurry electrode.

Synthesis and synergistic antibacterial efficiency of chitosan-copper oxide nanocomposites

Copper and chitosan are used for biomedical applications due to their antimicrobial properties. In this study, a facile method for the synthesis of chitosan-copper oxide nanocomposites (nCuO-CSs) was modified, yielding stable colloidal nCuO-CSs suspensions. Using this method, nCuO-CSs with different copper-to-chitosan (50–190 kDa) weight ratios (1:0.3, 1:1, 1:3) were synthesized, their physicochemical properties characterized, and antibacterial efficacy assessed against Gram-negative Escherichia coli and Pseudomonas aeruginosa, and Gram-positive Staphylococcus aureus. The nCuO-CSs with a primary size of ∼10 nm and a ζ-potential of >+40 mV proved efficient antibacterials, acting at concentrations around 1 mg Cu/L. Notably, against Gram-negative bacteria, this inhibitory effect was already evident after a 1-h exposure and surpassed that of copper ions, implying to a synergistic effect of chitosan and nano-CuO. Indeed, using flow cytometry and confocal laser scanning microscopy, we showed that chitosan promoted interaction between the nCuO-CSs and bacterial cells, facilitating the shedding of copper ions in the close vicinity of the cell surface. The synergy between copper and chitosan makes these nanomaterials promising for biomedical applications (e.g., wound dressings).

Effects of Exidia yadongensis polysaccharide as emulsifier on the stability, aroma, and antioxidant activities of fat-free stirred mango buffalo yogurt

Because of the poor stability and rheological properties of fat-free stirred yogurt fortified with fruit pulp, new functional polysaccharides as a natural emulsifier, which can increase viscosity in the aqueous phase, may be needed. This study aimed to evaluate the effects of Exidia yadongensis polysaccharide (EYP) as emulsifier on the stability, aroma, and antioxidant activities of mango buffalo yogurt at 4 °C for 25 days. The yogurt with 15 g/L EYP gave a higher content of 215 g/L total solids, 11.3 g/L exopolysaccharides, 0.10 g/L total polyphenols, 630.5 g/L water-holding capacity, and 11.43 g/kg total free amino acids, and maintained better texture, DPPH scavenging activity of 54.05 % and OH scavenging rates of 67.16 %. Moreover, the EYP exhibited the expected ability to weaken postacidification, syneresis, and growth of microorganism, and greatly promote the textural, rheological properties, suspension stability, microstructure, and aroma profiles of stirred mango-flavored buffalo yogurt (p < 0.05). In addition, the addition of 15 g/L EYP can inhibit protein degradation and improve the stability of secondary structure of the protein complex in mango yogurt during 25 days of storage. Therefore, EYP (15 g/L) could be used as natural positive functional factors and emulsifiers in such fat-free stirred yogurt industry.

Suspension stability of passion fruit nectar formulated with carboxymethyl cellulose: Analysis of sedimentation kinetics

This study evaluated the suspension stability of passion fruit nectar formulated with different concentrations of carboxymethyl cellulose (CMC). Passion fruit nectars with 0, 0.02, 0.1 and 0.2% (w/v) CMC were placed at rest in test tubes at room temperature (~25 °C) to measure the phase separation height for 87 h. Passion fruit nectars with 0 and 0.02% (w/v) CMC showed notable phase separation, while those with 0.1 and 0.2% (w/v) CMC were relatively stable suspensions. The analysis of sedimentation kinetics revealed that passion fruit nectars with 0 and 0.02% (w/v) CMC presented respectively: maximum sedimentation velocity of 0.426 m/s and 0.260 m/s, equilibrium sedimentation index of 46.494% and 20.434%, and sedimentation rate speed of 0.0362 and 0.0556%/s. A concentration of 0.2% (w/v) CMC is recommended in passion fruit nectar to maintain the appearance of a stable suspension, which is a characteristic desired by the consumer.

Investigating the Reactive Reinforcement Ability of Maleic Anhydride-Modified Cellulose Nanocrystals via In-Situ Emulsion Polymerization.

CNC-based nanocomposites have gained substantial interest because of their enhanced thermomechanical properties for high-end engineering applications. The chemical modification of CNCs expands their applicability, making them suitable for use in hydrophobic polymer matrices. The current study investigates the reactive reinforcing ability of maleic anhydride-modified cellulose nanocrystals during the in situ polymerization of a vinyl monomer, i.e., styrene. Highly crystalline nanocellulose (CNCBG) was isolated from Lagenaria siceraria (Bottle gourd) peels via Hydrochloric acid, which was further modified to synthesize maleic anhydride-modified cellulose nanocrystals (MACNCBG) and characterized employing various techniques. MACNCBG exhibited higher suspension stability than CNCBG due to the introduction of carboxyl groups. Furthermore, polystyrene-based nanocomposites of 3 and 5 wt % filler loading were prepared, respectively. While PSMACNCBG (5 wt %) displayed a premature failure, PSMACNCBG (3 wt %) demonstrated enhanced mechanical properties compared to PSCNCBG (3 wt %) and PS. At the same filler loading, MACNCBG demonstrated a more remarkable reinforcing ability than CNCBG, owing to its reactive tendency. The appearance of a new peak between 3000-2800 cm-1 corresponds to the C-H stretching of the formed C-C bond (between C=C of MACNCBG and benzal carbon of PS) in the FTIR spectra, confirming the reactive nature of MACNCBG.

Unravelling the polymorphic characteristics of carbamazepine through additive-assisted sonocrystallisation

ABSTRACT This paper investigates the influence of additives on the antisolvent crystallisation process of carbamazepine (CBZ) using methanol as the solvent and water as the antisolvent, with ultrasonic irradiation at a specific solvent-to-antisolvent (S/A) ratio of 1:2 and a 30-watt power ultrasonic horn. Various additives, such as Hydroxypropyl Methyl Cellulose (HPMC), Bovine Serum Albumin (BSA), Tween 80, and Sodium Dodecyl Sulphate (SDS), were employed to examine their effects on the morphology, stability (including suspension and thermal stability), crystallinity, and polymorphism of CBZ crystals. Raw CBZ exhibited irregular shapes during crystallisation, while SDS addition resulted in both plate-like and needle-like crystals. Conversely, BSA, HPMC, and Tween 80 induced the formation of needle, plate, and block-like crystal structures, respectively. Suspension stability ranked as SDS > BSA > HPMC > Tween 80. Regarding polymorphism, HPMC favoured Form 1, BSA and SDS favoured Form IV, and Tween 80 favoured Form I. Additionally, Tween 80 depicted similar preference for Form I polymorph as HPMC. Notably, Form II and Form III polymorphs were present to varying degrees in all samples, except for Tween 80. This study provides crucial insights into the controlled crystallisation of CBZ and the impact of additives on crystal properties, offering valuable information for tailoring CBZ crystal production for specific pharmaceutical applications.

A novel microencapsulated medium-temperature phase change material employing dicarboxylic acid for thermal energy storage

Microencapsulation enhances the performance of phase change materials (PCMs). However, the existing research on microencapsulation of dicarboxylic acids (DAs) is inadequate, with only one study dedicated to the development of microcapsules containing a low DA content and a shell that decomposes at low temperatures. In this study, glutaric acid (GA), as a representation of DA, was successfully microencapsulated with an enhanced encapsulation ratio. The results obtained by scanning electron microscopy (SEM) revealed a uniform spherical core–shell structure of the microencapsulated GA (MEGA). Fourier transform infrared spectroscopy (FT-IR) an X-ray diffractometer (XRD) analysis confirmed the absence of any chemical reaction between the core and shell materials. Additionally, differential scanning calorimetry (DSC) results demonstrated excellent heat storage. Notably, MEGA exhibited a thermal reliability index of 94.4 % after 200 accelerated thermal cycles. Thermogravimetry analyzer (TGA) results showed good thermal stability of MEGA. The dispersion stability and thermal conductivity of MEGA suspensions displayed significant enhancements compared to those of GA suspensions. Furthermore, compared with the base fluid, the MEGA suspensions with 1.0 wt%, 5.0 wt% and 10.0 wt% demonstrated reduced pumping power requirements by 16.9%, 54.6% and 70.0%, respectively. These findings suggest that MEGA holds promising prospects for applications in the medium temperature energy storage field.

Deposition of Human-Serum-Albumin-Functionalized Spheroidal Particles on Abiotic Surfaces: Reference Kinetic Results for Bioparticles.

Human serum albumin (HSA) corona formation on polymer microparticles of a spheroidal shape was studied using dynamic light scattering and Laser Doppler Velocimetry (LDV). Physicochemical characteristics of the albumin comprising the zeta potential and the isoelectric point were determined as a function of pH for various ionic strengths. Analogous characteristics of the polymer particles were analyzed. The adsorption of albumin on the particles was in situ monitored by LDV. The stability of the HSA-functionalized particle suspensions under various pHs and their electrokinetic properties were also determined. The deposition kinetics of the particles on mica, silica and gold sensors were investigated by optical microscopy, AFM and quartz microbalance (QCM) under diffusion and flow conditions. The obtained results were interpreted in terms of the random sequential adsorption model that allowed to estimate the range of applicability of QCM for determining the deposition kinetics of viruses and bacteria at abiotic surfaces.

Aggregation and Sedimentation Stability of Nanoscale Zeolitic Imidazolate Framework (ZIF‐8) Nanocomposites for Antimicrobial Agent Delivery Applications

ABSTRACTThe applications of nanoscale zeolitic imidazolate frameworks (ZIF‐8) for antimicrobial drug delivery depend on the aqueous suspension stability of the ZIF‐8 which is influenced by their crystallinity, size, shape, aggregation, and surface chemistry. This study evaluated the stability of ZIF‐8 nanoparticles in terms of their aggregation and sedimentation characteristics. ZIF‐8 nanocomposites were synthesized with methanol via sonication at 30°C for 1 h. The effect of drying methods (oven drying at 80°C, and vacuum drying at 35°C), number of washing steps (0 = no wash, 1, 2, 3), and washing medium (washing with water and ethanol instead of methanol, and redispersion in water and ethanol) on the suspension stability was evaluated. The impact of added xanthan gum (XG) and poly‐L‐lysine (PL) as suspension media was also evaluated. ZIF‐8 nanoparticles were also synthesized using ethanol and suspended in PL. % transmittance and zeta potential were measured for freshly prepared ZIF‐8 suspensions in PL and after freeze‐drying and resuspending in water. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and x‐ray diffraction (XRD) analysis were utilized for the assessment of the crystallinity, structure, and morphology of the samples. Antibacterial activity was evaluated by disc diffusion test against Escherichia coli. Dried methanol‐synthesized ZIF‐8 nanoparticles did not suspend in water; only the ZIF‐8 nanoparticles synthesized with reduced washing times and no drying treatment were resuspended in the water, XG and PL solutions. Instead, the ethanol‐synthesized ZIF‐8 nanoparticles were resuspended in water even after being washed three times and dried in a vacuum oven. SEM and TEM images and XRD patterns showed that alcohol can form well‐defined ZIF‐8 nanoparticles. FTIR spectra showed that ZIF‐8 had typical peaks of ZIF‐8 reported by others. Although particle size increased, the PL coating provided a 32.22% increase in zeta potential of ZIF‐8 nanoparticles from 36.25 to 47.93 mV (p &lt; 0.05) and prevented aggregation and sedimentation of the nanoparticles without changing their morphology. All the tested ZIF‐8 nanoparticles showed antibacterial activity with the PL‐coated ZIF‐8 having the highest effect followed by the ZIF‐8 nanoparticles synthesized in ethanol.

New thermal insulating polyurethane biofoams based on cherry seed oil

AbstractCherry fruits were used in clean technologies for preparation of hydroxyl components applied in polyurethane foams. Polyphenols from cherry fruits helped to obtain a stable suspension of nanosilver particles dispersed in diethylene glycol, while cherry seeds constituted a renewable source of oil, which was transesterified into biopolyol. Such biocomponents containing nanosilver particles were applied to obtain open cell heat insulating polyurethane foams resistant to a fungus strain Candida albicans. The influence of nanosilver concentration in diethylene glycol, reaction temperature, and catalyst concentration on the biopolyols and the properties of the final foams were subjected to a statistical analysis. It was found that the following process conditions were crucial in obtaining the most desired foams (in terms of their physical and mechanical properties): the catalyst content—0.225%, the concentration of DEG with nanoAg—25%, temperature—188 °C. Such an approach allowed us to obtain open cell polyurethane foams in line with Green Chemistry rules. Graphical abstract

Application of Cyrene solvent for the fabrication of polymethyl methacrylate, polyethyl methacrylate and composite films containing hydroxyapatite and diamonds

AbstractCyrene is a new biodegradable solvent, which represents a green alternative to many traditional toxic solvents for advanced polymers. Therefore, this investigation is motivated by interest in applications of Cyrene for polymer processing. The feasibility of solubilization of polymethyl methacrylate (PMMA) and polyethyl methacrylate (PEMA) in Cyrene is demonstrated. The ability to form relatively concentrated solutions of the high molecular mass polymers is an important factor for the formation of PMMA and PEMA films by a dip coating method. It was found that the polymer coatings provide corrosion protection of stainless steel in 30 g L−1 NaCl solutions. Another important finding is that the use of Cyrene facilitates the fabrication of stable suspensions of hydroxyapatite (HAp), microdiamond, and nanodiamond particles. Therefore, the problems of the dispersant selection for dispersion of chemically inert diamond and development of biocompatible dispersants are avoided using Cyrene. For the fabrication of composite films, HAp nanorods with reduced particle size are obtained using rutin as a chelating capping agent. Composite films containing HAp, microdiamond and nanodiamond in the PMMA or PEMA matrix are obtained. The composite films are promising for biomedical applications. It was found that the film morphology, composition and microstructure are influenced by the solvent–particle–polymer interactions and processing conditions.

Conductive water-based graphene suspension for electromagnetic interference shielding via spray coating on SiP module

Conductive inks have been widely used to develop electronic devices, such as sensors, RFID antennas, and transistors. Electronic utilization is a coating that forms conductive films for electromagnetic interference shielding (EMI Shielding). This process also can be employed to cover electronic modules called System in Package (SiP). A technology known as conformal shielding utilizes spray coating with metallic inks to form a conductive layer over the SiP. Traditionally, copper or silver inks have been the primary materials employed due to their high electrical conductivity. Conversely, these metallic inks are associated with significant costs, environmental impacts, and complex production methods. In this context, water-based graphene dispersion could be an alternative to EMI Shielding for electronic chips. Graphene is attractive due to its excellent electrical and thermal properties, reduced cost, and being an environmentally friendly material. In this study, a water-based graphene suspension was developed and applied via spray coating to form films for electromagnetic shielding. The graphene dispersion in water utilized Carboxymethyl cellulose (CMC). Characterizations of the graphene suspension, including morphology, particle size distribution, and chemical analysis, were conducted. The resistivity of the resulting films and their shielding effectiveness (SE) were measured. Electronic chip modules were painted to assess coverage. The study demonstrated the successful formulation of a stable water-graphene suspension exhibiting favorable electrical resistivity (2.8 × 10−2 Ω.cm) after drying at 300 °C for 1 h. The resulting film achieved a shielding effectiveness of −9 dB at 1.0 GHz. Graphene film completely covered the electronic chips, indicating an alternative conformal shielding.

Synthesis, characterization, and antifungal properties of chrome-doped hydroxyapatite thin films

The development of thin films of chromium-doped hydroxyapatite (20CrHAp) deposited on silicon substrate by the spin coating method was realized for the first time. A coherent investigation of the physicochemical properties of 20CrHAp thin films was also carried out for the first time. The obtained thin films were studied by various techniques such as, scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR) investigations and fractal analysis. By scanning electron microscopy (SEM) studies were obtained valuable information about the surface morphology of the 20CrHAp thin films. The zeta potential (ZP), Dynamic light scattering (DLS) and ultrasound measurements (US) were used in order to evaluate the stability of 20CrHAp suspension. The ratio between the hydrodynamic diameter obtained by DLS and the particle diameter obtained by SEM was 1.6. The SEM results on 20CrHAp thin films suggested that the sample possess a conglomerate of nanoparticles unevenly distributed on their surface. The surface morphology of the 20CrHAp thin films was studied with the aid of atomic force microscopy (AFM). The AFM topography of the 20CrHAp thin film's surface highlighted that the thin films present the morphology of a continuum deposited layer composed of non-uniform particle conglomerates. The presence of hydroxyapatite on the surface of silicium substrate was revealed by the results of Fourier transform infrared spectroscopy (FTIR) investigations. The antifungal evaluation of the 20CrHAp thin films was performed using Candida albicans 10,231 ATCC fungal strain. The antifungal assays results depicted that the 20CrHAp thin films inhibited the fungal biofilm formation. More than that, the results of the antifungal studies revealed that 20CrHAp thin films exhibited good inhibitory effects on the development of the fungal cells on their surface. Furthermore, our investigation delves into the realm of Minkowski Functionals and fractal/multifractal analysis as applied to the examined films. Our findings reveal that nanocomposite coatings containing 20CrHAp exhibit robust antifungal characteristics, suggesting their viability as a compelling solution for advancing antifungal devices in biomedical contexts.

Research on Magnetic Levitation Control Method under Elastic Track Conditions Based on Backstepping Method

The vehicle–guideway coupled self-excited vibration of maglev systems is a common control instability problem in maglev traffic while the train is suspended above flexible girders, and it seriously affects the suspension stability of maglev vehicles. In order to solve this problem, a nonlinear dynamic model of a single-point maglev system with elastic track is established in this paper, and a new and more stable adaptive backstepping control method combined with magnetic flux feedback is designed. In order to verify the control effect of the designed control method, a maglev vehicle–guideway coupled experimental platform with elastic track is built, and experimental verifications under rigid and elastic conditions are carried out. The results show that, compared with the state feedback controller based on the feedback linearization controller, the adaptive backstepping control law proposed in this paper can achieve stable suspension under extremely low track stiffness, and that it shows good stability and anti-interference abilities under elastic conditions. This work has an important meaning regarding its potential to benefit the advancement of commercial maglev lines, which may significantly enhance the stability of the maglev system and reduce the cost of guideway construction.

Innovative insights into nanofluid-enhanced gear lubrication: Computational and experimental analysis of churn mechanisms

This study offers unique insights into the churn lubrication mechanism in gear transmission systems through the utilization of nanofluids for the first time. Various performance parameters of the prepared nanofluid lubrication oil are measured, along with the discussion of suspension stability. Based on the overset mesh method and VOF multiphase flow model, a rotating fluid domain calculation model considering the nanofluid-air two-phase is proposed. The high-speed nanofluid lubrication experiment platform is established to track churn phenomena and identify the oil volume fraction on the gear surface. Comparing simulation results with experimental data confirms the calculation accuracy in depicting oil flow and churn lubrication. Result shows that the interaction between droplets and the gear surface involves splash, rebound, adhesion, and diffusion. The nanofluid exhibits improved adsorption, resulting in a higher oil volume fraction. When the rotation speed is increased, intensified oil spatter and atomization are observed. The ranking of nanofluid lubrication performance is Al2O3, SiO2, Fe3O4, CuO, and TiO2 particles, which are approximately aligned with contact angle magnitudes. For 3 % nanoparticles concentration, less oil is swung off, more is drawn into the gear meshing zone, and subsequently squeezed out. Image recognition results align with numerical simulation, indicating that the oil distribution of nanofluid is better than that of base fluid lubrication. This work serves as a foundational exploration for future nanofluid lubrication and heat dissipation, offering insights into preventing oil film rupture, tooth surface wear, gluing and other failure mechanisms.

Effect of ultrasound exposure time in the size distribution of lecithin liposomes in the nanoscale

Abstract The characteristics of liposome suspensions subjected to ultrasound were studied using the Nanoparticle Trajectory Analysis (NTA) technique. These were prepared with either DPPC or soy lecithin using the thin layer method. For each preparation protocol, the size and ζ potential probability densities were determined by averaging the densities obtained in several measurements. Ultrasound exposure changed the characteristics of the size and ζ potential distributions. For the size distribution, the exposure resulted in an increment of the number of liposomes with diameters in the range of ∼ 100 nm, the corresponding size distributions became slimmer, with mean diameters smaller than the ones without exposure. This is reflected in the reduction of the polydispersity index experienced by the liposome suspensions after sonication. For DPPC liposomes, it changed from ≈ 0.26 without exposure to ≈ 0.19 after 10 min sonication whereas for soy lecithin liposomes it changed from ≈ 0.30 without exposure to ≈ 0.21 after 10 min sonication. For the ζ potential, after 10 min exposure, the distributions became wider, with mean values more negative than the ones without exposure. The mean ζ potential, for DPPC liposomes, changed from ≈ −35 mV without exposure to ≈ −39 mV after 10 min sonication whereas for soy lecithin liposomes it changed from ≈ −38 mV without exposure to ≈ −42 mV after 10 min sonication. Therefore, our results show that exposure to ultrasound reduced the polydispersity and increased the stability of the liposome suspensions.

Antibacterial efficacy of decorated carbon nanotubes by nano silver against pseudomonas aeruginosa

Carbon nanotubes (CNTs) are considered as a promising nanomaterial for a variety of applications. It has desirable physicochemical characteristics of high surface area, superior mechanical and thermal strength, and electrochemical activity. In this study, CNTs decorated with silver nanoparticles (AgNPs) were manufactured by an arc discharge technique. As a result, etching produces stable AgNPs-CNTs aqueous suspensions of pure silver and carbon electrodes in ethanol vapor condensed in water. UV- visible photometer, x-ray Diffraction, transmission electron microscope, and energy dispersive x-ray characterized the synthesized AgNPs-CNTs. The synthesized AgNPs-CNTs crystals showed CNTs formation of an average 9.5 nm, with intermediate length position of about 75.8 nm decorated by homogeneous spherical AgNPs of average size 15.2 nm. The antibacterial efficiency of AgNPs-CNTs against Pseudomonas aeruginosa was established at a series of concentrations (45 g ml−1: 0.0879 g ml−1) while values for the MIC and MBC were determined. The MIC and MBC levels were found to be (>5.625 μg ml−1) and (>11.25 μg/ml) respectively. The bacteria cytotoxicity was evaluated through LDH and protein leakage levels. Treated samples with 3.2 μg ml−1 AgNPs-CNTs revealed significant injuries in the cell membrane by two times greater in LDH and protein leakage levels than samples treated by 5.0 μg ml−1 AgNPs. Results in this work substantiate the synergistic effect of combining AgNPs with CNTs to enhanced antibacterial properties and performance compared to AgNPs alone. The efficiency of using synthesized AgNPs-CNTs showed high antibacterial potential against Pseudomonas aeruginosa in a concentration-dependent manner. The arc discharge method can be adapted to incorporate different materials or change the synthesis conditions, allowing for the production of AgNPs-CNTs with tailored properties for specific applications.