Electrostatic Deposition Research Articles

Nanometer-scale ordered arrangement of diamond nanoparticles on substrates via electrostatic deposition

We demonstrate a nanometer-scale ordered arrangement of diamond nanoparticles (DNPs) on SiO2 surfaces via the technique of electrostatic deposition. Using the lift-off process combining electron beam lithography and surface functionalization with 3-aminopropyltriethoxysilane, the negative zeta potential of SiO2 surfaces are locally inversed to positive. Consequently, the DNPs are deposited on the limited SiO2 surface areas with ≥100 nm pitch line-and-space and dot array patterns where the electrostatic attractive interaction works. Since this approach does not rely on any specific material property other than zeta potential, it would be applicable to any material combination of charged nanoparticles and substrates.

Hydrocolloid coated oleosomes for development of oleogels

Oleosomes are a micron sized mass of oil droplets enclosed by a specific membrane of protein-phospholipid mixtures typically found in plants and microorganisms to serve as an energy reserve for potential needs. Interest in plant-derived oleosomes in the food industry has recently grown significantly, as these unique natural emulsions are made of unrefined natural oil phase. In a similar way, there is also significant interest in converting liquid oil emulsions into soft solid oleogel structures through physical trapping with water-soluble biopolymers. Natural oleosome suspensions were stabilized with xanthan and pectin hydrocolloids and converted for the first time in this study into oleosome templated oleogel structures. 1–1.5% of hydrocolloid was sufficient to encapsulate oleosomes when electrostatic deposition was used and upon drying a soft solid structure was obtained. Oleosomes coated with xanthan gum resulted in oleogels structures with higher firmness and elastic modulus values compared pectin coated samples. These findings provided novel information in designing the gels structures composed of unrefined, natural oil in the form of oleosomes.

Formulation of chitosan coated nanoliposomes for the oral delivery of colistin sulfate: in vitro characterization, 99mTc-radiolabeling and in vivo biodistribution studies

Colistin sulfate is a very important antibiotic for the treatment of multidrug-resistant Gram-negative infections. Unfortunately, it has low oral bioavailability and several side effects following parenteral administration. The present study aims to develop chitosan-coated colistin nanoliposomes to improve the stability in the gastrointestinal tract and to enhance the oral delivery of colistin. The chitosan-coated colistin nanoliposomes were obtained via thin-film evaporation and electrostatic deposition methods using either Span 60, Tween 65 or Tween 80 as surfactants with different cholesterol: surfactant: soya lecithin ratios. The influence of systems variables was further characterized by vesicle size analysis, zeta potential (ZP), poly dispersibility index (PDI), and also their entrapment efficiency percentage (EE %) was evaluated. Various systems were formed with vesicle sizes in the nano-range, 155.64 ± 12.53 nm to 315.64 ± 15.90 nm, and EE % of 45.2 ± 2.9% to 81.8 ± 2.9%. Moreover, the ZP value of the prepared nanoliposomes switched from a negative to a positive value after chitosan coating. To track the released colistin in vivo, technetium 99m (99mTc) was incorporated into the optimum system (S-3) system via direct coupling with colistin. Chitosan-coated 99mTc-colistin nanoliposome, 99mTc-colistin suspension, and 99mTc-chitosan-coated nanoliposomes (placebo) were administered orally into bacterial infection (Escherichia coli) bearing mice. The biodistribution results showed that chitosan-coated nanoliposome significantly enhanced the bioavailability of colistin compared to colistin suspension (the commercially available). Moreover, the system effectively improved the localization of colistin at the infected muscle. In conclusion, this approach offers a promising tool for enhanced oral delivery of colistin.

Al2O3-TiO2-PMMA Bio-Composite Coating Via Electrostatic Spray Technique

This work aims preparation of polymer-based biocomposite coating by electrostatic spray method onto 316L stainless steel substrate, the present work will compare the effects of incorporation of Al2O3 and TiO2 particles at a different percentage of (10,15 and 20 % wt. from Al2O3 and TiO2 with (90,85 and 80% wt. PMMA - based electrostatic deposition coating is studied. The structure and chemical composition of composite coatings were studied by using (SEM) & (EDS) and mechanical properties (Microhardness and adhesion strength) of Al2O3-TiO2-PMMA composite coating. The SEM&EDX result showed that the composite coating to be dense with uniform dispersants and continuous with a well homogenous mixture within coating exhibits a much-increased Microhardness and remarkably improved adhesion strength.

Cooking grease particles purification review and technology combination strategy evaluation for commercial kitchens

Effective emission control of cooking oil fumes (COFs), particularly for grease particles, has always been a cause of great concern for catering industry. The review and evaluation of combinations of purification technology are urgently required. This work presents a literature review and combination strategy evaluation of purification technology of grease particles of commercial kitchens. A variety of mainstream purification technologies, such as mechanical separation (M), filtration (F), washing absorption (W) and electrostatic deposition (E) are discussed. In order to establish a complete and efficient fume purification system for commercial kitchen, this study proposes the four-point principles of combined purification technologies as: (1) from easy to difficult (for grease particle diameter); (2) fire prevention and noise reduction; (3) electrostatic deposition postposition; (4) Absorption and dissolution (by-product from electrostatic). Based on the above principles and separation characteristics, the recommended combinations of purification strategies are M-E, F-E, M-F-E and M-E-F. The combination strategy of M-F-E is adopted as an example to evaluate and optimize COFs purification system use life cycle assessment approach. The results indicate that the optimization of the M-F-E purification system using rotating mesh plate instead of baffle filter can reduce the environmental impact of global warming and eutrophication by about 35% which reduces the emissions of CO2 and SO2 from 92.533 kg and 0.110 kg to 60.214 kg and 0.072 kg, respectively. Besides the review of relevant purification technologies, the study also proposes the combination of principles of purification technologies and the evaluation and optimization of life cycle assessment for the optimal design of combined purification system.

The Effect of Electrochemical Composite Coatings with LaF3-LaB6 Particles in Nickel-Copper Matrix on the Metallurgical Processes in Arc Welding of Low Alloy Ferrite-Pearlite Steels.

Development of welding consumables with fluorides and borides of rare earth metals is a promising area for improving the weldability of low alloy steels. As lanthanum fluoride and boride dissociate, lanthanum and boron dissolve in the weld pool and the welding arc plasma is saturated with fluorine. As a result of FeO, MnO, SiO2 deoxidation and FeS, MnS desulfurization, refractory lanthanum sulfides and oxides La2O3, La2S3 are formed in the weld pool, which can be the crystallization nuclei in the weld pool and the origin of acicular ferrite nucleation. The paper proposes a model of metallurgical processes in the arc and weld pool, as well as a model of electrochemical adsorption of Ni2+ cations in colloidal electrolytes during electrostatic deposition of nano-dispersed insoluble particles of LaF3 or LaB6 on the surface of wire. The paper discusses the constructional design of the welding wire and the technology for forming electrochemical composite coatings with copper and nickel matrix. The composite wires applied in the welding of low alloy steels make it possible to refine the microstructure, increase the tensile strength by 4% and the impact toughness of welds by 20%.

Tunable high internal phase emulsions stabilized by cross-linking/ electrostatic deposition of polysaccharides for delivery of hydrophobic bioactives

We have explored a controllable approach to produce polysaccharide-based high internal phase emulsions (HIPEs) without the use of any surfactants, synthetic particles, or synthesis of Pickering emulsions. This strategy required only the centrifugation of ultrasonication-produced shell cross-linked polysaccharide microspheres, and simultaneously provided facile control over the properties of HIPEs. By this means, the strong viscoelastic HIPEs with high oil volume fraction (up to 85.6%) can be stabilized solely by 0.5 wt% polysaccharide. We can further strengthen the HIPEs by generating an additional complex shell through the electrostatic deposition of non-cross-linked polysaccharides back on the cross-linked microsphere surface. Using β-carotene as a model hydrophobic bioactive, these HIPEs stabilized by cross-linking/electrostatic deposition of polysaccharides featured high encapsulation efficiency, oxidation stability, and pH/redox dual stimuli-responsive release. Further development of this strategy could exhibit a great potential to construct tunable HIPEs with desired functionalities for smart delivery and oral adsorption of hydrophobic food active ingredients.

Encapsulation of Soy Lecithin Nanoparticles in Gelatin Coating for the Fortification of Gelled Food Products with Phospholipids

Phospholipids are category of nutrients that are essential for growth and health maintenance. They are commonly supplied from animal-derived foods. However, plant-derived phospholipids like soy lecithin seems also to be potential alternative because they are well received by different category of population who have concerns about animal-derived foods. The purpose of the current investigation is to formulate gelatin-based matrix bearing soy lecithin as a model of gelled food product fortified with plant-based phospholipids. First an aqueous colloidal system containing lecithin nanoparticles is formulated. The average particle size of lecithin was 79.0 nm and its zeta-potential was -49.0 mV. Then, lecithin nanoparticles were encapsulated in gelatin coating using the layer-by-layer electrostatic deposition method. That led to the formation of gelatin-encapsulated-lecithin nanoparticles which has an average particle size 204.0 nm and a zeta-potential +4.0 mV. Upon cooling that system at 4oC, a hydrogel bearing lecithin nanoparticles is formed. The whole process was evaluated using different techniques in order to verify the encapsulation of lecithin nanoparticles within the gelatin matrix. The physical stability of all formulations before and after encapsulation was monitored during and after storage for 3 months. The concept of this investigation can be useful for fortification of some gelatin-based food products with plant-based phospholipids, which can be used as a dietary supplement for health maintenance and promotion among different populations.

Characteristics of highly sensitive and selective nitric oxide gas sensors using defect-functionalized single-walled carbon nanotubes at room temperature

One of the most important trends in modern medicine is the development of non-invasive methods that diagnose diseases by analyzing specific gases from human exhalation. Examination of such gases helps monitor various diseases. The ability of nanosensors to potentially detect conditions such as Rhinitis digestive diseases, liver transplant rejection, inflammation in the stomach, cystic fibrosis, encephalopathy, helicobacter pylon digestive cancer, respiratory diseases, and COVID-19, by examining nitric oxide (NO), has been discussed as well as studied increasingly in recent years. In this paper, we have proposed a low-cost detector that can measure NO gas from the exhaled air, which is applied to the ppb level at room temperature. A sensor that detects NO gas with high sensitivity by using single-walled carbon nanotubes (SWNTs) as nanomaterials, has been fabricated. The semiconductor-type gas sensors using SWNTs showed characteristics such as rapid detection, long-term reliability, reproducibility, and miniaturization at room temperature. To improve the selectivity for NO gas, SWNT network channels were formed between the Au electrodes, and SWNTs were functionalized with en-APTAS. A new rinse process was introduced to solve the problem of low sensitivity in SWNT-based NO sensors. With the introduction of the improved rinsing process, the recovery of the fabricated sensor increased from less than 20% to 90.34% when the device was rinsed ten times under optimized conditions. The improved rinsing process effectively straightened the rearrangement of the large amount of amine-functionalized SWNTs attached during the electrostatic self-assembled deposition. In addition, a 28.64% response for a 100 ppb concentration of NO gas was measured at room temperature. We also confirmed that the fabricated sensor does not react with carbon monoxide (CO) and volatile organic compounds (VOCs) gases owing to its high selectivity to NO gas.

Preparation and characterisation of edible layer-by-layer coatings of sodium polyacrylate/chitosan for the preservation of strawberries

To improve the preservation of strawberries during storage, an edible coating was prepared using a layer-by-layer self-assembly electrostatic deposition technology. Sodium polyacrylate (PAAS) was used as polyanion solution, and chitosan (CS) was used as polycation solution. The obtained coating was characterised to determine its self-repairing ability and its effect on the preservation of strawberries. The results showed that CS (9 mg/mL) and PAAS (5 mg/mL) could assemble, by hydrogen and ionic bonding, to form a new coating with no obvious pores and had a tight cross-sectional structure. The PAAS/CS self-assembled coating displayed high water resistance (water vapor transmission rate, 31.22 × 10-11 g• m/m2•s•Pa·), transparency (light transmittance, 87.5%), and excellent mechanical properties (tensile strength, 17.31 MPa; elongation at break, 13.72%). The self-repairing ability of the PAAS/CS coating upon scratching was manifested by the repair of the coating's morphology (repair rate, 81.05%), and the restoration of its mechanical properties. When compared with uncoated strawberries, PAAS/CS coating significantly reduced the weight loss rate, the rot rate during storage (p < 0.05), and the loss of anthocyanin and vitamin C. In conclusion, the PAAS/CS coating greatly improved the fresh-keeping of strawberries.

Functional properties of Lactobacillus casei C24 improved by microencapsulation using multilayer double emulsion

To provide their health effect, probiotics need to maintain their viability, adhere to the intestinal epithelium, and colonize it without losing their probiotic properties. In the present study, Lactobacillus casei was encapsulated in a double emulsion and then coated with alginate and chitosan using the layer-by-layer electrostatic deposition technique. The survival rate and functional properties of L. casei (cholesterol assimilation, surface hydrophobicity, auto-aggregation, and co-aggregation) were evaluated after the freeze-drying process and during the transit through the simulated gastrointestinal tract. Reservoir type multilayer microcapsules with a small particle size (6.2–12.2 μm) were obtained. Freeze-dried microcapsules maintained the initial cell count (9.4 log UFC/g) without affecting its functional properties. The resistance of L. casei cells to the conditions of salivary, gastric, and intestinal digestion was noticeably improved when increasing the number of layers in the microcapsules, especially when they were coated with alginate and chitosan. The alginate-chitosan layers provided additional protection to L. casei cell membranes, substantially preserving the cholesterol assimilation ability, surface hydrophobicity, auto-aggregation, and co-aggregation of L. casei after simulated in vitro digestion. This encapsulation method not only guarantees the presence of the probiotic in the gastrointestinal tract, but it does not lose its probiotic properties and ensures that it exerts its probiotic effect.

Nanoparticle-Assisted Pool Boiling Heat Transfer on Micro-Pin-Fin Surfaces.

Boiling heat transfer intensification is of significant relevance to energy conversion and various cooling processes. This study aimed to enhance the saturated pool boiling of FC-72 (a dielectric liquid) by surface modifications and explore mechanisms of the enhancement. Specifically, circular and square micro pin fins were fabricated on silicon surfaces by dry etching and then copper nanoparticles were deposited on the micro-pin-fin surfaces by electrostatic deposition. Experimental results indicated that compared with a smooth surface, the micro pin fins increased the heat transfer coefficient and the critical heat flux by more than 200 and 65–83%, respectively, which were further enhanced by the nanoparticles up to 24% and more than 20%, respectively. Correspondingly, the enhancement mechanism was carefully explored by high-speed bubble visualizations, surface wickability measurements, and model analysis. It was quantitatively found that small bubble departure diameters with high bubble departure frequencies promoted high heat transfer coefficients. The wickability, which characterizes the ability of a liquid to rewet a surface, played an important role in determining the critical heat flux, but further analyses indicated that evaporation beneath bubbles was also essential and competition between the wicking and the evaporation finally triggered the critical heat flux.

Effect of Annealing Temperature on Properties of Tin Oxide Films Prepared by Electrostatic Deposition Technique

Abstract In this work, tin oxide films were prepared by electrostatic spray deposition technique. The effect of post annealing temperature on properties of prepare film was performed. The structural, surface morphology and optical properties of tin oxide films were characterized by X-ray diffraction, field-emission scanning electron microscope, and UV-Visible spectrophotometer. The crystalline size is found to increase with increase the annealing temperature. Moreover, the effect of annealing temperature on physical properties of tin oxide films has been performed

Properties of Manganese Oxide Films Prepared by Electrostatic Deposition Technique

Abstract In this work, the electrostatic spray deposition technique was applied to prepare manganese oxide tin films. The effects of post annealing at various temperatures on the properties of manganese oxide film were studied. The properties of the films were assessed by X-ray photoelectron spectroscopy and field-emission scanning electron microscope. In addition, the electrochemical properties of the manganese oxide films were investigated. It was found that the prepared films could be used for super-capacitive, energy storage devices

Impact of albumin corona on mucoadhesion and antimicrobial activity of carvacrol loaded chitosan nano-delivery systems under simulated gastro-intestinal conditions

Emerging antibiotic resistance in pathogens has posed considerable challenges to explore and examine the natural antimicrobials (NAMs). Due to the labile nature of NAMs, nano-delivery systems (NDS) are required to protect them from physiological degradation and allow controlled delivery to the targeted site of infection. In this study, corona modified NDS were developed using bovine serum albumin (BSA) on a chitosan core (CS) for sustained delivery of carvacrol (CAR), a natural antimicrobial agent, in the intestine. The optimal nano-formulations of the core (CS-NDS) and corona modified (BSA-CS-NDS) systems were fabricated with an average diameter of 52.4 ± 10.4 nm and 202.6 ± 6 nm, respectively. A shift in zeta-potential (ZP) from positive (+21 ± 3.6 mV) to negative values (−18 ± 2.6 mV) confirmed the electrostatic deposition of BSA corona on CS core. Under the influence of various simulated gastrointestinal conditions, BSA corona provided extra stability to NDS (ZP -38.5 mV), by ensuring delayed release and limited degradation in the gastric conditions. Mucoadhesive studies with quartz crystal microbalance with dissipation (QCM-D) revealed that BSA corona reduced the mucoadhesion of NDS at gastric pH, which enabled the effective delivery of CAR to the intestinal phase for successful eradication of Salmonella enterica.

A novel complex coacervate formed by gliadin and sodium alginate: Relationship to encapsulation and controlled release properties

This paper investigated the formation of a novel complex coacervate between gliadin (G) and sodium alginate (SA) as well as its relationship with the encapsulation and controlled release properties by loading curcumin (Cur). G-SA coacervates (GSAC) were fabricated using the anti-solvent method to form gliadin nanoparticles (GNPs) and then electrostatic deposition with SA to form coacervates. Based on the turbidimetric analysis and ζ-potential results, coacervates were formed at a wide range of pH (1.0–7.0) through electrostatic interaction in the gliadin-SA system. The gliadin-SA interaction was spontaneous exothermic process shown by the isothermal titration calorimetry. The spherical particles of curcumin-loading G-SA coacervates (GSAC-Cur) with well-homogeneity and great-dispersion as well as particle aggregation were observed on SEM. At coacervated pHs, GSAC-Cur showed particle size from 433.55 to 1496.50 nm, PDI around 0.28, ζ-potential from −1.9 to −50.9 mV and encapsulation efficiency from 61.29% to 81.01%. Controlled release profiles confirmed that G-SA coacervates reduced the released speed of curcumin in the release process. In summary, we concluded that the properties of GSAC-Cur corresponding to the embedding and controlled release could be better by forming coacervates via pH-induced.

Immobilization of lysozyme on layer-by-layer self-assembled electrospun films: Characterization and antibacterial activity in milk

In this study, the electrospun cellulose acetate (CA) films were alternately deposited by lysozyme and sodium alginate (SA) on the nanofiber surface by layer-by-layer self-assembly technique. With the increasing number of layers, the films presented an increased average fiber diameter from 364 to 611 nm. The enhanced thermal stability was observed due to the layer-by-layer electrostatic deposition, as well as the formation of hydrogen bonds in the case of the CA(Lys-SA)9 film. The immobilized lysozyme exhibited the improved pH and temperature resistance, excellent storage stability, and retained over 70% of its initial activity after reusing 4 cycles. Moreover, these self-assembled films resulted in a substantial decrease in Staphylococcus aureus colonies in ultra-high temperature milk at 4 °C and 25 °C, respectively. The results suggested that the immobilization of lysozyme on layer-by-layer self-assembled electrospun films with antibacterial activity showed promising applications in milk and dairy products.

Enhancing emulsion functionality using multilayer technology: Coating lipid droplets with saponin-polypeptide-polysaccharide layers by electrostatic deposition

Electrically charged food-grade biopolymers can be used to form multilayer coatings around the lipid droplets in oil-in-water emulsions using a sequential layer-by-layer electrostatic deposition approach. In principle, this approach can be used to improve the stability and enhance the functionality of food emulsions. In this study, multilayer coatings were formed from saponins, polypeptides, and polysaccharides using medium chain triglyceride (MCT) lipid droplets as templates (pH 4.0). First, an emulsion containing negatively charged lipid droplets was created using quillaja saponin (QS) as an anionic emulsifier. Second, these anionic droplets were coated with a cationic polypeptide (poly-L-lysine, PLL) to form positively-charged droplets. Finally, these cationic droplets were coated with a negatively-charged polysaccharide, either pectin (PE) or κ-carrageenan (KC), to form anionic droplets. Overall, the 1-layer emulsions had the best resistance to salt, pH, and heat, indicating that quillaja saponins were effective emulsifiers. The 2-layer emulsions had better pH-stability than the 3-layer emulsions, which tended to strongly aggregate under acidic conditions. Conversely, the 3-layer emulsions had better salt-stability than the 2-layer emulsions, which tended to aggregate strongly even at low salt levels (50–100 mM NaCl). All the emulsions were relatively stable to heating (90 °C, 30 min). Overall, our results provide useful insights into the formulation of stable multilayer emulsions from food-grade emulsifiers and biopolymers. There appears to be little advantage to using the multilayer technology to enhance the physical stability of saponin-coated lipid droplets, but there may be advantages in terms of extending their functional properties, which will be explored in future studies.

Utilization of multilayer-technology to enhance encapsulation efficiency and osmotic gradient tolerance of iron-loaded W1/O/W2 emulsions: Saponin-chitosan coatings

Multilayer technology was used to improve the performance of multiple emulsions. W1/O/W2 emulsions were fabricated using 2 wt% polyglycerol polyricinoleate (PGPR) as a hydrophobic surfactant and 2 wt% saponin as a hydrophilic surfactant. The anionic saponin-coated W1/O droplets in the multiple emulsions were coated with a layer of cationic chitosan using electrostatic deposition. The influence of chitosan concentration (0.05–0.4 wt%) on the formation and stabilization of the W1/O/W2 emulsions was evaluated by measuring the ζ-potential, microstructure, and mean droplet diameter. The W1/O droplets became saturated at 0.3 wt% chitosan, which resulted in emulsions containing relatively small cationic droplets (d ≈ 400 nm; ζ ≈ +30 mV) that were resistant to droplet aggregation. The double-layer W1/O/W2 emulsions were highly effective at retaining iron (ferrous sulfate) within their internal aqueous phase, with more than 87% remaining after storage for 28 days at 25 °C. They also remained stable when exposed to an osmotic stress gradient, which was created by having different glucose levels (3–30 wt%) in the external aqueous phases, but a constant level (30 wt%) in the internal aqueous phase. The size of the saponin-chitosan coated W1/O droplets was unchanged from 30 to 6 wt% glucose in the external aqueous phase, while the saponin-coated ones were only stable from 30 to 21 wt% glucose. The chitosan coatings also inhibited the release of iron from the W1/O/W2 emulsions under osmotic stress. Overall, our results suggest that double-layer W1/O/W2 emulsions may be effective iron delivery systems for food applications.

The combination of a poly-caprolactone/nano-hydroxyapatite honeycomb scaffold and mesenchymal stem cells promotes bone regeneration in rat calvarial defects.

Bone tissue engineering goes beyond the limitations of conventional methods of treating bone loss, such as autograft-induced morbidity and a lack of integration for large grafts. Novel biomimicry approaches (using three-dimensional [3D] electrospinning and printing techniques) have been designed to offer the most appropriate environment for cells and thus promote bone regeneration. In the present study, we assessed the bone regeneration properties of a composite 3D honeycomb structure from the electrostatic template-assisted deposition process by an alternate deposition of electrospun polycaprolactone (PCL) nanofibers and electrosprayed hydroxyapatite nanoparticles (nHA) on a honeycomb micropatterned substrate. We first confirmed the cytocompatibility of this honeycomb PCL-nHA scaffold in culture with bone marrow-derived mesenchymal stem cells (BM-MSCs). The scaffold was then implanted (alone or with seeded MSCs) for 2 months in a rat critical-sized calvarial defect model. The observation of new bone synthesis in situ (monitored using microcomputed tomography every 2 weeks and a histological assessment upon extraction) demonstrated that the honeycomb PCL-nHA scaffold was osteoconductive. Moreover, the combination of the scaffold with BM-MSCs was associated with significantly greater bone volume and mineralized regeneration during the 2-month experiment. The combination of the biomimetic honeycomb PCL-nHA scaffold with patient mesenchymal stem cells might therefore have great potential for clinical applications and specifically in maxillofacial surgery.