Search Results (36)

Bitter melon seed oil (BMSO), as a by-product of bitter gourd fruit processing, is rich in active ingredients and has unique medicinal potential. However, its solubility and dispersibility in water are poor when used directly. Therefore, this study aims to develop an eco-friendly submicron emulsion containing BMSO for intravenous injection and evaluate its safety. The BMSO submicron emulsion (BMSOSE) was prepared by high-pressure homogenization. The size, polydispersity index (PDI), ζ-potential, Turbiscan stability index (TSI), apparent viscosity, and morphology were characterized; in addition, an in vitro hemolysis test and acute toxicity test in mice were investigated in detail to evaluate the emulsion. The results demonstrated that the formulation and technological parameters of the BMSOSE were as follows: BMSO, 8% (w/w); egg yolk lecithin, 1.2% (w/w); F-68, 0.2% (w/w); pH, 5.0; homogenization pressure, 600 Pa; and number of homogenization cycle, 9. The obtained BMSOSE droplets exhibited a spherical shape with uniform size distribution with an average diameter of 221.3 nm, a PDI of 0.2, and a ζ-potential of −36 mV. There was no significant change in the fatty acid composition of BMSO and the BMSOSE. The safety tests demonstrated that the BMSOSE had no signs of hemolysis and had no toxicity to mice with LD50 > 64 mL/kg. This study provides a foundation for further development of BMSO and its preparations. Full article

This work deals with the coating properties of synthetic latices comprising two kinds of polymers, specifically polyacrylate and polypyrrole, which were simultaneously formed by semi-continuous emulsion polymerization using a “one-pot” synthesis strategy. In this procedure, both the emulsion polymerization of acrylate monomers and the oxidative polymerization of pyrrole occurred concurrently in one reactor. Polyacrylate latices differing in polypyrrole loading were prepared by applying various dosages of pyrrole, specifically 0, 0.25, and 0.50, based on the fraction of acrylate monomers. The effect of the in situ incorporated polypyrrole component (having the nature of submicron composite polypyrrole-coated polyacrylate latex particles) on the physico-mechanical properties and chemical resistance of the resulting heterogeneous coating films was investigated. The interaction of incorporated polypyrrole and anti-corrosion pigments (see ZnS, Zn₃(PO₄)₂, ZnFe₂O₄, MoS₂, and ZnO) on the corrosion resistance of coatings was evaluated by using the electrochemical linear polarization technique. The polyacrylate latex prepared with the lowest polypyrrole loading (achieved by polymerizing 0.25 wt. % of pyrrole related to acrylic monomers) was found to be the optimum binder for waterborne anticorrosive coatings based on their properties and protective function. Their compatibility with the selected types of pigments was studied for these latex binders. In addition, their influence on the anti-corrosion efficiency of polyacrylate paint films was evaluated using the linear polarization electrochemical technique. For high corrosion resistance, the ZnS and MoS₂ pigments, showing compatibility with polyacrylate latices containing the polypyrrole component, proved to be advantageous. Full article

Bacterial infections impede the wound healing process and can trigger local or systemic inflammatory responses. Therefore, there is an urgent need to develop a dressing with antimicrobial and anti-inflammatory properties to promote the healing of infected wounds. In this study, BA/COs/NO-PL/AL hydrogels were obtained by adding brevilin A (BA) camellia oil (CO) submicron emulsion and nitric oxide (NO) to hydrogels consisting of sodium alginate (AL) and Pluronic F127 (PL). The hydrogels were characterized through dynamic viscosity analysis, differential scanning calorimetry, and rheology. They were evaluated through anti-inflammatory, antimicrobial, and wound healing property analyses. The results showed that BA/COs/NO-PL/AL hydrogels were thermo-responsive and had good ex vivo and in vivo anti-inflammatory activity, and they also exhibited strong antimicrobial activity against methicillin-resistant Staphylococcus aureus Pseudomonas aeruginosa (MRPA) and methicillin-resistant Staphylococcus aureus (MRSA). They were able to effectively promote healing of the infected wound model and reduce inflammation and bacterial burden. H&E and Masson’s staining showed that BA/COs/NO-PL/AL hydrogels promoted normal epithelial formation and collagen deposition. In conclusion, BA/COs/NO-PL/AL hydrogels are promising candidates for promoting the healing of infected wounds. Full article

Nanotechnology is the science of creating materials at the nanoscale by using various devices, structures, and systems that are often inspired by nature. Micro- and nanoparticles (MPs, NPs) are examples of such materials that have unique properties and can be used as carriers for delivering drugs for different biomedical applications. Chitosan (CS) is a natural polysaccharide that has been widely studied, but it has a problem with low water solubility at neutral or basic pH, which limits its processability. The goal of this work was to use a chemically modified CS with poly(ethylene glycol) methyl ether acrylate (PEGA) to prepare CS micronic and submicronic particles (MPs/NPs) that can deliver different types of antibiotics, respectively, levofloxacin (LEV) and Ciprofloxacin (CIP). The particle preparation procedure employed a double crosslinking method, ionic followed by a covalent, in a water/oil emulsion. The studied process parameters were the precursor concentration, stirring speeds, and amount of ionic crosslinking agent. MPs/NPs were characterized by FT-IR, SEM, light scattering granulometry, and Zeta potential. MPs/NPs were also tested for their water uptake capacity in acidic and neutral pH conditions, and the results showed that they had a pH-dependent behavior. The MPs/NPs were then used to encapsulate two separate drugs, LEV and CIP, and they showed excellent drug loading and release capacity. The MPs/NPs were also found to be safe for cells and blood, which demonstrated their potential as suitable drug delivery systems for biomedical applications. Full article

Due to the increasing difficulty of drilling in the later stages of oil and gas field development, the development of micro-pores and micro-fractures is becoming common. Conventional plugging agents have relatively large particle sizes. So, choosing the appropriate plugging agent can prevent leakages. Using the inverse emulsion polymerization method, acrylamide, 2-acrylamide-2-methylpropane sulfonic acid and acrylic acid were selected to be the main reaction monomers, N,N′-methylenebisacrylamide was used as a crosslinking agent, sorbitan monostearate and polyoxyethylene sorbitan anhydride monostearate were used as emulsifiers, and 2,2′-azobis(2-methylpropionamidine) dihydrochloride was used as the initiator to synthesize a nano-scale plugging agent for oil-based drilling fluid. The plugging agent was characterized using infrared spectroscopy, scanning electron microscopy, and thermogravimetry analysis. The results showed that the plugging agent is spherical and uniform in size, with particles being in the submicron range. Additionally, it exhibited strong temperature resistance. Finally, the performance of the plugging agent was evaluated via experiments conducted under normal temperature and pressure, high-temperature and high-pressure, and core-plugging conditions. After adding the plugging agent to the oil-based drilling fluid, the basic rheological properties of the oil-based drilling fluid were not significantly affected. Furthermore, the filtration loss was significantly reduced under normal temperature and pressure, as well as under high-temperature and high-pressure conditions, after aging. When the plugging agent with 3% concentration was added, the reduction rate of pore core permeability reached 96.04%. Therefore, the plugging agent for the oil-based drilling fluid can effectively improve the wellbore stability and has a promising potential for field applications. Full article

Supercritical CO₂ (scCO₂) is utilized in the supercritical fluid extraction of emulsions (SFEE) to swiftly extract the organic phase (O) from an O/W emulsion. The dissolved substances in the organic phase precipitate into small particles and remain suspended in the water (W) with the aid of a surfactant. The process can be continuously conducted using a packed column in a counter-current flow of the emulsion and scCO₂, at moderate pressure (8–10 MPa) and temperature (37–40 °C). To ensure the commercial viability of this technique, the organic solvent must be separated from the CO₂ to facilitate the recirculation of both streams within the process while minimizing environmental impact. Thus, the aim of this work was to design a plant to produce submicron materials using SFEE, integrating the recovery of both solvents. First, experimental equilibrium data of the ternary system involved (CO₂/ethyl acetate/water) were fitted with a proper thermodynamic model. Then, simulations of the whole integrated process at different scales were carried out using Aspen Plus^®, along with economical evaluations. This work proposes the organic solvent separation with a distillation column. Thus, the two solvents can be recovered and recycled to the process in almost their entirety. Furthermore, the particles in the aqueous raffinate are produced free of solvents and sterilized for further safe use. The costs showed an important economy scale-up. This work could ease the transfer of the SFEE technology to the industry. Full article

The impact of the encapsulation technology on the oxidative stability of fish-oil-loaded capsules was investigated. The capsules (ca. 13 wt% oil load) were produced via monoaxial or coaxial electrospraying and spray-drying using low molecular weight carbohydrates as encapsulating agents (e.g., glucose syrup or maltodextrin). The use of spray-drying technology resulted in larger capsules with higher encapsulation efficiency (EE > 84%), whilst the use of electrospraying produced encapsulates in the sub-micron scale with poorer retention properties (EE < 72%). The coaxially electrosprayed capsules had the lowest EE values (EE = 53–59%), resulting in the lowest oxidative stability, although the lipid oxidation was significantly reduced by increasing the content of pullulan in the shell solution. The emulsion-based encapsulates (spray-dried and monoaxially electrosprayed capsules) presented high oxidative stability during storage, as confirmed by the low concentration of selected volatiles (e.g., (E,E)-2,4-heptadienal). Nonetheless, the monoaxially electrosprayed capsules were the most oxidized after production due to the emulsification process and the longer processing time. Full article

Chitosan (CS) crosslinking has been thoroughly investigated, but the chemical reactions leading to submicronic hydrogel formulations pose problems due to various physical/chemical interactions that limit chitosan processability. The current study employs the chemical modification of chitosan by Michael addition of poly (ethylene glycol) methyl ether acrylate (PEGA) to the amine groups to further prepare chitosan particulate hydrogels (CPH). Thus, modified CS is subjected to a double crosslinking, ionic and covalent, in water/oil emulsion. The studied process parameters are polymer concentration, stirring speed, and quantity of ionic crosslinker. The CPH were structurally and morphologically characterized through infrared spectroscopy, scanning electron microscopy, light scattering granulometry, and zeta potential, showing that modified CS allows better control of dimensional properties and morphology as compared with neat CS. Swelling properties were studied in acidic and neutral pH conditions, showing that pH-dependent behavior was maintained after grafting and double crosslinking. The applicability of the prepared materials was further tested for drug loading and in vitro delivery of levofloxacin (LEV), showing excellent capacity. CPH were found to be cyto- and hemocompatible demonstrating their potential for effective use as a controlled release system for different biomedical applications. Full article

The micro-encapsulation procedure of calcium nitrate in urea-formaldehyde shell is well known. The most recent developed method for the synthesis of the calcium nitrate self-healing micro-capsules was based on the in-situ polymerization using water-in-oil emulsion. Although the microcapsules’ yield was significantly improved using this approach, incorporating the micro-capsules into concrete mixes has been found to reduce strength. One potential strength reduction cause might be the presence of sulfonic acid as a component in the continuous (oil) phase. As the anionic surfactant, Aerosol OT (AOT) has been widely used to prepare water-in-oil emulsions and to form aggregates in non-polar solvents; submicron calcium nitrate refined microcapsules were synthesized using AOT in hexane solution. While the aqueous phase in the original encapsulation procedure has not been altered, the continuous organic phase was prepared by dissolving AOT in hexane. The prepared microcapsules were characterized using Scanning Electron Microscopy (SEM). The preliminary assessment of the effect of incorporating of the refined microcapsules into cementitious materials has been carried out by preparing mortar mixes using 75% capsules’ concentration (by weight of cement). The reported yield values, average shell thickness, and average diameter of the prepared microcapsules were found satisfactory. Moreover, the mortar samples containing calcium nitrate refined microcapsules that were prepared using the proposed method did not experience significant reduction in their mechanical properties. Hence, such encapsulation procedure may be adopted for further investigation of the self-healing efficiency in cementitious materials of the microcapsules prepared using the proposed procedure. Future work shall be directed towards this end. Full article

Capsules with shells based on nanoparticles of different nature co-assembled at the interface of liquid phases of emulsion are promising carriers of lipophilic drugs. To obtain such capsules, theoretically using the Derjaguin–Landau–Verwey–Overbeek (DLVO) theory and experimentally using dynamic light-scattering (DLS) and transmission electron microscopy (TEM) methods, the interaction of like-charged silica nanoparticles and detonation nanodiamonds in an aqueous solution was studied and their ratios selected for the formation of submicron-sized colloidosomes. The resulting colloidosomes were modified with additional layers of nanoparticles and polyelectrolytes, applying LbL technology. As a model anti-cancer drug, thymoquinone was loaded into the developed capsules, demonstrating a significant delay of the release as a result of colloidosome surface modification. Fluorescence flow cytometry and confocal laser scanning microscopy showed efficient internalization of the capsules by MCF7 cancer cells. The obtained results demonstrated a high potential for nanomedicine application in the field of the drug-delivery system development. Full article

Taste is the most crucial organoleptic parameter affecting patient compliance in the case of drugs with poor palatability. Taste masking is a major challenge for the development of orally ingested active pharmaceutical constituents in the pharmaceutical industry. Numerous conventional taste-masking techniques have been extensively studied. In parallel, affecting the drug solubility or release is a major concern of conventional taste-masking techniques. Recently, many nanocarrier systems have been introduced, claiming the advantage of effective taste masking without affecting either the drug solubility or its release. In this review, we will present new techniques for taste masking, including taste-masking techniques utilizing nanocarrier systems such as liposomes, polymeric and solid lipid nanoparticles, polymeric micelles, submicron lipid emulsions, and nanogels. We will chiefly highlight the composition of these systems and their applications in designing oral therapeutic delivery systems successful in masking the taste of bitter molecules. Full article

Emulsification-diffusion method is often used to produce polymeric nanoparticles. However, their numerous and/or lengthy steps make it difficult to use widely. Thus, a modified method using solvent blends (miscible/partially miscible in water, 25–100%) as the organic phases to overcome these disadvantages and its design space were investigated. To further simplify the process, no organic/aqueous phase saturation and no water addition after the emulsification step were performed. Biodegradable (PLGA) or pH-sensitive (Eudragit^® E100) nanoparticles were robustly produced using low/medium shear stirring adding dropwise the organic phase into the aqueous phase or vice versa. Several behaviors were also obtained: lowering the partially water-miscible solvent ratio relative to the organic phase or the poloxamer-407 concentration; or increasing the organic phase polarity or the polyvinyl alcohol concentration produced smaller particle sizes/polydispersity. Nanoparticle zeta potential increased as the water-miscible solvent ratio increased. Poloxamer-407 showed better performance to decrease the particle size (~50 nm) at low concentrations (≤1%, w/v) compared with polyvinyl alcohol at 1–5% (w/v), but higher concentrations produced bigger particles/polydispersity (≥600 nm). Most important, an inverse linear correlation to predict the particle size by determining the solubility parameter was found. A rapid method to broadly prepare nanoparticles using straightforward equipment is provided. Full article

In this work, polymerizations of styrene (St) in the presence of divinylbenzene (DVB) as a crosslinking agent and sodium 4-vinylbenzenesulfonate (VBS) have been performed in Pickering emulsions, using silica nanoparticles (SNps) as stabilizing agents and ammonium persulfate as a hydrophilic initiator. In oil-in-water Pickering emulsions with alkaline continuous phase (pH = 9) at 1, 2, and 3 wt% DVB (relative to St), polydisperse spheroid copolymer submicronic nanoparticles were obtained. Comparatively, polymerizations performed in Pickering emulsions with acidic continuous phase (pH = 5) allowed preparing St-co-DVB microspheres with core–shell structures at 1 wt% DVB and St-co-DVB hybrid monoliths with bi-continuous morphologies at 2 and 3 wt% DVB. It is noteworthy that this work reports Pickering emulsion polymerization as a new strategy for preparing hybrid percolated scaffolds with bi-continuous porosity. The proposed mechanisms originated by pH, DVB, and VBS and the drastic impact caused on the final morphology obtained, either hybrid particles or monoliths, are discussed herein. Full article

Microfluidization is a preparation method that can be used to obtain emulsions with submicron droplet sizes. The first objective of this study was to evaluate the influence of homogenization pressure and cycles on droplet sizes using response surface methodology. Secondly, the influence of the diutan gum concentration incorporated in the optimized emulsion on rheological properties, microstructure, and physical stability was investigated. Taking the response surface analysis into account, the emulsion processed at 20,000 psi after four cycles seemed to show the smallest Sauter diameter values. Hence, this emulsion was the starting point to incorporate diutan gum. Interestingly, the formation of a 3D network in the emulsion, observed by FESEM, was provoked by diutan gum. The emulsion formulated with 0.4 wt.% of diutan gum presented rheological gel properties and enhanced physical stability. This work highlights the importance of selecting optimized processing variables using the microfluidization technique and extends the knowledge of using diutan gum in combination with zein. Full article

Phase-change materials (PCM) play off their advantages over conventional heat storage media when used within narrow temperature ranges. Many cooling and temperature buffering applications, such as cold storage and battery cooling, are operated within small temperature differences, and therefore, they are well-suited for the application of these promising materials. In this study, the storage capacities of different phase-change material emulsions are analysed under consideration of the phase transition behaviour and supercooling effect, which are caused by the submicron size scale of the PCM particles in the emulsion. For comparison reasons, the same formulation for the emulsions was used to emulsify 35 wt.% of different paraffins with different purities and melting temperatures between 16 and 40 °C. Enthalpy curves based on differential scanning calorimeter (DSC) measurements are used to calculate the storage capacities within the characteristic and defined temperatures. The enthalpy differences for the emulsions, including the first phase transition, are in a range between 69 and 96 kJ/kg within temperature differences between 6.5 and 10 K. This led to an increase of the storage capacity by a factor of 2–2.7 in comparison to water operated within the same temperature intervals. The study also shows that purer paraffins, which have a much higher enthalpy than blends, reveal, in some cases, a lower increase of the storage capacity in the comparison due to unfavourable crystallisation behaviour when emulsified. In a second analysis, the stability of emulsions was investigated by applying 100 thermal cycles with defined mechanical stress at the same time. An analysis of the viscosity, particle size and melting crystallisation behaviour was done by showing the changes in each property due to the cycling. Full article