Uniform Droplet Size Research Articles

Fabrication and characterization of Zanthoxylum schinifolium essential oil Pickering emulsion stabilized by bacterial cellulose nanofibrils/whey protein isolate complexes and fortified with cinnamaldehyde

The inherent hydrophobicity, high volatility, instability and pungent flavor of Zanthoxylum schinifolium essential oil (ZSEO) are important issues to restrict its preservation and practical applications. To overcome these drawbacks, the ZSEO-loaded Pickering emulsions stabilized by bacterial cellulose nanofibrils/whey protein isolate (BCNFs/WPI) complexes and fortified with cinnamaldehyde (CA) were fabricated, and their physical property and functionality were characterized. When the concentration of BCNFs/WPI complexes was 0.7 wt%, the emulsions had the smallest and uniform droplet size (<150 nm) and showed good stability over 30 d storage. Moreover, the emulsions with different CA contents (0–1.0 wt%) maintained a long-term stability with no significant droplet size change during 30 d storage. All Pickering emulsions showed a shear-thinning behavior, and their apparent viscosity and viscoelastic moduli gradually increased with the increase of BCNFs/WPI complexes contents. The presence of CA enhanced the physical stability of emulsions against environmental stresses such as acid, heat and salinity. Compared to free ZSEO, the ZSEO-loaded Pickering emulsions fortified with CA not only improved the stability of ZSEO, but also maintained or even enhanced its antioxidant and antimicrobial activity. This study would provide a promising strategy for ZSEO encapsulation and improve its stability and functionality in food applications.

On the effect of axial inlet angle on the droplet size distribution and mixing uniformity for swirl jet mixer at high phase ratios

The “short pass” problem of liquid-liquid two-phase mixing at high phase ratios limited the development and applications of jet mixer in industrial process. In this study, the effect of the axial inlet angle on the mixing characteristics of a swirl jet mixer was investigated through laser particle size analysis and computational fluid mechanics (CFD) coupled with population balance model (PBM). The result was shown that as the axial inlet angle increased, the dispersed phase droplet sizes decreased, and the droplet size distribution was widened for the fixed mixer configuration. At Re ≤ 3.000×104, tangential inlet was more conducive to improving mixing uniformity. Conversely, the axial inlet angle of 90° was optimal at Re ≥ 3.750×104. Numerical simulations revealed that the tangential inlet effectively intensified liquid-liquid interactions, including streamlines extension, increased vorticity, improved droplet size uniformity. Additionally, the increase of the axial inlet angle resulted in increased turbulence stress and shortened decay period, the reduction in droplet size, and a wide droplet size distribution. The research findings can serve as theoretical basis for the hydraulic design and promoted applications of swirl jet mixers.

Pickering Emulsion of Oleoresin from Dipterocarpus alatus Roxb. ex G. Don and Its Antiproliferation in Colon (HCT116) and Liver (HepG2) Cancer Cells.

Oleoresin of Dipterocarpus alatus Roxb. ex G. Don (DA) has been traditionally used for local medicinal applications. Several in vitro studies have indicated its pharmacological potential. However, the low water solubility hinders its use and development for pharmaceutical purposes. The study aimed to (1) formulate oil-in-water (o/w) Pickering emulsions of DA oleoresin and (2) demonstrate its activities in cancer cells. The Pickering emulsions were formulated using biocompatible carboxylated cellulose nanocrystal (cCNC) as an emulsifier. The optimized emulsion comprised 3% (F1) and 4% (v/v) (F2) of oleoresin in 1% cCNC and 0.1 M NaCl, which possessed homogeneity and physical stability compared with other formulations with uniform droplet size and low viscosity. The constituent analysis indicated the presence of the biomarker dipterocarpol in both F1 and F2. The pharmacological effects of the two emulsions were demonstrated in vitro against two cancer cell lines, HepG2 and HCT116. Both F1 and F2 suppressed cancer cell viability. The treated cells underwent apoptosis, as demonstrated by distinct nuclear morphological changes in DAPI-stained cells and Annexin V/PI-stained cells detected by flow cytometry. Our study highlights the prospect of Pickering emulsions for oleoresin, emphasizing enhanced stability and potential pharmacological advantages.

Synergistic collaborations between surfactant and polymer for in-situ emulsification and mobility control to enhance heavy oil recovery

Surfactant-polymer (SP) combined systems is an effective nonthermal method to enhance the heavy oil recovery, through in-situ emulsification and mobility control mechanisms. In this study, a novel SP system was developed using 0.2 wt% anionic surfactant (alkyl naphthol polyoxyethylene ether sulfonate, ANES) and 0.1 wt% polymer (partially hydrolyzed polyacrylamide, HPAM). The SP system had viscosity reduction rate of ∼ 98 %, viscosity ratio of oil to displaced water (μo/μd) of ∼ 3.95 and IFT of ∼ 0.29 mN/m, beneficial for decreasing the mobility ratio of water to heavy oil. Then, the applied performances including emulsion morphologies and stability, wettability alteration ability were systematically characterized. The results showed that the freshly O/W emulsions formed by SP system displayed uniform droplet size distribution, as well as high stability with tight interfacial film. In addition, the SP system exhibited excellent wettability alteration property with low contact angle of 18.3°. The synergistic collaboration mechanisms of surfactant and polymer include heavy oil–water interfacial tension reduction, in-situ emulsification, oil-viscosity reduction and water-viscosity increase. Finally, the static oil washing and dynamic sand-pack flooding experiments showed that the SP system exhibited high oil washing efficiency (62.89 %) and enhanced oil recovery efficiency (56.9 %) with improving the mobility controllability after the primary water-flooding process. This study indicated that the synergistic collaborations between surfactant and polymer had great potential to enhance the heavy oil recovery.

Tailored surface wettability and pore structure of hydrophobic SiO2/SiC membranes for preparing monodisperse emulsion with high-efficiency

The combustion efficiency of diesel can be significantly improved in the form of emulsion, contributing to the reduced emission of nitrogen oxides. It is thus worthwhile to develop an energy-efficient way to prepare stable diesel emulsions with uniform droplet size. Ceramic membranes with hydrophobic surface are highly desirable for high-efficient membrane emulsification process. We proposed a novel and straightforward approach of immersing silicon carbide (SiC) membrane into hydrophobic silica solutions obtained by co-hydrolysis to tailoring hydrophobic SiO2/SiC membranes. The effects of methyltriethoxysilane addition and aging days on the hydrophobicity of these silica particles were systematically investigated. Then, the deposition of silica particles on the SiC substrates was further controlled by regulating the dipping duration and dipping times. The membranes (M2-SiO2/SiC) prepared with 240 s and dipping 4 times showed an increased contact angle (136°), mean pore size of 0.4 μm, open porosity of 30 %, and pure water permeance of ∼ 1500 L·m−2·h−1·bar−1. Moreover, the modified membranes were demonstrated to be mechanically stable. Furthermore, monodisperse diesel emulsions with an average droplet size of 2.1 μm and droplet size distribution of 0.61 can be generated by using the optimized M2-SiO2/SiC membranes at high emulsifying flux (1910 L·m−2·h−1). This work proposed an efficient strategy to simultaneously optimize the surface wettability and pore structure of ceramic membranes, satisfactorily for membrane emulsification applications with high efficiency.

Enhancing Bone Cement Efficacy with Hydrogel Beads Synthesized by Droplet Microfluidics

Effective filling materials, typically bone cements, are essential for providing mechanical support during bone fracture treatment. A current challenge with bone cement lies in achieving continuous drug release and forming porous structures that facilitate cell migration and enhance osteoconductivity. We report a droplet microfluidics-based method for synthesizing uniform-sized gelatin hydrogel beads. A high hydrogel concentration and increased crosslinking levels were found to enhance drug loading as well as release performance. Consequently, the droplet microfluidic device was optimized in its design and fabrication to enable the stable generation of uniform-sized droplets from high-viscosity gelatin solutions. The size of the generated beads can be selectively controlled from 50 to 300 μm, featuring a high antibiotic loading capacity of up to 43% dry weight. They achieve continuous drug release lasting more than 300 h, ensuring sustained microbial inhibition with minimal cytotoxicity. Furthermore, the hydrogel beads are well suited for integration with calcium phosphate cement, maintaining structural integrity to form porous matrices and improve continuous drug release performance. The uniform size distribution of the beads, achieved through droplet microfluidic synthesis, ensures predictable drug release dynamics and a measurable impact on the mechanical properties of bone cements, positioning this technology as a promising enhancement to bone cement materials.

Parameter control, characterization and stability of soy protein emulsion prepared by microfluidic technology.

A flow-focusing microfluidic device driven by pressure was employed in soy protein emulsions with uniform droplet size and good morphology. The results suggested that pressure was an essential factor for droplet formation. The optimum parameter was at a continuous phase pressure of 140mbar and dispersed phase pressure of 80mbar. Under this condition, the droplet formation time was shortened to 0.20s, with average sizes of 39-43μm and coefficient of variation of about 2%. Emulsion stability was improved with increasing soy protein isolate (SPI) concentrations. At SPI concentrations higher than 20mg/mL, the emulsions exhibited improved stability against changes in temperature, pH and salt concentration. Emulsions prepared in this manner exhibited superior oxidative stability than those prepared by conventional methods utilizing homogenizers. This study showed that microfluidic technology can be applied to soy protein emulsions as an effective tool for preparing droplets with uniform size and enhanced stability.

Structure and surface properties of ozone-conjugated octenyl succinic anhydride modified waxy rice starch: Towards high-stable Pickering emulsion

In the present work, a dual-modified waxy rice starch (OOWRS) fabricated with OSA and ozone was successfully used to stabilize the O/W Pickering emulsion. The molecular structure, surface properties, and underlying stabilizing mechanism were systematically investigated. The results showed that oxidation occurring on the surface of OSA-modified waxy rice starch (OSAWRS) resulted in the presence of indentations and cracks. The relative crystallinity of starch was generally decreased with increasing degree of oxidation. Due to the introduction of carbonyl and the variation in surface structure, the hydrophobicity and acidity of OSAWRS were significantly enhanced after the ozone treatment. Remarkably, OOWRS stabilized Pickering emulsion exhibited a feature of typical O/W emulsion, and the 0.5 h and 1 h OOWRS emulsion exhibited a more uniform droplet size as well as a higher surface potential. We also noted that a weak-gel network was formed within the OOWRS emulsion system as the hydrophilic starch chains played a bridging role. Two reasons for the improved stability of the emulsion were the special gel structure and the enhanced electrical repulsion among the droplets. This research provides that ozone-conjugated OSA modification is a promising strategy for improving the emulsion ability of starch-based Pickering emulsions.

Atomization of High Viscous Liquids Using a MEMS Vibrating Mesh With Integrated Microheater

Aerosol generation is important for a wide range of applications including drug delivery, additive manufacturing, spray cooling, and numerous other applications. However, current aerosol generation devices often have poor droplet uniformity or are limited to low viscosity liquids ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$&lt;$</tex-math> </inline-formula> 2 cp). This work presents the development of a Microelectromechanical systems vibrating mesh atomizer capable of atomizing higher viscosity fluids while maintaining high droplet size uniformity. The overall system consists of microfabricated silicon vibrating mesh atomizer, a piezoelectric film, and a flexible thin film microheater. The Si vibrating mesh atomizer was designed to increase atomization thresholds, while the microheater is designed to reduce liquid viscosity to meet the atomization threshold. Atomizers with varying nozzle dimensions were experimentally validated using liquids with varying viscosity and physiochemical properties, such as water, glycerol, propylene glycol, and vegetable glycerin. The microheater was designed to provide local rapid heating with low power consumption of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$&lt;$</tex-math> </inline-formula> 1 W. The droplet size distribution results show that when fluid viscosity increases, the volume median diameter of droplets increases, and the spray angle decreases. The Si-vibrating mesh atomizer was able to atomize liquids up to 49.73 cP at room temperature compared to normal metallic vibrating mesh atomizers which have a threshold of approximately 2 cP. The integrated heater enabled atomization of liquids with viscosities as high as 111 cP with low heating ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$&lt;$</tex-math> </inline-formula> 100 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{\circ}$</tex-math> </inline-formula> C). 2023-0042

Numerical simulation of the effect of a wind-assisted spraying device during continuous mining

The continuous mining face is the main dust-producing area in a coal mine. The dust produced endangers the physical and mental health of underground workers and increases their risk of pneumoconiosis. To improve the lack of spraying in the middle part of the continuous mining machine and the poor dust reduction effect, we developed a wind-assisted spraying device placed in the middle of the continuous mining machine. Spraying experiments have shown that a round nozzle with a 2.4-mm aperture containing an X-shaped guide core has a longer effective range and wider atomization angle. Numerical simulations have shown that when the spray pressure is 7 MPa, a dust reduction spray field with uniform droplet size distribution can be formed. After applying the spray parameters obtained in the coal mine field and using the dust removal device, the total dust concentration in the driver's area of the continuous mining machine was significantly reduced.

Gas-assisted microfluidic step-emulsification for generating micron- and submicron-sized droplets

Micron- and submicron-sized droplets have extensive applications in biomedical diagnosis and drug delivery. Moreover, accurate high-throughput analysis requires a uniform droplet size distribution and high production rates. Although the previously reported microfluidic coflow step-emulsification method can be used to generate highly monodispersed droplets, the droplet diameter (d) is constrained by the microchannel height (b), dgtrsim 3b, while the production rate is limited by the maximum capillary number of the step-emulsification regime, impeding emulsification of highly viscous liquids. In this paper, we report a novel, gas-assisted coflow step-emulsification method, where air serves as the innermost phase of a precursor hollow-core air/oil/water emulsion. Air gradually diffuses out, producing oil droplets. The size of the hollow-core droplets and the ultrathin oil layer thickness both follow the scaling laws of triphasic step-emulsification. The minimal droplet size attains dapprox 1.7b, inaccessible in standard all-liquid biphasic step-emulsification. The production rate per single channel is an order-of-magnitude higher than that in the standard all-liquid biphasic step-emulsification and is also superior to alternative emulsification methods. Due to low gas viscosity, the method can also be used to generate micron- and submicron-sized droplets of high-viscosity fluids, while the inert nature of the auxiliary gas offers high versatility.

Creating liquid crystal microdroplet arrays for multiplexed sensing by spatially-controlled molecular patterning

In this study, we presented a spatially-controlled molecular patterning technique to prepare liquid crystal (LC) microdroplet arrays on glass substrates. This technique utilizes an oxygen plasma activated PDMS stamp to remove the pre-coated dimethyloctadecyl 3-(trimethoxysilyl) propyl ammonium chloride (DMOAP) molecules from glass substrates, producing a surface with complementary patterns and specific hydrophobicity. When LC molecules are introduced onto this produced molecular pattern, a LC microdroplet array with uniform droplet size and positional order is formed. By using the LC microdroplet array doped with a Hg2+ selective ligand, the lowest detectable concentration of Hg2+ is 200-fold lower than that of conventional LC-based sensors. In addition, multiplexed detection of Hg2+, Al3+, Fe3+ and pH value in real water samples with a high recovery rate (∼100%) was demonstrated by using the LC microdroplet arrays doped with different molecular probes. Due to the specific arrangement of the LC microdroplet arrays, the collected optical signal of LC microarrays can be transformed into numerical symbols. The developed spatially controlled molecular patterning technique could be used to prepare highly uniform LC microdroplet arrays with consistent optical signals, providing a simple method to prepare the LC-based sensing platforms with improved sensing performance.

Novel multilayer chitosan/emulsion-loaded syringic acid grafted apple pectin film with sustained control release for active food packaging

The clove essential oil (EO) emulsions were prepared using syringic acid grafted apple pectin (SAAP) and soy protein isolate (SPI). This emulsion was used to improve properties of pullulan film (inner layer), which can be used for active packaging. Furthermore, chitosan was employed as the outer layer of the multilayer film prepared to address the limitations of existing pullulan films. Mechanical, optical, and functional properties of multilayer films were determined. The emulsions produced by SAAP display better emulsifying properties, smaller and uniform droplet size distribution. In comparison with AP-SPI-Pul, water vapor and oxygen permeabilities of SAAP-SPI-Pul were lower, while antioxidant, antimicrobial properties and barrier properties to UV were improved. Chitosan film can be used as the outer layer to modify the hydrophilicity/hydrophobicity of films with water contact angle of 98.4°. SAAP-SPI-Pul-Chit film has characteristics of high-performance films with favorable optical and mechanical properties. Furthermore, antioxidant and antimicrobial properties, as well as fruit preservation properties of the SAAP-SPI-Pul-Chit films were strengthened, which is attributed to the sustained release of clove EO in films.

Research on the Preparation of Self-nano-emulsifying Drug Delivery System Containing Gynostemma pentaphyllum Dry Extract for Application in Skin Care Cosmetics

Abstract: Gynostemma pentaphyllum (Thunb.) Makino is a rich source of the herb in Vietnam. The gypenosides in this herb are triterpenoid saponins that have been shown to have moisturizing, antioxidant, and anti-aging effects on the skin. However, gypenosides are hydrophilic and have a large molecular weight with a bulk molecular structure which prevents them from penetrating and absorbing into the skin. To apply the natural active ingredients from herbs into skin care cosmetics, this research developed self-nano-emulsifying drug delivery systems (SNEDDS) containing Gynostemma pentaphyllum dry extract and applied them to emulgel skin care cosmetics. Prepared SNEDDS could self-emulsify in the water to form nanoemulsions with dispersed droplet sizes less than 20 nm with PDI &lt; 0.3. The proportion of saponin entrapped in the oil droplets of nano emulsification was more than 90%. When combined with emulgel excipients, the obtained cosmetic products had nano-sized dispersed droplets less than 200 nm with uniform droplet size distribution, which are promising for application when further research is carried out.&#x0D; Keywords: Self-nano-emulsifying Drug Delivery System (SNEDDS), Gymnostemma pentaphyllum dry extract, cosmetic, emulgel, nano-emulsion.&#x0D; &#x0D; &#x0D;

Atomization characteristics of different water/heavy fuel oil emulsions in a pressure-swirl injector

In the present study, different water in heavy fuel oil (HFO) emulsion fuels containing 5, 10, 15% water content have been prepared under ultrasound irradiation without surfactant. The stability of the prepared emulsion fuels has been investigated. The best stability was observed for the emulsion fuel containing 5% water (E5) due to its more uniform water droplet size distribution. Then, the atomization behavior and spray characteristics of the emulsion fuels have been investigated in a pressure-swirl injector using a high speed camera. The examined ranges for temperature and pressure were (60–110 °C), and (10–25 bar), respectively. The breakup length for each fuel sample in each operating condition was calculated through the image processing analysis. It was found that the micro explosion phenomena associated with the evaporation of the water droplets in the fuels has the most impact on the emulsion fuel spray characteristics. The best atomization performance was observed for E5 considering all examined fuel samples. A 68% decrease in the breakup length was observed for E5 compared to the neat HFO at 90 °C and 15 bar.

Ultrasonic surface acoustic wave-assisted separation of microscale droplets with varying acoustic impedance.

In droplet-based microfluidic platforms, precise separation of microscale droplets of different chemical composition is increasingly necessary for high-throughput combinatorial chemistry in drug discovery and screening assays. A variety of droplet sorting methods have been proposed, in which droplets of the same kind are translocated. However, there has been relatively less effort in developing techniques to separate the uniform-sized droplets of different chemical composition. Most of the previous droplet sorting or separation techniques either rely on the droplet size for the separation marker or adopt on-demand application of a force field for the droplet sorting or separation. The existing droplet microfluidic separation techniques based on the in-droplet chemical composition are still in infancy because of the technical difficulties. In this study, we propose an acoustofluidic method to simultaneously separate microscale droplets of the same volume and dissimilar acoustic impedance using ultrasonic surface acoustic wave (SAW)-induced acoustic radiation force (ARF). For extensive investigation on the SAW-induced ARF acting on both cylindrical and spherical droplets, we first performed a set of the droplet sorting experiments under varying conditions of acoustic impedance of the dispersed phase fluid, droplet velocity, and wave amplitude. Moreover, for elucidation of the underlying physics, a new dimensionless number ARD was introduced, which was defined as the ratio of the ARF to the drag force acting on the droplets. The experimental results were comparatively analyzed by using a ray acoustics approach and found to be in good agreement with the theoretical estimation. Based on the findings, we successfully demonstrated the simultaneous separation of uniform-sized droplets of the different acoustic impedance under continuous application of the acoustic field in a label-free and detection-free manner. Insomuch as on-chip, precise separation of multiple kinds of droplets is critical in many droplet microfluidic applications, the proposed acoustofluidic approach will provide new prospects for microscale droplet separation.

Novel atomizer concept for CCS applications: Impinging effervescent atomizer

The concept design, testing of spray characteristics, and performance comparison of an original type of atomizer, the impinging effervescent atomizer (IEA), are introduced in this study. The liquid impinging is beneficially deployed in plain-orifice and external mixing twin fluid atomizers. IEA uses a collision of two or more effervescent liquid streams to improve the atomization and alter the spray characteristics. The Phase Doppler Anemometry (PDA) measurement technique and high-speed visualization of the liquid discharge and spray structure were used. The discharge coefficient (Cd), atomization efficiency (ηa), spray characteristics as a spray cone angle (SCA), integral Sauter mean diameter (ISMD), integral relative span factor (IRSF), and droplet size and velocity distribution inside the spray were investigated. The correlations for Cd, SCA, ISMD and IRSF are provided for a fast and reliable atomizer design to fit any application and operating conditions. The IEA provides a controllable SCA governed mainly by the exit orifice geometry. The ISMD is primarily controlled by the gas to liquid ratio (GLR) and the inlet pressure (pin). The impinging angle (β) has little effect on ISMD. A narrower droplet size distribution, mass redistribution within the spray, and a more uniform droplet size spatial distribution were observed for the IEA in comparison to other tested atomizers. The IEA spray covers 116% more area than single-orifice effervescent sprays, and the area coverage can be controlled by β. This coverage increases by 177% if β changes from 15 to 45°. Spray eccentricity (e) decreases with the increase of the number of the exit orifices (No) resulting in a more uniform droplet spatial distribution. The β, GLR and pin have no effect on e. The ηa of the IEA is equivalent to other internally mixing twin-fluid atomizers; the atomization air contains more than 90% of the delivered energy. The favourable IEA spray characteristics, such as IRSF, ISMD, spray coverage, SCA and ηa, enable the potential use of IEA in mass-transfer related processes and especially in CO2 capture columns.

Effects of octenyl succinylation on the properties of starches with distinct crystalline types and their Pickering emulsions

Effects of octenylsuccinic anhydride (OSA) esterification on the morphology, crystalline structure, and emulsifying properties of three representative starches with different crystalline types, namely waxy corn starch (A-type), potato starch (B-type), and pea starch (C-type) were investigated. XRD patterns testified OSA substitution occurred principally in the amorphous region without affecting the crystalline patterns, whereas SEM verified esterification was mainly a surface phenomenon. However, OSA esterification caused a decrease in the peak intensity and area of small-angle X-ray scattering profiles, indicating the semi-crystalline lamellae ordering was impeded to a certain extent. Compared with A- and C-type starches, B-type starch had a stronger affinity for OSA, as manifested by its higher degree of substitution (DS), graver surface detriment, and depressed order of semi-crystalline lamellae. The emulsifying properties of all starches were pronouncedly improved by OSA modification, especially for A-type starch even with comparatively lower DS. Pickering emulsion stabilized by OSA-modified A-type starch (A-OSAS) with smaller droplet size and more uniform droplet size distribution exhibited more splendiferous stability relative to the other two modified starches. Moreover, rheological tests revealed A-OSAS possessed the highest apparent viscosity and storage modulus (G′), insinuating strong intermolecular interactions between starch granules at the interface and/or in the continuous phase.

Mammalian cell encapsulation in monodisperse chitosan beads using microchannel emulsification

Microchannel emulsification can produce droplets of uniform size at high throughput for wide-ranging applications in the food and drug industry. Mammalian cell encapsulation using emulsion-based systems is of significant interest for immobilized culture or transplantation applications. Microchannel emulsification has recently been applied to mammalian cell encapsulation using alginate. Here, we extend this approach to thermoresponsive hydrogels using chitosan as a model. The performance of the microchannel emulsification process was compared to a previously established stirred emulsification method for mesenchymal stromal cell encapsulation. Chitosan microbeads with controlled sizes ranging from 600 µm to 1500 µm in diameter at a coefficient of variation less than 10 % were obtained after adapting the microchannel system design, channel geometries and operating parameters that affect the capillary number. In a single pass through a 21 G syringe needle, the fraction of ruptured beads was significantly reduced for monodisperse microchannel-generated vs polydisperse stirred emulsion-generated beads of matching De Brouckere mean diameter. The viability of the immobilized cells immediately after the process was 95 % ± 2 % and no significant difference in cell survival and growth factor secretion was observed between microchannel and stirred emulsion-generated beads over 3 days of culture. Microchannel emulsification is a promising and scalable approach to microencapsulate mammalian cells in hydrogels that undergo temperature-dependent gelation.

Structural Characteristics and Emulsifying Properties of Soy Protein Isolate Glycated with Galacto-Oligosaccharides under High-Pressure Homogenization.

This study explored the Maillard reaction process during the glycation of soy protein isolate (SPI) with galacto-oligosaccharides (GOSs) under high-pressure homogenization (HPH) and its effects on the emulsifying properties of SPI. SPI-GOS glycation under moderate pressure (80 MPa) significantly inhibited the occurrence and extent of the Maillard reaction (p < 0.05), but homogenization pressures in the range of 80−140 MPa gradually promoted this reaction. HPH caused a decrease in the surface hydrophobicity of the glycated protein, an increase in the abundance of free sulfhydryl groups, unfolding of the protein molecular structure, and the formation of new covalent bonds (C=O, C=N). Additionally, the particle size of emulsions created with SPI-GOS conjugates was reduced under HPH, thus improving the emulsifying properties of SPI. A reduction in particle size (117 nm), enhanced zeta potential (−23 mV), and uniform droplet size were observed for the emulsion created with the SPI-GOS conjugate prepared at 120 MPa. The conformational changes in the glycated protein supported the improved emulsification function. All results were significantly different (p < 0.05). The study findings indicate that HPH provides a potential method for controlling glycation and improving the emulsifying properties of SPI.