Fabrication of Microparticles with Front–Back Asymmetric Shapes Using Anisotropic Gelation

Droplet-based microfluidics is a powerful tool for producing monodispersed micrometer-sized droplets with controlled sizes and shapes; thus, it has been widely applied in diverse fields from fundamental science to industries. Toward a simpler method for fabricating microparticles with front–back asymmetry in their shapes, we studied anisotropic gelation of alginate droplets, which occurs inside a flow-focusing microfluidic device. In the proposed method, sodium alginate (NaAlg) aqueous phase fused with a calcium chloride (CaCl2) emulsion dispersed in the organic phase just before the aqueous phase breaks up into the droplets. The fused droplet with a front–back asymmetric shape was generated, and the asymmetric shape was kept after geometrical confinement by a narrow microchannel was removed. The shape of the fused droplet depended on the size of prefused NaAlg aqueous phase and a CaCl2 emulsion, and the front–back asymmetry appeared in the case of the smaller emulsion size. The analysis of the velocity field inside and around the droplet revealed that the stagnation point at the tip of the aqueous phase also played an important role. The proposed mechanism will be potentially applicable as a novel fabrication technique of microparticles with asymmetric shapes.

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Preparation and properties of wet-spun microcomposite filaments from cellulose nanocrystals and alginate using a microfluidic device

BioResources ◽

10.15376/biores.16.3.5780-5793 ◽

2021 ◽

Vol 16 (3) ◽

pp. 5780-5793

Author(s):

Ji-Soo Park ◽

Chan-Woo Park ◽

Song-Yi Han ◽

Eun-Ah Lee ◽

Azelia Wulan Cindradewi ◽

...

Keyword(s):

Tensile Properties ◽

Sodium Alginate ◽

Calcium Chloride ◽

Microfluidic Device ◽

Cellulose Nanocrystals ◽

Average Diameter ◽

Coagulation Bath ◽

Al Content ◽

Orientation Index ◽

Cacl2 Solution

Cellulose nanocrystals (CNCs) were wet-spun in a coagulation bath for the fabrication of microfilaments, and the effect of sodium alginate (AL) addition on the wet-spinnability and properties of the microcomposite filament was investigated. The CNC suspension exhibited excellent wet-spinnability in calcium chloride (CaCl2) solution, and the addition of AL in CNC suspension resulted in the enhancement of the wet-spinnability of CNCs. As the AL content increased from 3% to 10%, the average diameter of the microcomposite filament decreased, and its tensile properties deteriorated. The increased spinning rate caused an increase in the orientation index of CNCs, resulting in an improvement in the tensile properties of the microcomposite filament.

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Application of Axiomatic Design Theory to a Microfluidic Device for the Production of Uniform Water-in-Oil Microspheres Adapting an Integration Method

Journal of Manufacturing Science and Engineering ◽

10.1115/1.4006771 ◽

2012 ◽

Vol 134 (4) ◽

Cited By ~ 2

Author(s):

Ki-Young Song ◽

Wen-Jun Zhang ◽

Madan M. Gupta

Keyword(s):

Aqueous Phase ◽

Microfluidic Device ◽

Design Theory ◽

Low Cost ◽

Applied Pressure ◽

Axiomatic Design ◽

Immiscible Fluids ◽

Hydrodynamic Flow ◽

Flow Focusing ◽

Axiomatic Design Theory

This work describes a novel microfluidic method to generate uniform water-in-oil (W/O) microspheres using the phase separation technique. Axiomatic design theory (ADT) was employed for the conceptual design of microchannel systems, and ADT verified that the proposed microfluidic system is a decoupled design. The integration of hydrodynamic flow focusing method and crossflow method is realized in a microfluidic device with oil phase and aqueous phase. The immiscible fluids are fed by continuous air pressure. By the hydrodynamic flow focusing method, the width of the dispersed focused aqueous phase is controlled. The focused flow enters T-junction geometry downstream, and the crossflow interferes with the focused flow. By varying the applied pressure to the crossflow, the W/O microspheres are formed at the T-junction. Based on this approach, the size of the W/O microspheres can be successfully controlled from 16 μm to 35 μm in diameter within about 5% of variation. The present method has advantages such as good sphericity, few satellite droplets, active control of the microsphere diameter, and high throughput with the simple and low cost process. To achieve the promising results, this integrating method reveals high potential for production of polymer based microspheres.

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Extraction of hafnium(IV) with organophosphorus reagents from solutions of mineral acids mixtures

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19793656 ◽

1979 ◽

Vol 44 (12) ◽

pp. 3656-3664

Author(s):

Oldřich Navrátil ◽

Jiří Smola ◽

Rostislav Kolouch

Keyword(s):

Ionic Strength ◽

Aqueous Phase ◽

Organic Phase ◽

Perchloric Acid ◽

Synergic Effect ◽

Salting Out ◽

Initial Concentration ◽

Mixed Complexes ◽

Synergic Extraction ◽

Mineral Acids

Extraction of hafnium(IV) was studied from solutions of mixtures of perchloric and nitric acids and of perchloric and hydrochloric acids for constant ionic strength, I = 2, 4, 6, or 8, and for cHf 4 . 10-4 mol l-1. The organic phase was constituted by solutions of some acidic or neutral organophosphorus reagents or of 2-thenoyltrifluoroacetone, 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone, or N-benzoyl-N-phenylhydroxylamine in benzene, chloroform, or n-octane. A pronounced synergic extraction of hafnium proceeds only on applying organophosphorus reagents from an aqueous phase whose acidity is not lower than 3M-(HClO4 + HNO3) or 5M-(HClO4 + HCl). The synergic effect was not affected markedly by a variation of the initial concentration of hafnium in the range 1 . 10-8 -4 .10-4 mol l-1, it lowered with increasing initial concentration of the organophosphorus reagent and decreasing concentration of the H+ ions. It is suggested that the hafnium passes into the organic phase in the form of mixed complexes, the salting-out effect of perchloric acid playing an appreciable part.

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Negative Pressure Provides Simple and Stable Droplet Generation in a Flow-Focusing Microfluidic Device

Micromachines ◽

10.3390/mi12060662 ◽

2021 ◽

Vol 12 (6) ◽

pp. 662

Author(s):

Nikita A. Filatov ◽

Anatoly A. Evstrapov ◽

Anton S. Bukatin

Keyword(s):

Microfluidic Device ◽

Negative Pressure ◽

Low Cost ◽

Control Valve ◽

Droplet Microfluidics ◽

Droplet Generation ◽

Electric Signal ◽

Absolute Pressure ◽

Flow Focusing ◽

Wide Range

Droplet microfluidics is an extremely useful and powerful tool for industrial, environmental, and biotechnological applications, due to advantages such as the small volume of reagents required, ultrahigh-throughput, precise control, and independent manipulations of each droplet. For the generation of monodisperse water-in-oil droplets, usually T-junction and flow-focusing microfluidic devices connected to syringe pumps or pressure controllers are used. Here, we investigated droplet-generation regimes in a flow-focusing microfluidic device induced by the negative pressure in the outlet reservoir, generated by a low-cost mini diaphragm vacuum pump. During the study, we compared two ways of adjusting the negative pressure using a compact electro-pneumatic regulator and a manual airflow control valve. The results showed that both types of regulators are suitable for the stable generation of monodisperse droplets for at least 4 h, with variations in diameter less than 1 µm. Droplet diameters at high levels of negative pressure were mainly determined by the hydrodynamic resistances of the inlet microchannels, although the absolute pressure value defined the generation frequency; however, the electro-pneumatic regulator is preferable and convenient for the accurate control of the pressure by an external electric signal, providing more stable pressure, and a wide range of droplet diameters and generation frequencies. The method of droplet generation suggested here is a simple, stable, reliable, and portable way of high-throughput production of relatively large volumes of monodisperse emulsions for biomedical applications.

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Conservation, Regeneration and Genetic Stability of Regenerants from Alginate-Encapsulated Shoot Explants of Gardenia jasminoides Ellis

Polymers ◽

10.3390/polym13101666 ◽

2021 ◽

Vol 13 (10) ◽

pp. 1666

Author(s):

Stefanos Hatzilazarou ◽

Stefanos Kostas ◽

Theodora Nendou ◽

Athanasios Economou

Keyword(s):

Sodium Alginate ◽

Calcium Chloride ◽

Genetic Stability ◽

Nutrient Medium ◽

Shoot Tips ◽

Mother Plant ◽

Short Term ◽

Alginate Encapsulation ◽

Gardenia Jasminoides ◽

Regeneration Response

The present study demonstrates the potential of the alginate encapsulation of shoot tips and nodal segments of Gardenia jasminoides Ellis, the short-term cold storage of artificial seeds and subsequent successful conversion to desirable, uniform and genetically stable plantlets. Shoot tips and first-node segments below them, derived from shoots of in vitro cultures, responded better than second-to-fourth-node segments on agar-solidified Murashige and Skoog (MS) nutrient medium and thus, they were used as explants for alginate encapsulation. Explant encapsulation in 2.5% sodium alginate in combination with 50 mM of calcium chloride resulted in the production of soft beads, while hardening in 100 mM of calcium chloride formed firm beads of uniform globular shape, suitable for handling. The addition of liquid MS nutrient medium in the sodium alginate solution doubled the subsequent germination response of the beads. The maintenance of alginate beads under light favored their germination response compared to maintenance in darkness. Encapsulated shoot tip explants of gardenia, which were stored at 4 °C for 4, 8 or 12 weeks, showed a gradual decline in their regeneration response (73.3, 68.9, 53.3%, respectively), whereas, non-encapsulated explants (naked), stored under the same time durations of cold conditions, exhibited a sharp decline in regeneration response up to entirely zeroing (48.9, 11.1, 0.0%, respectively). Shoots, derived from 12-week cold-stored encapsulated explants, were easily rooted in solid MS nutrient medium with the addition of 0.5 μM of Indole-3-acetic acid (IAA) and after transplantation of the rooted plantlets individually to pots containing a peat–perlite (3:1, v/v) substrate, they were successfully acclimatized in the greenhouse under the gradual reduction of 75 or 50% shading with survival rates of 95–100%. The genetic stability of the acclimatized plantlets was assessed and compared with the mother plant using inter simple sequence repeat (ISSR) markers. ISSR analysis confirmed that all regenerated plantlets were genetically identical to the mother plant. This procedure of artificial seed production could be useful for the short-term storage of germplasm and the production of genetically identical and stable plants as an alternative method of micropropagation in Gardenia jasminoides.

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DESIGN AND EVALUATION OF CONTROLLED-RELEASE OCULAR INSERTS OF BRIMONIDINE-TARTRATE AND TIMOLOL MALEATE

International Journal of Pharmacy and Pharmaceutical Sciences ◽

10.22159/ijpps.2017v9i1.15199 ◽

2016 ◽

Vol 9 (1) ◽

pp. 79 ◽

Cited By ~ 2

Author(s):

Preethi G. B. ◽

Prashanth Kunal

Keyword(s):

Controlled Release ◽

Drug Release ◽

Sodium Alginate ◽

Calcium Chloride ◽

Release Kinetics ◽

Water Soluble ◽

Moisture Loss ◽

Timolol Maleate ◽

Brimonidine Tartrate

Objective: The current work was attempted to formulate and evaluate a controlled-release matrix-type ocular inserts containing a combination of brimonidine tartrate and timolol maleate, with a view to sustain the drug release in the cul-de-sac of the eye.Methods: Initially, the infrared studies were done to determine the drug–polymer interactions. Sodium alginate-loaded ocuserts were prepared by solvent casting technique. Varying the concentrations of polymer—sodium alginate, plasticizer—glycerine, and cross-linking agent—calcium chloride by keeping the drug concentration constant, made a total of nine formulations. These formulations were evaluated for its appearance, drug content, weight uniformity, thickness uniformity, percentage moisture loss, percentage moisture absorption, and in vitro release profile of the ocuserts. Finally, accelerated stability studies and the release kinetics were performed on the optimised formulation.Results: It was perceived that polymer, plasticizer, and calcium chloride had a significant influence on the drug release. The data obtained from the formulations showed that formulation—F9 was the optimised formulation, which exhibited better drug release. The release data of the optimised formulation tested on the kinetic models revealed that it exhibited first-order release kinetics. Conclusion: It can be concluded that a natural bioadhesive hydrophilic polymer such as sodium alginate can be used as a film former to load water soluble and hydrophilic drugs like brimonidine tartrate and timolol maleate. Among all formulations, F9 with 400 mg sodium alginate, 2% calcium chloride and 60 mg glycerin were found to be the most suitable insert in terms of appearance, ease of handling, thickness, in vitro drug release and stability.

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Two Dimensional Flow Analysis of a Laboratory Centrifugal Pump

Volume 1: Turbomachinery ◽

10.1115/90-gt-050 ◽

1990 ◽

Cited By ~ 1

Author(s):

S. M. Miner ◽

R. D. Flack ◽

P. E. Allaire

Keyword(s):

Velocity Field ◽

Stagnation Point ◽

Centrifugal Pump ◽

Flow Rate ◽

Flow Analysis ◽

Tangential Component ◽

Design Flow ◽

Experimental Results ◽

Two Dimensional ◽

Flow Angle

Two dimensional potential flow was used to determine the velocity field within a laboratory centrifugal pump. In particular, the finite element technique was used to model the impeller and volute simultaneously. The rotation of the impeller within the volute was simulated by using steady state solutions with the impeller in 10 different angular orientations. This allowed the interaction between the impeller and the volute to develop naturally as a result of the solution. The results for the complete pump model showed that there are circumferential asymmetries in the velocity field, even at the design flow rate. Differences in the relative velocity components were as large as 0.12 m/sec for the radial component and 0.38 m/sec for the tangential component, at the impeller exit. The magnitude of these variations was roughly 25% of the magnitude of the average radial and tangential velocities at the impeller exit. These asymmetries were even more pronounced at off design flow rates. The velocity field was also used to determine the location of the tongue stagnation point and to calculate the slip within the impeller. The stagnation point moved from the discharge side of the tongue to the impeller side of the tongue, as the flow rate increased from below design flow to above design flow. At design flow, values of slip ranged from 0.96 to 0.71, from impeller inlet to impeller exit. For all three types of data (velocity profiles, stagnation point location, and slip factor) comparison was made to laser velocimeter data, taken for the same pump. At the design flow, the computational and experimental results agreed to within 17% for the velocity magnitude, and 2° for the flow angle. The stagnation point locations coincided for the computational and experimental results, and the values for slip agreed to within 10%.

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The Combined Effects of Co-Culture and Substrate Mechanics on 3D Tumor Spheroid Formation within Microgels Prepared via Flow-Focusing Microfluidic Fabrication

Pharmaceutics ◽

10.3390/pharmaceutics10040229 ◽

2018 ◽

Vol 10 (4) ◽

pp. 229 ◽

Cited By ~ 11

Author(s):

Dongjin Lee ◽

Chaenyung Cha

Keyword(s):

Mechanical Properties ◽

Cell Culture ◽

Microfluidic Device ◽

3D Cell Culture ◽

Breast Adenocarcinoma ◽

Adherent Cell ◽

Flow Focusing ◽

Spheroid Formation ◽

3D Scaffold ◽

Tumor Spheroids

Tumor spheroids are considered a valuable three dimensional (3D) tissue model to study various aspects of tumor physiology for biomedical applications such as tissue engineering and drug screening as well as basic scientific endeavors, as several cell types can efficiently form spheroids by themselves in both suspension and adherent cell cultures. However, it is more desirable to utilize a 3D scaffold with tunable properties to create more physiologically relevant tumor spheroids as well as optimize their formation. In this study, bioactive spherical microgels supporting 3D cell culture are fabricated by a flow-focusing microfluidic device. Uniform-sized aqueous droplets of gel precursor solution dispersed with cells generated by the microfluidic device are photocrosslinked to fabricate cell-laden microgels. Their mechanical properties are controlled by the concentration of gel-forming polymer. Using breast adenocarcinoma cells, MCF-7, the effect of mechanical properties of microgels on their proliferation and the eventual spheroid formation was explored. Furthermore, the tumor cells are co-cultured with macrophages of fibroblasts, which are known to play a prominent role in tumor physiology, within the microgels to explore their role in spheroid formation. Taken together, the results from this study provide the design strategy for creating tumor spheroids utilizing mechanically-tunable microgels as 3D cell culture platform.

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STANDARDIZATION OF MEDIUM FOR SYNTHETIC SEED GERMINATION OF SALVIA SCLAREA L.

Kongunadu Research Journal ◽

10.26524/krj79 ◽

2015 ◽

Vol 2 (1) ◽

pp. 118-120

Author(s):

Durgha H ◽

Ramya G ◽

Gogul Ramanth M ◽

Thirugnanasampandan R

Keyword(s):

Seed Germination ◽

Sodium Alginate ◽

Calcium Chloride ◽

Multiple Shoot ◽

Nodal Explants ◽

Synthetic Seed ◽

Ms Medium ◽

Shoot Induction ◽

Multiple Shoot Induction ◽

Salvia Sclarea

Young nodal explants (0.5-1cm) of Salvia sclarea L. was used for synthetic seed preparation.Synthetic seeds were prepared using 5% sodium alginate and 1.11% calcium chloride. Seed germination was observed on MS medium fortified with 1.4µM GA3+4.4µM BA after twenty days of culture. Further multiple shoot induction was observed after fifteen days of shootinduction.

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Determination of the effect of calcium chloride on sodium alginate on the restructuring of fish products

Ukrainian Food Journal ◽

10.24263/2304-974x-2019-8-3-14 ◽

2019 ◽

Vol 8 (3) ◽

pp. 584-596

Author(s):

Radion Nykyforov ◽

Yuriі Korenets ◽

Natalya Frolova ◽

Oleg Kuzmin

Keyword(s):

Sodium Alginate ◽

Calcium Chloride ◽

Fish Products

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