Emulsion Microencapsulation Research Articles

Double emulsion microencapsulation of ionic liquids for carbon capture

Double emulsion microencapsulation of ionic liquids for carbon capture

Influence of oil-phase alkane additives on the evaporation rate of double emulsion curing process

Short-chain alkanes have been proved to be effective fluorobenzene/polymer solution phase additions to prolong the evaporation for the curing process of double emulsion, which can significantly improve the surface finishing of shells generated by emulsion microencapsulation. This work reveals the mechanism of the inhibition of evaporation caused by alkane additions. The molecular simulations on various fluorobenzene solutions and oil/water interfaces indicate that the alkane additions have little effect on the diffusivity of fluorobenzene. A comparison between the early-stage solution of the evaporation model proposed in this work and the experimental data concludes that the activity of fluorobenzene is the major factor that determines the evaporation rate, while the activity of fluorobenzene decreases when alkanes with shorter chain lengths are added. Besides, the present evaporation model also sets up a correlation between the solution diffusion and the phase equilibrium of the oil and outer water phases in a double emulsion.

Calculation Methods of Solution Chemical Potential and Application in Emulsion Microencapsulation.

Several new biased sampling methods were summarized for solution chemical potential calculation methods in the field of emulsion microencapsulation. The principles, features, and calculation efficiencies of various biased Widom insertion sampling methods were introduced, including volume detection bias, simulation ensemble bias, and particle insertion bias. The proper matches between various types of solution in emulsion and biased Widom methods were suggested, following detailed analyses on the biased insertion techniques. The volume detection bias methods effectively improved the accuracy of the data and the calculation efficiency by inserting detection particles and were suggested to be used for the calculation of solvent chemical potential for the homogeneous aqueous phase of the emulsion. The chemical potential of water, argon, and fluorobenzene (a typical solvent of the oil phase in double emulsion) was calculated by a new, optimized volume detection bias proposed by this work. The recently developed Well-Tempered(WT)-Metadynamics method skillfully constructed low-density regions for particle insertion and dynamically adjusted the system configuration according to the potential energy around the detection point, and hence, could be used for the oil-polymer mixtures of microencapsulation emulsion. For the macromolecule solutes in the oil or aqueous phase of the emulsion, the particle insertion bias could be applied to greatly increase the success rate of Widom insertions. Readers were expected to choose appropriate biased Widom methods to carry out their calculations on chemical potential, fugacity, and solubility of solutions based on the system molecular properties, inspired by this paper.

The Effects of Extrusion and Internal Emulsion Microencapsulation Methods on the Viability of Lactobacillus acidophilus

The Effects of Extrusion and Internal Emulsion Microencapsulation Methods on the Viability of Lactobacillus acidophilus

In vitro sustained release study of Thymol from Sodium Alginate Beads synthesized by Emulsion Microencapsulation

In vitro sustained release study of Thymol from Sodium Alginate Beads synthesized by Emulsion Microencapsulation

Effect of different types of encapsulation on the survival of Lactobacillus plantarum during storage with inulin and in vitro digestion

The aim of this work was to investigate the effect of different microencapsulation methods (extrusion and internal emulsion microencapsulation) and inulin on the viability of Lactobacillus plantarum during storage at 4 °C. The inulin was added during microencapsulation at 0, 1 and 2%. The effect of the different phases of the gastrointestinal digestion on the survival of the microorganism during storage (0, 15 and 30 days) was also investigated. In both types of microcapsules, the best protection with higher survival of Lactobacillus plantarum during the 30 days of storage, was observed in the presence of 2% inulin with only 0.71 and 0.47 logs reduction for extrusion and emulsion microencapsulation respectively. From 15 days of storage the internal emulsion microcapsules did not maintain their structure during the in vitro digestion processes. At the end of the simulated gastrointestinal conditions (30 days), the number of cells were 7.40 and 6.53 log CFU g−1 for extrusion and emulsion microencapsulation respectively. In both microencapsulation methods, Lactobacillus plantarum showed a high survival (≥106 CFU g−1). However for long storage periods, the best method for increasing the survival of Lactobacillus plantarum to the gastrointestinal digestion was the extrusion microencapsulation.

Influence of sucrose on the stability of W1/O/W2 double emulsion droplets

Number of emulsion particles vs. time with various sucrose (Suc) concentration in rotating flow field. (Large sized W1/O/W2 double emulsion droplets with uniform wall thickness and diameters were prepared by adopting the emulsion microencapsulation method.)

Synthesis of millimeter-scale Al2O3 ceramic hollow spheres by an improved emulsion microencapsulation method

Millimeter-scale Al2O3 ceramic hollow spheres have been successfully prepared by an improved emulsion microencapsulation method. That is: Firstly, stable oil-in-water emulsion droplets, using alumina sol as continuous phases (water phase) and dimethicone as dispersion phase (oil phase), are prepared in advance by using self-made T-shape micro-emulsion channel as an emulsion droplet generator. Then, the prepared droplets suffer rotating process for 12h at 100°C in a rotary evaporator, and Al2O3 gel hollow spheres are produced. Finally, Al2O3 ceramic hollow spheres with wall thickness of 30~100μm and diameter of 600~2500μm are successfully prepared through calcining the produced gel hollow spheres at 1200°C for 4h. The main crystalline of the prepared Al2O3 ceramic hollow spheres is α-Al2O3. This method provides a novel synthesizing method for preparing millimeter-scale ceramic hollow spheres which have great potential application in Inertial Confined Fusion (ICF) required hollow pellet.

塑料微球表面制备聚乙烯醇涂层研究进展

In the procedures of designing polystyrene-polyvinyl alcohol-CH (carbon and hydrogen elements) (PS-PVA-CH) triple-layer microspheres, there are many methods such as drop-tower technique, emulsion micro-encapsulation, dip (spin) coating, interfacial polycondensation, and spraying technique to prepare the PVA coating. Drop-tower technique, emulsion micro-encapsulation and dip (spin) coating are most-commonly used. The advantages, disadvantages and the research progress of the three methods are summarized in this paper. Emulsion micro-encapsulation is suitable for preparing double-layer microspheres of sizes smaller then 500 m, with high survival ratio and good quality. However,the preparation process is easily influenced by artificial factors. Small-sized double-layer microspheres can also be prepared by the drop-tower technique, and the preparation period is short. But there are still some problems such as the difficulty in designing thedroplet generator, uneven PVA coating and the difficulty in preparing large-sized microspheres. Dip (spin) coating technique can be used to prepare PS-PVA microspheres with sizes larger than 1000 m, but the spread of PVA coating is affected by many factors in this method, and the prepared PVA coating is too thin and not uniform.

聚-α-甲基苯乙烯空心微球制备过程中的缺损研究

Poly-(-methylstyrene) (PAMS) microspheres were fabricated with W1/O/W2 double emulsion microencapsulation method,and the effects of polyvinylalcohol (PVA) and CaCl2 weight concentrations and the O/W2 phase ratio on the percentages of defected PAMS microspheres were studied. The weight concentrations of PVA and CaCl2 and the O/W2 phase ratio in the fabrication process of PAMS microspheres were optimized. The results show that, for the three parameters being 1.0%, 1.5%, and 0.01, respectively, the percentage of the defect-free PAMS microspheres without vacuoles in the shell wall can be up to 60%.

Pharmaceutical and immunological evaluation of a single-dose hepatitis B vaccine using PLGA microspheres

The objective of the study was to investigate the feasibility of a single-dose hepatitis B vaccine based on three kinds of poly ( d, l)-lactide-co-glicolide acid (PLGA) microspheres. PLGA microspheres loaded with recombinant hepatitis B surface antigen (HBsAg) were formulated using a double emulsion microencapsulation technique. The pharmaceutical characteristics of size, surface morphology, protein loading efficiency, antigen integrity, release of HBsAg-loaded PLGA microspheres and degradation of the polymer in vitro were evaluated. The degradation of the polymer corresponded with the composition of the polymer (lactide / glycolide ratio), molecular weight of the polymer (viscosity) and morphology of the microspheres. These PLGA microspheres were able to continuously release antigen under conditions that mimic the environment in vivo. The single subcutaneous injection of HBsAg-loaded PLGA50 / 50 microspheres, PLGA75 / 25 microspheres and a mixture of PLGA50 / 50, PLGA75 / 25, and PLGA50 / 50-COOH microspheres in mice resulted in comparable serum antibody titers to those of three injections of the conventional aluminum adjuvant formulated HBsAg vaccine. Based on these findings in vitro and in vivo, it was concluded that HBsAg was successfully loaded into the PLGA microspheres, which can auto-boost an immune response, and the HBsAg-loaded PLGA microsphere is a promising candidate for the controlled delivery of a vaccine.

Formulation and process parameters affecting protein encapsulation into PLGA microspheres during ethyl acetate-based microencapsulation process

The objective of this study was to investigate formulation and process parameters affecting protein encapsulation into PLGA microspheres during an ethyl acetate-based double emulsion microencapsulation process. Lysozyme was used as a model protein throughout this study. An aqueous lysozyme solution was emulsified in ethyl acetate containing 0.6 ∼ 1.2 g PLGA75 : 25. The primary emulsion was then transferred quickly to an aqueous phase to make a water-in-oil-in-water emulsion. Ethyl acetate quenching was performed on the double emulsion stirred for 5, 15, 30 or 45 min. The resultant microspheres were further hardened, collected and dried overnight under vacuum. The bicinchoninic acid assay was carried out to determine the quantity of lysozyme present in the aqueous continuous phase and inside the microspheres. While the primary emulsion was stirred without quenching, lysozyme in the inner water phase continued diffusing across the ethyl acetate phase into the aqueous continuous phase. Emulsion droplets were also broken into smaller ones with ongoing stirring; this event also contributed to lysozyme leaking out of the inner water phase. The amount of lysozyme leaching to the aqueous continuous phase ranged from 4.79 ± 2.1 to 51.9 ± 5.3% under the experimental condition. Ethyl acetate quenching stopped the primary emulsion droplets from being fragmented into smaller ones and caused PLA75 : 25 precipitation to form microspheres. As a result, the rate of ethyl acetate removal influenced lysozyme encapsulation efficiency, as well as microsphere size. Depending on the timing of ethyl acetate quenching, lysozyme encapsulation efficiencies were found to be 9.89 ± 4.53 ∼ 75.82 ± 6.55%. Optimization of the onset of ethyl acetate quenching and formulations could permit attainment of a desirable protein encapsulation efficiency.

이중유제법에 근거한 미립자 제조 공정 중 단백질의 분산매로의 전이 양상

The objective of this study was to investigate the patterns of protein leaching to an external phase during an ethyl acetate-based, double emulsion microencapsulation process. An aqueous protein solution (lactoglobulin, lysozyme, or ribonuclease; ) was emulsified in ethyl acetate containing poly-d,l-lactide-co-glycolide 75:25. The emulsion was transferred to a 0.5% polyvinyl alcohol solution saturated with ethyl acetate . After the double emulsion was stirred for 5, 15, 30, or 45 min, additional 0.5% polyvinyl alcohol was quickly added into the emulsion. This so-called quenching step helped convert emulsion microdroplets into microspheres. After 2-hr stirring, microspheres were collected and dried. The degree of protein leaching to and/or phase was monitored during the microencapsulation process. In a separate, comparative experiment, the profile of protein leaching to an external phase was investigated during the conventional methylene chloride-based microencapsulation process. When ethyl acetate was used as a dispersed solvent, proteins continued diffusing to the phase, as stirring went on. Therefore, the timing of ethyl acetate quenching played an important role in determining the degree of protein microencapsulation efficiency. For example, when quenching was peformed after 5-min stirring of the primary emulsion, the encapsulation efficiencies of lactoglobulin and ribonuclease were , respectively. In contrast, when quenching was carried out in 45 min, their respective encapsulation efficiencies were . By sharp contrast, different results were attained with the methylene-chloride based process: up to 2 hr-stirring of the primary and double emulsions, less than 5% of a protein appeared in . Afterwards, it started to partition from , and such a tendency was affected by the amount of PLGA75:25 used to make microspheres. Different solvent properties (e.g., water miscibility) and their effect on microsphere hardening were to be held answerable for such marked differences observed with the two microencapsulation processes.

Effects of ultrasound and additives on the function and structure of trypsin

Encapsulating proteins in polymeric microspheres is a useful mode of drug delivery, but the proteins are subjected to damage in the process of ultrasound emulsion microencapsulation. The objective of this study was to investigate the effects of ultrasound power and duration on the function and structure of trypsin, and the reason of protein denaturation when it was irradiated by 20 kHz ultrasound. The relatively stable enzyme, trypsin, was dissolved in aqueous solution in the presence and absence of additives to study the stability of trypsin during the ultrasound irradiation. The damage of the molecular structure of trypsin was detected via combined high performance liquid chromatogram and electrospray ionization mass spectrometry (HPLC–ESI-MS). The results showed that the activity of trypsin decreased with increasing ultrasound power from 100 to 500 W or extending the irradiation time from 1 to 20 min. This effect could be enhanced via aerating the solution for a duration 10 min at 300 W. Fragments of trypsin were detected in the treatment (300 W, 10 min) by HPLC–ESI-MS. The additives, Tween 80 and mannitol, could protect trypsin against the inactivation caused by ultrasound. The reason of inactivation was partly from the alteration of the molecular conformation and partly from the modification or damage of trypsin's molecular structure.