Size Of Microcapsules Research Articles

A probability characteristic of crack intersecting with embedded microcapsules in capsule-based self-healing materials

Abstract The micro-cracks in a material lead to a reduction in its overall strength and service life. The emerging capsule-based self-healing system provides a new strategy for repairing the cracks, effectively delaying the potential damage of the matrix, and prolonging the service life of composite materials. Determining the optimal size and dosage of microcapsules required to repair cracks in the matrix is essential for the development and design of capsule-based self-healing materials. This paper presents a novel two-dimensional capsule-based self-healing model composite material whose surface is paved by reproducible and random cells and some microcapsules are randomly dispersed in those cells to investigate the rupture behavior of microcapsules forced by growing cracks. An analytical model is proposed from the viewpoint of geometrical probability to express the probability characteristics of the embedded microcapsules stimulated by linear cracks in a two-dimensional capsule-based self-healing model composite. Additionally, the effect of the size and dosage of the embedded microcapsules on the intersection probability is analyzed, and the maximal probability is also found to improve the self-healing efficiency. Finally, the accuracies of these probability values and theoretical solutions are verified via computer simulation, and the results show that the developed model of the geometrical probability of the crack intersection with microcapsules randomly distributed in the cells of the matrix will help to provide a theoretical basis for the quantitative design of capsule-based self-healing materials.

Controlled preparation of alginate microcapsules with multiphase oil cores using microfluidic chip

This work presents a feasible method for controllable preparation of monodisperse spherical alginate microcapsules with structured multiphase oil cores, which have the potential to encapsulate multiple lipophilic actives that are not mutually soluble. Monodisperse (oil1 + oil2)-in-water ((O1 + O2)/W) droplets are generated using the assembled one-step co-flowing 3D-printed microfluidic chip. By cross-linking (O1 + O2)/W droplets with the calcium chloride collection solution, alginate microcapsules are obtained. It is noticed that the multiphase oil cores inside the microcapsules display self-adjustment behavior. The size and shell thickness of the alginate microcapsules, as well as the number of the cores inside the microcapsules, can be precisely tailored. Meanwhile, the factors that influence the sphericity of the microcapsules are investigated. Furthermore, we explore the impact of different types of the collection solutions on the final structure of the microcapsules. The proposed method shows excellent controllability in the design of alginate microcapsules with multiphase oil cores.

Pore-scale numerical investigation on the thermal storage properties of packed-bed systems with phase change material microcapsules

Phase change material (PCM) microcapsules are gaining increasing attention because it can overcome the shortage of PCM macrocapsules and increase the heat transfer area, while the pore-scale thermal performance of the PCM microcapsule packed-bed systems, as well as the influence of packing methods and microcapsule sizes on thermal storage, is still poorly understood. This paper introduces various spherical PCM microcapsule pack models, including single-layered, diameter-changed two-layered, and three-layered packing models, to investigate the charging process at pore scale. The indices of thermal storage properties such as charging time, temperature distribution, phase change fraction, pressure drop and thermocline degradation are studied with the finite element method. In the single-layered thermal storage system, the results show that the charging process can be improved by reducing the capsule size and using cross-packing methods. When the capsule size is reduced from 2 to 0.5 mm with cross packing, the charging time can be shortened by 72.97%, but remarkable pressure drop is created. The results indicate that the overall thermal storage performance of multi-layered packed-bed systems is better than that of single-layered packed-bed systems. The charging time of the diameter-changed two-layered and three-layered thermal storage systems can be reduced up to 16.21% and 24.32%, respectively, compared to the single-layered in-line pack with a d = 2 mm. The filling sequence plays a key role in multi-layered thermal systems. A packed-bed system with a diameter decreasing along the heat transfer fluid (HTF) flow direction has a better capacity to reduce thermocline degradation than other packed-bed systems.

Enhanced viability and improved in situ antibacterial activity of the probiotic LAB microencapsulated layer-by-layer in alginate beads coated with nisin

In the present study, a layer-by-layer technique was used to prepare alginate-nisin (Alg-N) as coating layer to encapsulate a potential probiotic-protective lactic acid bacteria (LAB) isolate in order to improve its both survival and antibacterial activities in situ. The isolate was identified as Pediococcus acidilactici according to the sequencing results of the PCR products. The mean size of Alg and Alg-N microcapsules was also equal to 762.63 and 501.77 μm, respectively based on the results of field emission scanning electron microscopy. In accordance with the zeta potential data, the Alg-N surrounding layer was confirmed. Furthermore, the Fourier transform infrared findings revealed the adsorption of nisin on the Alg beads. The antibacterial activity of the produced microcapsule on Staphylococcus aureus (100% inhibition) was significantly (P < 0.05) higher than that of the other foodborne bacteria studied. In addition, enhanced viability of the microencapsulated LAB in simulated gastrointestinal conditions and flavored milk, as well as its improved in situ inhibitory effect on S. aureus were verified.

Preparation and characterization of curcumin-loaded debranched starch/Mesona chinensis polysaccharide microcapsules: Loading levels and in vitro release

Curcumin has been shown a variety of biological activities, such as anti-inflammatory, antioxidant and anticancer properties. However, its poor water solubility and chemical instability limit the scope of its application. In the present work, a novel debranched waxy maize starch (DWMS)/Mesona chinensis polysaccharide (MCP) complex wall material was developed to encapsulate curcumin, and the structural properties and in vitro release behaviors of microcapsules were evaluated. Rheological results showed that encapsulation of curcumin significantly reduced the dynamic modulus (G′ and G″) of the system. Particle size (from 1283.0 nm to 970.2 nm) and zeta potential (from −13.8 mV to −41.7 mV) of microcapsules decreased with the increase of MCP concentration in the wall material. DWMS, MCP, and Cur interacted through hydrogen bonding to form Cur-loaded microcapsules as FT-IR and XRD results demonstrated. Furthermore, the encapsulation efficiency of curcumin in DWMS-MCP microcapsules reached up to 63.2% when the MCP concentration was 2%. The antioxidant activity of the microcapsules was enhanced with the increase of MCP, which may be attributed to the increase of encapsulation efficiency and the intrinsic antioxidant activity of MCP. The in vitro release results proved that all microcapsules achieved sustained release in both intestinal and gastric fluids.

Encapsulation of Polygonum bistorta root phenolic compounds as a novel phytobiotic and its protective effects in the mouse model of enteropathogenic Escherichia coli infection

BackgroundMicroencapsulation technology is the fundamental delivery system for encapsulating the natural bioactive compounds especially phenolic in order to developing bioavailability, stability and controlling release. This study was conducted to determine the antibacterial and health-promoting potential of the phenolic rich extract (PRE)-loaded microcapsules obtained from Polygonum bistorta root as a dietary phytobiotic in mice challenged by enteropathogenic Escherichia coli (E. coli).MethodThe PRE was obtained from Polygonum bistorta root using fractionation by different polarity solvents and the highest PRE was encapsulated by the combination of modified starch, maltodextrin, and whey protein concentrate as wall materials using a spray dryer. Then, the physicochemical characterization (particle size, zeta potential, Morphology and polydispersity index) of microcapsules have been assessed. For the invivo study, 30 mice at five treatment were designed and antibacterial properties were analyzed. Furthermore, relative fold changes in the ileum population of E. coli was investigated using Real time PCR.ResultsThe encapsulation of PRE resulted in the production of phenolic enriched extract-loaded microcapsules (PRE-LM) with a mean diameter of 330 nm and relatively high entrapment efficiency (87.2% w/v). The dietary supplementation of PRE-LM improved weight gain, liver enzymes, gene expression, morphometric characteristics of the ileum and decreased the population of E. coli present in the ileum significantly (p < 0.05).ConclusionOur funding suggested PRE-LM as a promising phytobiotic against E. coli infection in mice.

INFLUENCE OF MICROENCAPSULATION PARAMETERS ON THE SIZE AND MORPHOLOGY OF MICROCAPSULES BY ECO-FRIENDLY SOLVENT EVAPORATION METHOD ORIENTED TO MEDICAL TEXTILES

Application of microcapsules in medical textile has been studied and commercially developed widely in recent years. The aim of this work was to propose an eco-friendly microencapsulation by solvent evaporation method that can contribute to the manufacture of medical textile products using microcapsules. Quillaja saponin was used as bio-sourced surfactant and ethyl acetate was used as the less toxic, non-halogenated organic solvent. The influences of saponin concentration, stirring speed during emulsification step and the volume of ethyl acetate used to saturate the aqueous phase before emulsification on the microcapsule size and morphology were investigated. The results showed that eudragit microcapsules of ibuprofen with diameter in range from 17 to 34 µm, which were suitable for medical textile applications, were successfully elaborated. The saponin concentration varied from 0.025 to 0.1 wt%. The stirring speed was changed from 700 to 600 rpm. The volume of ethyl acetate used in saturation step was 0, 8 and 12 ml. In the scope of investigation, the saponin concentration and the volume of ethyl acetate used in saturation step did affect the microcapsule size and morphology while the stirring speed did not. The saturation step really helped to reduce the formation of irregular microparticles and to narrow the size distribution, but the microcapsules became more porous, weaker and were deformed significantly by drying in the fabric treatment process.

Damage-healing analysis of microencapsulated self-healing concrete subjected to tensile loading using a 2D micromechanical model

Self-healing concrete that employs microencapsulated healing agents has been proven to be an effective method for microcrack repairment in the concrete structure. However, there is a lack of efficient tools to evaluate the effect of the parameters of microcapsules on the mechanical behavior of the self-healing concrete. In this paper, the evolution of the damage-healing process of microencapsulated self-healing concrete subjected to tensile loading is numerically analyzed from a microscopic perspective by using a 2D micromechanical model. Based on the deformation and propagation evolution mechanism of microcracks, the contribution of microcracks to the total compliance tensor of microencapsulated self-healing concrete under tensile loading is deduced at various stages. According to the calculated total compliance tensor, the stress-strain and compliance-strain relations of microencapsulated self-healing concrete are discussed with special attention to the stress dropping and strain softening stages. Finally, parametric analysis was conducted using the constructed model to investigate the influence of size and content of microcapsules, the types of healing agent and the initial damage of the concrete on the mechanical behaviors of microencapsulated self-healing concrete. The constructed 2D model is significantly useful for the reasonable selection of the optimal parameters of microencapsulated self-healing concrete.

Emulsion Stabilization Strategies for Tailored Isocyanate Microcapsules.

We report on the stabilization of an oil-in-water (O/W) emulsion to, combined with interfacial polymerization, produce core-shell polyurea microcapsules (MCs) containing isophorone diisocyanate (IPDI). These will act as crosslinkers for mono-component adhesives. The emulsion stabilization was evaluated using three types of stabilizers, a polysaccharide (gum arabic) emulsifier, a silicone surfactant (Dabco®DC193), a rheology modifier (polyvinyl alcohol), and their combinations. Emulsion sedimentation studies, optical microscopy observation, and scanning electron microscopy enabled us to assess the emulsions stability and droplet size distribution and correlate them to the MCs morphology. Fourier transform infrared spectroscopy and thermogravimetric analysis revealed the MCs composition and enabled us to evaluate the encapsulation yield. All stabilizers, except DC193, led to spherical, loose, and core-shelled MCs. The rheology modifier, which increases the continuous phase viscosity, reduces the emulsion droplets sedimentation, keeping their size constant during the MCs' synthesis. This allowed us to obtain good quality MCs, with a smaller average diameter, of approximately 40.9 µm mode, a narrower size distribution and 46 wt% of encapsulated IPDI. We show the importance of the emulsion stability to tune the MCs morphology, size, and size distribution, which are critical for improved homogeneity and performance when used, e.g., in natural and synthetic adhesive formulations industry.

Comprehensive evaluation on the encapsulation performances of melamine-formaldehyde microcapsules affected by core oils

Core oils’ properties are significant for the microencapsulation process. 12 representative single componential core oils with different chemical structures, logP, solubility, interfacial tension (IFT) and viscosity were specially selected to fabricate melamine-formaldehyde (MF) microcapsules. Afterward, the effect of core oils’ properties on the performance of microcapsules was investigated. It was found that the morphology, the average particle sizes (7.83 µm∼27.06 µm), the encapsulation efficiencies (47.35 ± 3%∼92.86 ± 4%), zeta potentials (−52.37 ± 2.97 mV∼−65.03 ± 0.79 mV) and the rupture forces (0.28 ± 0.20mN∼0.82 ± 0.3mN) of microcapsules were influenced by core oils’ properties. Further comprehensive analysis indicated that logP≥ 1.66 and the solubility≥ 0.055 mL3/g were the premises for the successful encapsulation processes. Moreover, by increasing logP, IFT and viscosity, the size of microcapsules increased; as microcapsules size increased, the release rate decreased; the high IFT and the solubility increased the encapsulation efficiency of microcapsules; the mechanical property was influenced by logP. This work provided to use logP as the criterion to predict the encapsulation work, which hasn’t been studied before; and the correlations between microcapsules’ various performances and core oils’ properties were initially established. This work was meaningful since logP was used as a clear criterion to select core oils for encapsulation work and core oils’ properties were used to predict the application performances of microcapsules.

PREPARATION AND CHARACTERIZATION OF SONNERATIA ALBA LEAF EXTRACT MICROCAPSULES BY SOLVENT EVAPORATION TECHNIQUE

Objective: Sonneratia alba leaves were used by the community for traditional medicine to cure muscle pain, back pain, antioxidants, rheumatism, malaria, wounds, tuberculosis (TB) and as a spermicide. S. alba leaves extract was easy to damage because of the light exposure, change of pH, weather and a long period of storage time. The problem can be solved by coating the extract with a microencapsulation technique. The purpose of this research was to formulate the microcapsules of S. alba leaves extract with solvent evaporation technique using Ethocel 10 cP and Eudragit E100 as a matrix. Methods: S. alba leaves were extracted using ethanol 96%. This extract was dried by a rotary evaporator. The microencapsulation process of S. alba leaves extract was done by solvent evaporation technique (O/W: oil in water). The formula of S. alba leaves extract microcapsules was designed into six formulas (Eudragit E100: EA1, EA2, EA3 and Ethocel 10 cP: EB1, EB2, EB3). Microcapsules of S. alba leaves extract were characterized for particle size in terms of surface morphology by scanning electron microscope (SEM) and encapsulation efficiency. Antioxidant activity of the formulation have been evaluated by DPPH method. Physical characterization on microparticles was performed by conducting entrapment efficiency and SEM picture. Results: In this research, the microparticles containing S. alba extract has been developed by using ethyl cellulose (Ethocel 10 cP) and eudragit (Eudragit E100) as the polymer matrix. The results showed that a high concentration of polymer (Ethocel 10 cP and Eudragit E100) used in microencapsulation resulted in better S. alba leaves extract microcapsules in terms of physical characteristics. Particle size of microcapsules containing S. alba leaves extract were in the range of 0.701 to 1.163 μm. Encapsulation efficiency (% EE) was categorized as poor because the value were ≤ 80% to which 74.386% (EB3) and 75.248% (EA1). SEM picture of EA1 (Eudragit E100) revealed that the surface of microcapsule were rough and porous. When Ethocel 10 cP was used as a polymer, a smoother surface and less visible pores of microcapsule were obtained. The antioxidant ability of S. alba leaves extract microcapsule showed that IC50 values were 53.26 ppm. Conclusion: It can be concluded that microcapsules of S. alba leaves extract can be prepared by solvent evaporation technique using Eudragit E100 and Ethocel 10 cP as polymer. S. alba leaves has potent antioxidant activity either as an extract or after being formulated into microcapsules.

Preparation of microcapsules with IPDI monomer and isocyanate prepolymer as self-healing agent and their application in self-healing materials

Microcapsules were synthesized with the hybrid of Isophorone diisocyanate (IPDI) and terminal isocyanate prepolymer (CPU) as active healing agent, then the microcapsules were mixed with epoxy resin in order to form a metal anti-corrosion coating with excellent self-healing properties. Through process optimization and molecular design, the core material which was isocyanate hybrid (CPU-IPDI) with 17% Isocyanate group (-NCO) was synthesized by the reaction of IPDI and castor oil, and then the CPU-IPDI was encapsulated in the microcapsule with Diphenylmethane diisocyanate (MDI) as the shell by interface polymerization. Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric spectroscopy (TGA) confirmed the successful encapsulation of CPU-IPDI. The effect of the content of sodium lignosulfonate (NaLS) on the size and morphology of microcapsules were investigated. Optical microscopy (OM) and laser particle size analyzer show that the size of microcapsules decreases with the increase of the content of stabilizing agent. The microcapsules were prepared with 1% NaLS with a core content of 51.3%, an average particle size of 26.3 μm and a shell thickness of 1.44 ± 0.9 μm. In addition, the microcapsules loaded with CPU-IPDI were added to the epoxy coating, and the healing process of blank coating and self-healing coating was detected by SEM. The results show that the coating wound of containing 10% microcapsules has obvious healing. With saline infiltration and electrochemical impedance spectroscopy (EIS) test coating corrosion process, the results prove that after soaking in 3.5% NaCl solution for 7 days, the |Z| f = 0.01Hz value of the coating with 10 wt % microcapsules is about 1.9 × 106 Ω cm2, nearly three order higher than that of pure epoxy coating (3.1 × 103 Ω cm2), demonstrating the enhancement of protection ability.

Preparation of multicolor microcapsules and their application in smart color-switching textiles

Spiropyran and spiroxazine photochromics have attracted increasing attention in optical data storage, optical switches, and anti-counterfeiting for decades. To expand the applications of spiropyran and spiroxazine, the durability and multi-color changes of spiropyran and spiroxazine still need to be explored. In this article, based on the subtractive principle of dyes, multi-color spiropyran and spiroxazine microcapsules with uniform particle sizes were prepared by the interfacial polymerization method via using compounds (spiropyran and spiroxazine) of different colors as the core material, and polyurethane as the shell material. Among them, toluene diisocyanate and polyethylene glycol constitute the hard and soft segments of polyurethane, respectively. The color of spiropyran and spiroxazine microcapsules can effectively switch between color and colorless, showing excellent photo fatigue resistance. The average particle size of microcapsules is 2.951 µm, and the particle distribution index value is 0.314, which shows the particle size is small and uniform. The maximum thermal decomposition temperature is 426°C, demonstrating good thermal stability. The hydrophobic photochromic fabric was prepared by coating multi-color spiropyran and spiroxazine microcapsules on cotton knitted fabric and hydrophobic treatment. The hydrophobic photochromic fabric is hydrophobic and stain resistant, and exhibits multi-color dynamic switching and long-lasting use. After 50 cycles of washing, the water contact angle of the fabric remains about 109°, showing its good washing resistance and water repellency. In addition, spiropyran and spiroxazine microcapsules are also applied in template and screen printing to impart rich and dynamic color-changing effects to fabrics, fabricating photochromic fabrics. Photochromic fabrics have potential applications in civilian and military fields.

Effects of manufacturing conditions on the properties of boric acid/melamine-urea-formaldehyde microcapsules prepared by in situ polymerization: Its inhibition behavior on wood destroying fungi

Water-soluble boric acid (BA) was microencapsulated by in situ polymerization with a melamine-urea formaldehyde shell. The effects of core-shell ratio, time, and temperature on the microcapsule characteristics were investigated. The microencapsulated BA was tested for its effectiveness against wood-destroying fungi. The results showed that the core:shell ratio affected the individuality of the microcapsules (MCs), and the most individual microcapsules were those with the 1:1 core:shell ratio. The microencapsulation temperature at the 1:1 core:shell ratio affected the surface porosity and size spectrum of MCs. The surface was porous, and the size spectrum was narrow at 50 °C. The microencapsulation reaction time at the 1:1 core-shell ratio did not have a considerable effect on the MC size. Although the MC size spectrum varied in the studied parameters (core: shell ratio, temperature, time), the average MC sizes were large enough to pass through the bordered pits of the softwood cell wall. Slow boron release was obtained by optimizing the MC preparation parameters. The optimum microencapsulation parameters for slow release of BA were the 1:1 core:shell ratio, 50 °C, and time of 120 min. The capsules produced at optimum microencapsulation parameters were biologically active against the fungus Coniophora puteana and leaching resistance was improved.

Supercooling elimination of cryogenic-temperature microencapsulated phase change materials (MPCMs) and the rheological behaviors of their suspension

Phase change materials (PCMs) when amalgamated in a shell material to form microencapsulated-PCMs (MPCMs) usually exhibit high levels of supercooling due to the limited crystallization process. In the present study, various efforts were made to reduce this phenomenon, including increasing the MPCM size, employing nucleating agents, and embedding copper nanoparticles into the MPCM shells. It was observed that with an increase in the microcapsule size from 43 μm to 76 μm, the supercooling was reduced by a value of 10.2 °C from melting/freeing point peak temperature differences of 37.6 to 27.4 for the 1200 rpm and 800 rpm samples respectively. Comparatively, the implementation of octadecanol nucleating agent 30 wt % resulted in a reduction of supercooling by 22.9 °C. The introduction of Cu nanoparticles with a decane core can also reduce the supercooling degree by 4.6 °C, while the thermal conductivity the MPCM samples with a hexadecane core increased from 0.173 to 0.182 W m−1 K−1 before and after the addiction of the Cu nanoparticles. Furthermore, di(propylene glycol) methyl ether was used as a carrier fluid for the MPCMs to study the slurry rheological behaviors with various MPCM compositions. It was observed that the MPCM suspension with 10–20% MPCM mass concentration did not exhibit shear thinning, while the 30% sample conveyed shear thinning properties. Furthermore, near the crystallization temperature of the PCM, the slurry viscosity sharply rose, attributed to the volume changes and non-cooperative motion of MPCM microcapsules.

Characterization of hydrophilic and hydrophobic core-shell microcapsules prepared using a range of antisolvent approaches

This study describes three straightforward approaches to leveraging gel network-restricted antisolvent precipitation techniques as a means of preparing hydrophilic hydrophobic core-shell microparticles. Briefly, hydrophilic polysaccharides (sodium alginate (ALG), κ-carrageenan (CAR), and agar (AG)) were utilized to prepare microgel beads that were then immersed in zein solutions (70% ethanol aqueous solution, 70% urea aqueous solution, and zein in 70% acetic acid, respectively), thereby facilitating the controlled, slow antisolvent precipitation of the protein layer on the microbead surfaces and inducing hydrophilic hydrophobic core-shell structure formation. This technique can be readily applied to a range of gelling systems and can be tailored to target particle sizes and shell thicknesses. The resultant core-shell particles offer great promise for controlled delivery of fragrances, drugs, or other bioactive compounds in an application-specific fashion, and can be individually tailored based upon the selected input concentrations and preparation methods. Importantly, this technique is generalizable and can be extended to prepare diverse particles with a range of core-shell structures produced from a wide assortment of hydrophobic materials. • Core-shell microcapsules were prepared using a range of antisolvent approaches. • Size and shell thickness of microcapsules can be regulated. • Core-shell particles offer great promise for controlled delivery in an application-specific fashion.

Preparation and characterization of long-term antibacterial and pH-responsive Polylactic acid/Octenyl succinic anhydride-chitosan @ tea tree oil microcapsules

Encapsulation technology can increase the stability and maintain the volatile active substances of plant essential oils. In the present study, tree essential oil (TTO) was encapsulated with polylactic acid (PLA) modified by octenyl succinic anhydride chitosan (OSA-CS) as shell materials to form long-term antibacterial and pH-responsive microcapsules. The PLA/OSA-CS@TTO microcapsules were characterized by high performance liquid chromatography (HPLC), scanning electron microscopy (SEM) and antibacterial performance testing. The results showed that the average particle size of microcapsules was 10 μm, and the encapsulation efficiency and drug loading efficiency of TTO reached 81.5 % and 60.3 %. After 4800 min of release in media at different pH (5 and 7) still sequestered 55.32 % and 56.74 % of TTO which approved the shell of microcapsules responded to different pH values. The microcapsules remained stable for 80 days after drying, and preserving 39.7 % of the core material. The morphology of PLA/OSA-CS@TTO microcapsules revealed that the PLA/OSA-CS@TTO microcapsules presented smooth and firm structure. Antibacterial test for staphylococcus aureus of those microcapsules implied that the bacteriostatic rate reached 100 % after 72 h. Bio-based macromolecular modification strategies can provide inspiration for the development of green microcapsules.

Novel nano-encapsulated probiotic agents: Encapsulate materials, delivery, and encapsulation systems.

Gut microbes are closely associated with most human health. When ingested orally, probiotics can effectively regulate the composition and quantity of human intestinal microorganisms, which is beneficial to human health. However, probiotics will be affected by the harsh environment of the digestive tract during the in vivo transportation process, and ensuring the viability of probiotics is a great challenge. Probiotic encapsulating technology provides an effective solution to this problem. The introduction of extreme temperatures, large probiotic microcapsule sizes and the difficulty in controlling probiotic microcapsule particle sizes mean that traditional microcapsule encapsulation methods have some limitations. From traditional microcapsule technology to the bulk encapsulation of probiotics with nanofibers and nanoparticles to the recent ability to wear nano "armor" for a single probiotic through biofilm, biological membrane and nanocoating. Emerging probiotic nanoagents provides a new conceptual and development direction for the field of probiotic encapsulation. In this review, we presented the characteristics of encapsulated probiotic carrier materials and digestive tract transport systems, we focused on the encapsulation systems of probiotic nanoagents, we analyzed the shortcomings and advantages of the current agent encapsulation systems, and we stated the developmental direction and challenges for these agents for the future.

Preparation and evaluation of microcapsules containing Rimulus Cinnamon and Angelica Sinenis essential oils

Starch sodium octenyl succinate (SSOS) and maltodextrin (MD) are commonly used as wall materials to protect bioactive compounds, such as essential oils volatiles. In this work, Rimulus Cinamon (RC) and Angelica Sinenis (AS) essential oils (EOs) were encapsulated in (SSOS/MD) composite capsules via spray drying. The microcapsules were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and thermogravimetric (TG). The particle size, Zeta potential, drug loading (DL), encapsulation efficiency (EE), stability and in vitro release of the EOs microcapsules were investigated. The average particle size of microcapsules and emulsion was 12.6 ± 1.09 μm and 0.22 ± 0.01 μm, respectively. The DL% and EE% of microcapsules were 16.3 ± 0.40% and 96.6 ± 1.17%. No phase separation was found in the emulsion within 7 d, and the creaming index was 0%, showing good stability. After 6 months of storage, the retention rate of cinnamaldehyde in the microcapsules was about 67.6%, which significantly improved the stability of EOs. Thus, SSOS/MD can efficiently encapsulate EOs with high drug loading, encapsulation efficiency and stability.

Active Neutralizing Mats for Corrosive Chemical Storage.

Laboratories and industries that handle chemicals are ubiquitously prone to leakages. These may occur in storage rooms, cabinets or even in temporary locations, such as workbenches and shelves. A relevant number of these chemicals are corrosive, thus commercial products already exist to prevent material damage and injuries. One strategy consists of the use of absorbing mats, where few display neutralizing properties, and even less a controlled neutralization. Nevertheless, to the authors’ knowledge, the commercially available neutralizing mats are solely dedicated to neutralizing acid or alkali solutions, never both. Therefore, this work describes the development and proof of a completely novel concept, where a dual component active mat (DCAM) is able to perform a controlled simultaneous neutralization of acid and alkali leakages by using microencapsulated active components. Moreover, its active components comprise food-grade ingredients, embedded in nonwoven polypropylene. The acid neutralizing mats contain sodium carbonate (Na2CO3) encapsulated in sodium alginate microcapsules (MC-ASC). Alkali neutralizing mats possess commercial encapsulated citric acid in hydrogenated palm oil (MIRCAP CT 85-H). A DCAM encompasses both MC-ASC and MIRCAP CT 85-H and was able to neutralize solutions up to 10% (v/v) of hydrochloric acid (HCl) and sodium hydroxide (NaOH). The efficacy of the neutralization was assessed by direct titration and using pH strip measurement tests to simulate the leakages. Due to the complexity of neutralization efficacy evaluation based solely on pH value, a thorough conductivity study was performed. DCAM reduced the conductivity of HCl and NaOH (1% and 2% (v/v)) in over 70%. The composites were characterized by scanning electron microscopy (SEM), differential calorimetry (DSC) and thermogravimetric analysis (TGA). The size of MC-ASC microcapsules ranged from 2 μm to 8 μm. Finally, all mat components displayed thermal stability above 150 °C.