Preparation Of Microcapsules Research Articles

Preparation of Light-Colored Lignosulfonate Sunscreen Microcapsules with Strengthened UV-Blocking and Adhesion Performance

Preparation of Light-Colored Lignosulfonate Sunscreen Microcapsules with Strengthened UV-Blocking and Adhesion Performance

Preparation of ethyl cellulose–glycerol tribenzoate microcapsules in CO2/N2‐switchable hydrophilicity solvent and solvent recycling

AbstractIn this article, a novel method of microcapsule preparation was provided, that is, ethyl cellulose–glycerol tribenzoate microcapsule (EGM) was prepared using CO2/N2 switchable hydrophilicity solvent(N, N‐dimethylcyclohexylamine) combined with an emulsion method. Microcapsules were prepared and solvents were recovered by changing the properties of the solvent. The optimum preparation conditions of EGM were the materials ratio of 20%, the oil–water ratio of 4.5:5.5, emulsifier content of 2%, the Span80‐Tween80 ratio of 1:3, and the core‐shell ratio of 1. The morphology of EGM is spherical, and the particle size can be adjusted from 0.01 μm to 90 μm by controlling the agitation speed in the synthesis process. Surprisingly, the average yield(Y[%]) reached 95.36%, the effective content(W[%]) reached 41%, and the encapsulation rate(E[%]) reached 90.66% of EGM. The solvent recovery rate(SR[%]) of the first recovered is 96.37%. Significantly, this method not only provides a new idea for the preparation of microcapsules but also expands the application field of switchable hydrophilicity solvents, which makes it has great potential application value in the field of microcapsule preparation in the future.

Preparation of Mangosteen Peel Extract Microcapsules by Fluidized Bed Spray-Drying for Tableting: Improving the Solubility and Antioxidant Stability.

Mangosteen fruit has been widely consumed and used as a source of antioxidants, either in the form of fresh fruit or processed products. However, mangosteen peel only becomes industrial waste due to its bitter taste, low content solubility, and poor stability. Therefore, this study aimed to design mangosteen peel extract microcapsules (MPEMs) and tablets to overcome the challenges. The fluidized bed spray-drying method was used to develop MPEM, with hydroxypropyl methylcellulose (HPMC) as the core mixture and polyvinyl alcohol (PVA) as the coating agent. The obtained MPEM was spherical with a hollow surface and had a size of 411.2 µm. The flow rate and compressibility of MPEM increased significantly after granulation. A formula containing 5% w/w polyvinyl pyrrolidone K30 (PVP K30) as a binder had the best tablet characteristics, with a hardness of 87.8 ± 1.398 N, friability of 0.94%, and disintegration time of 25.75 ± 0.676 min. Microencapsulation of mangosteen peel extract maintains the stability of its compound (total phenolic and α-mangosteen) and its antioxidant activity (IC50) during the manufacturing process and a month of storage at IVB zone conditions. According to the findings, the microencapsulation is an effective technique for improving the solubility and antioxidant stability of mangosteen peel extract during manufacture and storage.

Preparation and characterization of microcapsules loaded with polyphenols-enriched Uncaria tomentosa extract using spray-dryer technique

Preparation and characterization of microcapsules loaded with polyphenols-enriched Uncaria tomentosa extract using spray-dryer technique

Preparation and performance of magnetic phase change microcapsules with organic-inorganic double shell

Magnetic microcapsulated phase change materials can achieve rapid magnetic localization temperature regulation and magnetic separation recycling. However, the efficient encapsulation of both inorganic magnetic material and organic phase change material is a challenge due to their poor compatibility. In this work, an aqueous dispersion containing methylol melamine and sodium alginate loaded with magnetic Fe 3 O 4 nanoparticles (SA-Fe 3 O 4 ) was prepared and mixed with a paraffin emulsion. After methylol melamine was initiated to in-situ polymerize at the interface of the paraffin emulsion droplets, primary magnetic phase change microcapsules (P-MPCM) composed of a paraffin core and SA-Fe 3 O 4 /melamine formaldehyde resin composite shell were formed. Then, SiO 2 sol particles were adsorbed on the surface of P-MPCM to form the final MPCM with a polymer-SiO 2 double-shell (PS-MPCM). The magnetic polymer-SiO 2 double-shell endows the PS-MPCM with rapid magnetic responsiveness (can be quickly collected under magnetic fields), high phase change enthalpy (184.4 J·g-1) and excellent structural stability. The phase change enthalpy and saturation magnetization of PS-MPCM have changed little after 200 thermal cycles. At the same time, the excellent photothermal conversion efficiency (93.9%) of PS-MPCM benefits for solar energy conversion utilization in actual application. This work provides a new way to obtain MPCM with high thermal conductivity (0.64 W·m-1·K-1), rapid magnetic response and excellent reusability, which can be potentially applied for directional temperature regulation. Magnetic polymer-SiO 2 double-shell phase change microcapsule (PS-MPCM) was prepared. PS-MPCM exhibits high encapsulation ratio of paraffin and Fe 3 O 4 nanoparticles (NPs). Sodium alginate was introduced to achieve efficient and stable loading of Fe 3 O 4 NPs. PS-MPCM exhibits excellent thermal conductivity, magnetic response and reusability. PS-MPCM can be potentially applied for magnetic localization temperature regulation.

Preparation and Characterization of Polystyrene Microcapsule Containing Phase Change Material by Volatile Exchange Impregnation

Preparation and Characterization of Polystyrene Microcapsule Containing Phase Change Material by Volatile Exchange Impregnation

Preparation and Characterization of Electromagnetic-Induced Rupture Microcapsules for Self-Repairing Mortars.

Cement-based materials are susceptible to internal cracks during service, leading to a reduction in their durability. Microcapsules can effectively self-repair cracks in cement-based materials. In this study, novel electromagnetic-induced rupture microcapsules (DWMs) were prepared by using the melt dispersion method with Fe3O4 nano-particles/polyethylene wax as the shell and epoxy resin as the repairing agent. The core fraction, compactness, particle size distribution, morphology, and chemical structure of DWMs were characterized. DWMs were subsequently incorporated into the mortar to measure the pore size distribution, compressive strength recovery, and maximum amplitudes of the pre-damaged mortar after self-repairing. DWMs were also evaluated for their ability to self-repair cracks on mortar surfaces. The results showed that the core fraction, remaining weight (30 days), and mean size of DWMs were 72.5%, 97.6 g, and 220 μm, respectively. SEM showed that the DWMs were regular spherical with a rough surface and could form a good bond with cement matrix. FTIR indicated that the epoxy resin was successfully encapsulated in the Fe3O4 nano-particles/polyethylene wax. After 15 days of self-repairing, the harmful pore ratio, compressive strength recovery, and maximum amplitude of the pre-damaged mortars were 48.97%, 91.9%, and 24.03 mV, respectively. The mortar with an initial crack width of 0.4–0.5 mm was self-repaired within 7 days. This indicated that the incorporation of DWMs can improve the self-repair ability of the mortar. This work is expected to provide new insights to address the mechanism of microcapsule rupture in self-repairing cement-based materials.

Microencapsulation of Olive Oil

Olive oil has been received a great importance around the globe because it provides unique functional value. Olive oil prevents the risks of several chronic and acute metabolic disorders because it is enriched with monounsaturated fatty acids, antioxidant phenolic compounds, vitamin E and vitamin K. Unfortunately, oxidative deterioration of fatty acids in olive oil provides short shelf life and reduces biological activities. It is responsible for undesirable organoleptic properties. It may belief that one of the solutions to preserve the quality of olive oil is microencapsulation. In this review, comprehensive information about techniques to prepare olive oil microcapsule is represented. To prepare olive oil microcapsule, emulsification of olive oil with different wall materials (matrixes) has been adopted as a primary step. Subsequently, dehydration of emulsion by spray drying or freeze drying or coacervation process has been adopted to prepare olive oil microcapsule. Moreover, microcapsule of olive oil has been prepared by extrusion technology. Biopolymers, such as proteins and polysaccharides have been used as wall material for encapsulation of olive oil. As stable emulsification is one of important issue to produce microcapsule, several emulsifiers, such as lecithin, tween 20 have been used during emulsion preparation. Different characteristics of the microcapsule of olive oil are summarized because it is influenced by several factors during preparation of microcapsule. In later exercise, several applications of encapsulated olive oil in food, pharmaceutical and cosmetic industries are represented in comprehensive way. It may expect that this review article will receive attention in industries and academic sectors.

One-step emulsification for controllable preparation of ethyl cellulose microcapsules and their sustained release performance

A simple and versatile strategy for controlled production of monodisperse ethyl cellulose (EC) microcapsules by a single-stage emulsification method has been developed. Monodisperse oil-in-water emulsions, obtained by a microfluidic device, are used as templates for preparing EC microcapsules. Oil-soluble ethyl acetate (EA) is miscible with water, so the interfacial mass transfer between EA and water occurs sufficiently, which leads to water molecules pass through the phase interface and diffuse into emulsion interior. Water molecules aggregate at the interface, and some merge into a large water drop in the central position of the emulsion. After evaporation of EA solvent, monodisperse EC microcapsules create large numbers of pits on the surface with a hollow structure. Curcumin is used as a model drug and embedded in the hollow structure. EC microcapsules have good, sustained drug release efficacy in a simulated intestinal environment, and the release process of EC microcapsules containing 6.14% drug-loaded capacity is fully consistent with the vitro drug release model. Such simple techniques for making EC microcapsules may open a window to the controlled preparation of other multifunctional microcapsules. Besides, it offers theoretical guidance for the study of EC microcapsules as drug carriers and expanding clinical application of curcumin.

Cover Image, Volume 139, Issue 25

This cover image designed by Di Zhao and Huiqin Liu delineates the preparation of functional silk fibers (SFs) by microencapsulation technology. This review describes the principles and techniques for the preparation of functional microcapsules. Functional SFs can be obtained by microcapsule finishing and printing technology, and even by electrospinning based on silk fibroin solution. Functional silk fibroin nanofibers have great promise for biomedical applications. DOI: 10.1002/app.52351

Preparation, Morphology and Release of Goose Liver Oil Microcapsules.

Goose liver oil (GLO) microcapsules were prepared by konjac glucomannan (KGM) and soybean protein isolate (SPI) for the first time as wall materials. The GLO could be effectively encapsulated, with an encapsulation efficiency of 83.37%, when the ratio of KGM to SPI was 2.9:1, the concentration of the KGM-SPI composite gel layer was 6.28% and the ratio of the GLO to KGM-SPI composite gel layer was 1:6. Fourier transform infrared spectroscopy and X-ray diffraction methods showed electrostatic interactions between KGM and SPI molecules and the formation of hydrogen bonds between the GLO and KGM-SPI wall components. The results of scanning electron microscopy showed a smooth spherical surface morphology of the microcapsules with a dense surface and no cracks. The confocal laser scanning microscopy showed that the microcapsules were homogeneous inside and no coalescence occurred. The encapsulated GLO has a significantly higher thermal and oxidative stability compared to free GLO. In the in vitro digestion experiment, 85.2% of the microcapsules could travel through gastric juice, and 75.2% could be released in the intestinal region. These results suggested that microcapsules prepared by KGM-SPI might be used as a carrier for the controlled release of GLO and could microencapsulate various oil-soluble nutrients in food products.

Preparation of core-shell microcapsules based on microfluidic technology for the encapsulation, protection and controlled delivery of phycocyanin

Phycocyanin (PC) is a naturally active protein with extensive potential physiological functions. However, the poor stability and low bioavailability of PC have limited its development in nutraceuticals. Therefore, we developed an efficient microfluidic device to fabricate core-shell microcapsules for PC entrapment and colonic delivery. Microfluidics utilizes microchannels and fluid flow rates to shear mutually incompatible fluids to form dispersed emulsion droplets, providing an opportunity to investigate the structure and size of emulsions and precisely control the production of emulsion droplets. By introducing intermolecular interactions, PC was effectively immobilized in the cavity of the inner core sodium alginate (SA) gel, ensuring a high encapsulation efficiency of up to 98% for SA-E microcapsules. The release effects of microcapsules with different wall thicknesses were evaluated by simulating gastrointestinal juice digestion experiments. The results revealed that the microcapsules with 20–30 μm wall thickness were more stable and had superior release performance in gastrointestinal fluid compared with the microcapsules with 10 and 50 μm wall thickness. In addition, after the simulated digestion process in artificial gastrointestinal fluid, the PC embedded in SA-E microcapsules still remained the same structure and exhibited good antioxidant and immunomodulatory activities. The enhanced stability and bioavailability of PC suggested that SA-E microcapsules can be used for PC entrapment and colonic delivery.

Preparation of Tung Oil Microcapsule and Its Effect on Wood Surface Coating.

Through the optimized preparation of tung oil microcapsules, five kinds of microcapsules containing different core material content were obtained to explore the influence of microcapsules on water-based paint film and the self-healing ability of microcapsules. The results showed that the microcapsules had good appearance, and the microcapsules were successfully prepared. The color difference in the paint film increased with the increase in microcapsule content, and the gloss decreased gradually. The mechanical test showed that adding microcapsules increased the toughness of the paint film to a certain extent, and the performance of the paint film was unchanged or better. The results showed that paint film with the core–wall ratio of 0.78:1 had the best performance and self-healing function when microcapsules were added.

Evaluation of Microencapsulated Essential Oils in Broilers Challenged with Salmonella Enteritidis: A Focus on the Body's Antioxidant Status, Gut Microbiology, and Morphology.

Restrictions on antibiotic use encourage researchers to seek natural substitutes with the same effects without adverse end effects resulting from antibiotic use. Savory and black pepper have been challenged against <i>Salmonella enteritidis</i> (<i>S. enteritidis</i>) bacterium using the spray dryer method to evaluate growth performance, antioxidant status, immune response, and intestinal health parameters in broilers. In this study, thyme essential oil (50%), savory (25%), peppermint (12.5%), and black pepper seeds (12.5%) were mixed to form essential oil-loaded spherical microcapsules with the particle size of 323 nm and encapsulation efficiency of 96.2%. The main bioactive compounds used in the core of microcapsules included thymol, carvacrol, p-cymene, γ-terpinene, and menthol. Moreover, modified starch (25%) and maltodextrin (55%) were used for the preparation of spherical microcapsules for the enclosed wall with 20% whey protein concentrate. The dietary addition of microcapsules containing essential oil significantly reduced the <i>S. enteritidis</i> population in both ileum and cecum (<i>P</i>&lt;0.05). The results revealed that the dietary inclusion of essential oil-loaded microcapsules significantly (<i>P</i>&lt;0.05) increased the villus height, villus width, V: C ratio, and the number of goblet cells and decreased the crypt depth. Microcapsules have antioxidant and antibacterial activity and their dietary use as feed additive at 0.5, 1, and 2 kg/t concentrations in broilers has been challenged and showed that the final weight, total feed intake, and FCR improved the body's antioxidant status, structure, and inflammation in the ileum tissue.

Preparation of Thermochromic Microcapsules of Bisphenol A and Crystal Violet Lactone and Their Effect on Coating Properties.

Thermochromic microcapsules were prepared with a thermochromic compound as core material and urea formaldehyde as wall material. The molar ratio of urea and formaldehyde, the mass ratio of core material to wall material, the concentration of emulsifier, and rotating speed were selected to make a four-level and three-factor L9(34) orthogonal test. It was found that the molar ratio of urea and formaldehyde had the greatest influence on the coating rate of microcapsules. The effects of molar ratio of urea and formaldehyde on the discoloration temperature and coating rate of microcapsules were studied. When the molar ratio of urea to formaldehyde was 1:1.6, the core material: wall material ratio was 4:7, the concentration of emulsifier was 5.0%, and the rotating speed was 1600 rpm, the performance of the microcapsules was the best. When the microcapsule content was 20.0%, the color difference of the paint film was the largest, the gloss and hardness of the paint film decreased with increasing microcapsule content, and the impact resistance of the paint film first increased and then decreased with increasing microcapsule content. The adhesion of the paint film remained unchanged, and was grade 1. When the microcapsule content was 20.0%, the performance of the paint film was at its best. This provides a basis for the application of thermochromic coatings.

Octaphenyl polyoxyethylene regulates the flexibility of pyraclostrobin-loaded soft microcapsules by interfacial polymerization for better foliar adhesion and pesticide utilization

In the preparation of microcapsules (MCs) by interfacial polymerization, octaphenyl polyoxyethylene (OP) is utilized as an emulsifier to control the particle size distribution of MCs. In the preparation system with polyisocyanate as the oil phase monomer, OP has a single hydroxyl (–OH) group that can react with the isocyanic group (–CNO) to prevent polymerization, and the aggregation of OP at the oil–water interface affects the polymer configuration. By the “steric hindrance” and “polymer chain end sealing” of OP, the compactness of the shells was reduced significantly to produce soft MCs. As OP-10 was added and used to increase in pyraclostrobin-loaded MCs preparation, the deformation, adhesion and release of pyraclostrobin-loaded MCs were improved. Therefore, the water scouring resistance of MCs on peanut leaves increased significantly as the MCs became soft. Unfortunately, the safety of zebrafish (Danio rerio) declined at the same time. By foliar spraying to control peanut leaf spot in the rainy season, MCs-2% OP-10, with the strongest resistance to rainfall, had the best effect on disease control. In conclusion, an effective strategy is to balance the foliar application efficiency and ecotoxicity of pesticide-loaded MCs by regulating the compactness and components of shells to control their deformation, adhesion and pesticide release.

Preparation and application of the novel resin microcapsules in self-repairing cement composites with polypropylene fibers

According to this article, the novel, highly absorbent, resin microcapsules prepared by the sharp hole-bath method, together with the polypropylene fibers, were used in the cementitious materials, with an aim to study the impacts of the dosage of polypropylene fibers, the mass fraction of microcapsules and the curing age on the strength of mortar and its self-repair effect. The uniaxial compression test and the permeability test were also applied to evaluate the mechanical properties of specimens and the self-repair effect of cracks. The results showed that when the amount of microcapsules is 1.5% and the amount of polypropylene fibers is 0.17%, the specimen reaches its peak strength, meanwhile the microcapsules have no negative effect on its initial compressive strength. When the amount of microcapsules is 0.75% and the amount of polypropylene fibers is 0.17%, the strength repair rate and the seepage repair rate of cement-based materials reach the best. In addition, the strength repair rates showed that, compared with the single addition of microcapsules, the ‘bridging effect’ of polypropylene fibers could help microcapsules better complete the crack self-repair work.

Stable Cellulose Nanofibril Microcapsules from Pickering Emulsion Templates.

Electrostatic attractions are essential in any complex formation between the nanofibrils of the opposite charge for a specific application, such as microcapsule production. Here, we used cationized cellulose nanofibril (CCNF)-stabilized Pickering emulsions (PEs) as templates, and the electrostatic interactions were induced by adding oxidized cellulose nanofibrils (OCNFs) at the oil–water interface to form microcapsules (MCs). The oppositely charged cellulose nanofibrils enhanced the solidity of interfaces, allowing the encapsulation of Nile red (NR) in sunflower oil droplets. Microcapsules exhibited a low and controlled release of NR at room temperature. Furthermore, membrane emulsification was employed to scale up the preparation of microcapsules with sunflower oil (SFO) encapsulated by CCNF/OCNF complex networks.

Preparation of Codonopsis pilosula polysaccharide microcapsules and its effect and mechanism on skin wound healing in rats.

In this study, after optimizing the extraction process of CPP (Codonopsis pilosula polysaccharides), CPPM (CPP microcapsules) were prepared. Subsequently, the structural characteristics and physicochemical properties were studied. The results showed that CPPM is a hollow sac-like structure with rough folds and protuberances and comes in spherical or ellipsoidal shapes with uniform particle size. CPPM has certain swelling degree, low hardness, good adhesion, and stability. Then, the effect of CPPM on wounds repair was investigated by a rat model. The results showed that CPPM could improve the wound healing rate. Histological evaluation showed CPPM could promote neovascularization and fibroblast proliferation. By investigating the healing mechanism, it was found that CPPM increased the hydroxyproline content in granulation tissue and had an excellent antioxidant ability, and then inhibited lipid peroxidation, in addition, it significantly increased the transcript levels of VEGF and miRNA-21 genes, indicating that CPPM play an influential role in vascular remodeling during wound healing by up-regulating the expression of VEGF and miRNA-21 genes.

One-pot efficient preparation of microcapsules based on photopolymerization for self-healing coatings

Self-healing microcapsules are currently one of the most promising functional materials due to their excellent performance. The preparation of self-healing microcapsules via photopolymerization is quite attractive considering its efficiency and environmental-friendliness. However, the influence of the preparation process and shell-formation materials on the formation and the morphology of microcapsule have not been systematically researched. This work combines photopolymerization technology and solvent evaporation to prepare microcapsule, and comprehensively explores the influence of process conditions and shell-formation materials on the microcapsules. Two preparation processes, UV-SR (photopolymerization first and then solvent removal) and SR-UV (solvent removal first and then photopolymerization), have been employed to prepare microcapsules. The SR-UV method is more suitable for preparing microcapsules with high core content and spherical core-shell morphology. The particle size distribution of microcapsules is related to the shear strength during initial emulsion preparation, and the size of microcapsules can be effectively controlled. At the same time, the effect of the shell-formation materials is also systematically studied. The method is universal for the preparation of microcapsules based on commercial UV-curable prepolymers, but the introduction of UV-curable monomers may lead to the transformation of microcapsules from core-shell structure to multi-core structure. Microcapsules can be uniformly dispersed in water-borne epoxy, and the coating based on microcapsules exhibits excellent self-healing properties.