Formation Of Microcapsules Research Articles

Facilitated synthesis and thermal performances of novel SiO2 coating Na2HPO4⋅7H2O microcapsule as phase change material for thermal energy storage

Novel microencapsulated phase change material (MEPCM) with SiO2 coating Na2HPO4⋅7H2O were synthesized by one-pot method. A possible formation mechanism of Na2HPO4⋅7H2O core and SiO2 shell was preliminarily analyzed. The morphology, composition, crystalline phase and thermal performances of the synthesized MEPCM was characterized by scanning electron microscopies (SEM), Transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetry analysis (TG) and thermal constants analyzer. Preliminary analysis indicated that the Na2HPO4⋅7H2O nanocrystals as the core was obtained by anti-solvent process with partially dehydration (loss of five crystal water molecules) from Na2HPO4⋅12H2O, and the SiO2 as the shell was formed by sol-gel method with hydrolysis and condensation of tetraethyl orthosilicate. Analysis results of FT-IR and XRD illuminated that only physical interaction occurred between the SiO2 shell and the Na2HPO4⋅7H2O core in the MEPCM. The results of SEM and DSC showed that the synthesized MEPCM displayed a flat cylinder structure and the particle size of about 8 μm, and exhibited a phase change temperature of 50.12 °C, latent heat of 159.8 kJ/kg and encapsulation ratio of 82.40%. Moreover, the formation of the phase change microcapsules could reduce the supercooling of Na2HPO4⋅7H2O to some degree and the MEPCM displayed a suitable thermal conductivity (0.3838 W/m⋅K) and an excellent thermal stability. The thermal properties of the MEPCM make it suitable for solar energy storage.

Study on thermal storage properties of microencapsulated organic ester as phase change material for cooling application

ABSTRACT The phase change materials (PCMs) are latent thermal energy storage materials to store and release energy in the form of latent heat with a change in internal energy. The microencapsulation technique overcomes the limitations faced by the PCMs during energy storage and release. In this study, the new ester-based non-paraffin PCM was microencapsulated into an organic shell using in-situ polymerisation technique. The as-prepared MPCMs was characterised using the field emission electron microscope (FESEM), fourier transform Infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) techniques. The results show that the MPCM characterised using FESEM has exhibited a good morphology. The chemical stability studies carried using FTIR spectroscopy also confirmed the formation of microcapsules was only by physical interaction. The DSC test results also signify that microcapsules have a latent heat of enthalpy of 65.32 kJ/kg, with onset melting temperature of 8.57°C. Thus, this ensures the MPCM to be considered as a potential candidate for the CTES application.

Formation of wax walled microcapsules via double emulsion using cross membrane emulsification at elevated temperatures

A novel micro encapsulation process has been developed via a double emulsion of water in oil in water, whereby the oil is molten during the process and is then solidified to form a solid wall afterwards. This has the potential for an improved encapsulation technique for hydrophilic components. A range of materials was used, including hexadecane, lanolin and cetyl palminate. Temperature controlled, cross membrane emulsification was used to ensure a narrow size distribution. Calculations of permeability, based on the leakage of fluorescein solutions, indicated a much higher rate that would be expected from such a hydrophobic, crystalline wall. Faster cooling gave rise to higher permeability. These suggest that pores are forming in thin walls during the solidification process and indicate the importance of process conditions on wall formation. Osmotic pressure differences are also a potential contributor.

Exploring the mechanism of hollow microcapsule formation by self-assembly of soy 11s protein upon heating

This study investigates the phenomenon of hollow microcapsule formation through simple heat treatment of soy 11s protein solution. Microscopies were used to monitor the morphological changes of proteins in the aqueous phase during fabrication; the corresponding changes in zeta potential, protein solubility and composition were examined. In the presence of 0.05 M sodium chloride, the 11s protein self-assembled into irregular flocs, which transformed into microgels or hollow microcapsules upon heating at 80 °C for 20 min. The key protein flocs-microcapsule transformation occurred within the first 60 s of heating and the microcapsules formed their perfect hollow spherical structure in 4 min of heating. A mechanism was proposed to describe the hollow structure formation in microcapsules. The samples with protein concentration of 2 g/L had more microgels formed, while those with 5 and 10 g/L protein was mainly composed of hollow microcapsules. It was found that as the particle radius approached the wall thickness, microgels formed instead of microcapsules.

Laser-induced carbon nanotube microcapsules formation through depletion enhanced deposition

We report a method to fabricate carbon nanotube (CNT) microcapsule through laser-induced bubble formation in a polyethylene glycol-modified CNT (PEG-CNT) solution in the presence of PEG. A low-power laser is focused on a heat-absorbing surface to create a bubble. While PEG-CNTs in the solution are deposited on the bubble surface to form a microcapsule. The shape stability of microcapsule during swelling process is measured in different concentrations of PEG solutions. The stable CNTs microcapsules form with uniform spherical shape within 8 seconds in a 2% PEG solution, while PEG-CNTs only randomly aggregate without the presence of PEG molecules. Thus, we propose that the deposition of PEG-CNTs is enhanced by PEG molecules due to depletion interaction. Comparing with other methods, assembling PEG-CNTs microcapsules at liquid-air interface of polymer solution by optical heating greatly reduce the time and provide good quality of CNTs microcapsules. This study may enable applications of PEG-CNTs microcapsules.

Encapsulation of Bioactive Ingredients by Extrusion with Vibrating Technology: Advantages and Challenges

Bioactive ingredients are present in functional foods and provide benefits to consumer health. However, for these compounds to be effective in the human organism, their bioactive features must be preserved during food processing and uptake by the organism. An effective technology to maintain bioactivity is encapsulation, which uses a coating material to protect bioactive ingredients. Not all encapsulation techniques are suitable for the effective protection of bioactive ingredients due to stages in the technique that might damage the bioactivity of the encapsulated ingredient. However, extrusion with vibrating technology has proven to be a technique with simple stages, thus enabling the formation of resistant microcapsules and maintaining the bioactivity of the encapsulated material. The aim of this revision is to show the state of the art on protection of bioactive ingredients using the encapsulation process by extrusion with vibrating technology. Therefore, the characteristics of vibrating technology in encapsulation by extrusion shall be addressed as well as the wall materials used, highlighting the features of the microcapsules obtained. For that, recent studies that have used the method in question specifically to protect bioactive ingredients will be discussed. Vibrating technology associated with extrusion, combined with a previous determination of parameters of suitable equipment and wall materials, allows for obtaining homogenous-sized and shaped microcapsules which provide effective protection to the bioactive compound.

Microcapsule and polymer reinforcement techniques developed asphalt for use of pothole repairs in winter and rainy seasons

This paper proposes a new Polymer Modified Asphalt (PMA) for cold mixtures used to patch potholes in the adverse weather conditions of low temperature and rain. The new PMA is based on the microcapsules and polymer reinforcement techniques. Test results of the PMA binder found that the PMA improved the performance of the asphalt in low temperature and improved the adhesion of the cold mixtures by importing corresponding foundational groups. For example, the conjugated olefinic bond was used in the microcapsule formation and polybutadiene was used to improve the performance in low temperature as compared with the matrix asphalt and terpene resin cutback asphalt (TRCA). The modifier and adhesive stored in the microcapsules were distributed evenly in the asphalt. Test results of the cold mixtures verified that the PMA mixtures had a better performance than the TRCA mixtures, involving cohesion, stability and freeze-thaw resistance. Field surveys taken over 12 months indicated that the pothole patches filled with the PMA patching materials met the requirement for ride-ability and traffic safety standards. Therefore, it is concluded that the PMA is an adequate asphalt binder for pothole repairs in cold temperature and wet conditions.

Effect of the Reaction Volume on the Microencapsulation of Pequi (caryocar Coriaceum Wittm.) Oil by Complex Coacervation

The oil from Pequi pulp, also known as pequi oil (PO) is a promising bioactive for the food industry, and complex coacervation is a simple encapsulation method to improve its stability and use as a food ingredient. The high reaction volume used is considered a challenge to microcapsule production by coacervation process. Therefore, the objective of this study was to evaluate the effect of the reaction volume on the formation, morphology, size, yield, and efficiency of pequi microcapsules. The complex coacervation was performed with wall material composed by polymers (gelatin and gum arabic) and pequi oil as the core material. The oil was mixed with gelatin, added the polysaccharide and pH was adjusted to 3.5, to allow the microparticle formation. The reaction volume treatments T1, T2, T3, and T4, related to wall material concentration, were 0.39, 0.77, 0.58, and 1.16 g 100 mL-1, respectively. The results of zeta potential were close to zero, without differences related to the reaction volume. Optical microscopy showed that, regardless of volume, microparticles of pequi oil presented defined walls, mononuclear core and particle size from 2.71 up to 7.27 µm, adequate for food application. In a smaller reaction volume (T1 and T3), the coacervates were aggregated due to the increase of the chemical interactions; in higher volumes (T3 and T4) the microcapsules showed an inverse behavior. The yield ranged from 58.40 up to 63.42 %. The encapsulation efficiency exhibited high values ??ranging from 90.05% ± 8.15 to 99.40% ± 0.21. The variation of reaction volume did not influence the formation of pequi oil microcapsules in the analyzed treatments, but the dispersion of the microcapsules changed. This study provided a new perspective on how the reaction volume influences the encapsulation by complex coacervation.

Bioinspired oral insulin delivery system using yeast microcapsules

Type 1 diabetes mellitus (DM) is a metabolic disorder associated with impaired carbohydrate metabolism. We present a promising bioinspired approach against type 1 DM using yeast microcapsule (YMC). The glucan component in the outer shell of baker's yeast undergoes receptor-mediated uptake by phagocytic cells through M cell-mediated endocytosis. Thus, a drug can be expected to be delivered to the systemic circulation via lymphatic transport if it is attached to the surface of YMC. For the first time, this possibility has been explored by surface loading of insulin onto YMC. The electrostatic interaction between oppositely charged YMC and insulin resulted in the formation of insulin-loaded yeast microcapsule (IYMC) which was confirmed by fluorescence imaging. Alginate coating provided to IYMC protects YMC from the harsh environment of the gastrointestinal tract and prevents the degradation of insulin in IYMC. Cellular uptake of FITC conjugated IYMC by RAW macrophages confirmed the proposed mechanism of insulin uptake. Moreover, an in vitro method using YMC-imprinted gel was developed for insulin release study from the bioinspired system. Molecular docking studies proved the interaction of insulin with β-glucan and alginate. A significant hypoglycemic effect was observed after oral administration of the alginate coated insulin-loaded yeast microcapsule (AL-IYMC) in diabetic rats. The AL-IYMCs could serve as a promising approach towards the oral delivery of insulin.

Electrodeposition of Ginseng/Polyaniline Encapsulated Poly(lactic-co-glycolic Acid) Microcapsule Coating on Stainless Steel 316L at Different Deposition Parameters.

Electrodeposition is commonly used to deposit ceramic or metal coating on metallic implants. Its utilization in depositing polymer microcapsule coating is currently being explored. However, there is no encapsulation of drug within polymer microcapsules that will enhance its chemical and biological properties. Therefore, in this study, ginseng which is known for its multiple therapeutic effects was encapsulated inside biodegradable poly(lactic-co-glycolic acid) (PLGA) microcapsules to be coated on pre-treated medical grade stainless steel 316L (SS316L) using an electrodeposition technique. Polyaniline (PANI) was incorporated within the microcapsules to drive the formation of microcapsule coating. The electrodeposition was performed at different current densities (1-3 mA) and different deposition times (20-60 s). The chemical composition, morphology and wettability of the microcapsule coatings were characterized through attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM) and contact angle analyses. The changes of electrolyte colors, before and after the electrodeposition were also observed. The addition of PANI has formed low wettability and uniform microcapsule coatings at 2 mA current density and 40 s deposition time. Reduction in the current density or deposition time caused less attachment of microcapsule coatings with high wettability records. While prolonging either one parameter has led to debris formation and melted microcapsules with non-uniform wettability measurements. The color of electrolytes was also changed from milky white to dark yellow when the current density and deposition time increased. The application of tolerable current density and deposition time is crucial to obtain a uniform microcapsule coating, projecting a controlled release of encapsulated drug.

Fabrication and characterization of microcapsule encapsulating EOR surfactants by microfluidic technique

During the process of enhanced oil recovery (EOR), surfactants are injected underground in order to draw more oil from the reservoir. Surface active agent molecules, however, can be easily absorbed by the pore surface of the reservoir rock, causing a massive waste. This paper introduces a novel method for designing a type of microcapsule loading EOR surface activator to solve the absorption problem for surfactants injection. The approach employs microfluidic technique to generate O/W/O double emulsion templates that can be used to fabricate hollowed microcapsules coupled with free radical polymerization. Factors including emulsifier concentrations, flow rates, viscosities and densities of the inner, middle and outer fluids which can affect the formation and morphology of emulsions and microcapsules have been systematically investigated and optimized as well. Additionally, morphological analysis confirms that the as-prepared monodisperse microcapsule has the capacity of encapsulating surfactant molecules owing to its hollowed structure. Finally, the diffusion permeability of the prepared microcapsules is examined, indicating that permeability of the microcapsule membrane can be controlled by adjusting the thickness and cross-linking degree of the microcapsule membrane. Overall, this study provides controllable and versatile preparation for this kind of microcapsule with potential in the field of enhanced oil recovery. The results can also provide valuable guidance for further investigation regarding the “smart” controllable release of EOR surface active agent.

Preparation of high performance copolymer microcapsule encapsulated heat storage material without supercooling

ABSTRACTThe methyl methacrylate (MMA)-based copolymer microcapsules encapsulating Rubitherm®27 (RT27) used as a phase change material were successfully prepared by microsuspension polymerization. The influence of three types of crosslinked comonomers such as ethylene glycol dimethacrylate), trimethylolpropane trimethacrylate, and divinylbenzene (DVB) on the microcapsule formation was studied at various ratios of MMA:crosslinked comonomer. It was found that using MMA:DVB at 70:30 wt% was the optimum ratio. The obtained microcapsules were nonspherical in shape with a dent and high shell strength. In addition, the latent heats of melting and crystallization of the encapsulated RT27 were about 140 J/g-RT27 which were close to those of the original RT27. However, the crystallization temperatures (Tc) of the encapsulated RT27 (14°C) were lower than that of the original RT27 (25°C) which was called supercooling. To prevent supercooling, the effect of nucleating agents (emulgen 150, 1-octadecanol, and RT58) on decreasing supercooling of the encapsulated RT27 was investigated. The results clearly presented that the addition of at least 5 wt% of RT58 significantly increased Tc (25°C) of the encapsulated RT27, whereas the observed latent heats were pretty close to original RT27.

Encapsulation of linseed oil in graphene oxide shells for preparation of self-healing composite coatings

Self-healing microcapsules were filled with a glue-like chemical that can repair damage and recover the original functions of materials. Graphene oxide (GO) was employed as the stabilizer of Pickering emulsions, and then the microcapsule shells were built upon the self-assembly of GO at oil/water interfaces. Linseed oil was encapsulated in the microcapsules as the healing agent. Several important factors were studied that affected the stabilization of the Pickering emulsions and the formation of the integral microcapsules, such as the pH value of GO aqueous solution, the GO/linseed oil mass ratio and the effect of surfactant. Chemical stitching of GO sheets by polyetheramine molecules were employed to enhance the chemical stability of the microcapsules. The waterborne polyurethane (PU) composite coatings containing 10 wt% microcapsules autonomously healed a scratch with 20 μm in width. After healing, the impedance modulus of the composite coatings was four orders of magnitude higher than neat PU.

All-Aqueous-Phase Microfluidics for Cell Encapsulation.

Cell-laden hydrogel microcarriers are widely used in diverse biomedical applications like three-dimensional (3D) cell culture, cellular therapy, and tissue engineering, where microcarriers were generally produced by oil, which is the common but not optimal choice, as oil may cause cytotoxicity or protein denaturation. Here, an all-aqueous-phase microfluidics is presented to achieve oil-free emulsification of cell-laden microcapsules and 3D cell culture. Aqueous solutions with different concentration gradients are used as an immiscible continuous phase and a dispersed phase, and oscillation from a solenoid valve facilitates the formation of microcapsules at the water-water interface. By adjusting aqueous-phase flow rates and oscillating frequencies, core-shell microcapsules with controllable structures can be stably and continuously generated. In further 3D cell culture, encapsulated cells maintained good viabilities and aggregated together. These features show that the oil-free microfluidic method may have broad prospects in many biomedical applications.

Microfluidic Formation of Hydrogel Microcapsules with a Single Aqueous Core by Spontaneous Cross-Linking in Aqueous Two-Phase System Droplets.

We report a simple process to fabricate monodisperse tetra-arm poly(ethylene glycol) (tetra-PEG) hydrogel microcapsules with an aqueous core and a semipermeable hydrogel shell through the formation of aqueous two-phase system (ATPS) droplets consisting of a dextran-rich core and a tetra-PEG macromonomer-rich shell, followed by a spontaneous cross-end coupling reaction of tetra-PEG macromonomers in the shell. Different from conventional techniques, this process enables for the continuous production of hydrogel microcapsules from water-in-oil emulsion droplets under mild conditions in the absence of radical initiators and external stimuli such as heating and ultraviolet light irradiation. We find that rapid cross-end coupling reaction of tetra-PEG macromonomers in ATPS droplets in the range of pH from 7.4 to 7.8 gives hydrogel microcapsules with a kinetically arrested core-shell structure. The diameter and core-shell ratio of the microcapsules can be easily controlled by adjusting flow rates and ATPS compositions. On the other hand, the slow cross-end coupling reaction of tetra-PEG macromonomers in ATPS droplets at pH 7.0 and lower induces structural change from core-shell to Janus during the reaction, which eventually forms hydrogel microparticles with a thermodynamically stable crescent structure. We believe that these hydrogel microparticles with controlled structures can be used in biomedical fields such as cell encapsulation, biosensors, and drug delivery carriers for sensitive biomolecules.

Ionic Liquid Microcapsules: Formation and Application of Polystyrene Microcapsules with Ionic Liquid Cores

The synthesis of 2–3 μm spherical microcapsules with a polymer shell and a liquid core composed of ionic liquid (IL) ([Bmim][NTf2]) is described. These discrete IL microcapsules are prepared quickly and in large quantity in a low temperature, one pot synthesis, by a modified coacervation technique. These IL microcapsules show ability to release dye from the IL core into solution through a polymer membrane and also concentrate metal ions from solution into the microcapsules.

Determination of optimal ultrasound conditions for preparation of O/W emulsions with encapsulated juniper berry essential oil (Juniperus communis L.)

The microencapsulation of essential oils can provide their evaporation and oxidation protection, flavor retention or/and masking of unpleasant taste. The microencapsulation process involves emulsions preparation and drying of the obtained emulsion droplets. The aim of this study is the determination of optimal conditions for preparation of the stable O/W emulsions containing juniper berry essential oil with minimal droplet size, as a preparatory stage for microcapsule formation. As the first step for pre-emulsions preparation, homogenization at 10000 rpm for 5 min. was chosen, which gave emulsions with droplet size between 1.82 and 2.51?m, depending on concentrations of the surfactant (Tween 20) and encapsulated essential oil. The second step was ultrasound emulsification during 5 minutes at a frequency of 99%, using pulsed 10:10 s (ON/OFF) ultrasound treatment, which was chosen as an optimal, creating emulsions of droplet sizes of 320 nm in diameter (for 5% essential oil and 1% Tween 20). The addition of wall material changed the size and stability of emulsions, which depends on type of biopolymer and its surface competition with used surfactant. The maltodextrin (MD), gum arabic (GA) and their mixture in equal ratio were used. GA emulsions can be singled out as the most stable without used surfactant, with D4,3 = 1.11 ? 0.003 ?m. Using MD as a wall material requires addition of surfactant (1% w/v) to form stable emulsions. The mixture of MD/GA can be used with or without surfactant. The addition of Tween 20 (1% w/v) decreases droplet size from 14.86 to 0.99 ?m, while utilization of the ultrasound contributes to the droplet size decrease and emulsions stability.

Microencapsulation of lactase by W/O/W emulsion followed by complex coacervation: Effects of enzyme source, addition of potassium and core to shell ratio on encapsulation efficiency, stability and kinetics of release

This study evaluated the technological viability of the formation of lactase microcapsules by coacervation (gelatin/gum arabic) containing potassium ions (cofactor). The impacts of the encapsulation and the cofactor on the enzyme properties obtained from Aspergillus oryzae and Kluyveromyces lactis were evaluated as a function of different pH values, temperatures, and storage times. The best microcapsules formed by coacervation showed good functional properties, such as low water activity (≤ 0.4) and particle size (≤ 93.52 μm), as well as high encapsulation efficiency (≥ 98.67%). The potassium ions were capable of reducing the flexibility of the polypeptide backbone, thereby increasing the stability of the enzyme. The microcapsules were also capable of increasing the stability of the enzyme under unfavorable pH values, high temperatures and during storage. An in vitro experiment showed that microcapsules were effective in the retention of about 90% of the enzyme in simulated gastric fluid, but as much as 95% of the enzyme can be released from the capsules in simulated intestinal fluid. The released enzyme retained 83% and 66% of the total enzymatic activity for the capsules produced with lactase from Kluyveromyces lactis and A. oryzae, respectively. These results are promising and demonstrated that these microcapsules are a promising technology to protect and deliver bioactive proteins during storage and delivery in the GI tract.

Co-encapsulation of coenzyme Q10 and vitamin E: A study of microcapsule formation and its relation to structure and functionalities using single droplet drying and micro-fluidic-jet spray drying

The objective of this research was to study the co-encapsulation of Coenzyme Q10 (CoQ10) and vitamin E (VE) using single droplet drying (SDD) and micro-fluidic-jet spray drying (MFJSD), to study the particle formation-structure-function relationships of the microcapsules. Single droplets of selected CoQ10 and VE-containing emulsions were studied for their particle formation under convective drying (at 70 and 90 °C for 10 min) and rehydration processes using the SDD device. The emulsions were also spray-dried (at 160 and 190 °C) by MFJSD to form monodisperse microcapsules, followed by analyses of powder properties and functionalities. Results from SDD showed emulsion droplets with 30% w/w solids content were associated with earlier crust formation (30 s faster) and less particle shrinkage during drying compared to those with 10% w/w solid content. Comparing the spray-dried microcapsules produced from the emulsions containing 30% and 10% w/w solids content, the former gave larger particle size (172–175 μm vs. 116 μm), higher microencapsulation efficiency (ME) (98–99% vs. 96%), lower tapped density (0.532–0.599 g/cm3 vs. 0.406–0.502 g/cm3) and better flow properties (Carr's index of 22.06–29.19% vs. 22.70–40.64%). Overall, the CoQ10 and VE retention, antioxidant capacities and colour of the microcapsules were relatively stable when spray-dried at 190 °C than at 160 °C.

Fabrication of the polyphosphates patched cellulose sulfate-chitosan hydrochloride microcapsules and as vehicles for sustained drug release

Polyphosphates are important polyanionic electrolytes that play a major role in stabilization and consolidation of colloids surface and interior microstructures. In this study, the polyelectrolyte complexes (PEC) microcapsules (sodium cellulose sulfate-chitosan hydrochloride, sample 1), and the patched ones via sodium tripolyphosphate (sample 2), sodium pyrophosphate (sample 3) and sodium hexametaphosphate (sample 4) were fabricated under mild conditions. The effects of polyphosphates on the formation of the PEC microcapsules were investigated systematically. Scanning electron microscope (SEM) and confocal laser scanning microscope (CLSM) observation showed that both of the sample 2 and sample 3 had more compact interior microstructures with higher fluorescence intensity, compared with the sample 4 with macroporous ones and sample 1 with irregular ones. Fourier transform-infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA) showed the electrostatic interactions occurred among the –NH3+ groups, –SO3− groups, HP3O104− groups, P2O74− groups and H2PO4− groups, and the sample 2 and sample 3 had a more thermal stability comparatively. The sample microcapsules showed good capacity of drug loading and encapsulation efficiency (max. 66.9 ± 4.6% and 74.2 ± 5.1%). In the in vitro release studies showed that the sample 2 and sample 3 had a larger accumulative drug release rate of 5-aminosalicylic acid (5-ASA) at the same time point and released completely at 12 h; the drug release mechanisms analysis indicated that the sample 1 and sample 3 were mainly diffusion controlled, while the sample 2 and sample 4 were followed the mechanism of non-Fickian transport. Under the polyphosphate’s consolidation, the PEC microcapsules fabricated with sustained drug release profiles could be used as the promising drug vehicles.