Formation Of Microcapsules Research Articles

Effect of enzymatically produced tuna oil acylglycerol on the characteristics of gelatin O/W emulsion during microencapsulation using complex coacervation

Complex coacervation is an effective process to deliver ingredients for functional food applications. A stable oil-in-water (O/W) emulsion with desired characteristics significantly affects the complex coacervation and the quality of final microcapsules. In this study, tuna oil was partially hydrolyzed using TL100 and ADL lipases to produce acylglycerols TL100-AC and ADL-AC, respectively. These lipids were subsequently stabilized by gelatin in the O/W emulsion, followed by the complex coacervation with sodium hexametaphosphate. The effect of lipids on emulsion properties, such as interfacial properties, rheological properties, protein conformation and microcapsule formation during complex coacervation, was investigated. Compared with tuna oil-based emulsion, acylglycerol-based ones exhibited reduced droplet size (<600 nm), zeta-potential, interfacial tension (<8 mN/m) and interfacial protein concentration (about 80%). The gelatin in the acylglycerol-based emulsions had reduced β-sheet and slightly increased random coil contents. Compared with the one containing tuna oil, the ones containing acylglycerol possessed higher complex coacervation yields (>75%). These changes were beneficial to the formation of coagulant and flocculant so that gelatin-stabilized acylglycerol-based O/W emulsion resulted in improved complex coacervation between gelatin and sodium hexametaphosphate. This study provides a scientific basis for designing specific gelatin O/W emulsions and microencapsulation for the stabilization and delivery of omega-3 fatty acids.

Use of Ora-pro-nóbis (Pereskia aculeata Miller) mucilage as a wall material in microencapsulation by complex coacervation

Innovative materials for the encapsulation of bioactive compounds are a permanent challenge. In this sense, the purpose of the study was to evaluate the use of Ora-pro-nobis mucilage (MOPN) as a wall material to replace Arabic gum (AG), in microencapsulation by complex coacervation of bocaiuva (Acrocomia aculeata) pulp oil. The MOPN was obtained from green leaves, and the pH, color, water activity, humidity, fixed mineral residue, proteins, lipids, and extraction effectiveness were determined. MOPN was employed as a partial or total replacement of AG in the microencapsulation of bocaiuva pulp oil. Dehydrated and wet mucilages were used to emulsion formation. The interaction between biopolymers, the effectiveness, efficiency of microencapsulation, and the morphological characteristics of microcapsules were confirmed. In addition, the bioactive compounds (chlorophyll and β-carotene) and antioxidant activity were evaluated. The microcapsules were produced using moist mucilage. Microcapsules obtained with AG/gelatin/ bocaiuva oil were considered as control samples. MOPN showed brown color and chlorophyll content of 72.44±5.74 mg 100 g-1. The interaction between AG and MOPN in microcapsule formation was proven for the formulations with 25 and 50% MOPN substitution. The effectiveness was 74.83 and 75.22%, and encapsulation efficiency was 79.18 and 74.59%, respectively, verified through optical micrograph. In addition, the microcapsules with 25 and 50% MOPN as wall material showed three times more antioxidant activity against ABTS, and two times more β-carotene compared to the control microcapsule.

Poly(vinylphosphonic acid) grafted hollow microspheres with nanoparticles-stacked polymer shell for uranium selective extraction: Dynamic role translation of ethyl α-cyanoacrylate

Hollow polymer microspheres (MPs) have attracted much attention in the field of separation science and technology due to their low density, high specific surface area, easy chemical modification, and abundant binding sites. However, traditional methods for preparing hollow microspheres typically involve surfactants and expensive templates, which are time-consuming and uneconomical, and are not suitable for large-scale production. Oil-soluble α-ethyl cyanoacrylate (ECA), a highly reactive monomer, has been employed to prepare hollow microspheres efficiently in the current study. Self-stabilizing encapsulation via fast interfacial polymerization of ECA would confer a special Pickering-like emulsion droplet reactor for rapid microcapsule formation. The ECA acts as both a monomer and a Pickering emulsifier during the reaction, in which case the newly formed polyECA (PECA) nanoparticles accumulate at the interface, forming a shell of PECA layer eventually. Excellent mechanical property of the PECA layers prevent droplets from coalescence, resulting in hollow PECA MPs after drying. To provide adsorption sites for chelating of uranyl ions, a water-soluble vinyl monomer grafted with ethylene phosphate (vinylphosphonic acid) was then introduced onto the non-reactive double bonds of the polyECA chain under mild reaction conditions, owning to the slightly amphiphilic nature of the PECA chain. The obtained adsorbent for uranium extraction is thus named as PECA-PO43− MPs. Owing to the accessible affinity sites and hollow structure, PECA-PO43− MPs displayed high adsorption capacities at pH = 7–9, showing remarkable selectivity for uranium even in the presence of various competition ions. Moreover, PECA-PO43− MPs exhibited high stability as well as excellent recyclability toward uranium capture after five regeneration cycles. Therefore, this work not only presents a new clue to fabricate novel functional MPs in a high-efficiency way, but also provides a novel platform for efficient uranium extraction.

Bifidobacteria Encapsulation and Viability of Probiotic Culture during Oral Delivery in a Milk Drink Matrix.

The use of an alginate hydrogel exclusively for the immobilization of bifidobacteria during oral delivery led to a decrease in the total number of bifidobacteria to 4.0 lg CFU/ml in pH gradients in models of the stomach and intestines, which required clarification of the composition of the protective coating. The introduction of resistant starch into the composition of the microcapsule contributed to the preservation of the viability of immobilized bifidobacteria up to 87% of the initial concentration when passing through the model environment simulating the human digestion system. The introduction of sodium carboxymethylcellulose into the composition of the hydrogel contributed to the regulation of the degradation of the polymer matrix and the controlled release of bifidobacteria. The use of sodium carboxymethylcellulose 0.5% in the formation of a polymer microcapsule provided the maximum encapsulation efficiency of 93.2% and the maximum decay rate of bacteria-loaded microcapsules of 95.7%. The modified alginate matrix contributes to maintaining the level of viable cells of probiotic microorganisms (Bifidobacterium bifidum 791) of at least 108 CFU/g when stored for three weeks. As a result of the research, a system for oral delivery of immobilized bifidobacteria in the structure of microparticles with a closed surface in the matrix of a milk drink has been developed, which increases the effectiveness of probiotics for human health in the composition of food products.

FINISHING TEXTILE MATERIALS WITH MICROCAPSULES AND NANOPARTICLES OF FUNCTIONAL SUBSTANCES

The results of studies aimed at the creation of new functional textile materials through the use of microencapsulated TE (textile excipients) and metal nanoparticles, metal and non-metal oxides, as well as clays of natural origin were summarized. The developed methods for the synthesis of capsule shells of various architectures, including natural and synthetic polyelectrolytes, were presented. The technologies for encapsulation of functional preparations for aromatic, repellent and antibacterial finishing of textile materials were described. A description of the formation of microcapsules based on a highly active repellent drug - alpha-cypermethrin is given. An antimicrobial preparation containing silver nanoparticles has been developed, and recommendations for its use have been given. The production of silver nanoparticles were based on the reduction of metallic silver from silver nitrate using reducing agents such as glucose, glyoxal, and sodium dithionite in various concentrations. The sizes of synthesized particles vary from 145 to 2 nm. Modifying compositions based on synthetic polyelectrolytes and new complex compounds with predictable prolonged stability, functional substances and macrocycles (cyclodextrins (CD) and crown ethers) have been obtained. A technique was presented for the synthesis and strong fixation on cellulose fiber by introducing silver ions into the cavity of β-cyclodextrin of bioactive Ag-containing preparations with nanometer-sized particles. Methods for obtaining nanosized particles of zinc oxide were presented. Zinc acetate and zinc chloride were used as precursors. The sizes of the obtained nanoparticles are 70-90 nm. The technological bases for obtaining polyfunctional coatings on textile materials by impregnation and printing methods using polymers were described. The resulting coatings exhibit enhanced antibacterial and self-cleaning properties. The polyfunctionality of the action of fluorinated aluminosilicate in the processes of textile chemistry was shown. For citation: Odintsova O.I., Vladimirtseva E.L., Kozlova O.V., Smirnova S.V., Lipina A.A., Petrova L.S., Erzunov K.A., Konstantinova Z.A., Zimnurov A.R., Bykov F.A., Melnikov A.G. Finishing textile materials with microcapsules and nanoparticles of functional substances. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2023. V. 66. N 7. P. 173-184. DOI: 10.6060/ivkkt.20236607. 6844j.

Encapsulation of propolis extract in ovalbumin protein particles: characterization and in vitro digestion

The encapsulation of propolis has shown promising results for the protection of bioactive compounds, local and gradual release and masking the astringent taste. Ovoalbumin is a protein of animal origin found in large amounts in egg whites, which has good properties as a wall material for particles.The objective of this study was to microencapsulate propolis by spray drying. The best condition for microencapsulation was achieved with 4% ovalbumin at 120 °C, where there was the greatest encapsulation efficiency (88.20%) and spherical shape. However, the increase of ovalbumin concentration resulted lower yields (< 52%). As for the scanning electron microscopy (SEM), the increase of ovalbumin concentration caused an increase of the size with average diameter and formation of spherical microcapsules. The phenolic compounds were already released in the gastric fluid condition (stomach).

Self-Assembly of DNA Homopolymers by Pathway Dependence to Evade Metastable States.

A pathway-dependent strategy is proposed to assist single-stranded DNA polyadenine (poly(dA)) in evading metastable states and to achieve morphological regulation from microcapsules to microbowls by fractional n-butanol addition and emulsification (shaking) in a soft emulsion template (water-in-n-butanol). The first stage is the formation of small microcapsules by a fourth solvent addition and shaking. The second stage is the expansion of the small microcapsules initiated by the fifth solvent addition and shaking, drawing them to a new pathway to evade metastable states. Osmotic re-equilibrium and shaking are two indispensable conditions for overcoming the energy barriers. The third stage is the buckling of the expanded microcapsules and the evolution into microbowls after the evaporation of n-butanol to reach a global free energy minimum stable state. Conversely, the conventional one-time solvent addition and shaking pathway do not obtain microbowls. This kinetics pathway-dependent strategy evades metastability and shapes DNA oligonucleotides into desired structures via self-assembly.

LPS-aggregating proteins GBP1 and GBP2 are each sufficient to enhance caspase-4 activation both in cellulo and in vitro

The gamma-interferon (IFNγ)-inducible guanylate-binding proteins (GBPs) promote host defense against gram-negative cytosolic bacteria in part through the induction of an inflammatory cell death pathway called pyroptosis. To activate pyroptosis, GBPs facilitate sensing of the gram-negative bacterial outer membrane component lipopolysaccharide (LPS) by the noncanonical caspase-4 inflammasome. There are seven human GBP paralogs, and it is unclear how each GBP contributes to LPS sensing and pyroptosis induction. GBP1 forms a multimeric microcapsule on the surface of cytosolic bacteria through direct interactions with LPS. The GBP1 microcapsule recruits caspase-4 to bacteria, a process deemed essential for caspase-4 activation. In contrast to GBP1, closely related paralog GBP2 is unable to bind bacteria on its own but requires GBP1 for direct bacterial binding. Unexpectedly, we find that GBP2 overexpression can restore gram-negative-induced pyroptosis in GBP1KO cells, without GBP2 binding to the bacterial surface. A mutant of GBP1 that lacks the triple arginine motif required for microcapsule formation also rescues pyroptosis in GBP1KO cells, showing that binding to bacteria is dispensable for GBPs to promote pyroptosis. Instead, we find that GBP2, like GBP1, directly binds and aggregates "free" LPS through protein polymerization. We demonstrate that supplementation of either recombinant polymerized GBP1 or GBP2 to an invitro reaction is sufficient to enhance LPS-induced caspase-4 activation. This provides a revised mechanistic framework for noncanonical inflammasome activation where GBP1 or GBP2 assembles cytosol-contaminating LPS into a protein-LPS interface for caspase-4 activation as part of a coordinated host response to gram-negative bacterial infections.

Preparation and characterization of tea tree oil-β-cyclodextrin microcapsules with super-high encapsulation efficiency

This study aimed to prepare tea tree oil-β-cyclodextrin microcapsules using an optimized co-precipitated method. The impact of the volume fraction of ethanol in the solvent system for microencapsulation on encapsulation efficiency was investigated and analyzed sophisticatedly. Super-high encapsulation efficiency was achieved when a 40% volume fraction of ethanol was used for the microencapsulation procedure, where the recovery yield of microcapsules and the embedding fraction of tea tree oil in microcapsules were as high as 88.3% and 94.3%, respectively. Additionally, considering the operation cost, including time and energy consumption, an economical preparation was validated so that it would be viable for large-scale production. Based on the results of morphological and X-ray diffraction analysis, the crystal structure appeared to differ before and after microencapsulation. The results of gas chromatography-mass spectrometry and Fourier transform infrared spectroscopy confirmed the successful formation of microcapsules. Furthermore, the antibacterial activity of the fabricated microcapsules was assessed by a simple growth inhibition test using Bacillus subtilis as the study object, and the hydrophilic property was proved by a water contact angle measurement.

Ultrafast Self-Healing Fiber/Matrix Composite with Single-Component Microcapsules Loaded with Cationic Catalyst

In this study, ultrafast self-healing of different damage modes in resin and fiber/matrix composites was achieved by incorporating single-component double-shell microcapsules loaded with a cationic catalyst. The formation of stable and size-controllable inner microcapsules was achieved using hydrophilic metal–organic frameworks (MOFs) as stabilizers for the Pickering emulsion. With adjustable nanospaces, MOFs served as a good platform for host–guest interactions, providing an ideal environment for capturing and storing the cationic catalyst. Unlike traditional two-component microcapsule systems, the cationic catalyst could be loaded relatively easily into the double-shell microcapsules. More importantly, a single-component microcapsule system could achieve immediate repair of microcracks in situ as the agents could immediately react with the cationic catalyst upon the rupturing of microcapsules. A satisfactory healing efficiency was achieved along with outstanding mechanical properties of the composite. For example, epoxy resin with 15 wt % microcapsules loading showed 95% healing efficiency within 10 min at room temperature, and the interlaminar shear strength of the composite reached 92% in 5 min.

Design and Development of Extracellular Matrix Protein-Based Microcapsules as Tools for Bacteria Investigation.

The extracellular matrix (ECM) plays an immense role in the homeostasis of tissues and organs, can function as a barrier for infectious agents, but is also exploited by pathogens during infection. Therefore, the development of well-defined 3D ECM models in the form of microcapsules to elucidate the interactions between ECM components and pathogens in confinement and study disease infectivity is important, albeit challenging. Current limitations are mainly attributed to the lack of biocompatible methods for the production of protein-based microcapsules. Herein, hollow ECM-based microcapsules from laminin-111 or laminin-111/collagen IV are generated to investigate the behavior of organisms within confined 3D extracellular matrices. Microcapsules are created using water-in-oil emulsion droplets stabilized by block copolymer surfactants as templates for the charge-mediated attraction of laminin or laminin-collagen proteins to the droplets' inner periphery, allowing for the formation of modular ECM-based microcapsules with tunable biophysical and biochemical properties and organism encapsulation. The release of E. coli-laden ECM-based protein microcapsules into a physiological environment revealed differences in the dynamic behavior of E. coli depending on the constitution of the surrounding ECM protein matrix. The developed ECM-based protein microcapsules have the potential to be implemented in several biomedical applications, including the design of in vitro infection models.

Preparation and characterization of sorafenib-loading microcapsules by complex coacervation of gum Arabic with chitosan or modified chitosan

Sorafenib is an oral multi-target kinase inhibitor that has been used to treat unresectable hepatocellular carcinoma and advanced renal cell carcinoma. The aim of the study was to prepare gum Arabic-chitosan (GA-CS) and gum Arabic-modified chitosan (GA-MCS) microcapsules containing sorafenib as the core phase by complex coacervation. The fluorescence microscopy, dynamic light scattering (DLS), drug loading, and encapsulation efficiency of the microcapsules were clarified. The GA-MCS microcapsule was successfully performed at approximate pH of 4 with a 1% modified chitosan -to- 5% gum Arabic ratio of 5:1 (v/v), while the GA-CS microcapsule was successfully prepared at pH 3.5 with a volume ratio of 1% chitosan -to- 5% gum Arabic 1:1 (v/v). Sorafenib was encapsulated in the microcapsules as shown through the fluorescence microscopy images. The formation of GA-CS and GA-MCS microcapsules with hydrodynamic sizes of 6.31 μm and 6.56 μm, respectively, was successfully achieved. The drug loading and encapsulation efficiency of the GA-MCS microcapsule was greater than that of the GA-CS microcapsule. The findings indicated that the GA-MCS microcapsule could be an appropriate formation to load sorafenib with a high encapsulation yield.

Optimization of the Electrospraying Parameters for Formulation of Biopolymeric Microcapsules

There has been a surge in applying alginate microcapsules in diverse fields due to the numerous advantages of their non-toxicity, simple synthesis, and mechanical and chemical stability. Electrospraying is a simple and excellent technique for producing small microcapsules. This study aimed to analyse the trends in the operational parameters of the electrospraying technique, observed extreme conditions of the electrospraying, and selected the best performing parameters for producing small and spherical microcapsules. Alginate concentration was found to produce smaller microcapsules when kept at a minimum. However, the Implosion of microcapsules formed with less than 2%w/v alginate concentration was observed. Voltage increment produced smaller capsules, and fibre formation began at 21kV. Lower feed rates favoured both smaller microcapsules and better sphericity. Reduction in the needle orifice also favoured the formation of smaller microcapsules with less sphericity. Overall, a needle gauge of 27G, a voltage of 21kV, a flowrate of 0.5ml/h, and 2% w/v calcium chloride concentration were the best parameter combinations for producing small and spherical microcapsules.

Encapsulation of anthocyanins from chokeberry (Aronia melanocarpa) with plazmolyzed yeast cells of different species

Microencapsulation is one of the methods of preservation of food ingredients that can be easily degraded. The study aimed to investigate how the type of yeast can affect the ability to microencapsulate anthocyanins. In this study, the possibility of microencapsulation of anthocyanins from black chokeberry (Aronia melanocarpa) was investigated using yeast such as Saccharomyces cerevisiae without plasmolysis (CON), Saccharomyces cerevisiae after plasmolysis (SCB), Saccharomyces pastorianus (SPA), Saccharomyces cerevisiae for top fermentation (SCA), and Saccharomyces bayanus (SBA). The yeast were exposed to the concentrated anthocyanin solution for sorption and freeze-dried to form the microcapsules. It was shown that the water content of the CON microcapsules was significantly higher than the plasmolyzed. This was reflected in the water activity, as the CON and SCB samples had aw values between 0.055 and 0.064. The CON samples were the brightest, while the b* parameter in the L*a*b* color evaluation system was the most variable parameter for all samples. In terms of encapsulation efficiency, SCA and SPA had the highest values, followed by 52.87 ± 0.22 and 53.88 ± 0.81%. The thermal analysis revealed a phase transition around in samples, suggesting its different structure during microcapsule formation and melting. The results obtained can significantly contribute to the beginning of research in the literature on yeast-mediated encapsulation of hydrophilic bioactive compounds.

Comparative analysis of spray-drying microencapsulation of Lacticaseibacillus casei in synbiotic legume-based beverages

This study investigated the effect of three carrier agents, viz. maltodextrin (MD), gum acacia (GA), and xanthan gum (XG), on three synbiotic legume-based beverages subjected to optimized spray-drying conditions. Several characteristics of the encapsulated synbiotic powders were evaluated, including moisture content, bulk, and tapped density, dissolution encapsulation efficiency, flow properties, particle density, porosity, color, and powder yield. The survivability of probiotic bacteria Lacticaseibacillus casei ATCC 335 was also observed under gastric acid, bile salts, and simulated gastrointestinal tract. The results showed that while the higher powder yield (11–23%) was shown by MD-coated beverage powders, GA-coated beverage powders showed better encapsulation efficiency (79.9–89.3%) as well as lower moisture content values (<5%). Moreover, among all the samples, GA-coated kidney bean beverage (KB) powder showed the maximum probiotic survivability (>7 log CFU/mL) in the case of gastrointestinal simulation and under gastric acid and bile juice. The scanning electron microscopy also showed the desirable particle morphology and formation of microcapsules preserving the probiotic activity. The thermal properties of GA-coated KB powder showed the peak degradation temperature as 143.44 °C, which suggested the use of appropriate drying temperatures for making stable encapsulated synbiotic powders. Thus, GA-coated KB powder holds the potential to be used as a functional food with synbiotic properties along with acceptable powder characteristics and maximum probiotic survivability.

Facile Fabrication of Dual Functional Graphene Oxide Microcapsules Carrying Corrosion Inhibitor and Encapsulating Self-Healing Agent.

Dual functional graphene oxide (GO) microcapsules were fabricated through self-assembly in Pickering emulsions, carrying corrosion inhibitor benzotriazole (BTA) on the microcapsule shells and encapsulating a self-healing agent epoxy monomer. The formation of the GO microcapsules was assisted by the interaction between BTA and GO, which provided robust encapsulation for the epoxy monomer. The loading capacity of BTA and epoxy monomer reached 90.5%. The addition of the GO microcapsules simultaneously promoted the corrosion protection and self-healing properties of the waterborne epoxy composite coatings. The healing efficiency of the composite coatings reached over 99.7% when the content of the microcapsules was 10 wt%. Meanwhile, the corrosion current density of the intact coatings was decreased for around 50 times.

Studies of Encapsulation Efficiency and Swelling Behavior of Riboflavin Encapsulated by Alginate and Chitosan

Vitamin B2, also known as riboflavin, has an important function to human tissue development and energy metabolism. Riboflavin is sensitive and unstable to external influences such as light and reducing agents. In addition, most of the absorption of nutrients occurs in the intestines so the release of riboflavin in gastric need to be avoided. To overcome this problem, riboflavin was microencapsulated with sodium alginate and chitosan polymer using ionic gelation emulsification method. The purpose of this research was to study the microencapsulation itself, and also to study the effect of the riboflavin composition used upon the encapsulation efficiency and the effect of pH medium on microcapsules swelling behavior. In this research, microcapsule characterization was also carried out using FTIR and SEM. The FTIR result shows that there are crosslinking which indicated by functional groups changes between the samples during the formation of microcapsules. The SEM result show that the dried microcapsule has rougher and wrinkled surface. In efficiency encapsulation study, microencapsulation was carried out by varying the composition of riboflavin, that is 50, 75, 100, 125, and 150 mg. Optimal encapsulation efficiency was obtained at 125 mg with an efficiency encapsulation of 51.56%. The microcapsules sample were also tested for their swelling ability by putting the microcapsules into the solution with various pH ranging from 1.2, 2.5, 4.1, 5.2, 6.8 and 8. The swelling test results showed that the characteristics of microcapsules were suitable for the human digestive system because the higher the pH of the medium, then the higher the microcapsules swelling ability.

Systematic study on interfacial polymerization mechanism of toluene diisocyanate and water for the preparation of polyurea microspheres

• Droplets-based microfluidics is used to generate TDI droplets in aqueous phase. • Polyurea microspheres were prepared by interface polymerization of TDI with water. • Interface polymerization mechanism of TDI with water is studied in details. Polyureas (PU) are important materials in wide range of applications from protective coatings and catalyst supports to biomaterials for drug release and hydrogels. However, it has been a challenging task to prepare porous PU with definite form or shape limited by the nature of the PU synthesis, that is, precipitation polymerization. New chemical and physical techniques of PU synthesis have gained great attention in order to fabricate these materials with diverse morphologies and structural features. In this communication, droplet-based microfluidics approach is adopted to convert conventional precipitation polymerization of PU synthesis to interface polymerization and PU microspheres with porous morphology are prepared. In this process, first toluene diisocyanate (TDI) droplets were generated in flowing PVA aqueous solution inside a tube and then converted to uniform porous PU microspheres through interface polymerization. The interface polymerization mechanism is discussed in details by controlling the polymerization time. It was found that polymerization of TDI with water was started at the interface of TDI droplet and water, and PU shell was formed around the TDI droplets, leading to formation of microcapsules. After the formation of PU shell, polymerization was continued inside the microcapsule by the diffusion of water molecules through the PU shell until all the TDI was finished and PU microspheres with porous morphology were obtained. This communication provides therefore a systematic study on interfacial polymerization of TDI with water to get porous PU microspheres and enabling technical advantages for potential applications to get PU materials with specific shapes and textural modifications.

Designing a corrosion resistance system using modified graphene oxide-epoxy microcapsules for enhancing the adhesion strength of the epoxy coatings

New microencapsulated material with advanced corrosion resistance activity and superior adhesion strength on the steel sample was synthesized by in-situ polymerization. In this process, urea-formaldehyde was used as capsule shell material for encapsulating modified graphene oxide. The formation of microcapsules was effectively evidenced by FT-IR, SEM, and TGA-DSC analyses. Initially, graphene oxide was modified by the adsorption of Catharanthus roseus L. (C.R) leaves extract and characterized by FT-IR, SEM, EDX, and DFT studies. GO-C.R and UF-GO-C.R (microcapsules) were separately impregnated into epoxy resin and fabricated on the steel substrates. The anti-corrosion performance of UF-GO-C.R/Epoxy in comparison with neat GO-C.R/Epoxy coated sample was evaluated by electrochemical impedance spectroscopy (EIS) and salt spray test. Results reveal that UF-GO-C.R microcapsules in epoxy matrix showed the protection efficiency of 83.6 % after the immersion period of 7 days in 3.5 % NaCl solution which was relatively higher than those with neat GO-C.R. In addition, the coating loaded with UF-GO-C.R microcapsules showed improvement in the adhesion of epoxy coatings on the steel surface which was evident from the increase in peel strength (290 N) through peel-off adhesion test.

Developing DHA microcapsules using linear dextrin aggregates of different chain length distributions

Linear dextrin aggregates (LDAs) were prepared in the current study as novel material for encapsulating docosahexaenoic acid (DHA). The high amylose corn starch was acid hydrolyzed and enzymically debranched into LDAs of varied chain length distributions (CLDs). Results showed that the encapsulation efficiency of microcapsules significantly increased from 68% to 81% correspondingly with the improved content of the intermediate linear dextrin (degree of polymerization, DP, ranges 10– 100). Meanwhile, the peroxide value was also showed a decrease of 2 mEq/kg during the storage. Molecular dynamic simulations further revealed that the linear dextrin with DP of 15 showed the highest interaction attraction while being encapsulated with DHA. The hypothesis is thus verified since the LDA with a specific CLD favors the formation of starch-based DHA microcapsules with better performance. When LDAs contained 22% intermediate linear dextrin, microcapsules showed the highest encapsulation efficiency (85%) and the lowest peroxide value (10 mEq/kg).