Microencapsulation Applications Research Articles

Microencapsulation of solid cores to prepare double emulsion droplets by microfluidics

We herein present an effective microfluidic method based on facile glass capillary assembly for encapsulating solid cores to prepare double emulsions. Visualization experiments are conducted to verify the effectiveness of the presented microfluidic device. It is indicated that, via the presented microfluidic device, solid cores can be controllably encapsulated into every generated double emulsion droplets under wide operating range of flow rate. The number of the encapsulated solid cores can be well manipulated by adjusting the flow rate of different phases. Particularly, by employing multiple injection microchannels, multiple kinds of solid cores can be encapsulated into a single droplet in different combinations. This microfluidic methods show good applicability to generate both solid-in-oil-in-water (s/o/w) and solid-in-water-in-oil (s/w/o) double emulsion droplets. We believe that the current microfluidic methods are capable to extend the application of microencapsulation in microcapsule preparation, drug detection, food delivery, single cell analysis, and synthesis of nanomaterials, etc.

Preparation of Template-Free Robust Yolk-Shell Gelled Particles from Controllably Evolved All-in-Water Emulsions.

A template-free all-aqueous bulk preparation of robust hollow capsules having a gelatin shell from all-in-water double emulsions is reported. The hot (>40 °C) quaternary system water/polyethylene glycol (PEG)/gelatin/alginate is shown to spontaneously form PEG-in-gelatin-in-PEG double water emulsion droplets having a multinuclear core. These droplets are stable upon cooling below the temperature at which gelatin gelled. In contrast, above the melting temperature of gelatin, multinuclear double emulsion droplets controllably evolve into stable mononuclear yolk (aqueous PEG)-shell (gelatin) capsules dispersed in the aqueous PEG continuous phase. It is demonstrated that the gelatin shell can accommodate negatively charged latex beads and be re-enforced by glutaraldehyde or silica. These capsules are also shown to encapsulate payloads, suggesting possible applications in microencapsulation, drug delivery, and synthetic biology.

A two-tier modified starch-oxidation followed by n-octenyl succinylation as gum Arabic substitute: Process details and characterization

Corn starch was oxidised using sodium hypochlorite to enhance its film forming property and reduce viscosity. This oxidised starch (OS) was further modified by n-octenyl succinic anhydride (OSA) to introduce hydrophobicity. This dual modified starch (OS-OSA) was characterized for crystalline and thermal attributes. The emulsion stability, viscosity and particle size of OS-OSA based emulsion with 60% soybean oil loading was compared with OS and gum Arabic (GA). The spray dried microcapsules using OS-OSA and GA as wall materials at 20% (w/v) containing emulsions demonstrated similar surface morphology (smooth surface devoid of cracks) and particle size. Microencapsulation with OS showed lower encapsulation efficiency (13%) than those with OS-OSA and GA (similar at 58%). The half-life of OS-OSA (39 weeks) microcapsules was lower than GA (44 weeks) but the final encapsulation efficiency after 18 weeks was similar in both cases. Thus OS-OSA corn starch can potentially replace gum Arabic for microencapsulation applications.

SIMULATION OF VINPOCETINE RELEASE PROCESS FROM MICROCAPSULES WITH HYDROPHOBIC SHELL

Nowadays microcapsules are widely spread in different industries. Microcapsules with vitamins, etheric and fatty oils are included into different cosmetics (creams, gels, serums). Microencapsulated probiotics are used in foods and fodder additives in veterinary. An important field of application of microencapsulation in pharmacy is the combination in the total dosage of drugs that are incompatible when mixed in free form. The aim of work is a comparative analysis of thermodynamic characteristics of vinpocetine release from the melt of beeswax and cacao butter 3:2 into water, solution of hydrochloric acid 0.01 M and ethanol. Materials and methods . For simulation of the process of vinpocetine release from the melt into different environments models component models of the studied systems were built and their atom charges were calculated by quantum-chemical method. Spatial models of the components were built in Hyper Chem 8.01. As an initial state for the thermodynamic characteristics of the calculation of vinpocetine release from the melt, a conformation of «melt-vinpocetine» system was used after thermodynamic equilibration by molecular dynamics simulation in Bioeurica program for 5 ns. For isolated systems a vibrational analysis was performed with the use of unrestricted Hartree-Fock method in STO-3G basis set in Orca 4.0 program. Results and discussion . Vinpocetine release from the melt of beeswax and cacao butter 3:2 into water with different pH values and to ethanol depends on its solubility in these environments, and also on solubility of the melt. Conclusion. The performed study of vinpocetine release from the melt of beeswax and cacao butter 3:2 by molecular dynamics simulation demonstrates the opportunity of vinpocetine release into water with pH=2 and into ethanol. The obtained results make it possible to assume a lower degree of vinpocetine release from the melt into ethanol compared with the solution of hydrochloric acid 0,01 M.

Extraction of Plant-based Capsules for Microencapsulation Applications.

Microcapsules derived from plant-based spores or pollen provide a robust platform for a diverse range of microencapsulation applications. Sporopollenin exine capsules (SECs) are obtained when spores or pollen are processed so as to remove the internal sporoplasmic contents. The resulting hollow microcapsules exhibit a high degree of micromeritic uniformity and retain intricate microstructural features related to the particular plant species. Herein, we demonstrate a streamlined process for the production of SECs from Lycopodium clavatum spores and for the loading of hydrophilic compounds into these SECs. The current SEC isolation procedure has been recently optimized to significantly reduce the processing requirements which are conventionally used in SEC isolation, and to ensure the production of intact microcapsules. Natural L. clavatum spores are defatted with acetone, treated with phosphoric acid, and extensively washed to remove sporoplasmic contents. After acetone defatting, a single processing step using 85% phosphoric acid has been shown to remove all sporoplasmic contents. By limiting the acid processing time to 30 hr, it is possible to isolate clean SECs and avoid SEC fracturing, which has been shown to occur with prolonged processing time. Extensive washing with water, dilute acids, dilute bases, and solvents ensures that all sporoplasmic material and chemical residues are adequately removed. The vacuum loading technique is utilized to load a model protein (Bovine Serum Albumin) as a representative hydrophilic compound. Vacuum loading provides a simple technique to load various compounds without the need for harsh solvents or undesirable chemicals which are often required in other microencapsulation protocols. Based on these isolation and loading protocols, SECs provide a promising material for use in a diverse range of microencapsulation applications, such as, therapeutics, foods, cosmetics, and personal care products.

Polymeric Materials for Perm-Selective Coating of Alginate Microbeads.

Application of microencapsulation to the immunoisolation of pancreatic islets holds promise for expanding the use of islet transplantation as a treatment option for Type 1 diabetes. It is generally believed that successful development of a reliable methodology will ideally allow for transplantation of pancreatic islets that are protected from the immune system, thereby obviating the need for the use of immunosuppressive drugs and their attendant side effects. In addition, this technology has the potential to expand the donor pool as islets from nonhuman donors could be used as xenografts in human patients. The complex polysaccharide, alginate, has been the most widely used polymer for microencapsulation of islets. However, it is known that alginate lacks appreciable permselectivity to confer immunoisolation of encapsulated islets, thus necessitating the routine permselective coating of alginate microbeads with polymers of amino acids, mainly, poly-L-lysine (PLL) and poly-L-ornithine (PLO). The protocol described in this chapter outlines the steps we have used in our studies on perm-selective coating of alginate microbeads for islet transplantation.

Microencapsulation of Bacterial Cells by Emulsion Technique for Probiotic Application.

Probiotics are dietary concepts to improve the dynamics of intestinal microbial balance favorably. Careful screening of probiotic strains for their technological suitability can also allow selection of strains with the best manufacturing and food technology characteristics. However, even the most robust probiotic bacteria are currently in the range of food applications to which they can be applied. Additionally, bacteria with exceptional functional heath properties are ruled out due to technological limitations. New process and formulation technologies will enable both expansion of the range of products in to which probiotics can be applied and the use of efficacious stains that currently cannot be manufactured or stored with existing technologies. Viability of probiotics has been both a marketing and technological concern for many industrial produces. Probiotics are difficult to work with, the bacteria often die during processing, and shelf life is unpredictable. Probiotics are extremely susceptible environmental conditions such as oxygen, processing and preservation treatments, acidity, and salt concentration, which collectively affect the overall viability of probiotics. Manufacturers have long been fortifying products with probiotics; they have faced significant processing challenges regarding the stability and survivability of probiotics during processing and preservation treatments, storage as well during their passage through GIT. Application of microencapsulation significantly improves the stability of probiotics during food processing and gastrointestinal transit.

MICROENCAPSULATION: A REVIEW OF APPLICATIONS IN THE FOOD AND PHARMACEUTICAL INDUSTRIES

Microencapsulation is a technique that has been widely used in the food and pharmaceutical industries. This technique can be used to reduce the cost of production, to increase the stability of compounds, to mask undesirable tastes, and to improve the release properties of compounds in food industries. Currently, microcapsules are utilized in beverage, bakery, meat, poultry, and dairy products. Moreover, microencapsulation has been used to increase stability, to mask bitter taste, to improve the release properties of drugs, and to provide specific drug delivery in pharmaceutical industries. The challenge of microencapsulation is in selection of the appropriate conditions for producing highly effective microcapsules. Many factors affect the quality of microcapsules, including preparation techniques, types of core material, and types of wall material. We provide an overview of the current research on the applications of microencapsulation in food and pharmaceutical industries, the selection of suitable conditions for developing high efficiency microcapsules, and future trends in microencapsulation.

Microencapsulated Pig Islet Xenotransplantation as an Alternative Treatment of Diabetes.

Islet transplantation is emerging as an attractive option for the treatment of type 1 diabetes mellitus (T1DM). However, some major obstacles are needed to be overcome, including shortage of islet supply and excessive immunosuppressive therapy. Xenotransplantation of bioartificial pancreas (BAP) made of microencapsulated pig islets will effectively solve these problems. Before widespread application of this therapy, several important issues should be addressed to further improve pig islet viability and functionality, such as pig islet source, optimization of microcapsule preparation, cryopreservation of implant, selection of biocompatible material, and implant site, as well as prevention of xenoreaction and biosafety concern. It is hoped that improvements in these critical aspects will lead to wider human application of microencapsulation of pig islets.

Incorporation of Microcapsules in Pineapple Intercellular Tissue Using Osmotic Dehydration and Microencapsulation Method

The objective of this study was to analyze the simultaneous application of microencapsulation (ME) and osmotic dehydration (OD) in the development of an innovative process to incorporate microcapsules into the intercellular spaces of pineapple tissue. Osmo-dehydrated pineapple impregnated with microcapsules (OPIM) was obtained when fresh pineapple rings were osmo-dehydrated in emulsions (600 g solids kg−1 emulsion) prepared with 40 % water, 45 % sugar, 12 % gum Arabic, and 3 % piquin pepper oleoresin (EP). Emulsion EP produced OPIM rings with 8 g oil kg−1 fruit. The β-carotene content of OPIM samples increased 28 % in relation to fresh fruit. In addition, OPIM rings showed an acceptable color and rehydration capacity. They were also evaluated for organoleptic acceptability, finding out that rehydrated OPIM samples did not present significant difference (p < 0.05) with regard to fresh fruit on a nine-point Hedonic scale. Scanning electron microscope (SEM) images revealed the presence of microcapsules of 1–5 μm into OPIM tissue. Based on these results, this technique can also be implemented in other fruit and vegetables. Its versatility opens a new method to design healthy products combining flavors and functional substances in an intelligent and creative way.

Colloidosomes: Synthesis, properties and applications

Colloidosomes represent a rapidly expanding field with various applications in microencapsulation, including the triggered release of cargoes. With self-assembled shells comprising colloidal particles, they offer significant flexibility with respect to microcapsule functionality. This review explores the various types of particles and techniques that have been employed to prepare colloidosomes. The relative advantages and disadvantages of these routes are highlighted and their potential as microcapsules for both small molecule and macromolecular actives is evaluated.

Challenges and solutions to incorporation of nutraceuticals in foods.

Manufacturers often cannot simply add a nutraceutical to a food when formulating functional foods that have acceptable sensory appeal as well as the desired health benefits. The appropriate application of microencapsulation for stabilizing nutraceuticals enables their effective delivery through food. Careful design of the delivery system helps protect sensitive nutraceuticals from the environment and processing stresses encountered during food manufacture, and prevents undesirable interactions of the nutraceutical with components in the food matrix. Microencapsulation technologies overcome hurdles associated with the successful delivery of nutraceuticals in healthy foods if due consideration is given to challenges at all stages throughout the supply chain. This encompasses stabilizing and protecting nutraceuticals from degradation in ingredient formats, during processing, in the final food product, and during intestinal transit until they are released at the desired site in the gastrointestinal tract to impart their targeted health effects.

Synthesis, characterization and emulsification properties of dodecenyl succinic anhydride derivatives of gum Arabic

Gum Arabic, GA, has been chemically modified using dodecenyl succinic anhydride (DDSA) in aqueous solution and the products have been characterized and their solution and emulsification properties evaluated. FTIR was used to confirm that derivatisation had occurred and the hydrophobe incorporation and reaction efficiency was determined by a simple titration method. The derivatives, DGA5 and DGA10 were found to contain 5 and 10 %w/w DDSA respectively. Surface tension and dye solubilisation measurements demonstrated that the modified GA samples aggregated in solution at a specific concentration, referred to as the critical aggregation concentration, CAC. The value of the CAC was found to be a function of the degree of substitution and values of 0.1% and 0.04% were obtained for DGA5 and DGA10 respectively. The emulsification properties of the polymers were assessed by determination of the droplet size as a function of polymer concentration and time using laser diffraction. The droplet size decreased for all samples as the polymer concentration increased but the minimum droplet size obtained increased in the order DGA10 < DGA5 < GA indicating enhanced emulsification efficiency with increasing hydrophobe content. The effect of ageing on emulsion stability was assessed and the droplet size of emulsions prepared with GA and DGA5 increased with time but remained constant for samples prepared with DGA10. Emulsion creaming was followed using the Turbiscan and it was noted that DGA5 and DGA10 were much more effective than GA at reducing creaming. The results have demonstrated that the modified gum Arabic samples have potential application for microencapsulation.

A Special Issue on Applications of Microencapsulation

A Special Issue on Applications of Microencapsulation

Potentials and Limitations of Bile Acids in Type 2 Diabetes Mellitus: Applications of Microencapsulation as a Novel Oral Delivery System

Type 2 diabetes (T2D) is a chronic metabolic disorder resulting from genetic and environmental factors that bring about tissue desensitization to insulin and consequent hyperglycemia. Despite strict glycemic control and the fact that new and more effective antidiabetic drugs are continuously appearing on the market, diabetic patients still suffer from the disease and its complications. Recent findings present a strong link between diabetes, inflammation, altered gut microbiota and bile acid (BA) disturbances. BAs are naturally produced in humans and are gaining an appreciable interest as an adjunct treatment for T2D due to their endocrine signalling and anti-inflammatory properties. However a significant limitation to their efficacy is their low oral absorption, poor targeted delivery, gut metabolism and inter- and intra-individual dose variations. Thus there is a need for a novel and robust formulation that will encapsulate the BAs and protect them until they reach the lower intestine allowing them to be clinically beneficial. Artificial Cell Microencapsulation (ACM) is a novel oral delivery system for biologically active molecules and has been used significantly in the delivery of various cells and therapeutics. ACM-BA formulation has the potential to optimise BA efficacy and safety profiles and may have a place in the treatment of diabetes. This review aims to investigate the applications of BAs in T2D and the use of ACM as a novel delivery system for their optimum delivery. Keywords: Microencapsulation, type 2 diabetes, bile acids, inflammation. Read more →

Characterization of spray dried chitosan–TPP microparticles formed by two- and three-fluid nozzles

Chitosan microparticles cross-linked by tri-polyphosphate (TPP) anions have been prepared by spray drying. Two different cross-linking methods have been employed — ex-situ cross-linking whereby aqueous solution of cross-linked chitosan nanoparticles has been spray-dried by a two-fluid nozzle, and a novel in-situ cross-linking method, whereby solutions of chitosan and TPP have been fed to a three-fluid nozzle and cross-linking occurred within individual droplets. The size and morphology of the resulting microparticles have been characterised and their dependence on the cross-linking ratio and the initial chitosan concentration determined. Particles produced by the three-fluid nozzle were found to have favourable properties in terms of stability in aqueous media and they allow the use of higher chitosan concentrations, which makes them suitable for microencapsulation applications.

Characterisation and applications of microcapsules obtained by interfacial polycondensation

This review highlights the materials, mechanisms and applications of microencapsulation by interfacial polycondensation in different areas. This technology entraps active ingredients inside microcapsules/microspheres, having an average diameter ranging from nanosize to several 100 µ. Polycondensation reactions take place at the boundary of two phases to form the shells of microcapsules or matrix microspheres. The emulsion can be classified into three types: water-in-oil, oil-in-water and oil-in-oil. According to the hydrophilic–lipophilic property of core phase, different active substances, such as proteins, enzymes, insecticides, herbicides, vitamins, catalysts, drugs, essential oils, dyes and phase change materials, have been successfully incorporated into different microcapsules/microspheres. Based on the shell-forming materials, this technology is capable of preparing polyamine, polyurea, polyurethane, polythiourea, polyester, polyepoxide, polyacrylamide and polysiloxane microcapsules. Over the past two decades, microcapsules prepared by interfacial polycondensation have been widely used in carbonless paper, cosmetics, pharmacy, agriculture, energy storage/transfer, thermal insulation/regulation and information and magnetic recording.

Electrostatic extrusion as a dispersion technique for encapsulation of cells and bioactive compounds

Significant development of cells and bioactive compound encapsulation technologies is taking place due to an exceptional possibility of their application in various scientific disciplines, including biomedicine, pharmacy, cosmetology, food and agricultural sciences, beverage production, industrial waste treatment. Despite the broad application of microencapsulation, the literature reviews on dispersion techniques for microcapsule/microbead production, their advantages, restrictions and drawbacks are scarce. The purpose of this paper is to assess the possibilities of electrostatic extrusion for encapsulation of biological material, including living cells in hydrogel microbeads. The paper presents an overview of the mechanisms of droplet formation and controlling experimental parameters for producing microbeads by means of electrostatic extrusion. Electrostatic droplet formation utilizes a special type of physical process taking advantage of electrostatic effects occurring in flowing conductive liquids after introduction of an electric field.When an electrostatic field is applied to the metal needle and an electric charge is induced in the liquid flowing out of the needle, the size of droplet detaching from the needle tip decreases as a funcion of applied electrostatic field. It has been shown that few parameters affect microbead size: applied voltage, electrode geometry, needle size, polarity arrangement and polymer concentration. The electrostatic droplet formation is one of the most precise methods, which enables one to produce spherical and uniform particles ranging from 100 ?m up to 1000 ?m. Most of the authors report that the encapsulated compounds (drugs, enzymes and living cells) remain unaltered after electrostatic extrusion. This technique seems to be particularly promising in biotechnology, pharmaceutical and cosmetics industries, where a low-temperature process, preserving heat-sensitive material is a prerequisite. Future efforts in developing of electrostatic extrusion should be directed towards adequately scaling-up for commercial purpose.

Preparation, characterization and release of amoxicillin from cellulose acetate and poly(vinyl pyrrolidone) coaxial electrospun fibrous membranes

Electrospinning is a method that has been used to prepare polymeric fibers, with diameters ranging from nanometers to a micrometer of polymers such as cellulose acetate (CA) and poly(vinyl pyrrolidone) (PVP), and to develop membranes with applications in microencapsulation, for controlled release of drugs and for chemical and biological sensors. This work shows the feasibility and optimal conditions for the preparation of fibrous composite membranes of cellulose acetate and poly(vinyl pyrrolidone), via electrospinning, and their morphology; FTIR, and mechanical characterization and the effect of pH on the release of amoxicillin were analyzed. Tubes of CA with diameters around 500 nm were obtained. It was found that the release behavior of the drug from these fibrous membranes was dependent on the pH of the medium. It was observed that the amount of amoxicillin released as a function of time for a pH equal to 7.2 was approximately three times higher than that observed for a pH equal to 3.0. This suggests a greater interaction of amoxicillin with components of the membrane at a pH equal to 3.0, most likely due to the formation of hydrogen bonds. These materials have potential application in gastrointestinal administration and for transdermal patches.

Microencapsulation as a Tool for Incorporating Bioactive Ingredients into Food

Microencapsulation has been developed by the pharmaceutical industry as a means to control or modify the release of drug substances from drug delivery systems. In drug delivery systems microencapsulation is used to improve the bioavailability of drugs, control drug release kinetics, minimize drug side effects, and mask the bitter taste of drug substances. The application of microencapsulation has been extended to the food industry, typically for controlling the release of flavorings and the production of foods containing functional ingredients (e.g. probiotics and bioactive ingredients). Compared to the pharmaceutical industry, the food industry has lower profit margins and therefore the criteria in selecting a suitable microencapsulation technology are more stringent. The type of microcapsule (reservoir and matrix systems) produced and its resultant release properties are dependent on the microencapsulation technology, in addition to the physicochemical properties of the core and the shell materials. This review discusses the factors that affect the release of bioactive ingredients from microcapsules produced by different microencapsulation technologies. The key criteria in selecting a suitable microencapsulation technology are also discussed. Two of the most common physical microencapsulation technologies used in pharmaceutical processing, fluidized-bed coating, and extrusion-spheronization are explained to highlight how they might be adapted to the microencapsulation of functional bioactive ingredients in the food industry.