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 function 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 up to 1000 mu 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

Encapsulation of flavors and aromas: Controlled release

Ongoing research on biodegradable/edible lms is being made, and there is a great interest to make this knowledge more widely available and used. In the last 30 years, considerable progress has been made in developing these materials driven by the increasing consumer demand for safe, high-quality, convenient food with long shelf lives, along with an ecological awareness of the limited natural resources and the environmental impact of packaging waste (Janjarasskul and Krochta 2010; Kester and Fennema 1986). Nevertheless, the use of edible lms or coatings to extend storage life of food is an ancient human practice of food preservation. Some examples of those old practices are fruit waxing used since the twelfth century in China, meat larding used in England since the sixteenth century (Kester and Fennema 1986), and the production of soy lms from soy milk (yuba) traditionally employed in the Orient to wrap and shape ground meats or vegetables (Gennadios and Weller 1991).Fil: Bertuzzi, Maria Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Investigaciones para la Industria Química. Universidad Nacional de Salta. Facultad de Ingeniería. Instituto de Investigaciones para la Industria Química; ArgentinaFil: Slavutsky, Anibal Marcelo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Investigaciones para la Industria Química. Universidad Nacional de Salta. Facultad de Ingeniería. Instituto de Investigaciones para la Industria Química; Argentina. Universidad Nacional de Salta. Facultad de Ingeniería; Argentin

Mehaničke karakteristike čestica alginat-lipozomi sa inkapsuliranim resveratrolom

In this work mechanical behavior of four different formulations of alginate-based beads was tested. The alginate beads were prepared by means of extrusion technique. As a model encapsulated bioactive substance resveratrol-loaded liposomes were used. The beads were composed as follows: 1.5% alginate beads; 1.5% alginate beads encapsulating liposomes; 1.5% alginate/30% sucrose beads encapsulating liposomes and 1.5% alginate/0.5% chitosan beads encapsulating liposomes. The mechanical properties (e.g. maximal forces required for reaching the default deformation, maximal stresses and the Young’s modulus) of aforementioned beads were determined by testing the single bead submerged in water using the AG-X plus Universal Testing Machine (Shimadzu, Japan). Results showed the decrease in maximal forces (stresses) and increase in elasticity of the examined beads upon encapsulation of resveratrol-loaded liposomes. After addition of sucrose and coating with chitosan, maximal forces respectively remained constant and decreased, while elastic modulus also remained constant and increased, respectively. Tested compression method can be used in the determination of mechanical properties of different alginate-based beads.U ovom radu su ispitane mehaničke karakteristike četiri različite formulacije čestica na bazi alginata. Čestice su pripremljenje koristeći metodu ekstruzije. Kao model supstanca za inkapsulaciju korišćni su lipozomi sa inkapsuliranim resveratrolom. Formulacije čestica su sledeće: 1,5% alginatne čestice; 1,5% alginatne čestice sa inkapsuliranim lipozomima; 1,5% alginatne čestice sa inkapsuliranim lipozomima sa dodatkom 30% saharoze i 1,5% alginatne čestice sa inkapsuliranim lipozomima sa dodatnim slojem 0,5% hitozana. Mehaničke karakteristike (tj. maksimalne sile potrebne za dostizanje unapred definisane deformacije, maksimalni naponi i Jungovi moduli elastičnosti) gore pomenutih čestica su određene testiranjem pojedinačnih čestica uronjenih u vodu, koristeći AG-X plus Universal Testing Machine (Shimadzu, Japan). Rezultati su pokazali da nakon inkapsulacije lipozoma sa resveratrolom u alginatne čestice dolazi do smanjenja maksimalne sile potrebne za postizanje zadate deformacije, kao i do povećanja elastičnosti ispitivanh čestica. Nakon dodatka saharoze i oblaganja alginatnih čestica slojem hitozana, maksimalna sila ostaje nepromenjana, odnosno dolazi do njenog smanjenja; slicno, vrednosti modula elastičnosti takođe ostaju konstantne, odnosno povećavaju se. Ispitivana metoda kompresije može se koristiti za određivanje mehaničkih karakteristika različitih čestica na bazi alginata

Thermal, morphological and mechanical properties of ethyl vanillin immobilized in polyvinyl alcohol by electrospinning process

In this study, polyvinyl alcohol (PVA) nanofibers with ethyl vanillin as active compound were prepared using electrospinning technique. The final products of electrospinning process were in the form of films consist of nanofibers. PVNethyl vanillin nanofibers, having fibers diameters in the range 100-1700 nm, were successfully electrospun from ethanol/water mixture of PVA and ethyl vanillin. The effects of immobilization process on ethyl vanillin thermal properties were investigated by differential scanning calorimetry (DSC). The results of DSC showed significant influence of immobilization process on thermal properties of ethyl vanillin. It was noticed that melting point of immobilized ethyl vanillin was lower (~55°C) compared to free flavor (~77°C). Our results showed that films based on PVNethyl vanillin nanofibers are mechanically stable

Encapsulation of natural antioxidant resveratrol in liposomes

Liposomes have been shown to be suitable systems for encapsulation and preserving the health-beneficial properties of a wide range of biological active ingredients such as resveratrol (RSV). The aim of this study was to encapsulate RSV in liposomes, with a goal to achieve the extended release and improved stability of RSV. Multilameral liposomes were prepared by means of two different methods: thin film method (TF) and proliposome method (PRO). In both methods, the ratio between added RSV and phospolipon 90G (P90G) was 1:20 w/w. Extrusion and sonication were applied in order to obtain unilameral liposomes. Both methods were efficient in capturing RSV within the microparticles, thus encapsulation efficiency had high values (92,9% in case of TF and 97,4% in case of PRO). The size reduction of liposomes resulted with particles of the average diameter ranged between 120 and 270 nm. Antioxidative activity was retained at a high level (approximately 95%). Franz diffusion cell was used for release studies and diffusion of RSV was monitored for 6h. According to the results, liposomes appeared to be suitable vehicles for encapsulation of resveratrol where PRO is particularly useful for encapsulation of antioxidants

Resveratrol loaded liposomes produced by different techniques

Several different methods for production of liposomes incorporating resveratrol were investigated and compared from the aspect of size distribution, surface charge, entrapment efficiency, phase behavior and stability. Thin film method and proliposome method provided high entrapment efficiency (92.9% and 97.4%, respectively). Extrusion and sonication techniques were applied to obtain particles of the average diameter between 120 and 270 nm. The sonicated liposomes incorporated resveratrol (44-56%) fewer than extruded vesicles (92-96%). Antioxidative activity of resveratrol was retained upon encapsulation. Differential scanning calorimetry was performed in order to study the interaction of liposomal membranes with resveratrol, and their physical state. The release studies performed in Franz diffusion cell showed that liposomes impart slow diffusion of resveratrol, where diffusion resistance derived from liposomal membrane ranged from 5.90 . 10(5) to 9.55 . 10(5) s/m depending on the size of particles. Cytotoxicity of the formulations was evaluated via morphological changes of keratinocytes treated by liposomes. Industrial Relevance: Resveratrol displays many health-beneficial properties and possesses a remarkably strong antioxidant activity. Although often consumed in food, the positive effects of resveratrol are restricted because it is prone to oxidation, poorly absorbed when orally administrated, and cytotoxic in higher total dosages (though relatively high local concentrations are required for an effect). Encapsulation is one way to improve bioavailability and stability of resveratrol; herein the main challenge is to find a suitable solution, as resveratrol is weakly water soluble. This has motivated us to design new formulations based on liposomes for delivering of resveratrol. In the food sector, liposomes have been investigated for delivering proteins, enzymes, antioxidants, flavors and vitamins. The mean advantage of liposomes over other encapsulation technologies (spray-drying, extrusion, and fluidized beds) is the stability that liposomes impart to water-soluble compounds in aqueous surroundings. Liposomes are able to stabilize the encapsulated materials against a range of environmental and chemical changes. Another important characteristic of liposomes is that, unlike many other existing encapsulants, they can be utilized in the entrapment, delivery, and release of poorly water soluble compounds, such as resveratrol, and they are also convenient for water-soluble, lipid-soluble, and amphiphilic compounds. As liposomes could be produced from naturally occurring components, regulatory issues that may prevent the application in food systems are potentially diminished, and new formulations could be quickly implemented. Despite benefits described here, up to date little use of liposomes in food systems has been made, as current manufacturing processes are mainly time consuming, often consisting of several steps with high costs of raw materials. Another problem is that devices available commercially which are utilized for production of liposomes are able to process only small quantities. Therefore, our research is devoted to the development of the process for liposome production which is easy to scale up, and at the same time, is effective as the common way based on thin film hydration process. The process elaborated in our study utilizes a commercial lipid mixture. The method used called proliposome method is based on replacement of ethanol solvent by aqueous media. For liposome downsizing, sonication (which can be easily modified to increase sample volume capability) is tested versus membrane extrusion (equipment for small-large batches is readily available). The goal of this article is to provide evidence for food manufacturers and food scientists to make broader use of resveratrol-loaded liposomes that can add value and improve the quality of existing food products

Effects of solvent and degree of fragmentation on total polyphenols and antioxidant activity of Thymus serpyllum extracts

Wild Thyme (Thymus serpyllum) is perennial, herbaceous plant of Lamiaceae family. It has aromatic, antioxidant, antiseptic, anthelmintic, repelent, antirheumatic, expectorant, antispasmotic, carminative, sedative and diuretic properties. Optimization of the extraction by maceration of T. serpyllum was carried out through varying degrees of fragmentation (0.3, 0.7 and 1.5) and the type of solvent (water, ethanol and mixtures of those in weight ratio 50:50 and 70:30). Extraction efficiency was expressed via total polyphenols content and antioxidant activity. The highest total polyphenols content and antioxidant activity were recorded in 50% ethanolic extract, with a degree of fragmentation of 0.3, 921,51 mg GA/g DW and 0,538 mM Trolox/g DW, respectively. No significant differences were observed between total polyphenols and antioxidant activity in water and in 70% ethanolic extracts. The lowest total polyphenols content and antioxidant activity were obtained in 96% ethanolic extract (70.73 mg GA/g DW and 0,142 mM Trolox/g DW, respectively)

Mechanical properties of composites based on unsaturated polyester resins obtained by chemical recycling of poly(ethylene terephthalate)

Composites based on unsaturated polyester (UPe) resins and fumed silica AEROSIL® RY 50, NY 50, RX 50 and NAX 50, as well as graphite, TiO2 or organically modified clay CLOISITE 30B were prepared in order to investigate the influence of reinforcing agents on the mechanical properties of composites. Unsaturated polyester resins were synthesized from maleic anhydride and products of glycolysis, obtained by depolymerization of poly(ethylene terephthalate) with dipropylene glycol (UPe1 resin) and triethylene glycol (UPe2 resin) in the presence of tetrabutyl titanate catalyst. The obtained unsaturated polyesters were characterized by FTIR spectroscopy, acid and hydroxyl values, and their mechanical properties were also examined. Significant increase of the tensile modulus, tensile strength and decrease of the elongation at break was observed for composites prepared after addition of 10 wt.% of graphite or 10 wt.% of TiO2 to the UPe resins, indicating strong interaction between matrix and filler particles. On the other hand, nanocomposites prepared using UPe2 and hydrophobically modified silica nanoparticles showed lower tensile strength and tensile modulus than polymer matrix. The presence of CLOISITE 30B had no significant influence on the mechanical properties of UPe1, while tensile strength and tensile modulus of UPe2 increased after adding 10 wt.% of clay. [Projekat Ministarstva nauke Republike Srbije, br. 172013

Encapsulation of natural antioxidant resveratrol in liposomes

Liposomes have been shown to be suitable systems for encapsulation and preserving the health-beneficial properties of a wide range of biological active ingredients such as resveratrol (RSV). The aim of this study was to encapsulate RSV in liposomes, with a goal to achieve the extended release and improved stability of RSV. Multilameral liposomes were prepared by means of two different methods: thin film method (TF) and proliposome method (PRO). In both methods, the ratio between added RSV and phospolipon 90G (P90G) was 1:20 w/w. Extrusion and sonication were applied in order to obtain unilameral liposomes. Both methods were efficient in capturing RSV within the microparticles, thus encapsulation efficiency had high values (92,9% in case of TF and 97,4% in case of PRO). The size reduction of liposomes resulted with particles of the average diameter ranged between 120 and 270 nm. Antioxidative activity was retained at a high level (approximately 95%). Franz diffusion cell was used for release studies and diffusion of RSV was monitored for 6h. According to the results, liposomes appeared to be suitable vehicles for encapsulation of resveratrol where PRO is particularly useful for encapsulation of antioxidants

Encapsulation of Thymus serpyllum L. aqueous extract in chitosan and alginate-chitosan microbeads

The aim of this study was to investigate encapsulation processes of Thymus serpyllum L. aqueous extract in chitosan and alginate-chitosan microbeads and its consecutive release. Chitosan microbeads were prepared in water-in-oil (W/O) microemulsion, while alginate-chitosan microbeads were prepared by electrostatic extrusion. The outer surface of microbeads was observed by optical microscopy. The interaction between chitosan or alginate-chitosan microbeads and extract compounds were analyzed by FT-IR. Release profiles of polyphenolic compounds from the microbeads in water was monitored. Experimental results show that the applied methods gave chitosan and alginate-chitosan microbeads with an average diameter of 390 μm and 890 μm, respectively. FT-IR analyses confirmed the presence of polyphenolic extract within the synthetized microbeads. The encapsulation efficiency was determined with respect to total polyphenolic content. Chitosan microbeads showed lower encapsulation efficiency of ∼10%, but prolonged release, compared to alginate-chitosan microbeads where encapsulation efficiency was ∼70%. The uniformity of the obtained microbeads was confirmed by optical microscopy. This study showed that, by some synthesis modification of both, chitosan and alginate-chitosan microbeads have the potential to be used for encapsulation of aqueous phenolic extracts