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3 Contents Title Page Copyright Agreement Form..1 Contents Abstract Introduction Definition of Microencapsulation Process Overview of Different Immobilization Techniques Benefits and Application of Microencapsulation Materials and Methods ) Apparatus Set up ) Experimental Method ) Camera set up Specifications ) Calculating Frequency of Vibrator Unit using High Speed Camera ) Other materials ) Experimental Procedures and Calculations...12 Results ) Formation of Microcapsules ) Determining the Velocity Flow at Nozzle Discussion ) Microencapsulation From a Mechanical Perspective ) Microencapsulation from a Chemical Perspective ) Advances and latest application of Microencapsulation..19 Conclusion...20 References

4 Abstract Applying a vibration on a laminar jet for controlled break-up into mono-disperse microcapsules is one among different extrusion technologies for encapsulation of animal and plant cells, microbes, enzymes and liquids. The Vibration technology is based on the principle that a laminar liquid jet breaks up into equally sized droplets by superimposed vibration. In the late 19 th century, Lord Rayleigh theoretically analyzed the instability of liquid jets. He showed that the frequency for maximum instability is related to the velocity of the jet and the nozzle diameter. The optimal vibration parameters are easily and quickly determined in the light of a stroboscope. Once determined, the parameters can be reset in the future, making the process highly reproducible. This experiment is intended to observe the microencapsulating process as it occurs under a high speed camera. This is intended to verify how frequency affects the production rate of microcapsules using Vibrating technology. Key Words: Microcapsules, Vibrating Technology, encapsulation process 3

5 Introduction 1.1 Definition of Microencapsulation Process Microencapsulation is simply a process by which tiny parcels of a gas, liquid, or solid active ingredient are packaged within a second material for the purpose of shielding the active ingredient from the surrounding environment (oxidation or hydrogenation). These capsules, which range in size from one micron (one-thousandth of a millimeter) to seven millimeters, release their contents at a later time by means appropriate to the application. Depending on the methodology used the Microencapsulation process may yield either microspheres or microcapsules. Microspheres are solid spheres with a matrix-encapsulated active agent whereas microcapsules consist of a solid shell and a liquid or solidified core. (see picture 1) Picture 1: Schematic drawing of Microcapsules and Microspheres. From left to right: Microcapsule with solution as core, Microcapsule with cell suspension as core, Microsphere with matrix encapsulated active agent. There are four typical mechanisms by which the core material is released from a microcapsule mechanical rupture of the capsule wall, dissolution of the wall, melting of the wall, and diffusion through the wall. Less common release mechanisms include ablation (slow erosion of the shell) and biodegradation. 4

6 1.2 Overview of Different Immobilization Techniques Depending on material, manufacturing technique and application, microcapsules are divided into different classes: solid particles are dispersed in a matrix while droplets are encapsulated either in mono- or polynuclear form. A second wall layer can be coated around the capsules to modify its permeability and stability. Based on different Criteria immobilization techniques are divided in two major groups: Immobilization based on binding at a carrier Immobilization based on encapsulation in matrices or membranes Microcapsules have been prepared by a variety of different methods that are often combined or overlap to a certain extend. For the sake of simplicity, the main microencapsulation techniques are categorized as mechanical, physic-chemical (simple and complex coacervation, phase separation) or chemical operations (in-situ Polymerization, interfacial polycondensation). Mechanical microencapsulation operations result from mechanical procedures than from a well-defined physical or chemical phenomenon. Various coating and spray drying 5

7 methods are routinely used in Industry. Extrusion of polymer solutions, through nozzles to produce either beads or capsules is routinely used on laboratory scale, where often, simple devices such as syringes are applied. If the droplet formation occurs in a well-controlled way (contrary to spraying) the technique is known as prilling. This is preferably done by pulsating of the jet or vibration of the nozzle. The use of coaxial air flow or an electromagnet field is other common techniques to form droplets. Mass production of beads can either be achieved by multi-nozzle systems, rotating disc atomizer or by recently developed jet-cutting technique. Centrifugal systems using either a multi-nozzle system or a rotating disk have also been developed for mass production of microcapsules. Figure 2, MICROENCAPSULATION TECHNIQUES 6

8 1.3 Benefits and Application of Microencapsulation To increase of bioavailability To alter drug release To improve patient s drug compliance To reduce the reactivity of the core in relation to outside environment To decrease evaporation rate of core material To convert liquid to solid form & To Mask the core taste Microencapsulation provides the unique attributes to a variety of products that are used in our daily lives, namely: scratch-and-sniff perfume advertisements laundry detergents, baking mixes, and aspirin. These microencapsulated products rely on mechanical rupture of the shell to release the core contents. Scratch-and-sniff perfume advertisements work because tiny perfume-filled microcapsules are coated onto the magazine page. When scratched, the shell wall ruptures, releasing the perfume. Carbonless copy paper utilizes the same release mechanism. Small capsules, 1 20 microns in diameter, coat the underside of the top sheet of paper. The capsules contain a dye precursor a clear chemical that by itself will not put a mark on the lower page, but darkens in color when exposed to an acidic component (such as attapulgite clay or phenolic resin). This acidic component coats the top of the lower sheet. When subjected to the high local pressure beneath a pen point, the capsules break, the two reactants mix, and the copy appears on the lower sheet. Another area where microencapsulation has been widely applied is in the detergent industry. Some powder detergents contain protein reactive enzymes such as protease, used in removing blood stains. The enzymes are encapsulated in a water-soluble polymer, such as polyethylene glycol, for aesthetic reasons and safe handling purposes. Released upon shell 7

9 dissolution in the washing machine, the enzymes attack the blood protein, thereby helping to remove the blood stain. Many packaged baking mixes include encapsulated ingredients to delay chemical reactions until proper temperatures are reached. Sodium bicarbonate is a baking ingredient that reacts with food acids to produce leavening agents, which give baked goods their volume and lightness of texture. To delay and control the leavening process, the sodium bicarbonate is encapsulated in a fat, which is solid at room temperature but melts at a temperature of about 125 F. Release of the core material is delayed until the proper temperature is reached. Microencapsulated products in the pharmaceutical industry are common, particularly when sustained release of a medication is required. Aspirin provides effective relief for fever, inflammation, and arthritis, but direct doses of aspirin can cause peptic ulcers and bleeding. The drug is therefore sometimes encapsulated in ethyl cellulose or hydroxypropyl methylcellulose and starch (aspirin tablets are formed by pressing together collections of these microcapsules). Rather than being released all at once, the aspirin diffuses through the shell in a slow, sustained dose. Microencapsulation is a growing field that is finding application in many technological disciplines. A wide range of core materials in addition to those listed above have been encapsulated. These include adhesives, agrochemicals, catalysts, living cells, flavor oils, pharmaceuticals, vitamins, and water. There are many advantages to microencapsulation. Liquids can be handled as solids, odor or taste can be effectively masked in a food product, core substances can be protected from the deleterious effects of the surrounding environment, toxic materials can be safely handled, and drug delivery can be controlled and targeted. 8

10 Figure 3, APPLICATIONS OF MICROENCAPSULATION TECHNIQUES 9

11 2.1) Apparatus Set Up Materials and Method Figure 4, MICROENCAPSULATION PROCESS SET UP 2.2) Experimental Method The process itself can be described schematically as follows (Figure 4): A liquid feed is pumped from a feed tank (3) to the nozzle head (5), whereupon exiting the vibrating device (2) induces the breakup of the flow into uniform droplets. These are formed into spheres by the surface tension of the liquid. The droplets are solidified during falling (8). This can be realized depending on the materials and/or coagulation system used by cooling, chemical reaction or drying. The head of the microsphere unit can be placed inside a heating chamber for temperature sensitive materials. The visual control of the process can be achieved either by using a stroboscopic lamp (6) or a camera set (7) for remote control. The electronic cabinet (1) that controls the microsphere unit can be integrated into an already existing control system. 10

12 2.3) Camera set (7) Specifications: ZR1000 以下是他的主要規格影片 :FHD:1920 x1080 (30fps) HD :1280x720 (15fps/20fps/30fps) STD:640x480 (30fps) HS1000:224x64 (1000fps) HS 480:224x160 (480fps) HS240:512x384 (240fps) HS 120:640x480 (120fps) HS :512x384 (30 ~ 240fps) HS :640x480 (30 ~ 120fps) 感光元件 :1/2.3 吋高速 CMOS( 背照射型 ) 總像素 :1679 萬 2.4) Calculating Frequency of Vibrator Unit using High Speed Camera: First shot with high-speed photography at 1000fps Then using computer to play six times slow motion Slow down to about 6 times in the film revolution for 1.33 seconds Thus, 1.33Hz * 33 * 6 times = around 263Hz 11

13 VIRATOR UNIT (253Hz = 15840RPM) Shock Absorbing Tripod Stand 2.5) Other Materials: Sodium Alginate (C 6 H 7 NaO 6 ) n Calcium Chloride, Anhydrous (CaCl2) Methylene Blue (C 16 H 18 ClN 3 S) Electronic Balance Syringe and Needle (2cc) Beakers and Ruler Strainer 2.6) Experimental Procedures and Chemical Preparation: a) An aqueous solution of Anhydrous Calcium chloride was prepared in a beaker at 25 C. b) In a separate beaker, a solution of sodium alginate with methylene blue was prepared; also at room temperature. c) A new syringe was then filled with the sodium alginate/methylene solution and set up on stand as shown in figure 4 of the set up process. d) As can be seen in figure 4, the beaker filled with aqueous Calcium Chloride solution was set up such as to receive the drops of alginate/methylene solution which afterwards would become an insoluble (Calcium Alginate) and separate out 12

14 as microspheres. 2 sodium alginate + calcium chloride calcium alginate + 2 sodium chloride e) The Vibrator at approximately RPM was place near the nozzle of the syringe so as disrupt fluid flow and creating droplet streams with narrow size distribution. 13

15 3.1 Formation of Microcapsules Results After carrying out the process several times the end product (microcapsules) were formed. The sizes of the capsules were different. Without the usage of the vibrator setup the capsules formed were generally larger (see figure 5) than those using the vibrator. Also, the Production rate and productivity was greater when using the vibration technology. FIGURE 5, CAPSULE FORMATION WITH VIBRATION TECHNOLOGY ON LEFT, WITHOUT ON RIGHT 3.2 Determining the Velocity Flow of Sodium Alginate Solution as it Exits the Syringe Nozzle Q is flow rate; A is Cross-sectional area, V is the velocity flow Given that Q = AV 2cc = 2000mm ³ T = 14 seconds D = 0.6mm 14

16 Q = 2000/14 = mm ³ / s A = πd ² / 4 = mm ² Q = AV V = / = mm / s V = 0.5m / s Figure 6, Productivity of Microcapsules with Vs. Without Vibrating Nozzle 15

17 Discussion 4.1 Microencapsulation From a Mechanical Perspective Because of the multitude of factors that must be taken into account when designing and preparing microcapsules, it is likely that microencapsulation will remain, to some extent, an art. However, this does not preclude a scientific understanding of microencapsulation processes. Researchers at SwRI are working to better understand the physical mechanisms governing compound fluid jet breakup and satellite formation, to design more efficient co-extrusion microencapsulation processes. These processes will be capable of producing capsules with narrower size distributions and more uniform shell thicknesses at higher production rates. Depending on the flow rates of core and shell materials, capsules are formed in one of two modes: drip (normal) or jet. In drip mode, core and shell liquids flow out of the concentric orifices at a low rate, and a compound drop begins to form at the nozzle tip. As is the case with a slowly dripping faucet, surface tension prevents the compound drop from immediately separating from the orifice. However, once it is large enough, the weight of the drop overcomes the cohesive force of surface tension, and the drop falls from the nozzle. As long as the fluid flow rates and temperatures remain constant, this process can produce uniform sized, but fairly large, capsules. Although drip mode produces uniform capsules, the production rate is quite low (approximately 20 to 30 capsules per minute). Increased output can only be realized by 16

18 using multiple nozzles. However, the cost of pumping and capsule collection equipment often prohibits scale-up of drip mode encapsulation processes. In this experiment tests have shown that the vibrating nozzle processes (laminar flow breakup) scale very well with Newtonian liquids. For industrial applications, it is possible to use multi-nozzle systems as well as high throughput settings. A close correspondence to theoretical calculations is seen (see Figure 7). For non-newtonian liquids, the scalability according to theoretical calculations is not possible anymore. On the other hand, the throughput can still be changed by using different number of nozzles. Especially when using non-newtonian liquids, the design of the unit is important. A small change in the nozzle shape or the set-up can change the quality of the product. Figure 7 17

19 4.2 Microencapsulation from a Chemical Perspective Sodium alginate is a polymer which can be extracted from brown seaweed and kelps. It is one of the structural polymers that help to build the cell walls of these plants. It has some unusual properties and a wide variety of uses as already described in the introduction part. The polymer can be represented like this: When sodium alginate is put into a solution of calcium ions, the calcium ions replace the sodium ions in the polymer. Each calcium ion can attach to two of the polymer strands. This is called cross-linking and can be represented like this: 18

20 Figure Advances and latest application of Microencapsulation For decades scientists have dreamed of plastics that heal themselves like human skin. Cracks in water pipes and car bonnets would seal up. Satellites could repair their own damage. Broken electronic chips in laptops and mobile phones would spontaneously sort out their own problems. This self-healing property is just another fascinating application of Microcapsules. The Polymer material contains a network of capillaries that deliver healing chemicals to damaged areas. The chemicals arrive via two separate streams. They combine to seal the gap in a two-stage reaction. Initially, they form a gel scaffold across the hole. The gel then slowly hardens into a robust, solid structure. 19

21 Conclusion Vibration assisted encapsulation yielded much higher production rates than the drip (normal) mode, but capsule uniformity was not as consistent. Standard deviations of capsule sizes were typically 35 to 50 percent of the mean capsule diameter. 20

22 References Morgan, James. Self-healing plastic mimics blood clotting. BBC News. Report, May 9, Accessed: May 13, 2014 Science & Food. Deconstructed Apple Pie. Posted, May 18, Accessed: May 13,2014 RSC Advancing the Chemical Sciences. Cross link Polymers. df. Accessed: May 13, 2014 Universe of Science. The Alginate worm Connection or when Algy meets Calcium. Accessed May 13, 2014 Franjione, John, Ph.D., and Vasishtha Niraj, Ph.D. The Art and Science of Microencapsulation. SWRI Publications. Accessed May 2, 2014 Kumar, Sathesh. Microencapsulation. Accessed May 1, 2014 Marison, Ian. Berger, Andreas. Heinzen, Christoph. Use of Vibration Technology for Het Break-Up for Encapsulation of Cells and Liquids in Monodisperse Microcapsules. Accesed: May 1,

23 Ravipharmabwm. Microencapsulation Techniques. Slideshare. Posted March 23, Accessed: April 29, 2014 The Present role of Microencapsulation. SCIENTIST LIVE. Posted March 4, Accessed April 25, Orive, Pedraz. Advances in Experimental Medicine and Biology, Volume Accessed April 24, 2014 Micro-encapsulation. Wikipedia, the free encyclopedia. Poste April Accessed April 22, Brandau, Thorsten & Brandau, Egbert. Vibrating Nozzle Processing in Industrial Microencapsulation. Brace GmbH. Published Sept., 18-21, 2005 by 15 th International Symposium on Microencapsulation, Parma, Italy. 22