藥物控制釋放有利於提高藥物療效、降低毒副作用，可減輕病人多次用藥的痛苦，因此藥物載體具有發展潛力。本研究利用鞘流現象設計一組微流道晶片設備，並且利用計算流體力學(CFD-RC®)來模擬此單一晶片結構的流體流動之現象，以利用此晶片來生成均一粒徑微膠囊，並且選用常見於藥物載體的褐藻酸鈉材料作為應用。經實驗證明，本研究中藉由此微流道晶片來結合內部膠化與外部膠化兩種不同生成褐藻酸鈣的機制，生成均一粒徑乳化球，來增加藥物投遞的專一性。本研究成功的利用所設計的微流道晶片設備，經由調控分離相與連續相的流量及利用黏度的差異可生成粒徑分佈70-300 µm的均一乳化球。在本論文將分成3個部分來探討:(1) 分離相與連續相流量改變對乳化球大小生成之關係；(2) 黏滯係數對生成之乳化球大小之關係；(3) 將褐藻酸鈉溶液混合奈米粒子溶液以作為分離相溶液作為生成均一粒徑藥物載體的可行性。由實驗結果一發現，當固定分離相流量時，越大的連續相流量，將得以生成越小的乳化球；相對的，在固定連續相流量的情形下，當分離相的流量越小，所生成的乳化球尺寸也越小。由實驗結果二發現當固定分離相黏度時，黏度越大的連續相，將得以生成越小的乳化球。

This study describes the process of formation of monodisperse calcium alginate microcapsules by using microfluidic T-junction geometries. We focus on the investigation of the velocity fields and pressure fields. The flow inside the module is studied by means of computational fluid dynamics (CFD-RC®). Based on sheath force, Water-in-Oil (W/O) emulsions of an aqueous solution of a biopolymer are emulsified in an oil phase. In the external gelation method, these fine emulsions, consisting of 1.5% w/v Na-alginates, are then dripped into a solution of 20% calcium salt to accomplish Ca-alginate microparticles (Ca-alg MPs) in an efficient manner. In the internal gelation method, these fine emulsions, consisting of 0.5% w/v Na-alginate and calcium carbonate, are then dripped into an oil solution containing 20% v/v glacial acetic acid and 1% v/v Tween 80 to accomplish Ca-alg MPs in an efficient manner. The mechanism is that acetic acid reacts with the calcium carbonate to release the calcium ions, and these calcium ions are then cross-linking with the Na-alginate to produce Ca-alg MPs.

Three main topics: (1) the emulsion sizes under oil flow rate and sample flow rate. (2) Effects of viscosity on the emulsion sizes. (3) We examined the encapsulation of nanoparticles (AgNPs and AuNPs), to verify the applicability of the microfluidic technique. Experimental data show that emulsions with diameters ranging from 70 µm to 300 µm with a variation less than 10% are precisely generated. The size and gap of the emulsions are tunable by adjusting the relative sheath/sample flow rate ratio. The approach in manipulation of microparticles will provide many potential usages for pharmaceutical application. The proposed method has advantages of being readily controlled; cost-effective and easy to operate, together with its ability to produces a uniform size and gap.

[1] S. C. Khanna, M. Soliva and P. Speiser, “Epoxy resin beads as a pharmaceutical dosage form, method of prepartion,” Journal of Pharmaceutical Science, 58, 1114, 1969.
[2]R. Arshady, “Microspheres and microcapsules, a survey of manufacturing techniques part II: Coacervation,” Polymer Engineering and Science, 30, 905, 1990.
[3] D. Torres, L. Boado, D. Blanco and J. L. Vila-Jato, “Comparison between aqueous and non-aqueous solvent evaporation methods for microencapsulation of drug-resin complexes,” International Journal of Pharmaceutics, 173, 171, 1998.
[4] 鍾志鴻，以幾丁聚醣微小球包覆肝素之特性研究，中原大學醫學工程研究所碩士論文，民國89年。
[5] R. Langer, “Drug delivery and targeting,” Nature, 392, 5, 1998.
[6] J. Siepmann and A. Gopferich, “Mathematical modeling of bioerodible, polymeric drug delivery systems,” Advanced Drug Delivery Reviews, 48, 229, 2001.
[7] T. Higuchi, “Mechanism of substained action medication,” Journal of Pharmaceutical Science, 52, 1145, 1963.
[8] U. Schmalfuss, R. Neubert and W. Wohlrab, “Modification of drug penetration into human skin using microemulsions,” Journal of Controlled Release, 46, 279, 1997.
[9] M. Trotta, S. Morel and M. R. Gasco, “Effect of oil phase composition on the skin permeation of felodipine from O/W microemulsions,” Pharmazie, 52, 50, 1997.
[10] M. J. Alvarez-Figueroa and J. Blanco-Mendez, “Transdermal delivery of methotrexate: Iontophoretic delivery from hydrogels and passive delivery from microemulsions,” International Journal of Pharmaceutics, 215, 57, 2001.
[11] L. Boltri, S. Morel, M. Trotta and M. R. Gasco, “In vitro transdermal permeation of nifedipine from thickened microemulsions,” Journal de pharmacie de Belgique, 49, 315, 1994.
[12] S. Kantaria, G. D. Rees and M. J. Lawrence, “Gelatin-stabilised microemulsion-based organogels: Rheology and application in iontophoretic transdermal drug delivery,” Journal of Controlled Release, 60, 355, 1999.
[13] J. Kemken, A. Ziegler and B. W. Muller, “Investigations into the pharmacodynamic effects of dermally administered microemulsions containing beta-blockers,” The Journal of Pharmacy and Pharmacology, 43, 679, 1991.
[14] J. Kemken, A. Ziegler and B. W. Muller, “Pharmacodynamic effects of transdermal bupranolol and timolol in vivo: Comparison of microemulsions and matrix patches as vehicle,” Methods and Findings in Experimental and Clinical Pharmacology, 13, 361, 1991.
[15] J. Kemken, A. Ziegler and B. W. Muller, “Influence of supersaturation on the pharmacodynamic effect of bupranolol after dermal administration using microemulsions as vehicle,” Pharmaceutical Research, 9, 554, 1992.
[16] T. Yotsuyanagi, T. Ohkubo, T. Ohhashi and K. Ikeda, “Calcium-induced gelation of alginic acid and pH-sensitive reswelling of dried gels,” Chemical Pharmaceutical Bulletin, 35, 1555, 1987.
[17] J. H. Cui, J. S. Goh, P. H. Kim, S. H. Choi and B. J. Lee, “Survival and stability of bifidobacteria loaded in alginate poly-l-lysine microparticles,” International Journal of Pharmaceutics, 210, 51, 2000.
[18] A. Martinsen, G. Skjak-Braek and O. Smidsrod, “Alginate as immobilization material: I. Correlation between chemical and physical properties of alginate gel beads,” Biotechnology and Bioengineering, 33, 79, 1989.
[19] W. Sabra, A. P. Zeng and W. D. Deckwer, “Bacterial alginate: Physiology, product quality and process aspects,” Applied Microbiology and Biotechnology, 56, 315, 2001.
[20] S. Takka and F. Acarturk, “Calcium alginate microparticles for oral administration: I. Effect of sodium alginate type on drug release and drug entrapment efficiency,” Journal of Microencapsulation, 16, 275, 1999.
[21] P. D. Vos, B. D. Haan and R. V. Schilfgaar, “Effect of the alginate composition on the biocompatibility of alginate-polylysine microcapsules,” Biomaterials, 18, 273, 1997.
[22] H. Akiyama, T. Endo, R. Nakakita, K. Murata, Y. Yonemoto and K. Okayama, “Effect of depolymerized alginates on the growth of bifidobacteria,” Bioscience Biotechnology and Biochemistry, 56, 355, 1992.
[23] C. D. Scott, “Immobilized cells: A review of recent literature,” Enzyme and Microbial Technology, 9, 66, 1987.
[24] N. Gerbsch and R. Buchholz, “New processes and actual trends in biotechnology,” FEMS Microbiology Reviews, 16, 259, 1995.
[25] X. D. Liu, W. Y. Yu, Y. Zhang, W. M. Xue, W. T. Yu, Y. Xiong, X. J. May, Y. Chen and Q. Yuan, “Characterization of structure and diffusion behaviour of Ca-alginate beads prepared with external or internal calcium sources,” Journal of Microencapsulation, 19, 775, 2002.
[26] A. Kikuchi, M. Kawabuchi, M. Sugihara and Y. Sakurai, “Pulsed dextran release from calcium-alginate gel beads,” Journal of Controlled Release, 47, 21, 1997.
[27] T. Ostberg, E. M. Lund and C. Graffner, “Calcium alginate matrices for oral multiple unit administration: IV. Release characteristics in different media,” International Journal of Pharmaceutics, 112, 241, 1994.
[28] X. Li, K. Abdi and S. J. Mentzer, “Cloning hybridomas in a reversible three-dimensional alginate matrix,” Hybridoma, 11, 645, 1992.
[29] G. Fundueanu, C. Nastruzzi, A. Carpov, J. Desbrieres and M. Rinaudo, “Physico-chemical characterization of Ca-alginate microparticles produced with different methods,” Biomaterials, 20, 1427, 1999.
[30] A. C. Hulst, J. Tramper, K. Van’t Riet and J. M. M. Westerbeek, “A new technique for the production of immobilized biocatalyst in large quantities,” Biotechnology and Bioengineering, 27, 870, 2004.
[31] C. M. Silva, A. J. Ribeiro, M. Figueiredo, D. Ferreira and F. Veiga, “Microencapsulation of hemoglobin in chitosan-coated alginate microspheres prepared by emulsification/internal gelation,” The AAPS Journal, 7, E903, 2006.
[32] X. D. Liu, D. C. Bao, W. M. Xue, Y. Xiong, W. T. Yu, X. J. Yu, X. J. Ma and Q. Yuan, “Preparation of uniform calcium alginate gel beads by membrane emulsification coupled with internal gelation,” Journal of Applied Polymer Science, 87, 848, 2003.
[33] K. Avgoustakis, A. Beletsi, Z. Panagi, P. Klepetsanis, A. G. Karydas and D. S. Ithakissios, “PLGA-mPEG nanoparticles of cisplatin: In vitro nanoparticle degradation, in vitro drug release and in vivo drug residence in blood properties,” Journal of Controlled Release, 79, 123, 2002.
[34] K. S. Huang, T. H. Lai and Y. C. Lin, “Manipulating the generation of Ca-alginate microspheres using microfluidic channels as a carrier of gold nanoparticles,” Lab on a Chip, 6, 954, 2006.
[35] K. S. Huang, T. H. Lai and Y. C. Lin, “Using a microfluidic chip and internal gelation reaction for monodisperse calcium alginate microparticles generation,” Frontiers in Bioscience, 12, 3061, 2007.
[36] D. A. Drew and R. T. Lahey, “Phase distribution mechanisms in two-phase flow in a circular pipe,” Journal of Fluid Mechanics, 117, 91, 1982.
[37] R. T. Lahey and D. A. Drew, “The analysis of two-phase flow and heat transfer using a multidimensional, four field, two fluid model,” Nuclear Engineering and Design, 204, 29, 2001.
[38] P. J. C. Taylor, “A device for counting small particles suspended in a fluid through a tube,” Nature, 171, 37, 1953.
[39] W. H. Coulter, “High speed automatic blood cell and cell size analyzer,” Proceedings of the National Electronics Conference, 12, 1034, 1956.
[40] R. Rodriguez-Trujillo, C. A. Mills, J. Samitier and G. Gomila, “Low cost micro-coulter counter with hydrodynamic focusing,” Microfluidics and Nanofluidics, 3, 171, 2007.
[41] M. Yamada, M. Nakashima and M. Seki, “Pinched flow fractionation: Continuous size separation of particles utilizing a laminar flow profile in a pinched microchannel,” Analytical Chemistry, 76, 5465, 2004.
[42] J. Takagi, M. Yamada, M. Yasuda and M. Seki, “Continuous particle separation in a microchannel having asymmetrically arranged multiple branches,” Lab on a Chip, 5, 778, 2005.
[43] K. Seiler, D. J. Harrison and A. Manz, “Planar chips technology for miniaturization and integration of separation techniques into monitoring systems,” Journal of Chromatography, 593, 253, 1992.
[44] F. F. Mandy, M. Bergeron and T. Minkus, “Principles of flow cytometry,” Transfusion Science, 16, 303, 1995.
[45] P. L. Judson and L. L. Van, “Flow cytometry,” Primary Care Update for OB/GYNS, 4, 87, 1997.
[46] B. C. Ferrari, G. Vesey, K. A. Davis, M. Gucci and D. Veal, “A novel two-color flow cytometric assay for the detection of cryptosporidium in environmental water samples,” Cytometry, 41, 216, 2000.
[47] Y. C. Tan, J. S. Fisher, A. I. Lee, V. Cristiniab and A. P. Lee, “Design of microfluidic channel geometries for the control of droplet volume, chemical concentration, and sorting,” Lab on a Chip, 4, 292, 2004.
[48] Y. C. Tan and A. P. Lee, “Microfluidic separation of satellite droplets as the basis of a monodispersed micron and submicron emulsification system,” Lab on a Chip, 5, 1178, 2005.
[49] S. L. Anna, N. Bontoux and H. A. Stone, “Formation of dispersions using “flow focusing” in microchannels,” Applied Physics Letters, 82, 364, 2003.
[50] V. Cristini and Y. C. Tan, “Theory and numerical simulation of droplet dynamics in complex flows—a review,” Lab on a Chip, 4, 257, 2004.
[51] Y. C. Tan, V. Cristini and A. P. Lee, “Monodispersed microfluidic droplet generation by shear focusing microfluidic device,” Sensors and Actuators B-chemical, 114, 350, 2006.
[52] K. Hettiarachchi, E. Talu, M. L. Longo, P. A. Dayton and A. P. Lee, “On-chip generation of microbubbles as a practical technology for manufacturing contrast agents for ultrasonic imaging,” Lab on a Chip, 7, 463, 2007.
[53] H. Zhang, E. Tumarkin, R. Peerani, Z. Nie, R. M. A. Sullan, G. C. Walker and E. Kumacheva, “Microfluidic production of biopolymer microcapsules with controlled morphology,” Journal of the American Chemical Society, 128, 12205, 2006.
[54] H. Zhang, E. Tumarkin, R. M. A. Sullan, G. C. Walker and E. Kumacheva, “Exploring microfluidic routes to microgels of biological polymers,” Macromolecular Rapid Communications, 28, 527, 2007.
[55] K. Liu, H. J. Ding, J. Liu, Y. Chen and X. Z. Zhao, “Shape-controlled production of biodegradable calcium alginate gel microparticles using a novel microfluidic device,” Langmuir, 22, 9453, 2006.
[56] S. Sugiura, T. Oda, Y. Izumida, Y. Aoyagi, M. Satake, A. Ochiai, N. Ohkohchi and M. Nakajima, “Size control of calcium alginate beads containing living cells using micro-nozzle array,” Biomaterials, 26, 3327, 2005.
[57] I. Kobayashi, S. Mukataka and M. Nakajima, “Novel asymmetric through-hole array microfabricated on a silicon plate for formulating monodisperse emulsions,” Langmuir, 21, 7629, 2005.
[58] GCC LaserPro Laser Engraver, Cutting Engraving System, http://www.laserproi.com/en/engr_prod_model_detail.php?ID=English_040909014546, GCC, 2003.
[59] Beer-Lambert Law-Wikipedia, The Free Encyclopedia, http://en.wikipedia.org/wiki/Beer-Lambert_law, 2007.