在這篇研究中展示了利用高分子電紡纖維的表面製造雙邊表面不對稱奈米球的方法(Janus Particles)。目前Janus Particles的方式大多利用平坦的二維平面輔助的方式製造，但我們使用一維的高分子基材反而更能夠提供更多的工作表面用以製造零維的不對稱奈米球。
這裡採用了混攙系統的靜電紡絲技術製造超高表體積比的纖維性基材，用以製造不對稱奈米球。我們使用兩種不同親疏水性的高分子, 聚甲基丙烯酸甲酯(Polymethyl methacrylate)和聚(四-乙烯吡啶) (poly 4-vinylpyridine),混攙藉以調整纖維表面的特性。
500奈米大小的二氧化矽奈米粒子首先吸附到高分子纖維表面，因為二氧化矽表面的矽醇(silanol)官能基和聚(四-乙烯吡啶)的吡啶(pyridine)官能基能夠提供吸附的作用力。聚甲基丙烯酸甲酯(PMMA)用作為強化纖維的疏水性，以抵抗在浸泡過程中纖維因為水的入侵而變形。
接著，經由熱誘導法使氧化矽半球陷入軟質材料中，再將暴露出的半球利用3-氨基丙基三甲氧基甲矽烷(3-aminopropyltrimethoxysilane)以化學氣相沉積法將其表面改質，以利金奈米粒子接於其上。最後再用溶劑溶掉高分子基材，收集不對稱奈米球。
在檢測產品方面，利用穿透式電子顯微鏡觀測氧化矽奈米球上面金奈米粒子是否為半球的分布。接著Cyto-viva光學顯微鏡也觀測這些不對稱奈米球分散在溶液中獨特的表現。在這篇研究中，不只展示了製造不對稱奈米球的方法。同時也探討經由膠體溶液電紡絲所製造出來的纖維上的相分離

A novel synthetic approach was successfully demonstrated as the efficient fabrication for Janus nanoparticles. Instead of using two-dimensional plane surfaces, one-dimensional polymer fibers provided even more interfacial area to confine or to encapsulate zero-dimensional colloids. A polymer-based electrospinning technique capable of making polymeric fiber mats was employed to produce substrates with high surface-to-volume ratio. A polymer blending system, the mixture of poly(methyl methacrylate) (PMMA) and poly(4-vinyl pyridine) (P4VP), was adapted to generate the electrospun fibers with desired surface properties.
Silica colloids were assembled onto the electrospun polymer substrates due to the interaction between silanol groups from silica colloid surface and pyridine groups from P4VP. The thermally-induced embedment under the precise temperature manipulation was conducted to protect one of the two hemispheres. Exposed hemispheric surface modification of embedded silica colloids was then carried out by the silanization reaction with 3-aminopropyl trimethoxysilane via a chemical vapor deposition. Uniform functionalization on Janus particles were further confirmed by the attachment of gold nanoparticles onto the amino-enriched hemispheric surfaces. Fabrication and characterization of Janus particles were discussed.
In this research, not only the fabrication of Janus particles from template-assisted method was demonstrated, but also the phase separation of fibers from emulsion electrospinning was discussed. Successful mass production of uniform Janus particles in this research work opens the great potentials of using these unique materials in the dual-functional devices, supra-structure materials, electronic papers, anisotropic image probes, and more.

7. Reference
1. Adeline Perro, S. p. R., Serge Ravaine, Elodie Bourgeat-Lamic and Etienne Duguet, Design and synthesis of Janus micro- and nanoparticles. Journal of Materials Chemistry 2005, 15, 3745.
2. De Gennes, Pierre-Gilles; Reviews of Modern Physics 1992, 64,(3), 645.
3. Glotzer, S. C., MATERIALS SCIENCE: Some Assembly Required. Science 2004, 306, (5695), 419-420.
4. Nie, Z.; Li, W.; Seo, M.; Xu, S.; Kumacheva, E., Janus and Ternary Particles Generated by Microfluidic Synthesis: Design, Synthesis, and Self-Assembly. J. Am. Chem. Soc. 2006, 128, (29), 9408-9412.
5. Suzuki, D.; Tsuji, S.; Kawaguchi, H., Janus Microgels Prepared by Surfactant-Free Pickering Emulsion-Based Modification and Their Self-Assembly. J. Am. Chem. Soc. 2007.
6. Takasi Nisisako, Toru Torii, Takanori Takahashi, Yoichi Takizawa, Synthesis of Monodisperse Bicolored Janus Particles with Electrical Anisotropy Using a Microfluidic Co-Flow System. Advanced Materials 2006, 18, (9), 1152-1156.
7. Binks, B. P.; Fletcher, P. D. I., Particles Adsorbed at the Oil-Water Interface: A Theoretical Comparison between Spheres of Uniform Wettability and "Janus" Particles. Langmuir 2001, 17, (16), 4708-4710.
8. Mutsumi Yoshida, K.-H. R., Joerg Lahann, Short-term biocompatibility of biphasic nanocolloids with potential use as anisotropic imaging probes. Biomaterials 2007, 28, 2446.
9. Wang, Y.; Hernandez, R. M.; Bartlett, D. J.; Bingham, J. M.; Kline, T. R.; Sen, A.; Mallouk, T. E., Bipolar Electrochemical Mechanism for the Propulsion of Catalytic Nanomotors in Hydrogen Peroxide Solutions. Langmuir 2006, 22, (25), 10451-10456.
10. Takei, H.; Shimizu, N., Gradient Sensitive Microscopic Probes Prepared by Gold Evaporation and Chemisorption on Latex Spheres. Langmuir 1997, 13, (7), 1865-1868.
11. C. J. Behrend, J. N. A., and R. Kopelman, Brownian modulated optical nanoprobes. APPLIED PHYSICS LETTERS 2004, 84, 154.
12. H.. Koo, D. Y. S. Y. D. Y. K., A Snowman-like Array of Colloidal Dimers for Antireflecting Surfaces. Advanced Materials 2004, 16, (3), 274-277.
13. Shepherd, R. F.; Conrad, J. C.; Rhodes, S. K.; Link, D. R.; Marquez, M.; Weitz, D. A.; Lewis, J. A., Microfluidic Assembly of Homogeneous and Janus Colloid-Filled Hydrogel Granules. Langmuir 2006, 22, (21), 8618-8622.
14. Takasi Nisisako, T. T., Takanori Takahashi, Yoichi Takizawa, Synthesis of Monodisperse Bicolored Janus Particles with Electrical Anisotropy Using a Microfluidic Co-Flow System. Advanced Materials 2006, 18, (9), 1152-1156.
15. T. Nisisako, T. T., Formation of Biphasic Janus Droplets in a Microfabricated Channel for the Synthesis of Shape-Controlled Polymer Microparticles. Advanced Materials 2007, 19, (11), 1489-1493.
16. Roh, K.-H.; Martin, D. C.; Lahann, J., Biphasic Janus particles with nanoscale anisotropy. Nat Mater 2005, 4, (10), 759-763.
17. Cayre, O. J.; Paunov, V. N., Contact Angles of Colloid Silica and Gold Particles at Air-Water and Oil-Water Interfaces Determined with the Gel Trapping Technique. Langmuir 2004, 20, (22), 9594-9599.
18. V.. Paunov, O. C., Supraparticles and Janus Particles Fabricated by Replication of Particle Monolayers at Liquid Surfaces Using a Gel Trapping Technique. Advanced Materials 2004, 16, (9-10), 788-791.
19. Li, Z.; Lee, D.; Rubner, M. F.; Cohen, R. E., Layer-by-Layer Assembled Janus Microcapsules. Macromolecules 2005, 38, (19), 7876-7879.
20. M.. Correa-Duarte, V. S.-M. B. R.-G. L. L.-M. A. K. W. K. M. G., Asymmetric Functional Colloids Through Selective Hemisphere Modification. Advanced Materials 2005, 17, (16), 2014-2018.
21. Cui, J. Q.; Kretzschmar, I., Surface-Anisotropic Polystyrene Spheres by Electroless Deposition. Langmuir 2006, 22, (20), 8281-8284.
22. He, Y. L., Kanshea Novel Janus Cu2(OH)2CO3/CuS microspheres prepared via a Pickering emulsion route Journal of Colloid and Interface Science 2007, 306, 296.
23. Hong, L.; Jiang, S.; Granick, S., Simple Method to Produce Janus Colloidal Particles in Large Quantity. Langmuir 2006, 22, (23), 9495-9499.
24. Pickering, S. U., J. Chem. Soc. 1907, 91, 2001.
25. Zhu, M. W. L., Y. M. Meng, T. Zhan, P. Sun, J. Wu, J. Wang, Z. L. Zhu, S. N. Ming, N. B., Controlled Strain on a Double-Templated Textured Polymer Film: a New Approach to Patterned Surfaces with Bravais Lattices and Chains. Langmuir 2006, 22, (17), 7248-7253.
26. Dzenis, Y., MATERIAL SCIENCE: Spinning Continuous Fibers for Nanotechnology. Science 2004, 304, (5679), 1917-1919.
27. Shin, C. C., G. G., Separation of liquid drops from air by glass fiber filters augmented with polystyrene nanofibers. Journal of Dispersion Science and Technology 2006, 27, (1), 5.
28. Hong, K. H. K., T. J, Polyaniline-nylon 6 composite nanowires prepared by emulsion polymerization and electrospinning process Journal of Applied Polymer Science 2006, 99, (2), 1277.
29. Pawlowski, K. J. B., H. L.; Raney, D. L.; Su, J.; Harrison, J. S.; Siochi, E. J., Electrospinning of a micro-air vehicle wing skin. Polymer 2003, 44, (4), 1309.
30. Riboldi, S. A. S., M.; Neuenschwander, P.; Cossu, G.; Mantero, S., Electrospun degradable polyesterurethane membranes: Potential scaffolds for skeletal muscle tissue engineering. Biomaterials 2005, 26, (22), 4606.
31. Khil, M.-S. C., D.-I.; Kim, H.-Y.; Kim, I.-S.; Bhattarai, N., Electrospun Nanofibrous Polyurethane Membrane as Wound Dressing. Journal of Biomedical Materials Research - Part B Applied Biomaterials 2003, 67, (2), 675.
32. Luong-Van, E. G., L.; Chua, K. N.; Leong, K. W.; Nurcombe, V.; Cool, S. M., Controlled release of heparin from poly(ε-caprolactone) electrospun fibers. Biomaterials 2006, 27, (9), 2042.
33. Demir, M. M. G., M. A.; Menceloglu, Y. Z.; Erman, B.; Abramchuk, S. S.; Makhaeva, E. E.; Khokhlov, A. R.; Matveeva, V. G.; Sulman, M. G.,, Palladium Nanoparticles by Electrospinning from Poly(acrylonitrile-co-acrylic acid)-PdCl2 Solutions. Relations between Preparation Conditions, Particle Size, and Catalytic Activity. Macromolecules 2004, 37, (5), 1787.
34. Li, D.; Wang, Y.; Xia, Y., Electrospinning of Polymeric and Ceramic Nanofibers as Uniaxially Aligned Arrays. Nano Lett. 2003, 3, (8), 1167-1171.
35. Jo, S. M. S., M. Y.; Ahn, Y. R.; Park, C. R.; Kim, D. Y., , Nanofibril formation of electrospun TiO2 fibers and its application to dye-sensitized solar cells. Journal of Macromolecular Science - Pure and Applied Chemistry 2005, 42A, (11), 1529.
36. Dong, H.; Fey, E.; Gandelman, A.; Jones, W. E., Synthesis and Assembly of Metal Nanoparticles on Electrospun Poly(4-vinylpyridine) Fibers and Poly(4-vinylpyridine) Composite Fibers. Chem. Mater. 2006, 18, (8), 2008-2011.
37. Taylor, G. I., Electrically Driven Jets., Proc. R. Soc. London, Ser. A 1969, 20, 1457.
38. Loscertales, I. G.; Barrero, A.; Guerrero, I.; Cortijo, R.; Marquez, M.; Ganan-Calvo, A. M., Micro/Nano Encapsulation via Electrified Coaxial Liquid Jets. Science 2002, 295, (5560), 1695-1698.
39. Z. Sun, E. Z. A. L. Y. J. H. W. A. G., Compound Core-Shell Polymer Nanofibers by Co-Electrospinning. Advanced Materials 2003, 15, (22), 1929-1932.
40. Li, D.; Xia, Y., Direct Fabrication of Composite and Ceramic Hollow Nanofibers by Electrospinning. Nano Lett. 2004, 4, (5), 933-938.
41. Liu, Z.; Sun, D. D.; Guo, P.; Leckie, J. O., An Efficient Bicomponent TiO2/SnO2 Nanofiber Photocatalyst Fabricated by Electrospinning with a Side-by-Side Dual Spinneret Method. Nano Lett. 2007, 7, (4), 1081-1085.
42. Bazilevsky, A. V.; Yarin, A. L.; Megaridis, C. M., Co-electrospinning of Core-Shell Fibers Using a Single-Nozzle Technique. Langmuir 2007, 23, (5), 2311-2314.
43. Xu, X.; Zhuang, X.; Chen, X.; Wang, X.; Yang, L.; Jing, X., Preparation of core-sheath composite nanofibers by emulsion electrospinning. Macromolecular Rapid Communications 2006, 27, (19), 1637-1642.
44. Mikhail Bognitzki, T. F. M. S. A. G. J. H. W. A. S. M. H., Preparation of fibers with nanoscaled morphologies: Electrospinning of polymer blends. Polymer Engineering & Science 2001, 41, (6), 982-989.
45. Peng, M.; Li, D.; Shen, L.; Chen, Y.; Zheng, Q.; Wang, H., Nanoporous Structured Submicrometer Carbon Fibers Prepared via Solution Electrospinning of Polymer Blends. Langmuir 2006, 22, (22), 9368-9374.
46. Poza, P.; Perez-Rigueiro, J.; Elices, M.; Llorca, J., Fractographic analysis of silkworm and spider silk. Engineering Fracture Mechanics 2002, 69, (9), 1035-1048.
47. Lazaris, A.; Arcidiacono, S.; Huang, Y.; Zhou, J.-F.; Duguay, F.; Chretien, N.; Welsh, E. A.; Soares, J. W.; Karatzas, C. N., Spider Silk Fibers Spun from Soluble Recombinant Silk Produced in Mammalian Cells. Science 2002, 295, (5554), 472-476.
48. Chakrabarti, K.; Nambissan, P. M. G.; Mukherjee, C. D.; Bardhan, K. K.; Kim, C.; Yang, K. S., Positron annihilation spectroscopy of polyacrylonitrile-based carbon fibers embedded with multi-wall carbon nanotubes. Carbon 2006, 44, (5), 948-953.
49. Raether, H., Surface Palsmons on smooth and roughness surfaces and on Gratings. Springer-Verlag Berlin Heidelberg New York London Paris Tokyo Book.
50. Kovacs, G. J.; Vincett, P. S., Formation and thermodynamic stability of a novel class of useful materials: Close-packed monolayers of submicron monodisperse spheres just below a polymer surface. Journal of Colloid and Interface Science 1982, 90, (2), 335-351.
51. Hyun Suk Kim, Hyoung-Joon Jin Seung Jun Myung Minsung Kang In-Joo Chin
,Carbon Nanotube-Adsorbed Electrospun Nanofibrous Membranes of Nylon 6. Macromolecular Rapid Communications 2006, 27, (2), 146-151.
52. G.. Han, B. G. L. Z. B. Y., Conductive Gold Films Assembled on Electrospun Poly(methyl methacrylate) Fibrous Mats. Advanced Materials 2006, 18, (13), 1709-1712.
53. Bin Ding, J. K., Eiji Kimura, and Seimei Shiratori, Layer-by-layer structured films of TiO2 nanoparticles and poly(acrylic acid) on electrospun nanofibres. Nanotechnology 2004, 15, 913.
54. Huynh, W. U.; Dittmer, J. J.; Alivisatos, A. P., Hybrid Nanorod-Polymer Solar Cells. Science 2002, 295, (5564), 2425-2427.
55. Yamanaka, J.; Yoshida, H.; Koga, T.; Ise, N.; Hashimoto, T., Reentrant Order-Disorder Transition in Ionic Colloidal Dispersions by Varying Particle Charge Density. Langmuir 1999, 15, (12), 4198-4202.
56. Agarwal, G. K.; Titman, J. J.; Percy, M. J.; Armes, S. P., Characterization of Vinyl Polymer/Silica Colloidal Nanocomposites Using Solid State NMR Spectroscopy: Probing the Interaction between the Inorganic and Organic Phases on the Molecular Level. J. Phys. Chem. B 2003, 107, (45), 12497-12502.
57. Shenderovich, I. G.; Buntkowsky, G.; Schreiber, A.; Gedat, E.; Sharif, S.; Albrecht, J.; Golubev, N. S.; Findenegg, G. H.; Limbach, H. H., Pyridine-15N - A Mobile NMR Sensor for Surface Acidity and Surface Defects of Mesoporous Silica. J. Phys. Chem. B 2003, 107, (43), 11924-11939.
58. Katherine C. Grabar, R. G. F., t Michael B. Hommer, and Michael J. Natan, Preparation and Characterization of Au colloids monolayer. Analytical Chemistry 1995, 67, (4), 735.
59. Mukhopadhyay, K.; Phadtare, S.; Vinod, V. P.; Kumar, A.; Rao, M.; Chaudhari, R. V.; Sastry, M., Gold Nanoparticles Assembled on Amine-Functionalized Na-Y Zeolite: A Biocompatible Surface for Enzyme Immobilization. Langmuir 2003, 19, (9), 3858-3863.
60. http://www.cytoviva.com/product_physical_properties.htm.
61. So, G. E. C. a. P. T. C., Lateral resolution enhancement with standing evanescent waves. OPTICS LETTERS 2000, 25, 46.
62. Tang, Y.; Li, A.; Wu, D.; Chen, Y., Fabrication and characterization of tunable uniform octahedral nanoporous inorganic silica membranes by assembly under a direct electric field. Nanotechnology 2006, 17, (8), 2023-2026.
63. Laibin Luo, A. E., One-Step Preparation of Block Copolymer Vesicles with Preferentially Segregated Acidic and Basic Corona Chains. Angewandte Chemie International Edition 2002, 41, (6), 1001-1004.
64. Satoh, M.; Yoda, E.; Hayashi, T.; Komiyama, J., Potentiometric titration of poly(vinylpyridines) and hydrophobic interaction in the counterion binding. Macromolecules 1989, 22, (4), 1808-1812.
65. Hartley, P. G.; Scales, P. J., Electrostatic Properties of Polyelectrolyte Modified Surfaces Studied by Direct Force Measurement. Langmuir 1998, 14, (24), 6948-6955.
66. Uchida, E.; Uyama, Y.; Ikada, Y., Zeta Potential of Polycation Layers Grafted onto a Film Surface. Langmuir 1994, 10, (4), 1193-1198.
67. Malynych, S.; Luzinov, I.; Chumanov, G., Poly(Vinyl Pyridine) as a Universal Surface Modifier for Immobilization of Nanoparticles. J. Phys. Chem. B 2002, 106, (6), 1280-1285.
68. Behrend, C. J.; Anker, J. N.; McNaughton, B. H.; Brasuel, M.; Philbert, M. A.; Kopelman, R., Metal-capped brownian and magnetically modulated optical nanoprobes (MOONs): Micromechanics in chemical and biological microenvironments. Journal of Physical Chemistry B 2004, 108, (29), 10408-10414.
69. O'Neal, D. P.; Hirsch, L. R.; Halas, N. J.; Payne, J. D.; West, J. L., Photo-thermal tumor ablation in mice using near infrared-absorbing nanoparticles. Cancer Letters 2004, 209, (2), 171-176.