本研究旨在探討monolayer spontaneous curvature、金屬離子binding以及膜融合三者之間的關係。膜融合是在細胞的生命活動中一個重要且常見的過程，例如：包有神經傳導物質的囊泡藉由鈣離子觸發，與神經細胞的細胞膜進行膜融合並將神經傳導釋出。我們將dioleoyl phosphatidylethanolamine/dioleoyl phosphatidylcholine/4 mol% dioleoyl phosphatidic acid脂質混合物製備成可以模擬生物系統的unilamellar vesicle以及為了量測spontaneous curvature的dispersion兩種樣品。影響膜融合的因素包括monolayer spontaneous curvature以及金屬離子binding。Monolayer spontaneous curvature（C0）是一種彈性性質，它量化脂質分子形成lamellar phase或是nonlamellar phase的趨勢，而nonlamellar phase的形成則被認為是在膜融合中一個重要的過程。從我們的實驗結果發現，膜融合的效率隨著spontaneous curvature的增加而增加。當金屬離子binding在脂質膜時會影響脂質膜的穩定性以及性質。從我們的實驗結果發現，spontaneous curvature和金屬離子binding皆會使脂質膜的厚度增加，但是，膜厚的變化並不足以影響膜融合；DOPE與DOPC頭基的不同造成金屬離子binding對spontaneous curvature的影響程度不同。我們也發現，金屬離子binding影響intra-monolayer與inter-monolayer，進而改變spontaneous curvature與脂質的自組裝結構，最後影響膜融合的效率。

In the present work, we investigate the correlation among spontaneous curvature, metal ions binding and membrane fusion of liposomes. Membrane fusion is an important process of many cellular events, such as neuronal signaling. In order to simulate the biological system, we use DOPE/DOPC/4 mol% DOPA lipid mixture to prepare the unilamellar vesicle. We also prepare lipid dispersion for the measurement of monolayer spontaneous curvature. There are many factors that can affect membrane fusion, including the monolayer spontaneous curvature and metal ions binding. Monolayer spontaneous curvature (C0) quantifies the tendency of forming lamellar phase or nonlamellar phase. Forming nonlamellar structure is considered to be associated with membrane fusion. When the spontaneous curvature become more negative, membrane fusion efficiency will increase. The binding of metal ions to biological membranes affects the stability and the properties of lipid bilayer, is associated with membrane fusion. Both spontaneous curvature and metal ions binding induce lipid membrane thicker. However, the difference of membrane thickness is too small to affect membrane fusion. The influence of metal ions binding to DOPE and DOPC spontaneous curvature is different, due to the difference of lipid headgroup composition. The binding of metal ions to lipid membrane affects lipid intra-monolayer and lipid inter-monolayer, changing the spontaneous curvature and liposome structure, and then, membrane fusion efficiency will be impacted.

1 Yeagle P. L. (2001) Cell Membrane Features.
Encyclopedia of life sciences, 1-7.
2 科技部高瞻自然科學教學資源平台
http://highscope.ch.ntu.edu.tw/wordpress/?p=986
3 http://biology.tutorvista.com/animal-and-plant-cells/
plasma-membrane.html
4 Kulkarni, C. V. (2012). Lipid crystallization: from self-assembly to hierarchical and biological ordering. Nanoscale, 4(19), 5779-5791.
5 Yeagle P. L. (2009) Lipids. Encyclopedia of life sciences, 1-8.
6 Natarajan, J. V., Darwitan, A., Barathi, V. A., Ang, M., Htoon, H. M., Boey, F., and Venkatraman, S. S. (2014). Sustained drug release in nanomedicine: a long-acting nanocarrier-based formulation for glaucoma. ACS nano, 8(1), 419-429.
7 Marsden, H. R., Tomatsu, I., & Kros, A. (2011). Model systems for membrane fusion. Chemical Society Reviews, 40(3), 1572-1585.
8 Gruner, S. M., Tate, M. W., Kirk, G. L., So, P. T. C., Turner, D. C., Keane, D. T., and Cullis, P. R. (1988). X-ray diffraction study of the polymorphic behavior of N-methylated dioleoylphosphatidylethanolamine. Biochemistry, 27(8), 2853-2866.
9 Marsh, D. (2007). Lateral pressure profile, spontaneous curvature frustration, and the incorporation and conformation of proteins in membranes. Biophysical journal, 93(11), 3884-3899.
10 Chen, Y. F., Tsang, K. Y., Chang, W. F., & Fan, Z. A. (2015).
Differential dependencies on [Ca2+] and temperature of the monolayer spontaneous curvatures of DOPE, DOPA and cardiolipin: effects of modulating the strength of the inter-headgroup repulsion. Soft matter, 11(20), 4041-4053.
11 Sessa, G., & Weissmann, G. (1968). Phospholipid spherules (liposomes) as a model for biological membranes. Journal of lipid research, 9(3), 310-318.
12 Torchilin, V. P. (2012). Multifunctional nanocarriers. Advanced drug delivery reviews, 64, 302-315.
13 Wikipedia https://en.wikipedia.org/wiki/Liposome
14 Blumenthal, R., Clague, M. J., Durell, S. R., & Epand, R. M. (2003).
Membrane fusion. Chemical reviews, 103(1), 53-70.
15 Neuronal transmission
http://www.geneticliteracyproject.org/2015/06/01/forget-what-you-
think-you-know-about-how-memory-works/
16 Endocytosis and Exocytosis.
http://www.lrn.org/Popup/Cells/figure3.4.html
17 Chernomordik, L. V., & Kozlov, M. M. (2008). Mechanics of
membrane fusion.
Nature structural & molecular biology, 15(7), 675-683.
18 Chen, X., Araç, D., Wang, T. M., Gilpin, C. J., Zimmerberg, J., &
Rizo, J. (2006). SNARE-mediated lipid mixing depends on the
physical state of the vesicles. Biophysical journal, 90(6), 2062-2074.
19 Harrison, S. C. (2008). Viral membrane fusion. Nature structural & molecular biology, 15(7), 690-698.
20 Mondal Roy, S., & Sarkar, M. (2011). Membrane fusion induced by small molecules and ions. Journal of lipids, 2011.
21 Malinin, V. S., Frederik, P., & Lentz, B. R. (2002). Osmotic and
curvature stress affect PEG-induced fusion of lipid vesicles but not
mixing of their lipids. Biophysical journal, 82(4), 2090-2100.
22 MacDonald, R. I. (1985). Membrane fusion due to dehydration by polyethylene glycol, dextran, or sucrose. Biochemistry, 24(15), 4058-4066.
23 Käsbauer, M., Lasic, D. D., & Winterhalter, M. (1997). Polymer
induced fusion and leakage of small unilamellar phospholipid
vesicles: effect of surface grafted polyethylene-glycol in the
presence of free PEG. Chemistry and physics of lipids, 86(2),
153-159.
24 Yasuhara, K., Tsukamoto, M., Tsuji, Y., & Kikuchi, J. I. (2012).
Unique concentration dependence on the fusion of anionic liposomes
induced by polyethyleneimine. Colloids and Surfaces A:
Physicochemical and Engineering Aspects, 415, 461-467.
25 Haluska, C. K., Riske, K. A., Marchi-Artzner, V., Lehn, J. M.,
Lipowsky, R., & Dimova, R. (2006). Time scales of membrane
fusion revealed by direct imaging of vesicle fusion with high
temporal resolution. Proceedings of the National Academy of
Sciences, 103(43), 15841-15846.
26 Elani, Y., Purushothaman, S., Booth, P. J., Seddon, J. M., Brooks, N.
J., Law, R. V., & Ces, O. (2015). Measurements of the effect of
membrane asymmetry on the mechanical properties of lipid
bilayers. Chemical Communications, 51(32), 6976-6979.
27 http://oasys2.confex.com/acs/225nm/techprogram/P596034.HTM
28 Wilschut, J., Duzgunes, N., Fraley, R., & Papahadjopoulos, D.
(1980). Studies on the mechanism of membrane fusion: kinetics of
calcium ion induced fusion of phosphatidylserine vesicles followed
by a new assay for mixing of aqueous vesicle contents.
Biochemistry, 19(26), 6011-6021.
29 http://www.liposomes.org/2012/05/fluorescent-liposomes-antsdpx-
fusion.html
30 Yang, Q., Guo, Y., Li, L., & Hui, S. W. (1997). Effects of lipid headgroup and packing stress on poly (ethylene glycol)-induced phospholipid vesicle aggregation and fusion. Biophysical journal, 73(1), 277.
31 Poccia, D., & Larijani, B. (2009). Phosphatidylinositol metabolism and membrane fusion. Biochem. J, 418, 233-246.
32 Churchward, M. A., Rogasevskaia, T., Brandman, D. M., Khosravani, H., Nava, P., Atkinson, J. K., & Coorssen, J. R. (2008). Specific lipids supply critical negative spontaneous curvature—an essential component of native Ca 2+-triggered membrane fusion. Biophysical journal, 94(10), 3976-3986.
33 Cacace, M. G., Landau, E. M., & Ramsden, J. J. (1997). The Hofmeister series: salt and solvent effects on interfacial phenomena. Quarterly reviews of biophysics, 30(03), 241-277.
34 Zhang, Y., & Cremer, P. S. (2010). Chemistry of Hofmeister anions and osmolytes. Annual review of physical chemistry, 61, 63-83.
35 Jurkiewicz, P., Cwiklik, L., Vojtíšková, A., Jungwirth, P., & Hof, M. (2012). Structure, dynamics, and hydration of POPC/POPS bilayers suspended in NaCl, KCl, and CsCl solutions. Biochimica et Biophysica Acta (BBA)-Biomembranes, 1818(3), 609-616.
36 Iraolagoitia, X. L. R., & Martini, M. F. (2010). Ca2+ adsorption to lipid membranes and the effect of cholesterol in their composition. Colloids and Surfaces B: Biointerfaces, 76(1), 215-220.
37 McCarley, R. L., Forsythe, J. C., Loew, M., Mendoza, M. F., Hollabaugh, N. M., & Winter, J. E. (2013). Release Rates of Liposomal Contents Are Controlled by Kosmotropes and Chaotropes. Langmuir, 29(46), 13991-13995.
38 Tanaka, T., & Yamazaki, M. (2004). Membrane fusion of giant unilamellar vesicles of neutral phospholipid membranes induced by La3+. Langmuir, 20(13), 5160-5164.
39 Nikolaus, J., Stöckl, M., Langosch, D., Volkmer, R., & Herrmann, A. (2010). Direct visualization of large and protein-free hemifusion diaphragms. Biophysical journal, 98(7), 1192-1199.
40 Lapinski, M. M., Castro-Forero, A., Greiner, A. J., Ofoli, R. Y., &
Blanchard, G. J. (2007). Comparison of liposomes formed by
sonication and extrusion: rotational and translational diffusion of an
embedded chromophore. Langmuir, 23(23), 11677-11683.
41 Wojdyr, M. (2010). Fityk: a general-purpose peak fitting
program. Journal of Applied Crystallography, 43(5), 1126-1128.
42 鄭有舜. (2004). X-光小角度散射在軟物質研究上的應用.
物理雙月刊, 26(2), 416-424.
43 Als-Nielsen, J., & McMorrow, D. (2011).
Elements of modern X-ray physics. John Wiley & Sons.
44 Shearman, G. C., Ces, O., Templer, R. H., & Seddon, J. M. (2006).
Inverse lyotropic phases of lipids and membrane curvature.
Journal of Physics: Condensed Matter, 18(28), S1105.
45 Pabst, G., Rappolt, M., Amenitsch, H., & Laggner, P. (2000).
Structural information from multilamellar liposomes at full
hydration: full q-range fitting with high quality x-ray data.
Physical Review E, 62(3), 4000.
46 Harper, P. E., Mannock, D. A., Lewis, R. N., McElhaney, R. N., &
Gruner, S. M. (2001). X-Ray diffraction structures of some
phosphatidylethanolamine lamellar and inverted hexagonal
phases*. Biophysical journal, 81(5), 2693-2706.
47 Tsang K. Y. (2015) The influences of lipid composition on the
physical properties and biological function of the cell membrane.
National Central University, Master Thesis.
48 Kollmitzer, B., Heftberger, P., Rappolt, M., & Pabst, G. (2013).
Monolayer spontaneous curvature of raft-forming membrane
lipids. Soft matter, 9(45), 10877-10884.
49 Warren, B. E. (1969). X-ray Diffraction. Courier Corporation.
50 Kucerka, N., Pencer, J., Sachs, J. N., Nagle, J. F., & Katsaras, J.
(2007). Curvature effect on the structure of phospholipid
bilayers. Langmuir, 23(3), 1292-1299.
51 Ristori, S., Di Cola, E., Lunghi, C., Richichi, B., & Nativi, C. (2009). Structural study of liposomes loaded with a GM3 lactone analogue for the targeting of tumor epitopes. Biochimica et Biophysica Acta (BBA)-Biomembranes, 1788(12), 2518-2525.
52 Brzustowicz, M. R., & Brunger, A. T. (2005). X-ray scattering from unilamellar lipid vesicles. Journal of applied crystallography, 38(1), 126-131.
53 Pabst, G., Koschuch, R., Pozo-Navas, B., Rappolt, M., Lohner, K., & Laggner, P. (2003). Structural analysis of weakly ordered membrane stacks. Applied Crystallography, 36(6), 1378-1388.
54 Varga, Z., Wacha, A., Vainio, U., Gummel, J., & Bóta, A. (2012). Characterization of the PEG layer of sterically stabilized liposomes: a SAXS study. Chemistry and physics of lipids, 165(4), 387-392.
55 Varga, Z., Berényi, S., Szokol, B., Őrfi, L., Kéri, G., Peták, I., ... & Bóta, A. (2010). A closer look at the structure of sterically stabilized liposomes: a small-angle X-ray scattering study. The Journal of Physical Chemistry B, 114(20), 6850-6854.