Evaluation of Materials Using Single Molecules as Nanoscale Probes Miyasaka lab. Yamada Keisuke 1 Contents I. Introduction The significance of measuring single molecules in evaluating microscopic properties of materials II. Single molecule imaging (SMI) methods Wide-field microscopy and its related techniques III. Evaluation of mesoporous materials with SMI Previous works: mesoporous silica My current research topic: mesoporous organosilica IV. Summary 2 Microscopic heterogeneity in condensed matter Ex. Solids of polymer Polymer chains Loose area Packed area Inhomogeneity in nanometer scale Free volume distribution, permittivity, density, viscosity, elasticity, etc. 3 The result of ensemble measurement Emission spectrum of a single molecule Each guest molecule is in different environment. Different electronic state → Position-dependent spectrum and lifetime Heterogeneity in structure, viscosity, etc. → Position-dependent diffusion coefficient of guest By measuring each guest molecule, nanoscale property changes in materials can be evaluated. 4 The motions of individual guest molecules strongly depend on microenvironment. Tracking the motion of guests can provide information on microscopic properties of materials: ・ Nanostructures ・ Mobility of guests (Free volume in polymer, Host-Guest Interaction, etc. ) ・ Spatial heterogeneity .... 5 Wide-field Microscope objective lens Laser DM Band-pass filter PC Back illumination CCD Camera 6 Defocus Imaging Method J. Opt. Soc. Am. B, 2003, 20, 554-559 The direction of the emitting dipole 8 mm Defocus by ~ 1 mm 7 Single Molecule Tracking (SMT) Biophysical J. (2001) 81, 2378. Poly(2-hydroxyethylacrylate) QuickTimeý Dz êLí£ÉvÉçÉOÉâÉÄ Ç™Ç±ÇÃÉsÉNÉ`ÉÉǾå©ÇÈÇž ǽDžÇÕïKóvÇÇ• ÅB X0 = 274.03 +/- 0.0339 pix. Y0 = 148.17 +/- 0.0351 pix. 330 nm x 2 y12 1 B.G. I0 exp 2 2 2w 2w x y Exp. Time: 500 ms 10 frame/s, 32.2 nm/pixel tracking ~ 10 nm in our experimental set up Actual precision of 8 Application of SMT to the evaluation of mesoporous silica What is mesoporous silica ? 2 nm Microporous hexagonal 50 nm Mesoporous cubic Macroporous Applications ・ Adsorption system ・ Molecular sensor ・ Drag delivery Lamellar ・ Periodic nanometer-scale pores ・ Large surface area ・ Easy-controlled structure and pore size C.T. Kresge,et al. Nature 359 (1992), p. 710. 9 How to synthesize the mesoporous material Reagent ; water, ethanol,surfactant, silane monomer, catalyst C.T. Kresge,et al. Nature 359 (1992), p. 710. 10 Evaluation TEM XRD (Transmission Electron Microscope) Intensity [a.u.] (X-Ray Diffraction) 1.0 1.5 2.0 2 /deg. 2.5 Kresge, C. T et al. ,Nature 1992, 359, 710~712. Measure the distance between pores ・ Space resolution in nano meter ・ Measure diameters of pore and observe the structure directly SMT (Single Molecule Tracking) ・ High time and space resolution ・ Evaluation mobility of guest molecules in pores 11 Previous Work CCD QuickTimeý Dz ÉVÉlÉpÉbÉN êLí£Év ÉçÉOÉâÉÄ Ç™Ç± ÇÃÉsÉ NÉ`ÉÉǾå©ÇÈ ÇžÇ½ Ç…ÇÕïK óv ÇÇ• ÅB Kirstein, J. et al. Nat. Mater. 2007, 6 (4), 303-310. Mesoporous Silica (silica framework) ・ record emission of fluorescent guest molecule in mesoporous ・ diffusion behavior show the surrounding structure Trajectory of guest molecule （show mesoporous strucuture） 12 Mesoporous Organosilica Organic groups: ethane, benzene, biphenyl, naphthalene, ... Inagaki, S. et al. Nature 2002, 416, 304-307. Fujita, S.; Inagaki, S. Chem. Mater. 2008, 20, 891-908. (Toyota Central R&D Laboratories) 13 Organic Silane monomer: BTEB Surfactant: Brij76 Fluorescent dye BP-PBI / Brij76, Exp. time: 250 ms BP-PBI O O O O N N O O QuickTimeý Dz Microsof t Video 1 êLí£ÉvÉçÉOÉâÉÄ Ç™Ç±ÇÃÉsÉN É`ÉÉÇ ¾å©ÇÈǞǽDžÇÕïKóvÇ Ç• ÅB O O O N O O O N TDI (Playing at 30 fps) 14 BP-PBI / Brij76 O O O O N N O O 4.2 × 10-3 μm2s-1 O O N O O N O TDI / Brij76 O (1D diffusion) 2.0 × 10-4 μm2s-1 (1D diffusion) Diffusion coefficient is strongly dependent on guests. 15 My Work Dual color SMT System Two kinds of guest molecules are incorporated into the same mesoporous structure. Host-guest interaction can be precisely evaluated. 325,442,488,532 nm 633,660,690 nm CCD1 DM CCD2 Optical filter BP-PBI TDI 16 Summary • I have shown the significance of measuring single molecules in evaluating microscopic properties of materials. • Wide-field microscopy and its related techniques permitted the tracking of translational and rotational motions of individual molecules. • Tracking single guest molecules in mesoporous silica visualized its mesostructures, and detail analysis of the trajectories evaluated the host-guest interaction. 17 Diffusion behavior dependence on guest molecule O O O O N N O O N O O N O O O O Fluorescence Imaging 19 Analytical method Analysis Fluorescence Imaging per 1 frame and determination position coordinate of molecule Analysis formula 2-Dimension Gaussian Function (x x0 )2 (y y0 )2 I(x, y) I 0 exp IBG 2 2 x 2 y 2 I(x, y) I 0 exp 1 2 1 IBG 2 x1 (x x0 )cos (y y0 )sin y1 (x x0 )sin (y y0 )cos Tracking translationaldiffusion of each molecule 20 Tracking translational motion 21 One-dimensional and Two-dimensional 4100 1800 4200 1D 2D 4300 y / nm y / nm 2000 2200 4400 4500 4600 2400 4700 11.2 11.4 x / nm 11.6x10 1D diffusion translation diffusion in mesoporous 3 13.0 13.1 13.2 13.3 13.4 x / nm 13.513.6x10 3 2D diffusion Diffusion in structural defect region surface diffusion 22 Principle Absorption I0 I I0 I I0 Fluorescence I Sensitive detector Single fluorescence molecules in dark space can be detected optically. 23 Characteristics The result of ensemble measurement 同じ資料に異なるゲスト分子をいれて、違いを評 価することで材料のロットによるばらつきを抑えて 議論できる。 そのための装置開発（２色SMT装置）もテーマで あることを述べる Ensemble Single molecule Emission spectrum of a single molecule • • • • Each molecule’s fluctuations High time resolution Evaluation mobility of guest molecules in pores The difference of microscopic environment 24 History Till the 90s… There are some problems of mesoporous material ・ irregularly space ・ broadly distribution in size ・ too small pore size to apply In the 90s … 1990 T.Yanagisawa et al. (Waseda Univ.) 1992 C.T. Kresge et al. (Mobil) ・ Control pore size of mesoporous silica ・ Build up the synthesis based on sol-gel process 25 Characteristics hexagonal cubic Lamellar C.T. Kresge,et al. Nature 359 (1992), p. 710. ・ Periodical meso structure of nano meter scale ・ Large surface area ・ Control the structure and pore size 26
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