Laboratorio Regionale LiCryL CNR-INFM

Transcription

1 Laboratorio Regionale LiCryL CNR-INFM c/o Physics Department - University of Calabria, Ponte P. Bucci, Cubo 33B, Rende (CS) Italy UNIVERSITÀ DELLA CALABRIA Dipartimento di FISICA

2 Researchers Dr. Michele Giocondo Dr. Alfredo Mazzulla Dr Federica Chiuchi Dr. Bruno Zappone Dr. Bruno Rizzuti Dr. Luca Sorriso Valvo Dr Maria P. De Santo Said Houmadi PhD student

3 Lab Facilities Langmuir DC Sputtering AFM SFA X-Ray reflectometry SEM-TEM +..

4 MAIN TOPICS Langmuir and Langmuir-Blodgett film of hydrophobin protein from the fungus Pleurotus ostreatus Microsecond Time Resolved Half Leaky Guided Modes Reflectometry for Ordered Complex Fluids Rapid Director Dynamics Investigations

5 Class I hydrphobin from pleurotus ostreatus

6 Isotherm pression-area collapse point Surface pressure Vs. Area isotherm of class I hydrophobin at air/water ph 5.5

7 Constant pressure measurements Area Vs. Time curve to keep constant a given surface pressure value. In this case the surface pressure is 14 mn/m. The plot points out the molecular depletion from the interface toward the subphase bulk.

8 Theoretical basis The experimental data were analyzed using the Volmer s equation¹ ² ³ mkt A coh Volmer s equation with A S n ¹Volmer, M. Z. Phys. Chem. (Leipzig), (1925), 115, 253. ²Fainerman et al, J. Phys. Chem. B (1999), 103, ³Wüstnck et al, J. Phys. Chem. B (2004), 108,

9 Results Parameter Whole Curve Fitting Subsets Fitting (range) m w (nm 2 ) П coh (N/m) n

10 Atomic Force Microscopy Height (nm) Length (µm) Horiz. distance : nm Vert. distance : nm Horiz. distance : nm Vert. distance : nm 1µm AFM topography image and section analysis of protein LB film deposited on silicon substrate, image size is 1 1 µm 2 and height scale 7 nm. We estimate the rodlets height with respect to the LB monolayer as ca. 2.3 nm, Consequently the height of rodlets is ca. 4.8 nm.

11 Atomic Force Microscopy Tapping mode AFM image of protein LB film on silicon wafer. Topography image (left) and phase image (right); the image size is 2 2 µm 2 and height scale 7 nm. The AFM tip does not interact in the same way with the layer and the rodlets leading to different phase contrasts on the monolayer and on the rodletes.

12 Oversimplified scheme of the molecular arrangement inside the LB monolayer and the observed rodlets Obtained assembly by LB technique Coexistance of monolayer and hydrophilic aggregates under form of rodlets Monolayer about 2.5 nm thick and rodlets with uniform thickness of about 5.0 nm

13 Time resolved HLGM Prism coupling of the beam Incidence angle Above the critical angle Exists an angular window where leaky modes propagate Powerful method to determine the director profile

14 Zero gap Cell 1,0 R 0,8 0,6 0,4 0,2 Transmission Total Reflection 0, Critical angle between the high and low index plates of LC cell Angle ( )

15 Filled Cell 1,0 0,8 0,6 R 0,4 0,2 0, Angle ( )

16 Incidence angle Above the critical angle Propagation of HLM

17 Setup Licryl He-Ne Laser lens Polarizer HP-IB bus Trigger Waveform generators Rotating table and sample Electrodes Analizer Photodiode Oscilloscope Amplifier Temperature control of the sample

18 Applied Voltage: square wave 25 KHz The dependence of the response on the burst amplitude has been checked at several fixed angles.

19 Reflectivity data vs time and angle map TIME ANGLE

20 Time dependence of reflectivity curves ss 0s ss 10 s ss 20 s ss 30 s ss 40 s R pp 0s pp 10 s pp 20 s pp 30 s pp 40 s R angle( ) sp 0s sp 10 s sp 20 s sp 30 s sp 40 s angle( ) 1.0 ps 0s ps 10 s ps 20 s 0.8 ps 30 s ps 40 s R R angle( ) angle( )

21 Typical fit result 1,0 1,0 0,8 0,8 0,6 0,6 R 0,4 P-P Conversion R 0,4 P-S Conversion 0,2 0,2 0, Angle ( ) 0, Angle ( ) 1,0 0,8 1,0 0,8 0,6 0,6 R 0,4 S-P Conversion R 0,4 0,2 0,2 S-S Conversion 0, Angle ( ) 0, Angle ( )

22 Tilt profile evolution tilt angle (deg) s 50 s 90 s 130 s 150 s 170 s 190 s thickness ( m)

23 Recent publications L. De Stefano, I. Rea, E. De Tommasi, I. Rendina, L. Rotiroti, M. Giocondo, S. Longobardi, A.Armenante, and P. Giardina Bioactive Modification of Silicon Surface using Self-assembled Hydrophobins from Pleurotus ostreatus. Submitted to Colloids and Surface B: Biointerfaces - manuscript ID: COLSUB-D (Sept. 2008) S. Houmadi, F. Ciuchi, M.P. De Santo, L. De Stefano, I. Rea, P. Giardina, A. Armenante, E. Lacaze and M. Giocondo. Langmuir-Blodgett film of hydrophobin protein from Pleurotus ostreatus at the air-water interface Langmuir, 24 (22), , (2008) /la802306r L. De Stefano, I. Rea, A. Armenante, I. Rendina, P. Giardina and M. Giocondo. Self-Assembled Biofilm of Hydrophobins Protect the Silicon Surface in the KOH Wet Etch Process. Langmuir 23 (15) 7920 (2007) V. Tkachenko, G. Abbate, A. Marino, F. Vita, M. Giocondo, A. Mazzulla, L. De Stefano. Optical characterization of liquid crystals by combined ellipsometry and half-leaky-guided-mode spectroscopy in the visible-near infrared range. J. Appl. Phys. 101, (2007) A. Marino, G. Abbate, V. Tkachenko, I. Rea, L. De Stefano and M. Giocondo. Ellipsometric study of liquid crystal infiltrated porous silicon Mol. Cryst. and Liq. Cryst. 465, 359 (2007) V. Tkachenko, G. Abbate, A. Marino, F. Vita, M. Giocondo, A. Mazzulla, L. De Stefano. High accuracy optical characterization of anisotropic liquids by merging standard techniques Appl. Phys. Lett. 89 (2006)