1Managed by UT-Battelle for the Department of Energy Presentation_name Molecular Photovoltaics and the Optical Activation of Neural Cells E. Greenbaum.

1 Managed by UT-Battellefor the Department of Energy Presentation_name

Molecular Photovoltaics and the Optical Activation of Neural Cells

E. Greenbaum1, M. S. Humayun2, B. R. Evans1, T. Kuritz1, I. Lee3, C. P. Pennisi4

1Oak Ridge National Laboratory, 2University of Southern California,3University of Tennessee, 4Aalborg University

March 18-19, 2009Oak Ridge, Tennessee

The Artificial Retina

3 Managed by UT-Battellefor the Department of Energy Presentation_name

4

7

PSI on a Heterostructure

S S S S S S SS S SS

Au

PSI PSI

OH

OH

OH

OH

OH

OH

OH

OH

OH

OH

OH

Measurement of Electrostatic Potential in Nanometer-Resolution: Schematic Illustration Kelvin Probe Method in Lift Mode

ha

c

b

d

–+ +

0 V

Au

–

+

–

Light

0 nm

0 V

5 V

-5 V0 nm

15 nm

30 nm

Lighton

Lighton

LightOff

LightOff

a b

AFM and KFM Images of PS I Reaction CentersAFM and KFM Images of PS I Reaction Centers Immobilized on GoldImmobilized on Gold

PS I Photovoltage Topography: Summary of Three Types of Measurements

Dark (A) Light (B) (B – A) a Light–Dark b

Periphery 1 (V) 0.77 ± 0.14 -0.47 ± 0.26 -1.24 ± 0.29 -1.13 ± 0.14

Center (V) 0.62 ± 0.08 -0.41 ± 0.24 -1.03 ± 0.25 -0.97 ± 0.04

Periphery 2 (V) 0.99 ± 0.20 -0.59 ± 0.26 -1.58 ± 0.32 -1.20 ± 0.19

No. of PS I Averaged 12 22 4

a Calculated difference between columns B and A. b On the same PS I.

The vertical arrows in above figure indicate three selected voltage points we used in this table: the two extremities and the center.

Conceptual Illustration of Idea

WERI-RbI retinoblastoma cellsWERI-RbI retinoblastoma cellsfused with (proteo)liposomes

Add (proteo) liposomes

WERI-RbI retinoblastoma cellsfused with (proteo)liposomes and loaded with fura-3

Load with the fura-3 dyeIlluminate with 600-700 nm

Spectral Properties of System

FIRST STEP: PSI RECONSTITUTION INTO PROTEOLIPOSOMES

RECONSTITUTION

19

Light triggers increase in cytosolic Ca2+ in proteoliposome-treated cells

Kinetic Time Course Experiments in the Presence and Absence of PSI and External Calcium

21

Spatial Distribution of the Electric Potential From Photosystem I Reaction Centers in Lipid Vesicles

22

Distribution of the Electric Potential Close to a PSI Reaction Center Inserted in the Vesicle

MembraneThe Role of Ionic Strength

0 0.1 M

IEEE Transactions on Nanobioscience, Vol. 7, No. 2, June 2008, Pennisi, Greenbaum & Yoshida