How to Wire Photosynthetic Proteins to Electrodes
New approach for connecting light-harvesting proteins enhances the current produced by a factor of four.
The Science
Plants and certain other organisms use intermittent sunlight to create long-lasting fuels. Scientists are creating devices to mimic this reaction. Researchers created a novel technique that wires a photosynthetic protein onto an electrode, turning sunlight into fuel. They achieved the highest utilization of a photosynthetic protein to date on a human-made bioelectronic device. The new platform efficiently wires multiple proteins of any type to an electrode.
The Impact
While proteins that turn sunlight into fuels are efficient light harvesters, manmade devices that harness the proteins struggle to mimic biology. The challenge, in part, is attaching a protein to an electrode while maintaining the ability of the protein to function. This new approach has overcome these obstacles and created efficient bioelectronics devices that convert light into electricity. With over a factor of four improvement in photocurrent when compared to other thin film systems, this new biohybrid system may provide an appropriate platform for fuel production in the form of hydrogen.
Summary
Scientists developed a new approach to overcome long-standing obstacles in the creation of effective biohybrid systems for converting light into electrical current. During photosynthesis, two plant proteins harvest light and transfer the captured energy. One of these proteins is called Photosystem I (PSI). While its high level of light harvesting efficiency has long made it an attractive component for photo-electrochemical cells, many of these bioelectronic devices suffer from poor electrical conductivity or relatively low production of electric current from harvested light (that is, photocurrent). Progress has been hampered by the inability to control protein orientation, stability, and density on electrode surfaces or attain effective electrical contact between proteins and the electrodes. In this work, researchers at Penn State University developed a novel technique to wire PSI proteins onto electrodes. This new bioelectronic design has a working electrode that takes advantage of its photo-electrochemistry through a hybrid biological and organic system. The scientists solved issues of orientation, stability, and density by embedding the protein in a near-native environment of a fatty bilayer membrane. They positioned the proteins strictly perpendicular to the membrane, yielding a dense two-dimensional crystalline array of the PSI proteins on the electrode surface. The advantage of the flat crystal morphology is that it allows additional functionality to be incorporated in situ, such as connecting PSI to a hydrogen-producing enzyme. The fatty bilayer also contains novel polymer electrolytes (called conjugated oligoelectrolytes) that efficiently conduct electrons from the gold electrode through the fatty bilayer to the PSI protein. This hybrid assembly achieved a photocurrent four times greater than previously observed for thin film systems on an inert electrode such as gold. This design may lead to efficient control of hydrogen production from light in designed bioelectronics devices.
Contact
John Golbeck
Penn State University
jhg5@psu.edu
Funding
This work was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences and the National Science Foundation.
Publications
P. O. Saboe, C. E. Lubner, N. S. McCool, N. M. Vargas-Barbosa, H. Yan, S. Chan, B. Ferlez, G. C. Bazan, J. H. Golbeck, and M. Kumar, “Two-dimensional protein crystals for solar energy conversion.” Advanced Materials 26, 7064 (2014). [DOI: 10.1002/adma.201402375]
Highlight Categories
Performer: University
Additional: Collaborations , Non-DOE Interagency Collaboration
