Electrochemically Gated Long‐Distance Charge Transport in Photosystem I

• Published in: Angewandte Chemie International Edition Vol. 58; no. 38; pp. 13280 - 13284
• Main Authors: López‐Martínez, Montse, López‐Ortiz, Manuel, Antinori, Maria Elena, Wientjes, Emilie, Nin‐Hill, Alba, Rovira, Carme, Croce, Roberta, Díez‐Pérez, Ismael, Gorostiza, Pau
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 16-09-2019
• Edition: International ed. in English
• Subjects: Bioelectricity; Charge exchange; Charge transport; current decay; Distance measurement; electrochemical gating; Electrochemistry; electron transfer; Electron transport; Energy conversion; Energy levels; Microscopy; Photosynthesis; Photosystem I; Probes; Proteins; Redox potential; Scanning tunneling microscopy; Solar energy; Solar energy conversion; current decay; electron transfer; photosynthesis; electrochemical gating; scanning tunneling microscopy
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201904374

The transport of electrons along photosynthetic and respiratory chains involves a series of enzymatic reactions that are coupled through redox mediators, including proteins and small molecules. The use of native and synthetic redox probes is key to understanding charge transport mechanisms and to the design of bioelectronic sensors and solar energy conversion devices. However, redox probes have limited tunability to exchange charge at the desired electrochemical potentials (energy levels) and at different protein sites. Herein, we take advantage of electrochemical scanning tunneling microscopy (ECSTM) to control the Fermi level and nanometric position of the ECSTM probe in order to study electron transport in individual photosystem I (PSI) complexes. Current–distance measurements at different potentiostatic conditions indicate that PSI supports long‐distance transport that is electrochemically gated near the redox potential of P700, with current extending farther under hole injection conditions.
Gating complex: By using electrochemical scanning tunneling microscopy (ECSTM), electron transport in individual PSI complexes was directly measured. It was observed that the distance decay rate β is electrochemically gated near the redox potential of P700, with current extending further for hole injection into photosystem I (PSI).