Photocurrent of a single photosynthetic protein

Abstract

Photosynthesis is used by plants, algae and bacteria to convert solar energy into stable chemical energy. The initial stages of this process--where light is absorbed and energy and electrons are transferred--are mediated by reaction centres composed of chlorophyll and carotenoid complexes. It has been previously shown that single small molecules can be used as functional components in electric and optoelectronic circuits, but it has proved difficult to control and probe individual molecules for photovoltaic and photoelectrochemical applications. Here, we show that the photocurrent generated by a single photosynthetic protein-photosystem I-can be measured using a scanning near-field optical microscope set-up. One side of the protein is anchored to a gold surface that acts as an electrode, and the other is contacted by a gold-covered glass tip. The tip functions as both counter electrode and light source. A photocurrent of ∼10 pA is recorded from the covalently bound single-protein junctions, which is in agreement with the internal electron transfer times of photosystem I.

Photophysical Properties of Oligo­(phenylene ethynylene) Iridium(III) Complexes Functionalized with Metal‐Anchoring Groups

“…[10][11][12] According to this idea, light has also been proposed as a control tool of molecular conductance in systems that do not undergo photochemical reactions. In addition to some experimental work, [13][14][15] theoretical studies in this area support this idea. [2,[16][17][18][19] For example, the effect of illumination on junctions comprising molecules of different lengths [20,21] or characterized by strong charge-transfer optical transitions [22] have been studied theoretically.…”

Spatial modulation of light transmission through a single microcavity by coupling of photosynthetic complex excitations to surface plasmons

“…Of a special interest is the photosynthetic light harvesting complex, photosystem I (PS I) [18][19][20][21][22] . Photosynthetic complexes are evolutionary tuned to efficiently capture solar light.…”

Enhanced photocurrent from Photosystem I upon in vitro truncation of the antennae chlorophyll

“…Although methods have been developed to measure the photocurrent of an individual PSI molecule, *10pA (Gerster et al 2012), photocurrent was obtained using a Nafion film dried with a redox mediator and PSI embedded in the film as depicted in Fig. 5.…”