Immobilization and Photocurrent Activity of a Light-Harvesting Antenna Complex II, LHCII, Isolated from a Plant on Electrodes

Abstract

A light-harvesting (LH) antenna complex II, LHCII, isolated from spinach was immobilized onto an indium tin oxide (ITO) electrode with dot patterning of 3-aminopropyltriethoxysilane (APS) by utilizing electrostatic interactions between the cationic surface of the electrode and the anionic surface of stromal side of the LHCII polypeptide. Interestingly, the illumination of LHCII assembled onto the ITO electrode produced a photocurrent response that depends on the wavelength of the excitation light. Further, LHCII was immobilized onto a TiO 2 nanostructured film to extend for the development of a dye-sensitized biosolar cell system. The photocurrent measured in the iodide/tri-iodide redox system of an ionic liquid based electrolyte on the TiO 2 system showed remarkable enhancement of the conversion efficiency, as compared to that on the ITO electrode.

Photocurrent generation by recombinant allophycocyanin trimer multilayer on TiO2 electrode

“…2b show the key parameters that were measured for a typical performance of the APC-trimer- (Fig. 2b) for this system on an exposure to 100 mW/cm 2 is similar to those recently reported in similar sensitized solar-cell systems (TiO 2 photoanodes and similar electrolyte solutions), in which the performance of a LHCII-sensitized solar-cell was I sc = 0.49 mA/cm 2 and V oc = 0.47 V, and the photocurrent response of a PSI-sensitized solar-cell was I sc = 0.362 mA/cm 2 and V oc = 0.5 V [2,5]. The I sc achieved with the recombinant APC trimer is over 50% higher than those with LHCII and PSI under a V oc of roughly 0.5 V, which indicates an enhanced photocurrent.…”

“…However, as in antenna complexes, the photocurrent in this case was ascribed to the photoexcited trimer and subsequent electron transfer, as demonstrated in previous reports ( Supplementary Fig. S5) [5,20].…”

“…2a); this demonstrated that the APC trimer complexes were not disassembled following the formation of the multilayer structure [9]. It is possible that electrostatic interactions, especially hydrogen bonds, which are strong noncovalent forces in biological systems through functional groups such as carbonyl, amide, or imidazole, especially in macromolecules, are responsible for the multilayer adsorption, as noted previously [5,15,18]. Previous reports suggested that photocurrent generation based on photoreaction center complexes (BR, PSI, and PSII) is a result of electron transfer and continuous re-reductions in solution, after charge separation originating from the initial photoexcitation [4,17,19].…”

“…Recently, the development of Grä tzel cells was inspired by the possibility of using biological macromolecules with pigments as sensitizers for dye-sensitized solar-cells [1]. So far, studies have focused on bacteriorhodopsin (BR), photosystem I (PSI), photosystem II (PSII), and light-harvesting complexes (LHCII) to create direct-conversion photovoltaic devices [2][3][4][5].…”

TiO2: A Critical Interfacial Material for Incorporating Photosynthetic Protein Complexes and Plasmonic Nanoparticles into Biophotovoltaics

“…This mechanism has an advantage to reduce the possibility of charge recombination [11]. Owing to such similarity, various DSC architectures have been explored to directly use natural extracted pigments [12,13] and photosynthetic LHCs [14][15][16][17] as photosensitizers to replace synthetic dyes in developing biophotovoltaic cells. Although the biophotovoltaic cells have much lower PCE than normal DSSCs, these hybrid systems serve as a unique platform to study the crucial processes including charge separation and transport at the interface of TiO 2 photoanode with natural photosensitizers and provide insights into the limiting factors.…”