Self-organized photosynthetic nanoparticle for cell-free hydrogen production

Abstract

There is considerable interest in making use of solar energy through photosynthesis to create alternative forms of fuel. Here, we show that photosystem I from a thermophilic bacterium and cytochrome-c(6) can, in combination with a platinum catalyst, generate a stable supply of hydrogen in vitro upon illumination. The self-organized platinization of the photosystem I nanoparticles allows electron transport from sodium ascorbate to photosystem I via cytochrome-c(6) and finally to the platinum catalyst, where hydrogen gas is formed. Our system produces hydrogen at temperatures up to 55 degrees C and is temporally stable for >85 days with no decrease in hydrogen yield when tested intermittently. The maximum yield is approximately 5.5 micromol H(2) h(-1) mg(-1) chlorophyll and is estimated to be approximately 25-fold greater than current biomass-to-fuel strategies. Future work will further improve this yield by increasing the kinetics of electron transfer, extending the spectral response and replacing the platinum catalyst with a renewable hydrogenase.

Novel Hydrogen Bioreactor and Detection Apparatus

“…In this calibration method, a precise current is applied to a Hoffman apparatus or similar electrolysis device, generating H 2 and O 2 from 1 mM KOH. The level of hydrogen detected by TCD may then be calculated by relating the voltage displayed [19]. This method provided consistent results in previous studies, but the accuracy of the electrolysis calculation depends on the accuracy of the assumed faradaic efficiency (not taking into effect inefficiencies caused by the generation of heat and side reactions, including hydrogen Fig.…”

“…2a. Our apparatus mimics a similar system at Oak Ridge National Laboratory, which has been described previously in a number of biohydrogen experiments [13,14,16,[19][20][21], with Table 1. The custom bioreactor designed for this system is shown in Fig.…”

Characterization and Evolution of Tetrameric Photosystem I from the Thermophilic Cyanobacterium Chroococcidiopsis sp TS-821

“…The TS-821 PSI tetramer has a sedimentation coefficient value of 28S ( Figure 6C). These values contrast with those of the isolated T. elongatus PSI trimer and monomer, which are 21S (dashed line in Figure 6C) and 12S, respectively (Iwuchukwu et al, 2010). These AUC results clearly support the identity of the larger species as a tetramer.…”

“…To confirm the presence of PSI tetramer observed by BN-PAGE, a two-step SDGC fractionation similar to what has been reported for isolation of the T. elongatus PSI trimer was developed (Iwuchukwu et al, 2010). After the first SDGC, the tetramer was readily detected and collected ( Figure 2A).…”

Integrated photosystem II-based photo-bioelectrochemical cells

“…Different bioelectrochemical devices that implement the RC, PSI and/or PSII as light harnessing components for the activation of PBFCs producing photocurrents [19][20][21][22] , or fuel products [23][24][25] have been proposed. These PBFCs require the immobilization and electrical contacting of the light harnessing components with the electrode supports to the extent that photo-induced electrontransfer processes occur between the photosynthetic RC, thus enabling the generation of photocurrents (or their use for the synthesis of fuel products).…”