Maximizing H2 production in Photosystem I/dithiol molecular wire/platinum nanoparticle bioconjugates

Abstract

Photosystem I/dithiol molecular wire/nanoparticle bioconjugates have been shown to photocatalytically generate dihydrogen at linear rates when continuously illuminated. In an effort to maximize H2 production, the pH and ionic concentration of the solution, the mobility of the electron donor, the length and degree of saturation of the molecular wire, and the intensity of the light were systematically investigated. Optimal conditions included a solution buffered at pH 6.0, cross-linked plastocyanin, rebuilt spinach PS I, and the use of 1,4-benzenedithiol to connect PS I to the Pt nanoparticle. Illumination of this optimized Photosystem I/dithiol molecular wire/nanoparticle bioconjugate at a light intensity of 70 microE m(-2) s(-1) generated a measured one time H2 production rate of 312 micromol H2 mg Chl(-1) h(-1).

9 Semi-artificial photosynthetic Z-scheme for hydrogen production from water

“…The free sulfhydryl group of the dithiol linker allows the tethering of Au or Pt nanoparticles [41,42]. An optimized PS1-Pt nanoparticle construct with cross-linked plastocyanin and 1,4-benzenedithiol yielded a H 2 production rate of 312 μmol H 2 mg Chl −1 h −1 [42]. [36] and [37]).…”

“…Finally, the 2-mercaptoethanol rescue ligand can be displaced by alkyl or aryl dithiol linkers [30, Brought to you by | New York University Bobst Library Technical Services Authenticated Download Date | 9/29/15 4:23 PM 40] and the PsaC-molecular wire construct can be assembled onto a P700/F X core complex of PS1. The free sulfhydryl group of the dithiol linker allows the tethering of Au or Pt nanoparticles [41,42]. An optimized PS1-Pt nanoparticle construct with cross-linked plastocyanin and 1,4-benzenedithiol yielded a H 2 production rate of 312 μmol H 2 mg Chl −1 h −1 [42].…”

10 Photosynthesis and hydrogen metabolism revisited. On the potential of light-driven hydrogen production in vitro

“…In the group of John Golbeck, PSI was successfully wired to nanoparticles of platinum via different dithiolate linkers [103,104,107]. It was shown that a variant of HydA can be linked to PSI by the same mechanism of 'cluster rescue' using a simple C6 dithiolate alkyl chain [108].…”

“…It was shown that a variant of HydA can be linked to PSI by the same mechanism of 'cluster rescue' using a simple C6 dithiolate alkyl chain [108]. The authors report a release rate of 30 μmol H 2 mg -1 Chl h -1 , which is 10% of the most successful platinum conjugate [104]. The coordination motif of the most terminal cluster was varied to Cys 3 Gly (HydA C97G ), with mercaptoethanol respectively 1,6-hexane dithiol providing the fourth site to the [4Fe4S] moiety.…”

“…This can be achieved by cross-linking partners, as demonstrated by the six-fold increase of H 2 release activity when changing from diffusible cytochrome c 6 to covalently-bound plastocyanin [103,104]. The latter, especially, requires an optimal orientation of the participating partners which is of increasing importance for large protein complexes with diminished diffusion mobility.…”