Carbon Dots as Versatile Photosensitizers for Solar-Driven Catalysis with Redox Enzymes.

Academic Article


  • Light-driven enzymatic catalysis is enabled by the productive coupling of a protein to a photosensitizer. Photosensitizers used in such hybrid systems are typically costly, toxic, and/or fragile, with limited chemical versatility. Carbon dots (CDs) are low-cost, nanosized light-harvesters that are attractive photosensitizers for biological systems as they are water-soluble, photostable, nontoxic, and their surface chemistry can be easily modified. We demonstrate here that CDs act as excellent light-absorbers in two semibiological photosynthetic systems utilizing either a fumarate reductase (FccA) for the solar-driven hydrogenation of fumarate to succinate or a hydrogenase (H2ase) for reduction of protons to H2. The tunable surface chemistry of the CDs was exploited to synthesize positively charged ammonium-terminated CDs (CD-NHMe2+), which were capable of transferring photoexcited electrons directly to the negatively charged enzymes with high efficiency and stability. Enzyme-based turnover numbers of 6000 mol succinate (mol FccA)-1 and 43,000 mol H2 (mol H2ase)-1 were reached after 24 h. Negatively charged carboxylate-terminated CDs (CD-CO2-) displayed little or no activity, and the electrostatic interactions at the CD-enzyme interface were determined to be essential to the high photocatalytic activity observed with CD-NHMe2+. The modular surface chemistry of CDs together with their photostability and aqueous solubility make CDs versatile photosensitizers for redox enzymes with great scope for their utilization in photobiocatalysis.
  • Authors

  • Hutton, Georgina AM
  • Reuillard, Bertrand
  • Martindale, Benjamin CM
  • Caputo, Christine
  • Lockwood, Colin WJ
  • Butt, Julea N
  • Reisner, Erwin
  • Status

    Publication Date

  • December 28, 2016
  • Keywords

  • Biocatalysis
  • Carbon
  • Clostridium acetobutylicum
  • Hydrogenase
  • Models, Molecular
  • Nanoparticles
  • Oxidation-Reduction
  • Photochemical Processes
  • Photosensitizing Agents
  • Protein Conformation
  • Shewanella
  • Succinate Dehydrogenase
  • Sunlight
  • Digital Object Identifier (doi)

    Pubmed Id

  • 27977174
  • Start Page

  • 16722
  • End Page

  • 16730
  • Volume

  • 138
  • Issue

  • 51