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An optoelectronic device, which converts light energy to electric potential, was designed and fabricated by using photosynthetic reaction centre (RC) proteins of purple bacterium Rhodobacter sphaeroides R-26, based on the structure and function of the dye sensitised organic solar cells. First, an electrochemical cell with three electrodes was created especially for this measurement. ITO covered by the MWCNT-RC containing sample served as the working electrode and the counter and the reference electrodes were platinum and Ag\AgCl, respectively. Water soluble ubiquinone-0 and ferrocene, in some experiments were used as mediators. In another experiment, the presence of the RCs in the active layer under dried conditions assured tuneable wavelength sensitivity, in general in the visible, but specially, in the near infrared (700-1000 nm) spectral range. The lifetime of the primary charge separation is in the ps time scale and that of the charge stabilisation can be modulated (at least theoretically) between ps and seconds. A successful combination of RC protein with a light energy converter device in spectroelectrochemical cell (wet conditions in buffered electrolyte) and in dried multilayer structure will be presented here. (C) 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Specific inhibitory reactions of herbicides with photosynthetic reaction centers bound to working electrodes were monitored in a conventional electrochemical cell and a newly designed microfluidic electrochemical flow cell. In both cases, the bacterial reaction centers were bound to a transparent conductive metal oxide, indium-tin-oxide, electrode through carbon nanotubes. In the conventional cell, photocurrent densities of up to a few μA/cm2 could be measured routinely. The photocurrent could be blocked by the photosynthetic inhibitor terbutryn (I 50 = 0.38 ± 0.14 μM) and o-phenanthroline (I 50 = 63.9 ± 12.2 μM). The microfluidic flow cell device enabled us to reduce the sample volume and to simplify the electrode arrangement. The useful area of the electrodes remained the same (ca. 2 cm2), similar to the classical electrochemical cell; however, the size of the cell was reduced considerably. The microfluidic flow control enabled us monitoring in real time the binding/unbinding of the inhibitor and cofactor molecules at the secondary quinone site.