An Evaluation of Sensor Performance for Harmful Compounds by Using Photo-Induced Electron Transfer from Photosynthetic Membranes to Electrodes

Abstract

Rapid, simple, and low-cost screening procedures are necessary for the detection of harmful compounds in the effluent that flows out of point sources such as industrial outfall. The present study investigated the effects on a novel sensor of harmful compounds such as KCN, phenol, and herbicides such as 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), 2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine (atrazine), and 2-N-tert-butyl-4-N-ethyl-6-methylsulfanyl-1,3,5-triazine-2,4-diamine (terbutryn). The sensor employed an electrode system that incorporated the photocurrent of intra-cytoplasmic membranes (so-called chromatophores) prepared from photosynthetic bacteria and linked using carbon paste electrodes. The amperometric curve (photocurrent-time curve) of photo-induced electron transfer from chromatophores of the purple photosynthetic bacterium Rhodobacter sphaeroides to the electrode via an exogenous electron acceptor was composed of two characteristic phases: an abrupt increase in current immediately after illumination (I0), and constant current over time (Ic). Compared with other redox compounds, 2,5-dichloro-1,4-benzoquinone (DCBQ) was the most useful exogenous electron acceptor in this system. Photo-reduction of DCBQ exhibited Michaelis-Menten-like kinetics, and reduction rates were dependent on the amount of DCBQ and the photon flux intensity. The Ic decreased in the presence of KCN at concentrations over 0.05 μM (=μmol·dm−3). The I0 decreased following the addition of phenol at concentrations over 20 μM. The Ic was affected by terbutryn at concentrations over 10 μM. In contrast, DCMU and atrazine had no effect on either I0 or Ic. The utility of this electrode system for the detection of harmful compounds is discussed.

The effect of some antiseptic drugs on the energy transfer in chromatophore photosynthetic membranes of purple non-sulfur bacteria Rhodobacter sphaeroides

“…The thoroughly characterized photosynthetic membranes of PNSB as well as isolated RC are convenient systems for studying the influence of various external factors, among them phenols (Escher et al 2001 ), herbicides (Kasuno et al 2016 ), certain drugs (dipyridamole and a number of its derivatives) and chemical chaperones (alkylated hydroxybenzenes) (Knox et al 2000 , 2001 , 2010 ). The functional parameters of the electron transfer chain are very sensitive to the structural and dynamic state of the transmembrane phototransforming complex, including the influence on its hydrogen bonds (McMahon et al 1998 ; Kriegl et al 2003 ; Goushcha et al 2003 ; Krasilnikov et al 2007 ).…”