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Evaluation of sensor performance for harmful compounds by using photo-induced electron transfer from photosynthetic membranes to electrodes
* 1 , 1 , 1 , 2 , 2 , 3 , 4 , 1 , 2
1  Department of Materials Chemistry, Faculty of Science and Technology, Ryukoku University, Otsu, Shiga 520-2194, Japan
2  Research Institute for Environmental Management Technology, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8569, Japan
3  Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo 152-8550, Japan
4  Institute for Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8566, Japan


The effect of harmful compounds such as KCN, phenol and herbicides such as 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), 1-chloro-3-ethylamino-5-isopropylamino-2,4,6-triazine (atrazine) and 2-N-tert-butyl-4-N-ethyl-6-methylsulfanyl-1,3,5-triazine-2,4-diamine (terbtryne) on the photocurrent of photosynthetic membranes (so-called chromatophores) was investigated by using the carbon paste electrode. The amperometric curve (photocurrent-time curve) due to the photo-induced electron transfer from chromatophores of the purple photosynthetic bacterium Rhodobacter sphaeroides to the electrode via an exogenous electron acceptor was composed of characteristic two phases: the abrupt increased current immediately after illumination (I0), and the constant current with time (Ic). 2,5-Dichloro-1,4-benzoquinone (DCBQ) was found to be most useful exogenous electron acceptor for this system than other redox compounds. Photo-reduction of DCBQ was observed as a Michaelis-Menten type kinetics, and reduction rates were dependent on the amount of DCBQ and photon flux intensity. In the presence of KCN, the only Ic decreased depending on the concentration of KCN higher than 0.05 μM (= μmol dm-3). The I0 decreased selectively by addition of phenol at the concentration higher than 20 μM. Terbtryne also affected only Ic when the concentration of terbtryne was higher than 10 μM. On the other hand, DCMU and atrazine did not affect both I0 and Ic. The utility of this electrode system as the detection of harmful compounds will be discussed in the conference.

Keywords: Rhodobacter sphaeroides; Chromatophore; Photo-induced electron transfer; Michaelis-Menten type kinetics; Carbon paste electrode; cyanide, phenol