Construction of Efficient Bio-Electrochemical Devices; An Improved Electricity Production from Cyanobacterium (Leptolyngbia sp.) Based on π-Conjugated Conducting Polymers/Gold Nanoparticles Composite Interfaces

Abstract

In this study, the electrochemical communication of Lyptolyngbia sp. (CYN82) were accomplished using two different DtP type conducting polymers 4-(4H-Dithieno[3,2-b:2’,3’-d]pyrrole-4-yl)aniline, P(DtP-Py-NH2) and 5-(4H-dithieno [3,2-b:2’,3’-d]pyrol-4-yl) naphtalene-1-amine, P(DtP-Nptyl-NH2) via electropolymerization. After that, p-aminothiophenol and 2-mercaptoethane functionalized AuNPs were cross-linked to DtP polymers modified GE as a result of electropolymerization. Bioelectrodes were obtained by attaching of Leptolyngbia sp. onto the conducting polymer/AuNP modified GEs and stabilized on the electrode surface by using a dialysis membrane. These electrode structures were generated enhanced photocurrent due to high wiring capacity and high electron transfer ability. Electrons are formed as a result of oxidation in CYN82 by photosynthesis in water under visible light is easily transferred to the GE by DtP/AuNP structure (Figure 1). Photocurrent experiments were proved the transfer of electrons were achieved and the effect of P(DtP-Py-NH2) and P(DtP-Nptyl-NH2) polymers reveal that the photocurrent obtained from the electrode using polymer is almost eight-fold greater than the electrode without using polymer. This result indicates that the polymer is highly effective in electron transfer. Another important point in obtaining the enhanced photocurrent is the use of gold nanoparticles in the electrode structure. Results clearly show that the photocurrent measured from the electrodes with AuNP is higher than the other electrodes (without AuNP). Conductivity of AuNP and oligoaniline bridges serves a very suitable surface for fast electron transfer from CYN82 to the gold electrode. A 25 nA cm-2 photocurrent was observed by GE/Leptolyngbia sp.. After the electrode modifications, a significant improvement in the photocurrent up to 630 nA cm-2 was achieved. Bioelectrodes P(DtP-Py-NH2)/AuNP/CYN82 and P(DtP-Nptyl-NH2)/AuNP/CYN82 were tested with diuron, clorpyrifos and atrazine which are the important pesticides as by the decrease in photocurrent which is resulted from inhibition of photosynthesis by pesticides [1].