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    1,10-Phenanthroline Derivatives as Mediators for Glucose Oxidase
    (Elsevier Advanced Technology, 2010) Öztekin, Yasemin; Krikstolaityte, Vida; Ramanaviciene, Almira; Yazıcıgil, Zafer; Ramanavicius, Arunas
    This study is focused on possible application of some 1,10-phenanthroline derivatives (PDs) in the development of biosensors and biofuel cells Differently from some other studies, the PDs that were not involved into structures of metal complexes were investigated. Five PDs [1,10-phenanthroline monohydrate (PMH), 5-nitro-1,10-phenanthroline (5NP), 5-amino-1,10-phenanthroline (5AP), 5-amino,6-nitro-1.10-phenanthroline (5A6NP) and 5,6-diamino-1,10-phenanthroline (56DAP)] were selected for this study Bioelectrochemical responses of PDs and glucose oxidase (GOX)-modifiecl graphite rod electrodes (GREs) were studied amperometrically and potentiometrically The best redox mediators for GOX were found on PDs containing amino groups SAP and 56DAP Amperometrical measurements have shown that 5NP derivative was also acting as a redox mediator but activity of 5NP was approximately four times lower than 5AP and three times lower than 56DAP This study clearly illustrates that some PDs can be applied as redox mediators for oxidases and are suitable for the development of reagent-less biosensors and biofuel cells. Since amino groups can be very easily involved in the formation of chemical bounds, the amino-PDs are interesting compounds for the development of nanobiotechnological tools by bottom-up technique.
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    Biofuel Cell Based on Anode and Cathode Modified by Glucose Oxidase
    (WILEY-V C H VERLAG GMBH, 2013) Krikstolaityte, Vida; Oztekin, Yasemin; Kuliesius, Jurgis; Ramanaviciene, Almira; Yazicigil, Zafer; Ersoz, Mustafa; Okumus, Aytug
    A single compartment biofuel cell (BFC) based on an anode and a cathode powered by the same fuel glucose is reported. Glucose oxidase (GOx) from Aspergillus niger was applied as a glucose consuming biocatalyst for both anode and cathode of the BFC. The 5-amino-1,10-phenanthroline modified graphite rod electrode (GRE) with cross-linked GOx was used as the bioanode, and the GRE with co-immobilised horseradish peroxidase and GOx was exploited as the biocathode of the BFC. The open-circuit voltage of the designed BFC exceeded 450mV and a maximal power density of 3.5 mu W/cm(2) was registered at a cell voltage of 300mV.
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    Enzymatic polymerization of polythiophene by immobilized glucose oxidase
    (ELSEVIER SCI LTD, 2014) Krikstolaityte, Vida; Kuliesius, Jurgis; Ramanaviciene, Almira; Mikoliunaite, Lina; Kausaite-Minkstimiene, Asta; Oztekin, Yasemin; Ramanavicius, Arunas
    In this study 'green', environmentally friendly enzymatic reaction-based synthesis of conducting polymer polythiophene (PTP) is proposed. Glucose oxidase (GO(x)) was shown as an effective catalyst, which, in the presence of glucose, produces hydrogen peroxide suitable for the oxidative polymerization of PTP under ambient conditions at neutral pH. Enzymatically induced formation of the PTP layer over GO(x)-modified graphite rod electrode (GRE) was demonstrated and evaluated amperometrically and by attenuated total reflectance - Fourier transform infrared (ATR-FTIR) spectroscopy. Surface morphology of GO(x)- and PTP-modified GR electrodes was characterized by atomic force microscopy. It was clearly shown that the apparent kinetic Michaelis constant (K-M(app.)) of GO(x)/PTP-modified GRE increased by increasing the duration of polymerization reaction. Therefore, enzymatic polymerization could be applied in adjustment and/or tuning of K-M(app.) and other kinetic parameters of GO(x)-based electrodes used in biosensor design. (C) 2014 Elsevier Ltd. All rights reserved.