Gluconobacter oxydans (G. oxydans) cells together with an osmium redox polymer (ORP) [Osmium (2,2’‐bipyridine)2(poly‐vinylimidazole)10Cl]Cl were combined with a glassy carbon paste electrode (GCPE) to form a bioanode for a microbial fuel cell (MFC) based on G. oxydans. Although there are G.oxydans/ ORP combined bioanode in the literature, as far as it is known, this system is the first one where G.oxydans/ORP bioanode is combined with a cathode and a MFC is formed. After the optimization of experimental parameters, analytical characteristics of ORP/G. oxydans/GCPE bioanode were investigated. ORP/G. oxydans/GCPE showed two linear ranges for ethanol substrate as 1.0–30 mM (R2=0.902) and 30–500 mM (R2=0.997) and analytical range as 1.0–1000 mM. Limit of detection (3.0 s/m) and limit of quantification (10 s/m) values were calculated as 1.29 mM and 4.30 mM respectively where the RSD value was 1.16 % for n=5. Combining the developed bioanode in the presence of 5.0 mM K3Fe(CN)6 mediator with a Pt wire cathode a double compartment MFC was obtained via a salt bridge. G. oxydans/GCPE bioanode based MFC had maximum power density of 0.133 μW cm−2 (at 33.5 mV), maximum current density as 8.73 μA cm−2 and OCP value of 156 mV. On the other hand, ORP/G. oxydans/GCPE based MFC showed maximum power density as 0.26 μW cm−2 (at 46.8 mV), maximum current density as 15.079 μA cm‐2 and OCP value of 176 mV.

We have performed a study on the performance of two microbial glucose sensors based on immobilized Gluconobacter oxydans (G. oxydans). The first one was prepared by modifying a glassy carbon paste electrode (GCPE) containing the microbial cells with graphene oxide (GO), the other one by modifying it with graphene-platinum hybrid nanoparticles (graphene-Pt NPs). The electrode was characterized by following the voltammetric signals of the oxidation of hexacyanoferrate(II) to hexacyanoferrate(III) via the oxidative enzymes contained in G. oxydans which convert glucose to gluconic acid. Optimizations were conducted with a conventional GCPE containing G. oxydans. After material optimization, the biosensors were applied to the determination of glucose. The linear and analytical ranges for GO based biosensor range from 1 to 75 μM (linear) and 1 to 100 μM (analytical), respectively, with a limit of detection (LOD) of (3 s/ m) 1.06 μM (at an S/m of 3). On the other hand, the graphenePt hybrid nanoparticle based biosensor showed two linear ranges (from 0.3 to 1 µM and from 1 to 10 μM), a full analytical range from 1 to 50 μM, and an LOD of 0.015 μM. The graphene-Pt hybrid NP based sensors performs better and was applied to the determination of glucose in synthetically prepared plasma samples where it gave recoveries as 101.8 and 104.37 % for two different concentrations. Selectivity studies concerning fructose, galactose, L-ascorbic acid and dopamine were also conducted.

a Poly(3,4-ethylene-dioxythiophene) (PEDOT) electrode was prepared by electroporimerization of 3,4ethylene-dioxythiophene (EDOT) in the presence of sodium dodecyl sulfate (SDS). The electrode was combined with centri-voltametry for the first time and applied for dopamine (DA) detection. Under the working conditions, SDS brings PEDOT electrode high density of negative charges which attracts positive charged DA. Also by applying centrifugation, effective accumulation of DA onto electrode surface was achieved. Two linear ranges 1x10 -9 M -1x10 -5 M and 2x10 -5 M -1x10 -1 M with two LOD values 5.9 nM and 3.1 nM were found for the developed system. Sample application and interference study were also conducted.

In this work, a carbon felt electrode (CFE) was modified with a multiwalled carbon nanotube‐gold‐platinum (MWCNT−Au‐Pt) hybrid nanomaterial and integrated with an osmium redox polymer (OsRP, [Os(2, 2’‐bipyridine)2(poly‐vinylimidazole)10Cl]Cl) and Gluconobacter oxydans DSM 2343 (G. oxydans) cells. The developed electrode was used as the bioanode in a 5.0 mM K3Fe(CN)6 mediator containing phosphate buffer (pH 6.5) anolyte and combined with a Pt wire cathode in phosphoric acid medium (pH 3.5). As a result, a two chamber microbial fuel cell (MFC) was formed, in which an activated Nafion membrane was used as a proton exchange membrane. The OsRP/G.oxydans/MWCNT−Au‐Pt/CFE based bioanode was electrochemically examined in differently deoxygenated bioanode chambers and additionally the amounts of hybrid nanomaterial and OsRP were optimized. In terms of MFC characteristics, it was found that an anaerobic OsRP/G.oxydans/MWCNT−Au‐Pt/CFE bioanode based MFC had a maximum power density of 32.1 mW m−2 (at 90 mV), a maximum current density of 1032 mA m−2 and a charge transfer efficiency (E%) value of 22.30 (open circuit potential 180 mV).

A carbon paste electrode (CPE) was modified by titanium(IV) oxide microparticles and then gold nanoparticles were dispersed in chitosan and immobilized on the CPE surface. As result a nanostructure modified composite electrode was obtained. Carcinoembriyonic antigen (CEA) was chosen as model analyte and the developed electrode was used as CEA immunosensor transducer for the first time. Two linear ranges of 0.01–1 ng/mL and 1–20 ng/mL with corresponding correlation coefficients R2=0.986 and R2=0.990, were found respectively. The limit of detection of the developed immunosensor was calculated as 0.01 ng/mL with 2.8 % relative standard deviation (n=5). The developed system was applied for CEA detection in synthetically prepared serum sample and very promising recovery values were obtained.