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Due to their various beneficial application-based properties, such as behavior, structure, and size, the synthesis of silver nanoparticles (Ag-NPs) with different structures has become an interesting yet common task for researchers to produce nanostructures for applications in various fields. This is because silver nanoparticles have interesting and unique properties, such as optical and catalytic, resulting from their different structures and sizes. These properties extend the use of nanostructures in various fields of research, especially in medicine, pharmacy, electronics, etc. Also, variations in their parameters affect the structures and sizes of Ag-NPs. This review provides an overview/brief presentation of various methodologies used to synthesize different application-based silver nanoparticles and lists areas where these nanoparticles are suitable for use according to their specific structures and sizes.

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This study is focused on the investigation of electrocatalytic effect of glucose oxidase (GOx) immobilized on the graphite rod (GR) electrode. The enzyme modified electrode was prepared by encapsulation of immobilized GOx within enzymatically formed poly(1,10-phenanthroline-5,6-dione) (pPD) film. The electrochemical responses of such enzymatic electrode (pPD/GOx/GR) vs. different glucose concentrations were examined chronoamperometrically in acetate-phosphate buffer solution (A-PBS), pH 6.0, under aerobic or anaerobic conditions. Amperometric signals of the pPD/GOx/GR electrode exhibited well-defined hyperbolic dependence upon glucose concentration. Amperometric signals at 100mM of glucose were 41.17 and 32.27 µA under aerobic and anaerobic conditions, respectively. Amperometric signals of the pPD/GOx/GR electrode decreased by 6% within seven days. The pPD/GOx/GR electrode showed excellent selectivity in the presence of dopamine and uric acid. Furthermore it had a good reproducibility and repeatability with standard deviation of 9.4% and 8.0%, respectively.

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Poly(3-aminophenylboronic acid), (PAPBA) film was formed on the graphite rod surface by potential cycling. The PAPBA-modified graphite rod (PAPBA/GR) electrode prepared in this way was used for potentiometric fluoride determination. The linear calibration range was from 5×10(-4) to 5×10(-2)M with the slope of the linear part of the calibration curve of 42.5mV/logC. No interference effect of the most common ions such as sodium, potassium, chloride, nitrate, iodide, calcium, zinc, aluminum, sulfate and sorbitol was observed during electrochemical determination of fluoride. On the other hand, the PAPBA/GR electrode showed not only good sensitivity and selectivity, but also relatively rapid response to changes of analyte concentrations in the range of 20s. The sensor was successfully applied for fluoride determination in real sample - toothpaste.

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Applicability of square wave voltammetry for the determination of Cu(II) ions by PolyLut/GC and PolyKae/GC electrodes was evaluated in this study. For this luteolin and kaempferol were electrochemically polymerized on glassy carbon (GC) electrode surface in order to get polyluteolin and polykaempferol-modified glassy carbon electrodes (PolyLut/GC and PolyKae/GC, correspondingly). The formation of polyphenol layer on the GC electrode surface was evidenced by atomic force microscopy. Square wave voltammetry was found to be more sensitive in comparison with differential pulse voltammetry. It was determined that PolyLut/GC and PolyKae/GC electrodes offered great sensitivity towards Cu(II) ions with very low limit of detection, good reproducibility, sufficient stability and excellent selectivity of analytical signal.

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This study reports direct electron transfer (DET) from immobilized glucose oxidase (GOx) via grafted and electropolymerized 1,10-phenanthroline monohydrate (PMH). The layer of poly-1,10-phenanthroline (PPMH) was gained via electrochemical deposition, which was used to create the PPMH-modified GC-electrode (PPMH/GC-electrode). Further, the GOx was immobilized on the PPMH/GC-electrode. The effect of surface-modification by the PPMH on the electron-transfer between enzyme and electrode-surface and some other electrochemical/analytical-parameters of newly designed enzymatic-electrode were evaluated. The PPMH/GC-electrode showed superior DET to/from flavine adenine dinucleotide cofactor of GOx, while some redox-compounds including ferrocene and K(3)[Fe(CN)(6)] were completely electrochemically inactive on the PPMH/GC-electrode. It was also found that the resulting GOx/PPMH/GC-electrode functioned as a "direct response type" glucose-biosensor. The biosensor showed excellent selectivity towards glucose and demonstrated good operational-stability. According to our best knowledge, this study is the first scientific report on electrochemical-polymerization of PMH on the GC-electrode in non-aqueous media followed by its application in the design of glucose-biosensor.

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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)-modified graphite rod electrodes (GREs) were studied amperometrically and potentiometrically. The best redox mediators for GOX were found on PDs containing amino groups: 5AP 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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The regenaration of acid and base from the solutions containing metallic salts was achieved by salt splitting method (SSM) using not only anion-exchange membranes (AEM) but also cation-exchange membrane (CEM). In these experiments, while the ion exchange membrane was anion-exchange membrane, acid solutions were used as an anolyte and different salts of potassium were used as a catholyte. In addition to these experiments, while the ion exchange membrane was cation-exchange membrane, base solutions were used as a catholyte and different salts of potassium were used as an anolyte. The effects of current density, initial concentrations of anolyte and catholyte solutions, the type of salt solution and the type of the ion-exchange membranes on the recovery ratio of bases and acids were investigated. The results of the experiments were investigated with the Statistical Package for Social Sciences (SPSS) program. The obtained results show that this technique can be used not only for recovering the acid and base wastes of industry but also for removing the impurities in order to obtain pure acids and bases in laboratory conditions.

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