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    A novel electrochemical biosensor based on palladium nanoparticles decorated on reduced graphene oxide-polyaminophenol matrix for the detection and discrimination of mitomycin C-DNA and acyclovir-DNA interaction
    (Elsevier B.V., 2023) Yanık, Suzan; Emre, Deniz; Alp, Meltem; Algı, Fatih; Yılmaz, Selehattin; Bilici, Ali; Özkan-Ariksoysal, Dilsat
    Both the design of molecules that will interact specifically with DNA and the determination of the mechanism of action of this drug on DNA are important as they allow the control of gene expression. In particular, rapid and precise analysis of this type of interaction is a vital element for pharmaceutical studies. In the present study, a novel reduced graphene oxide/ palladium nanoparticles/ poly(2-amino-4-chlorophenol) (rGO/Pd@PACP) nanocomposite was synthesized by chemical process to modify pencil graphite electrode (PGE) surface. Here, the performance of the newly developed nanomaterial-based biosensor for drug-DNA interaction analysis has been demonstrated. For this purpose, it was determined whether this system, which was developed by selecting a drug molecule (Mitomycin C; MC) known to interact with DNA and a drug molecule (Acyclovir; ACY) that does not interact with DNA, performs a reliable/accurate analysis. Here, ACY was used as a negative control. Compared to bare PGE, the rGO/Pd@PACP nanomaterial modified sensor exhibited 17 times higher sensitivity performance in terms of guanine oxidation signal measured by differential pulse voltammetry (DPV). Moreover, the developed nanobiosensor system provided a highly specific determination between the anticancer drug MC and ACY by discrimination the interactions of these drugs with double-stranded DNA (dsDNA). ACY was also preferred in studies for the optimization of the new nanobiosensor developed. ACY was detected in a concentration as low as 0.0513 μM (51.3 nM) (LOD), and limit of quantification (LOQ) was 0.1711 μM with a linear range from 0.1 to 0.5 μM.
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    A review on recent electroanalytical methods for the analysis of antiviral COVID-19 drugs
    (2021) Emre, Deniz; Özaltın, Nuran; Yılmaz, Selehattin
    Currently, there are no specific drugs for the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, designated as coronavirus disease 2019 (COVID-19). Several therapeutic options including antiviral, antithrombotic, immunosuppressive, and anti-rheumatic drugs are researched all over the world. Analytical methods are needed in every step of innovation, research, development, and manufacturing process of pharmaceuticals, therefore new analytical methods for pharmaceuticals are developed and validated increasingly over time. In this review, recent reports on electroanalytical techniques for the determination of selected COVID-19 drugs, favipiravir (FAV), remdesivir (REM), lopinavir (LOP) / ritonavir (RIT), and hydroxychloroquine (HCQ) were emphasized. Electroanalysis of antiviral active pharmaceutical ingredients carried out at various modified or non-modified electrodes by cyclic voltammetry (CV), linear sweep voltammetry (LSV), differential pulse voltammetry (DPV), and square wave voltammetry (SWV) were compiled from the literature. The effects of supporting electrolyte and pH on the current and potential of the analytical signal were evaluated. Scan rate results obtained by the CV method showed whether the redox process of the drug active ingredient diffusion or adsorption controlled at the electrode used in the selected solvent-supporting electrolyte and pH systems. Linearity range and the limit of detection (LOD) of applied electroanalytical methods were compared by combining the results obtained from drug active ingredients given in references.
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    Adsorption of uranium (VI) from aqueous solutions using boron nitride/polyindole composite adsorbent
    (John Wiley and Sons Inc, 2024) Emre, Deniz; Selçuk Zorer, Özlem; Bilici, Ali; Budak, Erhan; Yılmaz, Selehattin; Çalışkan Kılıç, Necla; Gökırmak Söğüt, Eda
    Turbostratic boron nitride (tBN) surface is modified with polyindole (PIn) by a facile polymerization technique and the uranyl adsorption efficiency of this mesoporous hybrid is investigated. The successful surface modification is confirmed by FT-IR, Raman, XRD, TEM, SEM, EDX, EDS mapping XPS, BET, and zeta potential techniques. The batch experiments are performed in various temperatures (T), contact times (t), pH, and initial solution concentrations (C0) to evaluate its adsorption performance. The optimum adsorption performance is achieved at pH = 5.0–5.5, T = 307 K, t = 10 min, C0 = 18 mg L−1. These experimental results are evaluated using Freundlich, Redlich–Peterson, and Langmuir isotherm models, which presents equivalent regression coefficients. Maximum adsorption capacity (qm) of the nanoadsorbent (tBN/PIn), determined by the Langmuir isotherm, is 315.29 mg g−1. The adsorption kinetics of uranyl ions on tBN/PIn are in harmony with the pseudo-second order model. tBN/PIn nanoadsorbent provides high adsorption efficiency even at exceptionally low UO22+ concentration range (4–40 mg L−1) and low adsorbent mass (0.005 g). XPS analysis results show that 0.05% of uranium is adsorbed on tBN/PIn via mainly U-O coordination. The results of present study demonstrate that tBN/PIn can a potential adsorbent for removing uranium from aqueous solutions.
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    Fabrication of PAMP/Au and GO/PAMP/Au nanosensors for electrochemical detection of paracetamol in pharmaceutical preparations
    (Springer, 2021) Bilici, Ali; Denizhan, Nuray; Emre, Deniz; Yılmaz, Selehattin; Soylukan, Caner; Algi, Fatih
    This paper reports on the modification of Pencil Graphite Electrode (PGE) surface with the poly(2-amino-4-methylphenol)/gold (PAMP/Au) and graphene oxide/poly(2-amino-4-methylphenol)/gold (GO/PAMP/Au) nanocomposites, in two steps. The first step is based on the one-pot preparation of composites by template-free chemical oxidation process. In the second step, composites are deposited at PGE surface by electro-oxidation process. Both nanocomposites and modified PGE surfaces are characterized by X-Ray Diffraction method (XRD), Scanning Electron Microscopy (SEM), EDAX, and CV analyses. The electrochemical performances of modified electrodes (abbreviated as PAMP/Au-PGE and GO/PAMP/Au-PGE) were investigated. The limit of detection values for PGE, PAMP/Au-PGE, and GO/PAMP/Au-PGE were found to be 2.74 × 10–6, 5.29 × 10–7, and 2.91 × 10–8 mol/dm3, respectively. The limit of quantification values were determined as 9.14 × 10–6, 1.76 × 10–6, and 9.69 × 10–8 mol/dm3 for PGE, PAMP/Au-PGE, and GO/PAMP/Au-PGE, respectively.
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    Graphene quantum dots-polyfluorene hybrid nanobiosensor for mitomycin C-DNA interaction sensing
    (Elsevier Ltd, 2024) Emre, Deniz; Denizhan, Nuray; Özkan-Arıksoysal, Dilsat; Bilici, Ali; Sonkaya, Ömer; Algı, Fatih; Yılmaz, Selehattin
    A novel graphene quantum dots (GQD) / polyfluorene (PF) nanocomposite was deposited on the disposable pencil tip graphite electrode (PGE) and proven to be an efficient nanosensor for analysis of the electrochemical interaction between the antitumor compound mitomycin C (MC) with double stranded DNA (ds-DNA). This modified electrode (GQD@PF-PGE) was prepared in four steps: hydrothermal, chemical oxidation, ultrasonication and electro-oxidation processes. GQD, PF, GQD@PF and GQD@PF-PGE have been characterized by different analytical techniques such as SEM, TEM, XRD, FTIR, UV–Vis, EIS. Compared to bare PGE, GQD@PF modified PGE performed approximately 56 times more sensitive analysis when evaluating the guanine oxidation signals measured by DPV. CV and EIS measurements also showed that GQD@PF-PGE possesses a fast electron transfer as compared to bare electrode and exhibit a remarkable electrocatalytic activity towards both guanine and MC electrooxidation. Comprehensive optimization studies have also been carried out for the developed new nanobiosensor.
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    Porous graphitic carbon nitride nanosheets coated with polyfluorene for removal of Malachite green and Methylene blue dyes and Cu (II) ions
    (Elsevier Science Sa, 2022) Sogut, Eda Gokirmak; Emre, Deniz; Bilici, Ali; Kilic, Necla Caliskan; Yilmaz, Selehattin
    Dyes and heavy metal ions are of great interest for environmental studies as they are common pollutants in industrial applications. Therefore, development of innovative adsorbents has received tremendous interest in wastewater treatment studies. In this study, a new hybrid adsorbent (g-C3N4/AFP) was prepared by modifying porous graphitic carbon nitride surface (g-C3N4) with 2-amino fluorene polymer (AFP) and investigated its adsorptive behaviour for removal of representative dyes and heavy metal from aqueous solution. Experimental data obtained from batch tests were analysed using two parameters (Freundlich, Langmuir and Dubi-nin-Radushkevich) and three parameters (Sips) isotherm models. Langmuir isotherms were the best model to describe the experimental results of Methylene blue (MB) and Malachite green (MG) dye adsorptions, while Freundlich isotherms were the best for Cu (II) ions. Sips isotherm model was found to have the highest regression coefficient (>= 0.99) among the two-parameters isotherms studied. The maximum adsorption capacities of g-C3N4 and g-C3N4/AFP were found to be 226.88 and 327.83 for MG, 85.73 and 221.85 for MB and 184.51 and 452.19 mg g(-1) for Cu (II), respectively. This increase in adsorption capacity can be explained by the improved textural properties of the new hybrid adsorbent and the presence of multiple functional groups in its structure. A possible adsorption mechanism was suggested using FTIR and pH(pzc) data.
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    Salvia officinalis leaf extract-stabilized NiO NPs, ZnO NPs, and NiO@ZnO nanocomposite: Green hydrothermal synthesis, characterization and supercapacitor application
    (Springer Heidelberg, 2024) Zenkin, Kuebra; Durmus, Sefa; Emre, Deniz; Bilici, Ali; Yilmaz, Selehattin
    In this study, NiO nanoparticles (NiO NPs) and NiO@ZnO nanocomposite were synthesized for the first time using a Salvia officinalis (S. officinalis) extract-assisted hydrothermal process. The S. officinalis leaf extract served as a natural reducing and capping agent. The synthesized NiO NPs, ZnO NPs, and NiO@ZnO nanocomposite were thoroughly characterized using various techniques, including Fourier-transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV-Vis), powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), energy-dispersive spectrometry (EDS) mapping, vibrating sample magnetometer (VSM), and cyclic voltammetry (CV) analysis. The direct and indirect band gap energies of NiO NPs, ZnO NPs, and NiO@ZnO were found to be 3.00, 2.28, and 2.71 eV, and 2.63, 1.91, and 2.23 eV, respectively. The crystallite sizes were analyzed using PXRD spectra through Scherrer and Williamson-Hall (W-H) methods. TEM analysis revealed that the average particle sizes of NiO NPs, ZnO NPs, and NiO@ZnO were 16.0, 207.5, and 31.0 nm, respectively. The magnetic properties of all nanomaterials were assessed via the VSM technique. Specific capacitance (Cs) values, determined from CV voltammograms, were 196.8, 632.4, and 785 Fg-1 at a scan rate of 25 mVs-1 for NiO NPs, ZnO NPs, and NiO@ZnO, respectively. These findings suggest that the green-synthesized NiO@ZnO nanocomposite holds significant potential as a high-performance electrode material for supercapacitor applications.