Yazar "Ozcan, Merve" seçeneğine göre listele

Listeleniyor 1 - 4 / 4
  • Küçük Resim Yok
    Öğe
    Construction of High-Performance Amperometric Acetaminophen Sensors Using Zn/ZnO-Decorated Reduced Graphene Oxide Surfaces
    (Electrochemical Soc Inc, 2020) Ozcan, Merve; Basak, Adem; Uzunoglu, Aytekin
    Sensitive and selective monitoring of acetaminophen (APAP), which is small but an important molecule used to relieve pain and inflammation, is of great importance in pharmacy. This study reports the development of zinc (Zn)/zinc oxide (ZnO)/reduced graphene oxide (rGO)-based electrochemical APAP sensors with a high sensitivity in a wide linear range. The Zn/ZnO/rGO nanohybrids were synthesized using a facile chemical precipitation method. The Zn and ZnO nanoparticles were anchored on the surface of rGO simultaneously. The XRD and TEM results indicated the presence of Zn and ZnO nanoparticles on the rGO surface, which was also confirmed by XPS and TGA analyses. The electrochemical performance of the sensors was investigated using cyclic voltammetry (CV) and chronoamperometry (CA) methods. The electrochemical performance results showed that the sensors had a high sensitivity of 166.5 6 mu A.mM(-1).cm(-2) in the linear range between 0.05 to 2 mM, which is considerably wide compared to the literature. Overall, the Zn/ZnO/rGO nanohybrids displayed a great promise to be employed in the development of electrochemical APAP sensors due to their a high sensitivity, wide working window, excellent fabrication reproducibility, good storage stability, selectivity, and real sample analysis results. (C) 2020 The Author(s). Published on behalf of The Electrochemical Society by IOP Publishing Limited.
  • Küçük Resim Yok
    Öğe
    Evaluation of the relationship between fungal infection, neutrophil leukocytes and macrophages in cervicovaginal smears: Light microscopic examination
    (Wolters Kluwer Medknow Publications, 2015) Demirezen, Sayeste; Donmez, Hanife Guler; Ozcan, Merve; Beksac, Mehmet Sinan
    Background: Right after opportunistic fungi become pathogenic, they face immune system cells including macrophages and neutrophil leukocytes. Although the relationship between fungi and immune cells are being widely studied by using animal models and culture techniques, cervicovaginal smears have not been used to evaluate this interaction yet. Aim: The aim of this study was to investigate the interactions between fungal infection, macrophages and neutrophil leukocytes in cervicovaginal smear. Materials and Methods: Papanicolaou-stained cervicovaginal smears from 2307 women, aged between 18 and 73 years, were examined by light microscopy. Periodic acid-Schiff stain was also used to confirm the presence of fungal cell walls. Results: Fungal infections were detected in 239 of 2307 patients (10.4%), and these cases were taken as the study group. Cases without any infectious agents (n = 1800, 78%) were considered as the control group. When the study and control groups were statistically compared in view of macrophages and neutrophil leukocytes, a significant relationship between presence of fungal infection, macrophages and neutrophil leukocytes was detected (P < 0.05). Furthermore, macrophages and neutrophil leukocytes were found to work against the fungal infection together (P < 0.05). Additionally, when the relationship between the existence of yeast or filamentous forms and these immune cells were evaluated, a significant correlation was not found (P > 0.05). Conclusions: Our findings indicate that macrophages and neutrophils may play a determining role in host defense against fungal infection together, but neither yeast nor filamentous forms affect the presence of neutrophil leukocytes and macrophages. As a result of this, both yeast and filamentous forms may have pathogenic effects.
  • Küçük Resim Yok
    Öğe
    Modification of Commercial Pt/C Catalyst with Graphene Nanoplatelets for Sensitive and Selective Detection of Acetaminophen in Commercial Tablets
    (Electrochemical Soc Inc, 2020) Sarikaya, Sumeyye; Ozcan, Merve; Uzunoglu, Aytekin
    Here, commercial Pt/C catalyst was modified with graphene nanoplatelets (GNPs) to construct electrochemical acetaminophen (APAP) sensors with high sensitivity and wide linear range. Physical mixture of Pt/C and GNPs with various contents were used to prepare ink formulations for the construction of electrochemical APAP sensors. The carbon content was kept constant to show the effect of GNPs content in the catalyst layer while decreasing the total Pt loading on the electrode surface. The Pt/C and GNPs were characterized using XRD, TEM, XPS, SEM, and EDS techniques. The analytical results indicated that the performance of the sensors was improved after GNPs introduction in Pt/C catalyst. It is of the note that while the amount of precious metal, Pt, on the electrode surface was decreased, the overall sensor performance was enhanced, confirming the importance of the catalyst support on the electrochemical performance of the catalyst systems. The sensors displayed a wide range of 0.1-3.0 mM with a high sensitivity of 209.07 mu A. mM(-1). cm(-2). The reliability of the constructed sensors was evaluated by the determination of APAP concentration in commercial tablets and excellent recovery values were achieved.
  • Küçük Resim Yok
    Öğe
    Ni/NiO/Ni-B/graphene heterostructure-modified electrodes and their electrochemical activities towards acetaminophen
    (Royal Soc Chemistry, 2021) Ipekci, Hasan Huseyin; Ozcan, Merve; Turkyilmaz, Busra Gizem; Uzunoglu, Aytekin
    The surface of graphene was decorated with nickel/nickel oxide/nickel-boron particles to develop high-performance electrochemical sensors. The nanohybrid structures were prepared via a one-step reduction method under an oxygen-rich atmosphere to obtain an oxide phase besides metallic nickel nanoparticles. In addition, the use of NaBH4 as the reducing agent enabled simultaneous formation of Ni-B species on the graphene surface. XRD, XPS, TEM, Raman, and TGA analyses were implemented to characterize the samples. The XRD and XPS results revealed the presence of Ni/NiO/Ni-B on the surface of graphene. The electroanalytical performance of the nanocomposite was investigated against acetaminophen, which is an extensively exploited antipyretic and analgesic drug. The analytical performance results showed that the Ni/NiO/Ni-B/Gr-based sensors had a very wide working window between 10 mu M and 2500 mu M (y (mu A) = 10.706x (mM) + 0.3151 (R-2 = 0.9993)). The excellent storage stability, selectivity, and recovery results along with the high analytical performance make the novel Ni/NiO/Ni-B/Gr hybrid systems promising materials for the development of novel sensor platforms.