Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 39Citation - Scopus: 46Surface Free Energy Analysis of Ito/Au Multilayer Thin Films on Polycarbonate Substrate by Apparent Contact Angle Measurements(Elsevier, 2020) Özbay, Salih; Erdoğan, Nursev; Erden, Fuat; Ekmekçioğlu, Merve; Özdemir, Mehtap; Aygün, Gülnur; Özyüzer, LütfiA detailed surface free energy (SFE) knowledge of transparent conducing oxide (TCO)/metal/TCO electrodes is necessary for their applications related to surface wettability. However, SFE analysis of these surfaces has not been performed systematically previously. In this study, ITO and ITO/Au/ITO multilayer thin films were coated onto O-2 plasma treated polycarbonate (PC) substrates by magnetron sputtering. The wettability characteristics of untreated PC, O-2 plasma treated PC, ITO, Au interlayer, and ITO/Au/ITO multilayer thin films were evaluated by apparent contact angle measurements of nine different test liquids having various surface tensions. Following this, Lifshitz-van der Waals, acidic, basic, dispersive, and polar components of SFE were calculated using acidbase, geometric and harmonic mean approaches. In the present study, in which the significance of calculation methods and selected liquid pairs on SFE parameters were investigated, the effect of Au interlayer presence on SFE parameters were also evaluated simultaneously. The results showed that the total SFE values of ITO/Au/ITO multilayer thin films were found to be higher than that of ITO surface. The reasons behind this difference were discussed in terms of SFE components obtained using various liquid pairs by different methods. The results were also supported with XRD, XPS, AFM, and TEM analysis.Article Citation - WoS: 45Citation - Scopus: 47Impedimetric Detection of Pathogenic Bacteria With Bacteriophages Using Gold Nanorod Deposited Graphite Electrodes(Royal Society of Chemistry, 2016) Moghtader, Farzaneh; Çongur, Gülşah; Zareie, Hadi M.; Erdem, Arzum; Pişkin, ErhanElectrochemical impedance spectroscopy (EIS) is applied for the detection of bacteria using bacteriophages as a bioprobe together with gold nanorods (GNRs). Escherichia coli-E. coli K12 was used as a model target bacteria and also for the propagation of its specific T4-phages. Gold nanorods (GNRs) were synthesized via a two-step protocol and characterized using different techniques. EIS measurements were conducted in an electrochemical cell consisting of a three electrode system. Single-use pencil graphite electrodes (PGE) were modified by the physical adsorption of GNRs to increase their interfacial conductivity and therefore sensitivity for impedimetric measurements. Therefore, interfacial charge-transfer resistance values (Rct) sharply decreased after GNRs deposition. Phages were adsorbed on these electrodes via a simple incubation protocol at room temperature, which resulted in an increase in Rct values, which was concluded to be as a result of nonconductive phage layers. These phage-carrying GNRs-PGEs were used for impedimetric detection of the target bacteria, E. coli. Significant increases at the Rct values were observed which were attributed to the insulation effects of the adsorbed bacterial layers. This increase was even more when the bacterial concentrations were higher. In the case of the non-target bacteria Staphylococcus aureus (S. aureus), conductivity noticeable decreases (due to nonspecific adsorption). However, in the case of E. coli, the Rct value increase is time dependent and reaches maximum in about 25-30 min, then decreases gradually as a result of bacterial lysis due to phage invasion on the electrode surfaces. In contrast, there were no time dependent changes with the non-target bacteria S. aureus (no infection and no lytic activity). It is concluded that the target bacteria could be detected using this very simple and inexpensive detection protocol with a minimum detection limit of 103 CFU mL-1 in approximately 100 μL bacterial suspension.Article Citation - WoS: 17Citation - Scopus: 22Responsive pentablock copolymers for siRNA delivery(Royal Society of Chemistry, 2015) Uz, Metin; Mallapragada, Surya K.; Alsoy Altınkaya, SacideIn this study, temperature and pH responsive cationic and amphiphilic pentablock copolymers, which consist of the temperature responsive triblock Pluronic F127 sandwiched between pH responsive PDEAEM (poly(2-diethylaminoethyl methacrylate)) end blocks, were used for the first time in the development of polyplex and gold nanoparticle (AuNP) based multicomponent siRNA delivery systems (MCSs). Copolymers in both systems protected siRNA from external effects, provided cell entry and endosomal escape. The thermoreversible micellization of the hydrophobic PPO block facilitated the cellular entry while the PDEAEM blocks enhanced the endosomal escape through protonated tertiary amine groups by pH buffering. The synergistic advantages of the different blocks showed an enhanced effect in the MCSs due to attachment and surface configuration reasons. The siRNA transfection efficiency of MCSs against luciferase expressing SKOV3 cells was 15% higher than both the polyplexes alone and the commercial siRNA transfection agent Lipofectamine RNAiMax at the same applied dose, without any toxicity. The results indicated that the multicomponent systems based on the responsive cationic pentablock copolymers and gold nanoparticles have promising potential as an efficient siRNA delivery vector for future applications.Article Citation - WoS: 3Citation - Scopus: 3Gold Nanorod Encapsulated Bubbles(Royal Society of Chemistry, 2015) Tomak, Aysel; Zareie, Hadi M.A simple method has been described for synthesizing gold nanorods (GNRs) encapsulated bubbles in a controlled manner. The method involves the use of nitrogen gas in the seed-mediated synthesis method routinely used for synthesis of GNRs. Control over the morphology of the nanostructures was achieved by nitrogen gas flow. The synthesized structures were examined by UV-Vis Spectroscopy, Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). New structures of this type could conceivably serve as plasmonic biosensors, nanodevices and photothermal theranostics with dual modality imaging functionality. © The Royal Society of Chemistry 2015.