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: 4Citation - Scopus: 2Elastic and Anelastic Behavior Associated With Structural Transitions in CsPbBr3(Amer Chemical Soc, 2025) Luo, Pingjing; He, Zhengwang; Yang, Dexin; Aktas, Oktay; Ding, Xiangdong; Zhang, XuefengStrain coupling and relaxation dynamics critically influence the photovoltaic and photoluminescent performances of metal halide perovskites. Here, resonant ultrasound spectroscopy is employed to study the elastic and anelastic properties associated with the octahedral tilting transitions in the optoelectronic semiconductor CsPbBr3 over the temperature range 303-468 K. The cubic-to-tetragonal transition near 405 K is marked by pronounced elastic softening accompanied by a sharp increase in acoustic loss. High anelastic loss below this transition reveals the presence of mobile ferroelastic twin walls that become pinned by lead vacancies at a temperature interval near 380 K in the tetragonal phase. The elastic softening in the cubic phase is strongly correlated to dynamic effects such as the local polar fluctuations. This local disordered effect is further verified by the anomalously high attenuation in the orthorhombic structure, in which the ferroelastic twin walls might become mobile.Article Citation - WoS: 1Citation - Scopus: 1Monomer-Engineered Quinone-Based Conjugated Polymers for High-Rate Aqueous Zinc-Ion Batteries(Amer Chemical Soc, 2025) Canakci, Utku Cem; Gecalp, Yasmin; Canturk, Batu Sercan; Erdogmus, Mustafa; Erozen, Yaren Naz; Buyukcakir, OnurConjugated polymers (CPs) with their extended pi-conjugated structures have recently attracted tremendous attention as organic cathodes in aqueous zinc-ion batteries (AZIBs). In this study, two quinone-pyrrole conjugated polymers, QpCP-1 (benzoquinone monomer) and QpCP-2 (anthracenetetrone monomer), were synthesized to investigate the impact of monomer engineering on electrochemical performance, aiming to enhance specific capacity without sacrificing rate performance and cycle life. At 0.1 A g-1, QpCP-1 delivered a higher specific capacity (178 mA h g-1) than QpCP-2 (134 mA h g-1). However, while QpCP-1's capacity declined with increased current density, QpCP-2 demonstrated superior rate capability, retaining 78% of its initial capacity when the current density increased 20-fold (from 0.1 to 2.0 A g-1). This enhanced rate performance is attributed to QpCP-2's extended conjugated structure and increased accessible quinone-rich redox-active sites. Furthermore, QpCP-2 underwent gradual activation, resulting in a 30% increase in specific capacity, and demonstrated remarkable cycling stability over 10,000 cycles at 2.0 A g-1. The charge storage mechanism involving the coinsertion of H+ and Zn2+ was investigated through a series of ex situ characterization techniques. This work provides insights into the potential of CPs in AZIBs by elucidating the impact of monomer engineering and structural influences on electrochemical performance.Article Fabrication of Flexible Nanoporous Platinum Films Via One-Pot Liquid Crystal Templated Synthesis(Amer Chemical Soc, 2025) Demir, Seren; Polat, Pelin; Tertemiz, Necip Ayhan; Vural, Beyza; Babahan, Elian Melissa; Orhan, Ozan Baran; Balci, Fadime MertNanoporous platinum (NPP) thin films are crucial for applications in electrocatalysis, fuel cells, nanophotonics, and gas sensing. Conventional fabrication methods, such as dealloying, often leave residual elements that degrade the performance of the NPP thin films in applications such as electrocatalysis. In this study, for the first time, we introduce a novel method to fabricate ultrapure, flexible, large-area NPP thin films through a one-pot, liquid crystal-templated synthesis. A hexagonal lyotropic liquid crystal (LLC) phase, composed of a strong acid, a nonionic surfactant, water, and hexachloroplatinic acid, serves as a template. The LLC films, prepared with hexachloroplatinic acid concentrations of 0.1-0.5 M, exhibit distinct optical textures under a polarizing optical microscope and display low-angle diffraction patterns when analyzed with an X-ray diffractometer. Calcination at 450 degrees C yields ultrapure, conductive, and black colored NPP films. Importantly, we fabricate freestanding NPP thin films and successfully transfer them onto both rigid and flexible substrates. Bending tests reveal that a four-layer flexible NPP film having a thickness of around similar to 174 nm maintains a stable sheet resistance (similar to 30 ohm/sq) after several hundred bend cycles (1000 cycles). These findings highlight the potential of ultrapure NPP films with high nanopore and ligament density for applications in electrocatalysis, fuel cells, gas sensors, broadband absorbers, bioelectronics, and flexible electronics.Article Durable ZrB2–ZrC Composite Materials as Advanced Electrodes for High-Performance Supercapacitors(Amer Chemical Soc, 2025) Paksoy, Aybike; Gungor, Ahmet; Yildirim, Ipek Deniz; Arabi, Seyedehnegar; Erdem, Emre; Balci-Cagiran, OzgeBoride and carbide-based materials attract increasing attention as promising options for energy storage applications. This research focuses on synthesizing pure boride and carbide compounds of zirconium (ZrB2 and ZrC) and their composite powders using mechanical activation-assisted route and subsequent heating processes. The chemical and microstructural characterization results indicate that the synthesized composite powders are of high purity, possess submicron-scale particle sizes (below 400 nm), and exhibit a high surface area of up to 9.41 m2/g. Supercapacitor devices, using the resulting powders as symmetrical electrodes, exhibit high energy density values ranging from 5.8 to 8.8 Wh/kg. The ZrB2-15 wt % ZrC composite sample achieves the highest power density at 155 W/kg, compared to 118 W/kg for the pure ZrB2 sample. Cycling tests demonstrate exceptional capacitance retention (99.4-99.9%) and cyclic stability, even after 5000 cycles, highlighting the high durability of the composite samples. These findings show that ZrB2-ZrC composites exhibit high energy and power density values and excellent cycling performance, making them strong candidates for use in high-performance supercapacitor devices.Article Citation - WoS: 2Citation - Scopus: 2Modulating Cancer Stem Cell Characteristics in CD133+ Melanoma Cells through Hif1α, KLF4, and SHH Silencing(Amer Chemical Soc, 2025) Ozdil, Berrin; Güler, Günnur; Avci, Cigir Biray; Calik-Kocaturk, Duygu; Gorgulu, Volkan; Uysal, Aysegul; Guler, Gunnur; Aktug, HuseyinMalignant melanoma is a highly aggressive form of skin cancer, partly driven by a subset of cancer stem cells (CSCs) with remarkable capacities for self-renewal, differentiation, and resistance to therapy. In this study, we examined how silencing three key genes-Hif1 alpha, KLF4, and SHH-affects CSC characteristics. Using small interfering RNA (siRNA)-based approaches, we observed significant changes at both the gene and protein levels, shedding light on how these pathways influence melanoma progression. Our results demonstrated that silencing these genes reduces the stem-like features of CSCs. Notably, Hif1 alpha silencing triggered a marked decrease in hypoxia-related gene expression, while targeting SHH led to a reduction in Gli1, a downstream effector of SHH signaling, highlighting its potential as a therapeutic target. We also observed changes in epigenetic markers such as HDAC9 and EP300, which play crucial roles in maintaining stemness and regulating gene expression. Interestingly, these interventions appeared to reprogram CSCs, pushing them toward a phenotype distinct from both traditional CSCs and non-stem cancer cells (NCSCs). Our findings emphasize the importance of targeting key signaling pathways in melanoma CSCs and underscore the value of mimicking the tumor microenvironment in experimental models. By revealing the dynamic plasticity of melanoma CSCs, this study offers fresh insights into potential therapeutic strategies, particularly using siRNA to modulate pathways associated with tumor progression and stem cell behavior.Article Citation - WoS: 5Citation - Scopus: 5Light-Induced, Liquid Crystal-Templated Fabrication of Large-Area Pure Nanoporous Gold Films With High-Density Plasmonic Cavities(Amer Chemical Soc, 2024) Orhan, Ozan Baran; Polat, Nahit; Demir, Seren; Balci, Fadime Mert; Balci, SinanNanoporous gold (NPG) films are three-dimensional gold (Au) frameworks characterized by a uniform distribution of nanoscale irregular pores. Typically produced via a dealloying process, where the less noble silver (Ag) is selectively etched out, NPG films offer a large surface area, excellent chemical stability, remarkable catalytic activity, unique optical properties, and biocompatibility. These attributes make them invaluable for applications in catalysis, plasmonics, biosensors, and nanophotonics. However, the presence of residual Ag from the dealloying process can limit their performance in certain applications. In this study, we report a novel method for the fabrication of ultrapure, large-area NPG films (several cm2) using a light-induced and liquid crystal-templated method. A hexagonal lyotropic liquid crystal containing a strong acid and a nonionic surfactant is combined with an aqueous solution of HAuCl4, followed by the photochemical synthesis of gold nanoparticles (NPs) within the liquid crystal. After calcination of the Au NP-containing liquid crystal film at high temperature, pure NPG films are produced. We demonstrate surface-enhanced Raman spectroscopy (SERS) of Rhodamine 6G (R6G) molecules adsorbed on the NPG films and detect extremely low concentrations (below 10-6 M) of R6G. Additionally, we thoroughly investigated the formation and optical properties of the NPG films. The results reveal that the ultrapure NPG films contain high-density plasmonic nanocavities, where substantial electromagnetic fields are generated, leading to significant enhancement of optical processes at nanoscale dimensions.Article Citation - WoS: 3Citation - Scopus: 3Light-Induced Synthesis of Single-Crystalline Gold Microplates in an Open System(Amer Chemical Soc, 2023) Akkuş, Betül; Mert Balcı, FadimeBottom-up synthesis of large single-crystalline gold microplates is of key importance to catalysis, nanophotonics, bioengineering, and plasmonics. However, easy, low-cost, room-temperature, and high-yield synthesis of large gold microplates with several micrometers in lateral size and a few tens of nanometers in thickness by using photochemical synthesis in an open system is still challenging. We herein report on an easy and cost-effective photochemical synthesis of single-crystalline gold microplates with lateral sizes up to around 40 mu m and tens of nanometers in thickness in a few hours of reaction time in an open system containing a lyotropic liquid crystal, which is formed by self-assembly of 10-lauryl ether in a strong acid, sulfuric acid, along with water. We have found that by changing the reaction parameters, such as the reaction time, the concentration of gold ions in the liquid crystal, etc., the thickness and size of the microplates can be easily controlled. Most importantly, the liquid crystalline phase is completely preserved after completion of the photochemical reaction. The microplates can be easily isolated and transferred to different media such as alcohol and water for further studies, or they can be immediately used on a substrate after completion of the reaction. The results obtained in this study will allow us to understand the growth mechanism of gold microplates in open systems, and they will find applications in a variety of critical areas, such as plasmonics, nanophotonics, and catalysis.Article Citation - WoS: 7Citation - Scopus: 8Lithium Extraction From Aqueous Systems by Λ-mno<sub>2</Sub>-deposited Pu Electrospun Mats(Amer Chemical Soc, 2023) Akgun, Berk; Baba, Alper; Demir, Mustafa M.There has been a strong increase in demand for lithium, so the extraction of lithium from natural water resources has become a remarkable remedy to reduce the harmful environmental impact of conventional lithium extraction processes. One of the most effective methods of separating lithium from natural water sources is adsorption using lithium ion sieves as adsorbents. However, the powdered nature of the adsorbents makes them challenging to process. In this study, flexible and free-standing polyurethane (PU) electrospun mats associated with lambda-MnO2 particles were fabricated to extract lithium from aqueous systems. Bead-free and smooth nanofibers were electrospun from a volumetric mixture of DMF:THF (1:2) at 30 wt % of PU solution. lambda-MnO2 powder was deposited on the electrospun mat by vacuum-assisted deposition. The lithium extraction performance of the mats was found to be 21% using single-layer filtration and increased to 77% with multistage filtration. Moreover, using the optimized conditions, lithium extraction achieved up to 14% in a spiked brine sample taken from Lake Tuz (Central Anatolia, Turkey), where the Mg2+/Li+ ratio is higher than 85.Article Citation - Scopus: 11Fabrication of Helix Aspersa Extract Loaded Gradient Scaffold With an Integrated Architecture for Osteochondral Tissue Regeneration: Morphology, Structure, and in Vitro Bioactivity [1](Amer Chemical Soc, 2023) Tamburaci, Sedef; Perpelek, Merve; Aydemir, Selma; Baykara, Basak; Havitcioğlu, Hasan; Tihminlioğlu, FundaRegeneration of osteochondral tissue with its layered complex structure and limited self-repair capacity has come into prominence as an application area for biomaterial design. Thus, literature studies have aimed to design multilayered scaffolds using natural polymers to mimic its unique structure. In this study, fabricated scaffolds are composed of transition layers both chemically and morphologically to mimic the gradient structure of osteochondral tissue. The aim of this study is to produce gradient chitosan (CHI) scaffolds with bioactive snail (Helix aspersa) mucus (M) and slime (S) extract and investigate the structures regarding their physicochemical, mechanical, and morphological characteristics as well as in vitro cytocompatibility and bioactivity. Gradient scaffolds (CHI-M and CHI-S) were fabricated via a layer-by-layer freezing and lyophilization technique. Highly porous and continuous 3D structures were obtained and observed with SEM analysis. In addition, scaffolds were physically characterized with water uptake test, micro-CT, mechanical analysis (compression tests), and XRD analysis. In vitro bioactivity of scaffolds was investigated by co-culturing Saos-2 and SW1353 cells on each compartment of gradient scaffolds. Osteogenic activity of Saos-2 cells on extract loaded gradient scaffolds was investigated in terms of ALP secretion, osteocalcin (OC) production, and biomineralization. Chondrogenic bioactivity of SW1353 cells was investigated regarding COMP and GAG production and observed with Alcian Blue staining. Both mucus and slime incorporation in the chitosan matrix increased the osteogenic differentiation of Saos-2 and SW1353 cells in comparison to the pristine matrix. In addition, histological and immunohistological staining was performed to investigate ECM formation on gradient scaffolds. Both characterization and in vitro bioactivity results indicated that CHI-M and CHI-S scaffolds show potential for osteochondral tissue regeneration, mimicking the structure as well as enhancing physical characteristics and bioactivity.Article Citation - WoS: 6Citation - Scopus: 6Ion and Molecule Sieving Through Highly Stable Graphene-Based Laminar Membranes(Amer Chemical Soc, 2023) Yuan, Gang; Jiang, Yu; Wang, Xiao; Ma, Jiaojiao; Ma, Hao; Wang, Xiang; Hu, ShengBiological ion channels use both their sizes and residual groups to reject large ions and molecules and allow highly selective permeation of small species with similar sizes. To realize these properties in artificial membranes, the main challenge is the precise control of both the channel size and the interior at the nanoscale. Here we report the permeation of ions and molecules through interlayer channels in graphene-based laminar membranes. The amino groups decorated on channel walls are found to form hydrogen bond networks with intercalated water molecules, thus providing a highly stable laminate structure and a controlled channel size. Solutes with hydration diameters of >10 angstrom are precisely sieved out. Small species permeate through with selectivities of up to a few thousand, governed by their distinct electrical interactions with channels depending on the atomistic distance from the charged species to the channel walls. Our work offers important insights into manipulating channel structures for enhanced separation performance at the nanoscale.