Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection

Permanent URI for this collectionhttps://hdl.handle.net/11147/7148

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Access Right: Closed AccessAuthor: search.filters.author.Vakifahmetoglu, Cekdar

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Now showing 1 - 6 of 6
  • Article
    Enhanced Doxorubicin Cytotoxicity on Breast Cancer Spheroids by Aptamer Targeted Co-Delivery With Hyaluronidase
    (Wiley, 2025) Kavruk, Murat; Demirel, Dide Su; Bonyadi, Farzaneh; Guner, Buket Cakmak; Dursun, Ali Dogan; Vakifahmetoglu, Cekdar; Ozalp, Veli Cengiz
    Breast cancer is one of the most prevalent solid tumors in women and can be classified into subtypes based on molecular characteristics, such as hormone receptor status and HER2 expression. Aptamers, highly specific affinity molecules, are extensively studied for targeted drug delivery using nanocarriers to enhance anti-cancer efficacy. This study focused on HER2-responsive co-delivery of doxorubicin and hyaluronidase via aptamer-gated mesoporous silica nanoparticles to improve therapeutic outcomes in solid tumors. SK-BR-3 spheroids are employed as a model for resistant tumor environments in solid tumors. Previous research is shown that conjugating cytotoxic drugs with nanoparticles or cells enhances drug penetration into tumor spheroids. In this work, doxorubicin is loaded into mesoporous silica nanoparticles and capped with HER2-specific aptamers, while the particle surface is functionalized with hyaluronidase. This dual-functionalized nanocarrier system achieves an approximate to 8.5-fold increase in cytotoxicity compared to aptamer-targeted delivery lacking hyaluronidase. The enhanced effect is attributed to hyaluronidase-mediated loosening of the spheroid structure, facilitating nanoparticle penetration and localized release of doxorubicin at high concentrations on HER2-positive cells.
  • Article
    Citation - WoS: 2
    Citation - Scopus: 2
    Sintering Under High Heating Rates
    (Annual Reviews, 2025) Karacasulu, Levent; Maniere, Charles; Vakifahmetoglu, Cekdar; Marinel, Sylvain; Biesuz, Mattia
    Rapid sintering using a high heating rate is growing in technological and scientific interest. This is motivated by the promise of reducing the carbon footprint of sintering and developing materials with properties and microstructures different from those achievable by conventional heating. For instance, rapid heating can induce suppression of grain growth, the possibility of obtaining modified space charges and elemental segregations, and the development of out-of-equilibrium materials. Severe challenges still exist for the industrial exploitation of rapid sintering technologies, and, nowadays, only fast firing can be considered mature. Most of these limitations are related to the homogeneity of the sample and the possibility of obtaining complex shapes. This review investigates developments in rapid sintering by comparing different processes, suggested mechanisms, and future challenges.
  • Article
    Citation - WoS: 3
    Citation - Scopus: 1
    Porous Polymer-Derived Ceramics for Environmental Applications: Sorption, Filtration, and Catalysis
    (Elsevier B.V., 2025) Icin, Oyku; Zeydanli, Damla; Biesuz, Mattia; Soraru, Gian Domenico; Vakifahmetoglu, Cekdar
    Polymer-derived ceramics (PDCs), obtained from preceramic polymers, have emerged as promising materials for environmental applications due to their high thermal and chemical stability, tunable nano-microstrucure and porosity, and versatile surface functionalities. This review focuses on the recent advances in porous PDCs and their use in key environmental fields such as sorption, filtration, and catalysis. A comparative analysis of precursor chemistry, synthesis strategies, and resulting structural properties is presented, emphasizing how these factors influence performance in environmental remediation tasks. By consolidating findings across specific application areas, the work aims to clarify the functional potential of PDCs and identify current research gaps and opportunities for future development in environmental material science.
  • Article
    Design and Performance of SiOC Foam-Silica Aerogel Composites for Hot and Cold Thermal Management Applications
    (Elsevier Ltd, 2025) Icin, Oyku; Vakifahmetoglu, Cekdar
    This study focuses on the fabrication of monolithic preceramic polymer-derived ceramic (SiOC) foam-silica aerogel composites by filling the open cells of ceramic foam with a silica aerogel solution using the sol-gel technique. The effects of different drying techniques (ambient pressure vs CO2 supercritical drying) and surface modification agents, including trimethylchlorosilane (TMCS) and hexamethyldisilazane (HMDZ), are comprehensively investigated. These factors are analyzed for their influence on the composites' morphology, porosity, chemical structure, and thermal insulation performance. The drying technique and surface modification agents are found to play a critical role in achieving a high filling ratio of silica aerogel within the composites. Pure silica aerogels exhibit specific surface areas (SSAs) reaching similar to 1120 m(2).g(-1), while the SiOC foam-silica aerogel composites demonstrate SSAs of 385-440 m(2).g(-1). Nearly all samples achieve a total porosity of similar to 93 vol%. Surface modification effectively tailors the surface properties, imparting hydrophobicity with a water contact angle of 133 degrees. Thermal conductivity at room temperature ranges between 38 and 43 mW<middle dot>m(-1)<middle dot>K-1. The potential applications of these SiOC foam-silica aerogel composites as thermal insulators are assessed under extreme thermal conditions. For instance, a 14 mm thick composite has a temperature of -27 degrees C when subjected to a cold source at -78 degrees C. Instead, when exposed directly to a butane flame (similar to 1200 degrees C), the backside of the composite recorded only similar to 57 degrees C.
  • Article
    Citation - WoS: 2
    Citation - Scopus: 2
    Hybrid Preceramic Aerogels for Oil and Solvent Cleanup
    (Wiley-v C H verlag Gmbh, 2025) Icin, Oyku; Vakifahmetoglu, Cekdar
    This study presents the first synthesis and characterization of monolithic hybrid preceramic aerogels using distinct drying techniques: ambient pressure (ambigels) and CO2 supercritical drying. Polymeric ambi/aerogels, derived from polyhydromethlysiloxane (PHMS) and divinylbenzene (DVB), are processed at 200 degrees C, while hybrid ceramic-polymer (ceramer) is produced through pyrolysis at 600 degrees C. Despite variations in drying methods, polymer and ceramer ambi/aerogels exhibit comparable microstructural characteristics, bulk density, pore size and volume, and specific surface area (542-841 m(2) g(-1)). Polymeric and ceramer ambigel with 90 vol% total porosity yield a compressive strength, reaching 2.5 MPa, demonstrating a low thermal conductivity of 0.046 W m-1 K-1. Sorption tests are conducted using oil and organic solvents in aqueous media to benefit their high hydrophobicity (112 degrees < theta < 142 degrees). Aerogels exhibit high sorption capacities: 13.17 g g(-1) for sesame oil, 11.74 g g(-1) for toluene, and 9.19 g g(-1) for n-hexane. The sorption rate for the oil is nearly 10 times slower than that for toluene and n-hexane. Regarding regeneration and reusability, polymer and ceramer aerogels show consistent sorption properties cycles tested for n-hexane and toluene.
  • Article
    Citation - WoS: 13
    Citation - Scopus: 13
    On the Temperature Measurement During Ultrafast High-Temperature Sintering (uhs): Shall We Trust Metal-Shielded Thermocouples?
    (Elsevier Sci Ltd, 2024) Biesuz, Mattia; Karacasulu, Levent; Vakifahmetoglu, Cekdar; Sglavo, Vincenzo M.
    Temperature measurement upon ultrafast high-temperature sintering (UHS) is a crucial task. Herein, we provide some arguments posing concerns about the use of metal-shielded thermocouples as temperature probes in UHS. The discussion is based on literature data and on some ad hoc experiments. In detail, we show at least two cases in the literature where the use of a shielded thermocouple causes a substantial underestimation of the UHS temperature. The argumentation is based on comparing the thermocouples read and the observed phase and microstructural evolution. Moreover, by means of a simple experimental design, we show that a metal shield on the thermocouple tip can substantially reduce the measured temperature. Since the metal shield is orders of magnitude more thermally conductive than the graphite felt used as heating element in UHS, it efficiently removes heat from the thermocouple tip region. As such, data acquired from shielded thermocouples must be treated with care.