Researcher:
Karaz, Selcan

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Master Student

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Selcan

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Karaz

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Karaz, Selcan

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2022 - 20236

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Researcher Of Publications: search.filters.isAuthorOfPublication.7266cb5a-b247-4eec-910b-e0350016f04a

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Now showing 1 - 6 of 6
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    Enteric coating of drug loaded aerogel particles in a wurster fluidized bed and its effect on release behaviour
    (Editions de Sante, 2023) Ulker, Zeynep; Demir, Enis; Işık, Murat; Ekmekçiyan, Nadin; Department of Chemical and Biological Engineering; Department of Chemical and Biological Engineering; N/A; N/A; N/A; Erkey, Can; Şenses, Erkan; Akgün, Işık Sena; Darvishi, Saeid; Karaz, Selcan; Faculty Member; Faculty Member; PhD Student; PhD Student; Master Student; Department of Chemical and Biological Engineering; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); College of Engineering; College of Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; 29633; 280298; N/A; N/A; N/A
    Ibuprofen loaded and unloaded alginate aerogel particles were successfully coated with methacrylic acid-ethyl acrylate copolymer in a Wurster fluidized bed. Pores of both aerogels were well-preserved during the coating process. Effects of drug loading, polymer rheology, and atomizing pressure on coating thickness and coating layer surface morphology were investigated. Coatings were conducted at circulatory particle motion regime. Due to low weight of unloaded aerogels, this regime was achieved at lower air flow rates than ibuprofen loaded aerogels. Coatings of ibuprofen loaded aerogels were conducted between 1.3 and 1.5 bar atomizing pressures and at 60 °C. Unloaded aerogels were coated at a constant and high atomizing pressure of 1.7 bar and at 60 °C. At this condition, coating thickness of unloaded aerogels increased linearly from 25.6 μm to 53.4 μm with increasing coating time from 10 to 50 min. For ibuprofen loaded aerogels, coating thickness increased non-linearly from 15.9 μm to 84.1 μm with increasing coating time from 10 to 180 min. Ibuprofen release from aerogels in acidic medium was prevented via coating. In the basic medium, the fastest release was obtained from uncoated aerogels and 57% of ibuprofen was released in 30 min while 44% of crystalline ibuprofen dissolved at the same time. The slowest release rate was achieved via coating and 13% of the drug was released from coated aerogels in 30 min. © 2023 Elsevier B.V.
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    Effect of polymeric viscoelastic environment on multiscale structural dynamics of lipid bilayers
    (Cell Press, 2022) N/A; N/A; Department of Chemical and Biological Engineering; Karaz, Selcan; Şenses, Erkan; Master Student; Faculty Member; Department of Chemical and Biological Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 280298
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    Liposomes under shear: structure, dynamics, and drug delivery applications
    (Wiley-VCH, 2023) Department of Chemical and Biological Engineering; N/A; Şenses, Erkan; Karaz, Selcan; Faculty Member; Master Student; Department of Chemical and Biological Engineering; College of Engineering; Graduate School of Sciences and Engineering; 280298; N/A
    The targeted delivery to specific locations while not causing damage to healthy tissues efficiently remains a challenge in drug delivery systems. Through addressing this issue, stimuli-responsive materials have been under investigation. As one of the fundamental forces associated with blood flow, shear stress is taken as an advantage to design shear-sensitive drug carriers. Although blood flow is modeled as laminar flow under normal conditions, in case of constrictions caused by endothelial shear stress, cardiovascular diseases, or angiogenesis due to tumor formation, local shear stress can dramatically increase. To date, shear-sensitive materials have been investigated under two main categories: shear-disaggregated and shear-deformed nanoparticles based on their structural mechanism after exposure to high-shear stress. Among them, liposomes are promising materials with their soft and deformable structure, high biocompatibility, controlled-release properties, and sensitivity to shear stress. Herein, in this review, the effects of shear stress on liposomes in terms of their structural changes, flow regimes, rheological properties, and drug delivery applications are discussed. It is believed that this work provides a basis for designing more effective drug delivery systems considering the complexity of the human body.
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    Multiscale dynamics of lipid vesicles in polymeric microenvironment
    (Mdpi, 2022) N/A; N/A; N/A; N/A; N/A; Department of Electrical and Electronics Engineering; Department of Chemical and Biological Engineering; Department of Chemical and Biological Engineering; Karaz, Selcan; Han, Mertcan; Akay, Gizem; Önal, Asım; Nizamoğlu, Sedat; Kızılel, Seda; Şenses, Erkan; Master Student; Master Student; PhD Student; PhD Student; Faculty Member; Faculty Member; Faculty Member; Department of Electrical and Electronics Engineering; Department of Chemical and Biological Engineering; Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; College of Engineering; College of Engineering; N/A; N/A; N/A; N/A; 130295; 28376; 280298
    Understanding dynamic and complex interaction of biological membranes with extracellular matrices plays a crucial role in controlling a variety of cell behavior and functions, from cell adhesion and growth to signaling and differentiation. Tremendous interest in tissue engineering has made it possible to design polymeric scaffolds mimicking the topology and mechanical properties of the native extracellular microenvironment; however, A fundamental question remains unanswered: that is, how the viscoelastic extracellular environment modifies the hierarchical dynamics of lipid membranes. in this work, we used aqueous solutions of poly(ethylene glycol) (PEG) with different molecular weights to mimic the viscous medium of cells and nearly monodisperse unilamellar DMPC/DMPG liposomes as a membrane model. Using small-angle X-ray scattering (SaXS), dynamic light scattering, temperature-modulated differential scanning calorimetry, bulk rheology, and fluorescence lifetime spectroscopy, we investigated the structural phase map and multiscale dynamics of the liposome-polymer mixtures. the results suggest an unprecedented dynamic coupling between polymer chains and phospholipid bilayers at different length/time scales. the microviscosity of the lipid bilayers is directly influenced by the relaxation of the whole chain, resulting in accelerated dynamics of lipids within the bilayers in the case of short chains compared to the polymer-free liposome case. at the macroscopic level, the gel-to-fluid transition of the bilayers results in a remarkable thermal-stiffening behavior of polymer-liposome solutions that can be modified by the concentration of the liposomes and the polymer chain length.
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    A facile method for cross-linking of methacrylated wood fibers for engineered wood composites
    (Elsevier B.V., 2023) Bengü, Başak; Biçer, Aziz; Yarıcı, Tugay; N/A; N/A; N/A; Department of Chemical and Biological Engineering; Department of Chemical and Biological Engineering; Sarıoğlu, Ebru; Turhan, Emine Ayşe; Karaz, Selcan; Erkey, Can; Şenses, Erkan; PhD Student; PhD Student; Master Student; Faculty Member; Faculty Member; Department of Chemical and Biological Engineering; Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM), Koç University Boron and Advanced Materials Application and Research Center (KUBAM) / Koç Üniversitesi Bor ve İleri Malzemeler Uygulama ve Araştırma Merkezi (KUBAM); Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; College of Engineering; N/A; N/A; N/A; 29633; 280298
    Chemical modifications are widely used to enhance the properties of wood composites and create a strong bonding mechanism for enhancing the dimensional stability, water resistance as well as decreasing carcinogenic formaldehyde emission. Esterification is the most-known modification way to enhance the durability of wood composites, but it does not improve mechanical performance. In this work, we demonstrated a two-step, easy and quick wood surface modification strategy based on microwave heating and UV crosslinking. Firstly, the fiber surface was reacted with methacrylic anhydride, then using methacrylated groups on wood, the fibers are covalently linked. As a proof-of-concept the fibers cross-linked within five minutes under UV radiation using benzophenone solution. Then, the effect of crosslinked wood fiber on the properties of mechanical and swelling of fiberboard were studied. Using SEM, FTIR-ATR, and swelling tests, we investigated the wood-based products' reaction mechanism, morphology, and internal bonding strength. The chemical cross-linking gives stronger bonding, compared to hydrogen bonding, between fibers even in wet conditions, resulting in a cross-linked foam-like structure. Also, wood panels were fabricated, compared to unmodified fibers, the internal bond strength and dimensional stability of fiberboards increased slightly. Overall, these results show that chemical cross-linking of wood fibers can be a fast and promising way to produce multi-functional wood composites.
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    PublicationOpen Access
    Tissue-like optoelectronic neural interface enabled by PEDOT:PSS hydrogel for cardiac and neural stimulation
    (Wiley, 2022) Department of Electrical and Electronics Engineering; Department of Chemical and Biological Engineering; N/A; Han, Mertcan; Karaz, Selcan; Eren, Güncem Özgün; Doğru-Yüksel, Itır Bakış; Yıldız, Erdost; Kaleli, Humeyra Nur; Şenses, Erkan; Şahin, Afsun; Nizamoğlu, Sedat; Master Student; Master Student; PhD Student; Faculty Member; Faculty Member; Faculty Member; Department of Electrical and Electronics Engineering; Department of Chemical and Biological Engineering; Koç University Research Center for Translational Medicine (KUTTAM) / Koç Üniversitesi Translasyonel Tıp Araştırma Merkezi (KUTTAM); Graduate School of Sciences and Engineering; Graduate School of Health Sciences; College of Engineering; School of Medicine; N/A; N/A; N/A; N/A; N/A; N/A; 280298; 171267; 130295
    Optoelectronic biointerfaces have made a significant impact on modern science and technology from understanding the mechanisms of the neurotransmission to the recovery of the vision for blinds. They are based on the cell interfaces made of organic or inorganic materials such as silicon, graphene, oxides, quantum dots, and ?-conjugated polymers, which are dry and stiff unlike a cell/tissue environment. On the other side, wet and soft hydrogels have recently been started to attract significant attention for bioelectronics because of its high-level tissue-matching biomechanics and biocompatibility. However, it is challenging to obtain optimal opto-bioelectronic devices by using hydrogels requiring device, heterojunction, and hydrogel engineering. Here, an optoelectronic biointerface integrated with a poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate), PEDOT:PSS, hydrogel that simultaneously achieves efficient, flexible, stable, biocompatible, and safe photostimulation of cells is demonstrated. Besides their interfacial tissue-like biomechanics, ?34 kPa, and high-level biocompatibility, hydrogel-integration facilitates increase in charge injection amounts sevenfolds with an improved responsivity of 156 mA W?1, stability under mechanical bending , and functional lifetime over three years. Finally, these devices enable stimulation of individual hippocampal neurons and photocontrol of beating frequency of cardiac myocytes via safe charge-balanced capacitive currents. Therefore, hydrogel-enabled optoelectronic biointerfaces hold great promise for next-generation wireless neural and cardiac implants.